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X I I SOLAR ACTIVITY PROGRAM F l a r e P a t r o l Camera and Spectrograph at the Climax Observing S t a t i o n
SOLAR ACTIVITY PROGRAM Page A. Organization of Technical Panel on Solar A c t i v i t y 501 B. Summary of Panel Actions 501 C. Project Objectives and Results 505 12.1 Flare Patrol - Instrumentation 506 12.2 Line Profiles of Flares - Instrumentation 507 12.3 White Light Corona - Instrumentation 509 12.4 Improved Coronal Line Emission Studies 511 12.5 Indirect Detection of Flares - Instrumentation 512 12.6 HAO Operations - Climax and Boulder 514 12.8 Spectroscopic Studies of Solar Flares 516 12.9 McMath-Hulbert Flare Patrol Operations 517 12.10 Solar Radio Noise Patrol - Boulder 518 12.11 Rapid Data Presentation 519 12.12 Solar Radio Noise Patrol - Hawaii 519 12.13 Solar A c t i v i t y Flare Patrol - Hawaii 521 12.14 Flare and Plage Patrol - Mt. Wilson 523 12.15 Solar Radio Noise Patrol - Ithaca 523 12.16 Flare Patrol Equipment 524 12.17 Flare Patrol Instruments & F i l t e r s - Procurement 525 12.18 Flare Patrol Equipment 526 12.19 Solar A c t i v i t y Data Reduction and Publication 527 12.20 Hawaii Flare Patrol - HAO Assistance 529 12.21 Indirect Solar Flare Detection, New York - Instrumentation. . . . 529 12.22 Solar H-alpha and Radio Noise Patrol, Washington, D.C 530 500
X I I . SOLAR ACTIVITY A. Organization of Technical Panel on Solar A c t i v i t y 1. Establishment of Panel. In December 1954 and i n February 1955, formal invitations were issued to prospective members to j o i n the Panel. A.H. Shapley was asked to convene the f i r s t meeting at which time he was elected Chairman and W.O. Roberts, Secretary. Subsequently, A.H. Shapley withdrew as Chairman, although remaining on the Panel, and W.O. Roberts was appointed Chairman. A member of the IGY Secretariat was appointed Secretary. The make-up of the Panel was as follows. 2. Composition of the Panel. ( A f f i l i a t i o n at time of appointment.) Panel Members Horace W. Babcock John W. Evans Leo Goldberg John P. Hagen S. B. Nicholson W. 0. Roberts Helen Dodson Prince A. H. Shapley Mt. Wilson and Palomar Observatories Upper Air Research Observatory, Sacramento Peak Observatory of University of Michigan Naval Research Laboratory Mount Wilson Observatory High Altitude Observatory McMath-Hulbert Observatory, University of Michigan Central Radio Propagation Laboratory, NBS Consultants. Cdr. 0. E. Heam Lt. Cdr. D. P. Wencker Cdr. W. T. Doyle c. Secretariat (IGY Staff) U.S. Naval Research Laboratory U.S. Naval Research Laboratory U.S. Naval Research Laboratory Gerhard Schilling (to July 1956) John DePue (July 1956 to July 1957) Stanley Ruttenberg (from July 1957) 3. Panel Meetings. Five regular meetings and one ad hoc meeting of the Panel were held. F i r s t Meeting Ad Hoc Meeting Second Meeting Third Meeting Fourth Meeting F i f t h Meeting March 1, 1955 Sept. 1, 1955 Sept. 2, 1955 March 22, 1956 July 9, 1957 July 9, 1958 Boulder, Colorado Dublin, Ireland Dublin, Ireland Columbus, Ohio Boulder, Colorado Boulder, Colorado B. Summary of Panel Actions 1. Basic U.S. Program. The basic U.S. Program was outlined by U.S. representatives at the meeting of the ICSU Special Consnittee for the International Geophysical Year (CSAGI) i n Rome, September 30 - October 4, 1954. A large part of the U.S. Program involved continuation of current work with more emphasis on patrol and on prompt re- porting of summary results to workers i n the disciplines participating i n the overall 501
SOLAR ACTIVITY IGY work. The U.S. program provided for ( i ) more extensive observations at existing solar observatories; ( i i ) f l a r e patrols to include both photographic and visual ob- servations; ( i i i ) more extensive daily measurements of sunspots; ( i v ) measurements of the quantity and quality of solar radiation; (v) radio observations of the corona. 2. CSAGI Resolutions. The U.S. Program was consistent with the CSAGI resolutions adopted i n the Rome meetings; however, some major extensions to the world program were approved and action taken on them by the Panel as indicated below: a. I n s t a l l a t i o n of a solar patrol station i n Hawaii. The Panel approved a reso- lut i o n to the USNC Executive Committee regarding solar observations i n Hawaii. I t was noted that sites i n the longitude of Hawaii would be highly suitable for the operation of an optical flare patrol on a modest scale and the Panel recommended the establishment of a station for this purpose i n that area. A project was approved which provided funds to the University of Hawaii for the construction of special photographic flar e patrol equipment. While the operation of this patrol work was carried out by personnel of the University of Hawaii, the overall project was under the guidance of the High Altitude Observatory. b. Equipping one or more stations to observe the radio frequency spectrum of bursts and outbursts. Two stations had been established under other auspices to observe the radio frequency spectrum of bursts and outbursts at the University of Michigan, Ann Arbor, Michigan, and the Radio Astronomy Station, Fort Davis, Texas. These i n s t i - tutions consented to have their programs included as contributions to the U.S. - IGY program. c. Equipping one or more stations to observe sudden enhancement of atmospherics and sudden cosmic noise absorption as a flare warning device. The Panel approved con- struction by the High Altitude Observatory of three sets of instruments for use i n the indirect f l a r e detection program. These receivers were set up at the observatory at Boulder, Colorado; Sacramento Peak, New Mexico, and McMath-Hulbert Observatory, Pontiac, Michigan. d. Further patrol work on solar magnetic f i e l d s . This recommended extension to the world-wide program by CSAGI was included i n the U.S. Program by contributory e f f o r t s of the Mt. Wilson Observatory. This station undertook to carry out an observational pro- gram that provided for mapping the magnetic f i e l d pattern of the entire solar disk on a day-to-day basis. Specially developed instrument and electronic-optical techniques were used to c a r r y out this work. 3. Budget. At i t s f i r s t meeting, March 1, 1955, the Panel reviewed the scope of the program i n terms of the budget for Solar A c t i v i t y that had been submitted to Congress in January 1955. A revised schedule of project allocations was prepared based on ( i ) CSAGI resolutions adopted at the Rome meeting ( i i ) a report from the Technical Panel on Cosmic Rays ( i i i ) and additional general thoughts of Panel members on the proposed scope of the program. 4. New Instrumentation. In the formulation of the U.S. program i t was early recognized that need existed for the development of new instrumentation for the observational pro- gram. One such piece of equipment for use i n the flare patrol program was the SECASI heliograph that was constructed for the Panel by the Society for the Study and Construc- tion of Scientific and Industrial Apparatus, France. On-the-spot investigations by Panel members of a prototype of this instrument were made before the order was placed for this piece of equipment. To resolve a problem at McMath-Hulbert Observatory occa- sioned by the fact that a f u l l f l a r e patrol would t i e up the larger research instruments at that s i t e , the Panel, at i t s i n i t i a l meeting, requested the IGY Executive Committee to allocate suf f i c i e n t funds for the procurement of a SECASI instrument for use at that observatory. The Panel noted the weaknesses i n the U.S. program imposed by budget 502
SOLAR ACTIVITY limitations, particularly with respect to flar e patrol instruments of different types and qualities at the several observatories and requested additional funds from the Executive Committee to procure three more SECASI Patrol Instruments for i n s t a l l a t i o n at Sacramento Peak, Naval Research Laboratory and the High Altitude Observatory. Because of budget limitations i t was necessary to reduce the number of SECASI instruments to be procured. Accordingly, only two heliographs were procured and they were installed at the Naval Research Laboratory and McMath-Hulbert Observatory. As added components to the heliograph, two H-Alpha f i l t e r s from Lavallois of Paris, having a band-pass of 0.75 Angstroms, were obtained for the Naval Research Laboratory and the McMath-Hulbert Observatory. To provide the necessary f i l t e r s for the telescopes at Climas, Sacramento Peak and the University of Hawaii, three Halle H-Alpha f i l t e r s , having a band-pass width of 0.5 Angstroms, were obtained for i n s t a l l a t i o n at these stations. 5. Flare Coverage. In recognition of the gap that existed during the three hours immediately following the sunrise on the East Coast because of the Atlantic Ocean and the relative paucity of flare stations i n Eastern U.S., the Panel sought to secure assistance from favorably located observatories i n eastern United States to undertake additional patrol observations. The observations were intended to supplement the more complete coverage resulting from the programs of the Western observatories, and were considered particularly important to the IGY Cosmic Ray Program because of the impact zones of solar cosmic-ray particles. Efforts on the part of the Panel to obtain support for this purpose from private observatories were unsuccessful. 6. Balloon Telescope Project. The Panel discussed an Office of Naval Research sugges- tion to place a telescope i n a balloon to photograph solar granulation from above the lower atmosphere i n order to improve resolution. The Panel agreed on the great worth of the project but f e l t that i t did not properly belong i n the IGY program and should be supported independently on i t s own merit, 7. AAVSO SEA Program. Four Brown recorders were loaned by the National Bureau of Standards to the American Association of Variable Star Observers for i t s SEA (sudden enhancements of atmospherics) program and f u l l operation commenced about three months after the beginning of the IGY. Operators worked voluntarily and the Panel provided a modest amount of funds for chart paper and minor organization expenses. Monthly re- ports were prepared and a l l SEA data were completed and published on a quarterly basis m the CRPL F series, ' 8. Solar Granulation Program. The Panel considered a request to assist i n support of solar research studies at the RCA Observatory at Rocky Point, New York. Funds of $25,000 to $60,000 were sought to continue taking dally granulation photographs and their analysis and to undertake flar e observations. An 8" telescope was used m seeking to determine i f short or long-period changes exist i n the number of granules found on the photospheric surface. Opinion was mixed on the value of the granule studies and lack of su f f i c i e n t funds limited Panel action on this matter of the flar e proposal. 9. Programs Not Funded by IGY Appropriation. In some areas of the IGY solar a c t i v i t y program, there was considerable support to research in s t i t u t i o n s from Air Force and Navy research agencies. The programs supported i n this way were closely related to the IGY objectives and were incorporated, as contributed programs, into the U.S. IGY program. However, early i n the IGY, cutbacks in government allocations for research forced the sponsoring agencies to notify several IGY participating i n s t i t u t i o n s that funds for certain programs, which happened to be closely related to IGY projects at these i n s t i - tutions, would be sharply curtailed or withdrawn. The Panel and the NAS-IGY staf f made strong representations to the government agencies involved as to the importance of the IGY programs that would be seriously affected by this cutback. Means were found to overcome most of these funding problems and the threatened programs were able to proceed. 503
SOLAR ACTIVITY 10. October 1958 Eclipse. Plans to obtain eclipse observations of the flash spectrum and other phenomena at the October 1958 Eclipse i n the South Pacific were discussed at various times by the Panel. Following detailed consideration of this program, the Panel approved the following resolution to the IGY Executive Committee. "The Panel recommends that the USNC Program for the IGY should include the optical and radio observations of the t o t a l Eclipse of the Sun and the South Pacific on 12 October 1958 by the Harvard College Observatory, High Altitude Observatory, the Naval Research Laboratory, the Upper Air Research Observatory, and other well-qualified i n s t i t u t i o n s with the proviso that the eclipse efforts w i l l not be supported by IGY funds. The Panel further recommends that efforts be made by USNC to obtain l o g i s t i c support for the eclipse observations through the Department of Defense IGY Panel on Solar A c t i v i t y . " Such support was ob- tained and the eclipse expedition took place. The optical observations were not accom- plished, however, because of clouds but the NRL rocket program was successful. (See Project 10.21.) 11. Publication. a. Rapid Presentation of Data. The establishment of a system for more prompt reporting of current solar and geophysical a c t i v i t y was a major objective of the U.S. program. To achieve this purpose, the Panel approved a project for the weekly and quarterly preparation and dissemination of solar a c t i v i t y reports to approximately 300 stations. These reports were prepared and distributed by the High Altitude Observatory in collaboration with the Central Radio Propagation Laboratory at Boulder of the National Bureau of Standards. The weekly reports included observations of the sun through the previous day. The quarterly reports represented a more accurate and com- plete report of solar a c t i v i t y for a three-month period and were issued about two months after the end of the period. b. Solar Data Publication. Plans for f i n a l solar data publication i n the IGY Annals were discussed at considerable length by the Panel. The Ohman (CSAGI reporter for Solar A c t i v i t y ) proposal for solar data publication was reviewed and modified by the Panel for presentation by the U.S. representative at the F i f t h CSAGI Conference at Moscow i n August 1958. The Panel favored issuance of a solar volume with tabular, synoptic and daily map data with black and white representation. Use of f i l m strips for photographs and other materials providing an adequate catalogue of a l l available information is included i n the Annals which would l i s t the a v a i l a b i l i t y of such data in specific f i l m strips and i n o r i g i n a l records of different observatories. The Panel further recommended that a limited ntmiber of sample reproductions of the materials from the f i l m strips be included i n half-tone reproduction. Positive and negative flar e reports also should be tabulated. Many flares i n - dicated positively by some stations correspond to negative results of other stations and i t was deemed worthy of e f f o r t to secure inclusion of these negative observations in the record. The Panel placed considerable emphasis on the need for the publication of such a record either on f i l m strips or i n the Annals. At the F i f t h CSAGI Conference i n Moscow, 1958, tentative decisions were made on the type of material to be included i n the Solar A c t i v i t y volumes of the IGY Annals. The High Altitude Observatory accepted the task of coordinating some of the material to be included. c. Data Reduction. At i t s i n i t i a l meeting, the Panel set aside $26,000 i n the Solar A c t i v i t y budget for reduction and publication of data. The Panel emphasized i t s firm belief that for many years to come there would be a large need for support from various groups for the analysis and publication of the results based on observations taken during the IGY at various observatories and that the budget did not provide for this need. Subsequently, the Panel reviewed the overall needs of the solar a c t i v i t y program for data reduction and publication, i n the l i g h t of more specific information 504
SOLAR ACTIVITY on the World Data Centers and subsequent a c t i v i t i e s i n the solar f i e l d . Recommendations were approved to provide $37,686 to the Central Radio Propagation Laboratory of the National Bureau of Standards to reduce and publish the appropriate solar a c t i v i t y data. 12. Data Scholar Program. In response to a request from the U.S. National Committee for the IGY for recommendations for the data scholar program, sought by the Fulbright Commission, the Panel nominated Drs. L. and M. d'Azambuja of the Meudon Observatory, Dr. Walter Steiger, University of Hawaii, and Dr. Fokker of the NERA organization. The Panel also urged that, after completion of the IGY observational program, a l l active participants who played a direct role i n obtaining observations for the IGY could bene- f i t by leisurely examination of observations of other in s t i t u t i o n s made during f a i r l y extended v i s i t s within this country and abroad. 13. Post-IGY Observational Program. The Panel considered i t feasible and desirable to continue solar flare patrol observations on a continuing program level similar to that during IGY at several observatories, providing adequate funding w i l l be available. Some of the observatories would need funds; others possibly could provide their own support. For the period January to June 1959, $50,000 was considered r e a l i s t i c to support optical patrols and $15,000 for radio noise patrols. This proposal was re- commended to the U.S. National Committee i n response to the Cosmic-Rays Panel request that such a program be adopted as part of the U.S. recommendations to CSAGI at i t s F i f t h Conference in Moscow, August 1958. 14. Data Analysis. In response to a memo i n May 1957 from the Executive Director, the Panel reviewed the types of studies that would be most valuable s c i e n t i f i c a l l y to provide maximum u t i l i z a t i o n of IGY data. The Panel established two broad categories of analysis considered to be of high importance for programs that should be i n i t i a t e d promptly: ( i ) analysis of s t r i c t l y solar phenomena, to provide data on the fundamental physical properties of the solar emission responsible for sun-earth effects i n any or a l l geophysical disciplines; ( i i ) specific s o l a r - t e r r e s t r i a l studies that encompass comparison of solar data with those from other IGY disciplines. A l i s t of research proposals was prepared by the Panel as i l l u s t r a t i v e of the type and magnitude of the solar a c t i v i t y data analysis program that the Panel considered desirable. Hope was expressed that competent research groups could be stimulated to undertake programs of the types presented by the Panel. The Panel further suggested that some studies be undertaken at an early date i n order to permit, i f possible, the establishment of improved observing and recording techniques before the IGY observa- tional programs were concluded. Unfortunately, this plan could not be adopted as funds for the IGY analysis program were not obtained i n time. A t o t a l of $862,755 eventually was granted to IGY participating i n s t i t u t i o n s for analysis of upper atmos- phere data. C. Project Objectives and Results 1. Summary of Program. The U.S. Program i n solar a c t i v i t y included the basic patrols carried on by existing solar observatories supplemented by an intensive photographic patrol for solar flares with new instrumentation and specialized studies of flares and other unusual solar phenomena. Thus the program contributed to the 24-hour watch on the sun during the IGY and provided detailed astrophysical data on many of the solar events which may be associated with the t e r r e s t r i a l phenomena studied i n the purely geophysical disciplines. Projects provided for the procurement, i n s t a l l a t i o n , and opera- tion of solar a c t i v i t y equipment and for the collection, reduction, analysis, and pub- l i c a t i o n of data. 505
SOLAR ACTIVITY 2. Order of Project Description. The projects that are described i n the following pages are i n numerical order to correspond with the ori g i n a l formulation of the program. For convenience, the projects are grouped below to r e f l e c t s i m i l a r i t y of purpose. Flare and Plage Patrol 12.1, 12.6, 12.9, 12.13, 12.14, 12.16, 12.17, 12.18, 12.20 Line Profiles of Flares 12.2 White Light Corona 12.3 Coronal Line Emission 12.4 Indirect Flare Detection 12.5, 12.21 Spectroscopic Studies of Solar Flares 12.8 Solar Radio Noise Patrol 12.10, 12.12, 12.15, 12.22 Data Reduction and Publication 12.11, 12.19 3. Cancelled Project. Project Number 12.7 was eliminated from the program. Project 12.1 - Flare Patrol - Instrumentation 1. Objectives. This project at the High Altitude Observatory provided for the re- building of a flar e patrol instrument that had been i n use prior to the IGY. 2. Operations. This project was subsequently combined with projects 12.18 and 12.20 and carried out under their operation. 3. Personnel. This work was supervised by W.O, Roberts, Director, HAO. 506
SOLAR ACTIVITY Projec t 12.2 - Line P r o f i l e s of Flares - Instrumentation 1. Objectives. This p r o j e c t a t the High A l t i t u d e Observatory provided f o r the modi- f i c a t i o n of the Climax coronagraph and associated spectrograph to permit the taking of rapid-sequence spectra of solar f l a r e s . Thus a "map" of the f l a r e i s obtained i n terms of i n t e n s i t y of H-alpha and other emission l i n e s which would enable the study of the morphology of f l a r e i n i t i a t i o n and development. 2. Operations. I n order to accommodate the high i n t e n s i t y of f l a r e s , the shutter mechanism was modified to reduce minimum exposures from 1/2 t o 1/500 second. A high dispersion (3 A/mm) Bausch and Lomb g r a t i n g and a g r a t i n g borrowed from Mt. Wilson were i n s t a l l e d such t h a t e i t h e r one could be r e a d i l y used. The Mt. Wilson g r a t i n g was of lower dispersion but also scattered less l i g h t ; the lower dispersion was us e f u l on occasions when a wider wavelength range was required. For a " f l a r e f i n d e r " a small observing instrument was constructed w i t h an ob j e c t i v e lens of approximately 3-lnch aperature, followed by a m u l t i p l e f i e l d lens p a i r , one w i t h a c l e a r f i e l d , the other w i t h an o c c u l t i n g d i s c . A conventional b i r e f r i n g e n t f i l t e r was used. This made possible the observing, r e s p e c t i v e l y , of disc phenomena in c l u d i n g f l a r e s , and of prominences and limb f l a r e s . I n a d d i t i o n , i t was possible to make simultaneous observations of f l a r e spectra and the monochromatic solar image i n H-alpha. For limb f l a r e s , s p ectral-height gradients could be obtained. The " f l a r e f i n d e r " telescope operated as pa r t of the HAO's f l a r e p a t r o l . 3. Personnel. This work was under the supervision of W.O. Roberts; Donald B i l l i n g s and Robert Low were concerned w i t h the design and co n s t r u c t i o n and R.T. Hansen w i t h the i n s t a l l a t i o n of the equipment. 4. Results. A great number of extremely i n t e r e s t i n g spectra of solar f l a r e s were obtained by the Climax observers (D. K e i t h Watson, David Dodgen and G, W i l l i a m C u r t i s ) w i t h these instruments; some, while s t i l l developing the observing procedures before the a c t u a l s t a r t of the IGY. Analyses by Z i r i n and Tandberg-Hanssen, d i r e c t e d toward determining the physical conditions of f l a r e s , are l i s t e d i n the bibliography below. 5. Bibliography. E. Tandberg-Hanssen, G. W i l l i a m C u r t i s , and D. Ke i t h Watson: "The Emission of He I , 10830 during the Great Flare o f August 26, 1958." Ast r o p h y s l c a l Journal, v o l . 129, 1958, p. 238. Donald B i l l i n g s . "H-alpha P r o f i l e s and Opacity of Small Flares." Astronomical Journal, v o l . 63, 1958, p. 302. H. Z i r i n , E. Tandberg-Hanssen, "Physical Conditions i n Limb Flares and Active Prominences. IV. Comparison of Active and Quiescent Prominences," Astrophyslcal Journal, v o l . 131, 1960, p. 717. E. Tandberg-Hanssen and H. Z i r i n : "Physical Conditions i n Limb Glares and Active Prominences. I . The Loop Prominences of November 12 and 22, 1956." Aatrophysieal Journal, v o l . 129, 1959, p. 40. H. Z i r i n : "Physical Conditions i n Limb Flares and A c t i v e Prominences. I I . A Remarkable Limb F l a r e , December 18, 1956." Astrophyslcal Journal, v o l . 129, 1959, p. 414. E. Tandberg-Hanssen: "Physical Conditions i n Limb Flares and A c t i v e Prominences. I I I . The Difference Between the Surge and Loop Prominences of December 19, 1956." Astrophyslcal Journal, v o l . 130, 1959, p. 1. 507
SOLAR ACTIVITY H. Z i r i n : "Spectre d'une er u p t i o n au bord du disque s o l a i r e . " CR Aca. Sci. v o l . 244, p. 2893 (meeting of June 12, 1957). ' H. Z i r i n , D. Keith Watson, and G. W i l l i a m C u r t i s . "Spectra of Quiescent and Loop Prominences." ASP, v o l . 70, 1958, p. 406. 508
SOLAR ACTIVITY Project 12.3 - White L i g h t Corona - Instrumentation 1. Ob.iectives. This p r o j e c t a t the High A l t i t u d e Observatory provided f o r the design and c o n s t r u c t i o n of an instrument ( w h i t e - l i g h t corona photometer, or K-coronameter) to be used to measure and record the brightness of the polarized component o f l i g h t scattered by f r e e electrons i n the e l e c t r o n , or K, corona, as d i s t i n c t from the emis- sion corona. Such observatidns are important to the study of the physics of the sun and may e l u c i d a t e those solar phenomena which r e s u l t i n various t e r r e s t r i a l events. Routine observations had never been attempted previously. 2. Operations. I n order t o minimize s c a t t e r i n g of l i g h t a conventional Lyot corona- graph was used as the basic instrument. A r o t a t i n g half-wave p l a t e , e l e c t r o - o p t i c quarter-wave p l a t e , and a p h o t o e l e c t r i c detector comprised the p o l a r i z a t i o n analyser. The instrument was constructed and tested a t Boulder and then i n s t a l l e d a t the mountain observatory a t Climax, where i t was mounted on the 26-foot e q u a t o r i a l table provided under other support a t HAO. A scanning aperature of 2.4 minutes of arc was employed; the detection of the K-corona was normally possible out to one solar radius from the limb. A polar p l o t of the polarization-radiance was obtained i n u n i t s of the radiance of the center of the solar d i s k . 3. Personnel. The p r o j e c t d i r e c t o r was W.O. Roberts; s c i e n t i f i c supervision was under Dr. Gordon Newkirk of HAO and Dr. Gerard Wlerick (on leave from Paris Observatory as a F u l b r i g h t s c h o l a r ) . Mr. James A x t e l l , a graduate student a t the U n i v e r s i t y of Colorado, c a r r i e d out much of the c o n s t r u c t i o n and was responsible f o r the observations, which were part of h i s Ph.D program. 4. Data. Observations were reduced, tabulated and published as volumes i n the IGY WDC-A, Solar A c t i v i t y (HAO) r e p o r t series (see B i b l i o g r a p h y ) . 5. Results. From some f i f t y - f i v e days of usable observations during IGY, i t proved possible to develop models o f the e l e c t r o n corona above the q u i e t d i s k , the polar r e - gions, and a c t i v e regions. The l a s t of these turns out to depart from the s p h e r i c a l l y symmetrical model and was compared w i t h models of the r a d i o corona. A comparison of the 21-cm p i c t u r e of the sun and the i n t e n s i t y of the K-corona showed s t r i k i n g resem- blances between regions of enhanced 21-cm r a d i a t i o n and regions of enhanced e l e c t r o n density, and suggests t h a t the enhanced r a d i a t i o n i s of thermal o r i g i n from regions of high density. I t i s expected t h a t continued observation of t h i s k i n d , along w i t h more d e t a i l e d radio and coronal spectrographic observations, w i l l improve understanding of the physics of a c t i v e regions. 6. Bibliography. a. Papers Presented a t Meetings. G. Wlerick, J. A x t e l l , R. Lee: " P h o t o e l e c t r i c Observations of the Electron Solar Corona." Summer Meeting, Am. A s t r . Soc., Berkeley, C a l i f o r n i a , 1956. G. Newkirk, J r . : "A Model of the Electron Corona w i t h Reference to Radio Observations." Paris Symp. on Radio A s t r . (lAU Symp. No. 9 and URSI Symp. No. 17, P a r i s , August 1958. (Published i n the Proceedings. Paris Symposium on Radio Astronomy, R.N. Bracewell, ed., Stanford U n i v e r s i t y , 1959). b. Published Papers. G. Wlerick, J. A x t e l l . "A New Instrument f o r Observing the Electron Corona," Astrophysical Journal, v o l . 126, no. 2, September 1957, pp. 253-258. 509
SOLAR ACTIVITY G. Newkirk, J r . , C.W. C u r t i s , K. Watson: "Observations of the Solar E l e c t r o n Corona, September 1956-January 1958." IGY Solar A c t i v i t y Report Series. No. 4, IGY World Data Center A: Solar A c t i v i t y , HAO, Univ. of Colorado, August 1958. G. Newkirk, J r . : "Emission-Line P o l a r i z a t i o n i n Prominences." Pub. Astro. Society of P a c i f i c , v o l . 70, no. 413, A p r i l 1958, pp. 185-190. G. Wlerick, J. A x t e l l . "Construction d'un coronometre K pour mesurer l a b r i l l a n c e de la composante polarisee de la couronne. Premieres observations." CR Aca. Sci.. v o l . 244, 1957, pp. 1143-1146. 510
SOLAR ACTIVITY Project 12.4 - Improved Coronal Line Emission Studies 1. Ob.iectives. I n response to the needs of the various programs of the IGY the High A l t i t u d e Observatory made numerous improvements i n i t s coronal emission l i n e studies. I n t e n s i t i e s were reported on an absolute i n t e n s i t y scale, and were measured from the f i l m s p h o t o e l e c t r i c a l l y , by a sound procedure of photometric a n a l y s i s . For some regions, height gradient studies were made, and also coronal l i n e p r o f i l e a n a l y s i s . Attempts were also made t o develop more meaningful Indices o f coronal a c t i v i t y , i n an e f f o r t to have them more accurately represent the integrated emission of the higher temperature l i n e s of the corona. 2. Personnel. W.O. Roberts was the supervisor of t h i s work; Donald B i l l i n g s and Dorothy T r o t t e r were the p r i n c i p a l s c i e n t i s t s involved i n t h i s p r o j e c t . 3. Results. A set of X5303, X6374, X5694, and X5445 coronal l i n e i n t e n s i t i e s , measured on the same absolute scale and r e l a t i v e l y independent of observing c o n d i t i o n s , have been made av a i l a b l e f o r the e n t i r e current solar cycle. These compare favorably w i t h deter- minations by other s t a t i o n s using the same scale. Meaningful d a i l y indices using these data are also a v a i l a b l e . 4. Bibliography. D. T r o t t e r : "Indices of the Solar Corona, July 1957-December 1959." IGY Solar A c t i v i t y Report Series No. 13. IGY World Data Center A: Solar A c t i v i t y , HAO, Univ. of Colo., December 1960. H. Z i r i n , D. Ke i t h Watson, and G. W i l l i a m C u r t i s : "Spectra of Quiescent and Loop Prominences." PASP, 70, 406, 1958. 511
SOLAR ACTIVITY Project 12.5 - I n d i r e c t Detection of Flares - Instrumentation 1. Objectives. For t h i s p r o j e c t a t the High A l t i t u d e Observatory three automatic recording instruments f o r i n d i r e c t f l a r e d e t e c t i o n u t i l i z i n g enhancements of atmos- pherics (near 27 kc) and absorption of g a l a c t i c radio noise (near 18 Mc) were designed and constructed. These were provided f o r use a t Boulder, Sacramento Peak, and the McMath- Hulbert Observatory; from Department of Army funds, a f o u r t h instrument a t Hawaii was added to the net i n l a t e IGY. These instruments cont r i b u t e d t o the i n t e r n a t i o n a l solar p a t r o l operated f o r the b e n e f i t of the upper atmosphere research program. 2. Operations. I t i s known t h a t during a solar f l a r e , i o n i z i n g r a d i a t i o n increases the e l e c t r o n density m the ionosphere, p a r t i c u l a r l y i n the D-region, r e s u l t i n g i n two e f f e c t s t h a t can be r e a d i l y monitored as an index to f l a r e a c t i v i t y . a. SEA (Sudden Enhancement of Atmospherics). This e f f e c t arises from the i n - creased propagation of electromagnetic r a d i a t i o n from l i g h t n i n g discharges v i a D-layer r e f l e c t i o n . I t was decided to monitor these l i g h t n i n g signals a t a frequency of approximately 27 kc. b. SCNA (Sudden Cosmic Noise Absorption). During f l a r e s g a l a c t i c or cosmic radio noise i s absorbed i n the ionosphere to an extent varying w i t h frequency and e l e c t r o n density. A frequency of about 18 Mc was chosen as a reasonable compromise between low frequencies s u f f e r i n g from considerable t e r r e s t r i a l i n t e r f e r e n c e and high frequencies where the absorption i s i n t r i n s i c a l l y weak. I n a d d i t i o n to the 27 kc and 18 Mc si g n a l s , the l e v e l of shortwave broadcast signals i n the 18 Mc range was recorded. A l l recording was done w i t h a Sanborn h o t - s t y l u s recorder, on a time-sharing basis. 3. Personnel. W.O. Roberts was the supervisor of t h i s p r o j e c t ; Robert Lee c a r r i e d out the e l e c t r o n i c development and design of the equipment. 4. Results. The data were used f o r the warning network and also compiled and pub- lished i n the HAO reports of solar a c t i v i t y and the NBS F-Series, Part B, "Solar- Geophysical Data." From the operation of one of the u n i t s a t Boulder, i t was discovered t h a t the SCNA recorder was s u f f i c i e n t l y stable to permit q u a n t i t a t i v e measurements of the absolute change i n transmission of the s i g n a l through the ionosphere. From t h i s , J. Warwick and H. Z i r i n were able to c a l c u l a t e the v a r i a t i o n s of i o n i z i n g f l u x radiated by f l a r e s ( S c i e n t i f i c Report No. 9, ARDC contract AF 19 (604) - 1491. 10 January 1958). 5. Bibliography. a. Papers Presented a t Meetings. J. Warwick, H. Z i r i n : "Cosmic Noise Absorption m the Upper Atmosphere." Am. Ast. Soc, December 1956. b. Published Papers. R.H. Lee- "Radio Equipment f o r Detecting Solar Flares." HAO Solar Research Memorandum No. 57, February 24, 1956. R.H. Lee- "Solar Flare Detection f o r IGY." E l e c t r o n i c s , March 1, 1957. A. Boischot, J. Warwick: "Radio Emission Following the Flare of August 22, 1958." JGR, v o l . 64, 1959, p. 683. 512
SOLAR ACTIVITY C. Warwick, J. Warwick. "Flare Associated Bursts a t 18 Mc/sec." Paris Symposium on Radio Astronomy (Stanford U n i v e r s i t y Press, R. N, Bracewell, ed., 1959). J. Warwick, H. Z i r i n : " D i u r n a l Absorption i n the D-Region." JATP, v o l . 11, 1957, p. 187. J. Warwick- "Absorption of Cosmic Radio Noise During the Great Aurora of 11 February 1958." Science, v o l . 127, 1958, p. 1047. 513
SOLAR ACTIVITY Project 12.6 - HAO Operations - Climax and Boulder 1. Objectives. This p r o j e c t , a t the High A l t i t u d e Observatory, enabled the obser- vatory g r e a t l y to expand the scope of operations f o r the IGY. A d d i t i o n a l services made possible by t h i s p r o j e c t included a radio warning system l i n k i n g Sacramento Peak, Climax, and Boulder; reduction of new data obtained; and preparation of the data f o r the Data Center; as w e l l as providing f o r increased observing time i n connection w i t h the f l a r e p r o f i l e equipment (12.2) and K-coronameter (12.3). 2. Operations. a. O p t i c a l Flare P a t r o l . A photographic and v i s u a l f l a r e p a t r o l was maintained a t Climax on a sunrise to sunset basis, on every clear day, f o r most of the IGY. Immediate reports of the larger f l a r e s were made to the Regional Warning Centers on the basis of v i s u a l observations. F i l m reductions were made i n Boulder a t the end of each month and the f i n a l f l a r e compilations submitted to the IGY World Data Centers. A number of requests f o r copies or p r i n t s of these solar f i l m s f o r s p e c i f i c time periods have been honored. By f a r the largest requests came from the Japanese National Committee f o r the IGY on behalf of Dr. Takeo Hatanaka who obtained a p o s i t i v e copy of the e n t i r e f i l m . b. Spectrography of Solar Flares. Under sponsorship of IGY instrumentation grant 12.4, c e r t a i n modifications were made to the Climax coronagraph system to f a c i l i t a t e spectrographic observations of f l a r e s . As an e c l i p s i n g telescope, the instrument per- mits e x c e p t i o n a l l y pure observations of features above the solar limb and, accordingly, primary emphasis was placed on solar limb events, although a number of very u s e f u l spectra of dis k f l a r e s were also obtained. Analyses of some of the spectra have been completed under support of other HAO programs, and reported i n the l i t e r a t u r e . c. I n d i r e c t Flare Detector. The " I n d i r e c t Flare Detector" i s a c a r e f u l l y c o n t r o l l e d radio receiver designed to record solar f l a r e s by t h e i r e f f e c t s on the earth's iono- sphere. These e f f e c t s are manifested as sudden enhancement of atmospherics (SEA), sudden cosmic noise absorption (SCNA), and sudden short wave fadeout (SSWF). The HAO u n i t was operated continuously during the IGY a t a noise-free s i t e j u s t n o r t h of Boulder. Solar e f f e c t s were reported i n i t i a l l y i n the HAO "Preliminary Re- ports of Solar A c t i v i t y , " and l a t e r i n the CRPL "Compilations of Solar Geophysical Data." The Sanborn tapes f o r each day (recording the 18 Mc and 27 kc s i g n a l l e v e l s ) were submitted to the IGY WDC-A f o r Solar A c t i v i t y to be mounted and microfilmed side- by-side w i t h comparable records from McMath-Hulbert Observatory and Sacramento Peak Observatory, records from the U n i v e r s i t y of Hawaii s t a t i o n were added near the end of IGY. A comparison of records from the several independent s t a t i o n s permits a com- p l e t e l y unambiguous i d e n t i f i c a t i o n of even some of the smallest ionospheric e f f e c t s , an analysis which would not be possible from a single s t a t i o n ' s records. The micro- f i l m s of the combined s t a t i o n s were d i s t r i b u t e d by the WDC to each of the c o n t r i b u t o r s , and also made a v a i l a b l e to other research people upon request. The Boulder SCNA/SEA records have been extensively studied, p r i n c i p a l l y by Dr. James Warwick working under a research contract w i t h the E l e c t r o n i c s Research Directorate of AFCRC, and reported i n the l i t e r a t u r e . d. Electron Coronameter. The coronameter a t Climax i s one of the few instruments i n the world capable of recording the brightness of the sun's white l i g h t corona out- side of e c l i p s e . This component of the corona (the "K" corona) i s due to s c a t t e r i n g of photospheric l i g h t by electrons i n the sun's atmosphere, and i s thus a manifestation of the corona's r a d i a l extension i n t o space. Regular observations are usu a l l y possible to a height of 1 - 2 solar r a d i i , although i t i s believed t h a t the corona may extend as 514
SOLAR ACTIVITY f a r as the o r b i t of the e a r t h . I f t h i s i s the case, then v a r i a t i o n s of the corona must play an important r o l e i n e s t a b l i s h i n g conditions i n the earth's upper atmosphere. 3. Personnel. W.O. Roberts was p r o j e c t d i r e c t o r f o r these a c t i v i t i e s ; the p r i n c i p a l s c i e n t i f i c personnel were Donald B i l l i n g s , James Warwick, R.T. Hansen, Gordon Newkirk, H. Z l r i n , David Dodgen, D. Ke i t h Watson, G. Wi l l i a m C u r t i s , Gerard Wlerick, Robert Lee, and James A x t e l l . 4. Results and Bibliography. For d e t a i l s on the various observational programs, see proje c t s 12.1 t o 12.5. 515
SOLAR ACTIVITY Project 12.8 - Spectroscopic Studies of Solar Flares 1. Ob.iectives. The purpose of t h i s p r o j e c t a t the McMath-Hulbert Observatory was to obtain spectra of f l a r e s throughout the course of t h e i r development. The program i n - cluded the photography of very high d i s p e r s i o n , high r e s o l u t i o n spectra f o r selected wavelength regions as w e l l as broad wavelength coverage a t low di s p e r s i o n . The equip- ment was already i n use a t the Observatory and thus t h i s p r o j e c t provided only f o r some support of personnel. 2. Operations. The very high d i s p e r s i o n spectra were secured w i t h the vacuum spectro- graph i n the McGregor Solar Tower. H3! spectra a t moderate dispersion and r e s o l u t i o n were photographed w i t h the Stone spectrograph i n the 50-foot McMath-Hulbert Solar Tower. I n a d d i t i o n , a Wadsworth-type spectrograph w i t h r e l a t i v e l y low dispersion was used m conjunction w i t h the 50-foot Solar Tower Telescope t o record spectra from approximately X6600 to X,3600. 3. Personnel. Robert R. McMath was the p r o j e c t d i r e c t o r , 0,C. Mohler and Helen Dodson Prince were the p r i n c i p a l s c i e n t i s t s associated w i t h the p r o j e c t . 4. Data, Inasmuch as these were special observations not covered by IGY data ex- change agreements, the spectra were retained a t McMath-Hulbert f o r a n a l y s i s . 5. Results, Many spectra of small, moderate and large f l a r e s were obtained w i t h the various instruments. The spectra were analyzed under p r o j e c t 22,4, 516
SOLAR ACTIVITY Project 12.9 - McMath-Hulbert Flare P a t r o l Operations 1. Objectives. The purpose of the p r o j e c t a t the McMath-Hulbert Observatory, Univer- s i t y of Michigan, was to carry out a continuous p a t r o l of the sun, whenever weather permitted, during which motion p i c t u r e records were obtained of solar a c t i v i t y i n the l i g h t of the red hydrogen l i n e . Ha. E x i s t i n g equipment a t the McMath-Hulbert Observa- to r y provided only f o r high r j a g n i f i c a t i o n studies of r e l a t i v e l y small areas of the solar d i s k , and equipment was acquired (through p r o j e c t 12.17) f o r the continuous recording of solar f l a r e s over the e n t i r e d i s k . The observations and measurements were c a r r i e d out a t the McMath-Hulbert Observatory where extensive a u x i l i a r y f a c i l i t i e s were already a v a i l a b l e i n the form of motion-picture processing equipment, microdensitometers, and other measuring devices. The services of several members of the Observatory s t a f f were contributed without a d d i t i o n a l cost to the p r o j e c t . Observations were also made w i t h the i n d i r e c t r adio f l a r e detector supplied through p r o j e c t 12,5. 2. Operations. The SECASI f l a r e p a t r o l instrument was delivered i n Janmry 1958 and placed i n t o r o u t i n e operation on February 17, 1958; up t o t h a t time, observations be- tween 1200 and 1800 UT were c a r r i e d out, whenever regular schedules permitted, w i t h the e x i s t i n g equipment at the observatory. Some problems were encountered a d j u s t i n g the exposure to s u i t U.S., rather than French, f i l m emulsions; operating time was i n - creased to cover the period 1200 to 2200. Films were exchanged w i t h NRL where a s i m i l a r instrument was operated (see p r o j e c t 12.22) and Miss Ruth Hedeman, McMath- Hulbert, v i s i t e d NRL to discuss apparent differences I n f l a r e i n t e n s i t i e s , obtained w i t h the two instruments. 3. Personnel. R.R. McMath was the p r o j e c t supervisor; A. de Radder and Ruth Hedeman, re s p e c t i v e l y , were responsible f o r the observation, measurement and analysis of the solar events. O.C. Mohler and H. Dodson Prince p a r t i c i p a t e d a c t i v e l y i n a l l phases of the f l a r e p a t r o l program. 4. Data. A l l f l a r e s observed were measured, c l a s s i f i e d , and reported to IGY World Data Centers. These reports are published i n the CRPL-F se r i e s , and i n the I.A.U. Quarterly B u l l e t i n s on Solar A c t i v i t y . 5. Results. During the ten months t h a t the f l a r e p a t r o l was i n operation (1958 March to December), the telescope was i n use f o r 1391 hours. I n t h i s i n t e r v a l 452 events c l a s s i f i e d as f l a r e s and 1153 events c l a s s i f i e d as subflares were recorded. E s s e n t i a l l y complete coverage was provided f o r the usable observing weather w i t h i n the hours assigned f o r t h i s f l a r e p a t r o l . 517
SOLAR ACTIVITY Project 12.10 - Solar Radio Noise P a t r o l - Boulder 1. Objectives. This p r o j e c t a t the Central Radio Propagation Laboratory, Boulder Laboratories of the National Bureau of Standards, c o n t r i b u t e d solar radio observations a t 167 Mc and 460 Mc as part of the o v e r a l l program to study solar processes during a time of maximum a c t i v i t y . 2. Operations. Equipment was operated a t the Gunbarrel H i l l f i e l d s i t e near the Laboratory. Observations were made on both frequencies throughout the e n t i r e IGY. However, during the IGC only equipment on 167 Mc was operated. 3. Personnel. R.J. Slutz as D i v i s i o n Chief had the a d m i n i s t r a t i v e r e s p o n s i b i l i t y as pr o j e c t d i r e c t o r f o r t h i s work. The work was performed under the d i r e c t i o n of R.S. Lawrence; W.E. Nodlne operated the equipment and O.E. Youngdahl was responsible f o r the sc a l i n g of the data. 4. Data. A l l data of 167 Mc were scaled and submitted to the IGY World Data Centers. The 460 Mc data were reduced only through March 1958, and were submitted t o the IGY World Data Centers. Data appeared i n : CRPL-F Series. Part B "Solar-Geophysical Data" (or CRPL "Com- p i l a t i o n s of Solar-Geophysical Data") and the lAU Quarterly B u l l e t i n on Solar A c t i v i t y . 5. Results. See p r o j e c t 22.7 f o r discussion of analysis of upper atmosphere and solar radio data at CRPL. 518
SOLAR ACTIVITY Project 12,11 - Rapid Data Presentation 1. Objectives. This p r o j e c t a t the High A l t i t u d e Observatory provided f o r an increase i n the comprehensiveness of the reports prepared by HAO on current solar and geophysical a c t i v i t y , f o r d i s t r i b u t i o n to a l l IGY s t a t i o n s and s c i e n t i s t s having need of them. 2. Operations. Maps of the s o l a r d i s k were prepared summarizing c e r t a i n s o l a r data, other data were compiled i n tabular form, and appropriate t e x t was included. Reports were airmailed weekly to some 200 addresses. I n additon, HAO provided immediate reports of observations of major solar events t o the IGY World Warning Agency and also to rocket and cosmic-ray groups f o r the i n i t i a t i o n of s p e c i a l experiments. 3. Personnel. W.O. Roberts was the p r o j e c t supervisor; Dorothy T r o t t e r was responsible f o r compiling the weekly summaries, and f o r a l e r t i n g i n t e r e s t e d groups when major f l a r e a c t i v i t y was i n progress. Project 12.12 - Solar Radio Noise P a t r o l - Hawaii 1. Objectives. This 200 Mc solar radio noise p a t r o l located a t Makapuu, Oahu, and operated by the U n i v e r s i t y of Hawaii f i l l e d the large longitude gap between Boulder/ Sacramento Peak and Sydney/Tokyo. A continuous recording was made of the s o l a r r a d i o noise l e v e l , and background noise l e v e l was measured a t regular i n t e r v a l s . 2. Operations. A simple temporary p a t r o l s t a t i o n was constructed, u t i l i z i n g a radio r e c e i v e r , recorder, parabolic antenna, and an antenna mounting and d r i v e system. The record was examined d a i l y and any disturbance tabulated, g i v i n g onset time, maximum time, d u r a t i o n , type, and r e l a t i v e i n t e n s i t y , 3. Personnel. The p r o j e c t was c a r r i e d out by Prof, Iwao Miyake of the U n i v e r s i t y of Hawaii. 4. Data. A l l data were scaled and submitted to the IGY World Data Centers. The noise i n t e n s i t y i n watts/cm^ was not calculated from the data c o l l e c t e d be- cause the a c t u a l e f f e c t i v e area of the parabolic antenna was questionable, and the l i n e voltage r e g u l a t o r was not able to hold the voltage s u f f i c i e n t l y constant to maintain the c a l i b r a t i o n over a long period of time. 5. Results. A summary of the number of each type of a c t i v i t y recorded, and the number of coincidences w i t h i n t 5 minutes w i t h solar f l a r e s i s given i n Table I . A study of the coincidences of radio fade-outs w i t h radio noise was made. 519
SOLAR ACTIVITY MONTH TABLE I NUMBER OF ACTIVITIES OF TYPE NO. DAYS COINCIDENCES RECORDED ( + 5 min.) w i t h SOLAR FLARES 4A 4B 8 9A 9B 1957 July 1 12 9 33 0 2 2 7 1 1 0 0 0 17 10 Aug. 0 22 7 73 0 2 2 8 0 8 0 1 1 31 6 Sept. 4 18 10 50 0 1 1 6 2 7 1 1 1 30 13 Oct. 1 24 11 27 0 0 0 7 0 1 0 1 0 20 2 Nov. 1 2 9 28 0 0 0 2 1 0 0 0 0 19 5 Dec. 22 25 14 76 0 0 0 8 3 2 1 2 2 31 6 TOTAL 6 MOS. 29 103 58 287 0 5 5 38 7 19 2 5 4 148 42 1958 Jan. 6 25 18 40 2 0 0 5 4 2 1 1 1 30 3 Feb. 0 8 12 9 0 0 0 8 2 2 0 0 0 27 0 Mar. 1 8 4 7 0 0 0 9 2 4 1 0 0 31 4 Apr. 4 11 11 50 0 1 1 1 2 0 0 1 1 28 0 May 1 7 22 14 0 0 0 1 1 1 1 0 0 31 0 June 3 1 2 3 0 1 1 2 0 0 0 0 0 27 0 July 0 9 6 7 0 0 0 1 0 0 0 0 0 27 4 Aug. 0 5 2 33 0 3 3 6 0 1 2 2 0 25 5 Sept. 3 4 3 28 0 0 0 2 0 1 0 0 0 30 2 Oct. 0 1 6 20 0 0 0 5 1 5 2 1 1 29 1 Nov. 1 4 3 10 0 0 0 9 2 0 0 1 1 30 4 Dec. 3 12 7 48 0 0 0 8 2 2 0 1 0 28 8 TOTAL YEAR 22 95 96 269 2 5 5 57 16 18 7 7 4 343 31 1959 Jan. 7 5 3 26 0 0 0 18 0 4 0 0 0 28 11 Feb. 1 16 3 44 0 0 0 6 2 2 0 0 0 28 3 Mar. 1 4 3 11 0 0 0 6 0 0 0 0 0 31 7 Apr. 0 21 5 52 0 0 0 6 1 2 2 0 0 30 2 May 2 27 5 42 0 0 0 5 0 1 0 1 1 30 10 June 0 8 6 60 0 0 0 3 3 3 0 0 0 29 8 TOTAL 6 MOS. 11 81 25 235 0 0 0 44 6 12 2 1 1 176 41 520
SOLAR ACTIVITY Project 12.13 - Solar A c t i v i t y Flare P a t r o l - Hawaii 1. Objectives. This p r o j e c t a t the U n i v e r s i t y of Hawaii provided f o r the construc- t i o n and operation of a simple f l a r e p a t r o l instrument u t i l i z i n g a b i r e f r i n g e n t f i l t e r , telescope and 35 mm recording camera. The instrument was i n s t a l l e d a t Makapuu Point on the i s l a n d of Oahu i n Hawaii, thus improving the longitude coverage of s t a t i o n s monitoring solar a c t i v i t y during the IGY, and supplementing the l a t e afternoon hours of U.S. s t a t i o n s and morning hours of s t a t i o n s f a r t h e r west (Japan, A u s t r a l i a , e t c . ) . I n general, t h i s work was coordinated w i t h other f l a r e p a t r o l work a t Mt. Wilson Ob- servatory, Sacramento Peak, High A l t i t u d e Observatory, McMath-Hulbert Observatory, and the Naval Research Laboratory. 2. Operations. Makapuu Point a t the northeast t i p of Oahu was chosen as the best compromise between observing c o n d i t i o n s , a c c e s s i b i l i t y , and f a c i l i t i e s . A concrete- block b u i l d i n g , which was not being used a t the time, was i n existence there; arrange- ments were made to lease t h i s b u i l d i n g from the Hawaiian Telephone Company f o r a nominal sum. E l e c t r i c power and telephone service were a v a i l a b l e and water was brought i n from a nearby Coast Guard i n s t a l l a t i o n . An o p t i c a l bench was constructed i n s i d e the b u i l d i n g where the main o p t i c a l t r a i n and recording camera were located. The HAO h e l i o s t a t was located outside the b u i l d i n g on the south side; the beam from the h e l i o s t a t was d i r e c t e d through a hole i n the w a l l to the o p t i c a l t r a i n . The f l a r e p a t r o l photographed the sun i n the l i g h t of H-alpha a t i n t e r v a l s of 2 minutes throughout the day. Close v i s u a l monitoring of the sun enabled t h i s time i n t e r v a l to be decreased t o 15 seconds i n case of the occurrence of a f l a r e . A Halle b i r e f r i n g e n t f i l t e r w i t h a h a l f angstrom band pass a t H-alpha was used. The f i l m (Eastman Spectroscopic, Type 4-E) was developed d a i l y and studied w i t h a f i l m p r o j e c t o r . The time of onset, maximum, and ending of a l l f l a r e s were recorded, i n a d d i t i o n to t h e i r r e l a t i v e i n t e n s i t y and area, and t h e i r heliographic p o s i t i o n . Various improvements were made i n the o p t i c a l system during the course of the IGY, r e s u l t i n g i n considerable improvements i n the image q u a l i t y . These included some minor modifications t o cut do\m scattered l i g h t , replacement of the f r o n t p o l a r i z i n g element of the f i l t e r to improve image c o n t r a s t , and replacement of a s t i g m a t i c o b j e c t i v e lens. Under a cooperative arrangement, cosmic r a d i o noise equipment (Project 12.11) and cosmic-ray neutron and meson monitors (Project 2.6) were operated also at Makapuu Point. 3. Personnel. The p r o j e c t d i r e c t o r was W.R. Steiger. F u l l - t i m e observers were, suc- cessively, John W. L i t t l e and Roy Nojima. Several students i n the Physics Department were also connected w i t h the observing and data reduction aspects o f the program. 4. Data. A l l f l a r e s observed were c l a s s i f i e d and reported d a i l y by radio to the National Bureau of Standards Radio Warning Service and to HAO f o r i n c l u s i o n m the reports of solar a c t i v i t y . Monthly summaries, i n c l u d i n g reports of surges, eruptive prominences, and sudden disappearances were mailed to World Data Centers A, B, and C. 5. Results. During t h i s 18-month period t h i s observatory was able to make p a t r o l observations of the sun 60 per cent of the time, on the average, during the hours between 1800 t o 0200 UT. A t o t a l of 639 f l a r e s was reported, which was d i s t r i b u t e d i n importance as f o l l o w s . Class % 3 to 3+ 0.8 2 to 2+ 9 1 to 1+ 40 1- 50 521
SOLAR ACTIVITY 6. Bibliography. W. Steiger and J. L i t t l e : "On the F e a s i b i l i t y of a Solar Observatory i n the Hawaiian Islands." Publ. A s t r . Soc. of the P a c i f i c , v o l . 70, Dec. 1958, pp. 556-60. W. Steiger: "The Hawaii Solar Flare P a t r o l f o r the IGY." Proc. Hawaii Acad. of S c i . , v o l . 31, 1956 ( a b s t r a c t ) , pp. 14-15. W. Steiger: "Hawaii's Role i n the IGY." Proc. Hawaii Acad, of S c i . , v o l . 33, 1958 ( a b s t r a c t ) , p. 24. Related t o Project 12.11: W. Steiger and J. Warwick: "Observations of Cosmic Radio Noise a t 18 ^k: i n Hawaii." JGR, v o l . 66, 1961, pp. 57-66. Related t o Project 2.6: R.B. Brode, R.R. Brown, and W.R. Steiger. "Solar Flare Cosmic-Ray Increase of May 4, 1960." JGR, v o l . 65, Dec. 1960, pp. 4200-01. 522
SOIAR ACTIVITY Project 12.14 - Flare and Plage P a t r o l - Mt. Wilson 1. Ob.lectives. This p r o j e c t , assigned to the Leuschner Observatory, U n i v e r s i t y of C a l i f o r n i a , provided f o r a f e l l o w s h i p a t Mt. Wilson (through a cooperative arrangement w i t h the Mt. Wilson and Palomar Observatory) t o allow more d e t a i l e d observing and prompt reduction and r e p o r t i n g of the solar a c t i v i t y observations w i t h Mt. Wilson equipment than would have normally taken place under the regular schedule of Mt. Wilson. 2. Operations. As a t the other p a t r o l s t a t i o n s , the sun was observed r o u t i n e l y , f i l m was examined and scaled and f l a r e s reported to HAO f o r i n c l u s i o n i n the solar a c t i v i t y summaries. 3. Personnel. Dr. Otto Struve, Leuschner Observatory (now D i r e c t o r , Nat. Radio Observatory, Greenback, W. Va.) was a d m i n i s t r a t i v e p r o j e c t d i r e c t o r ; Dr. Seth B. Nicholson, Mt. Wilson, supervised the observations. 4. Data. A l l data f o r the IGY period were submitted to the IGY World Data Centers. Project 12.15 - Solar Radio Noise P a t r o l - Ithaca 1. Objectives. This 200 Mc ra d i o noise p a t r o l a t Co r n e l l U n i v e r s i t y was operated as a part of the IGY program as an adjunct to a larg e r program a t the U n i v e r s i t y i n radio astronomy. The O f f i c e of Naval Research supported t h i s program f o r some time, but IGY funds were required to continue operation of the solar radio noise p a t r o l from m i d - A p r i l through December 1958. 2. Operations. The 200 Mc solar f l u x p a t r o l and an ionospheric disturbance monitor were operated d a l l y . Unusual events were reported by telegraph to the IGY World Warning Agency. 3. Personnel. Marshall Cohen was p r o j e c t d i r e c t o r . S. Michel Colbert assisted w i t h the observations and the equipment maintenance. 4. Data. Data from the IGY period were submitted to the IGY World Data Center, and published i n the NBS-CPRL-F se r i e s . 5. Results. The rep o r t s o f large s ^ l a r disturbances aided the IGY World Warning Agency (AGIWARN) i n i t s e f f o r t to forecast geomagnetic disturbances. The f l u x data i t s e l f forms a p a r t of the complete solar h i s t o r y of the period. 6. Bibliography. Data are published i n "Quarterly B u l l e t i n of Solar A c t i v i t y " published by I n t e r n a t i o n a l Astronomical Union, Zurich. 523
SOLAR ACTIVITY Project 12.16 - Flare P a t r o l Equipment 1. Ob.lectives. This p r o j e c t a t the Sacramento Peak Observatory (GRD, AFCRL), Sunspot, New Mexico, provided f o r the c o n s t r u c t i o n and i n s t a l l a t i o n of a solar f l a r e p a t r o l telescope f o r use during IGY; observations by the Observatory s t a f f were supported under the regular program of the Observatory. 2. Operations. Construction of the f l a r e p a t r o l instrument was c a r r i e d out a t Sacramento Peak; an Acme camera was supplied under Project 12.18. The equipment con- s i s t e d of a 5-inch simple lens telescope mounted on an e x i s t i n g 10-foot e q u a t o r i a l spar along w i t h other solar p a t r o l instruments. A servo system actuated by photo c e l l s guided the spar accurately on the sun. The l i g h t from the o b j e c t i v e traversed an Ha b i r e f r i n g e n t f i l t e r w i t h an 0.3 angstrom pass band. The 16 mm solar image and a clock were photographed on 35 mm f i l m i n the Acme camera, timed to take exposures a t 2-1/2 minute i n t e r v a l s during a l l cloudless d a y l i g h t hours. Photometric standards were im- pressed on the f i l m f o r q u a n t i t a t i v e measurements of f l a r e brightnesses a t the center of the Ha l i n e . The f l a r e p a t r o l observations were a part of a more extensive p a t r o l program a t Sacramento Peak, i n c l u d i n g coronal, prominence, and sunspot ionospheric and geomagnetic observations. 3. Personnel. J.W. Evans was p r o j e c t d i r e c t o r . Harry Ramsay w i t h two assi s t a n t s conducted the observational program. 4. Data. A l l f i l m was examined and f l a r e s tabulated. This information was supplied to the IGY World Data Center. 5. Results. The Sacramento Peak f l a r e p a t r o l has continued observations, and r e - corded about 8000 f l a r e s ( i n c l u d i n g those of importance 1- ) since the beginning of IGY, A s t a t i s t i c a l study of t h i s considerable body of homogeneous data i s i n progress w i t h the a i d of a large computer. 524
SOLAR ACTIVITY Project 12.17 - Flare P a t r o l Instruments and F i l t e r s - Procurement 1. Objectives. This p r o j e c t a t the Naval Research Laboratory provided f o r the pur- chase of two Lyot heliographs and f i v e H-alpha f i l t e r s f o r use i n the IGY program. 2. Operations. a. Two Lyot heliographs (on behalf of NRL and McMath-Hulbert) were obtained from the Society f o r the Study and Construction of S c i e n t i f i c and I n d u s t r i a l Apparatus (SECASI), Bordeaux, France, The apparatus consists of an astronomical telescope f o r automatic recording of solar events i n the H-alpha emission region of the solar spec- trum on 35 mm motion p i c t u r e f i l m . This instrument has a f o c a l length o f 1.40 meters and aperture of f/10. Exposure times are c o n t r o l l e d p h o t o e l e c t r i c a l l y as a f u n c t i o n of sky transparency. Guiding of the instrument i s accomplished by means of a photo- e l e c t r i c sun-follower d r i v e n on an e q u a t o r i a l mounting. A console i s provided f o r a f i l t e r thermostat which may be adjusted to w i t h i n 0.01 degree. b. Two H-alpha f i l t e r s (on behalf of NRL and McMath-Hulbert) were obtained from the Optique e t Precision d i L a v a l l o i s of Paris, the f i l t e r s having a band pass of 0.75 angstroms, which i s adjustable f o r wider scanning of the H-alpha emission region. c. Three H-alpha f i l t e r s (on behalf of Climax, Sacramento Peak, and U n i v e r s i t y of Hawaii) were obtained from the Bernard Halle Nachfl. of B e r l i n , the f i l t e r s having a band pass w i d t h of 0.5 angstroms f o r high contrast w i t h i n the H-alpha region. 3. Personnel. R.J. Coates was p r o j e c t d i r e c t o r . 4. Results. The instruments and f i l t e r s were delivered e a r l y i n 1958 and put i n t o operation soon t h e r e a f t e r ; t h i s equipment m a t e r i a l l y strengthened the U.S. solar p a t r o l work. 525
SOLAR ACTIVITY Project 12.18 - Flare P a t r o l Equipment 1. Objectives. This p r o j e c t a t the High A l t i t u d e Observatory of the U n i v e r s i t y of Colorado provided support f o r o p t i c a l f l a r e p a t r o l instrumentations a t the U n i v e r s i t y of Hawaii^ Sacramento Peak, and the High A l t i t u d e Observatory. 2. Operations. a. Makapuu Point. Hawaii. HAO cooperated w i t h the U n i v e r s i t y of Hawaii i n con- s t r u c t i n g a completely new f l a r e p a t r o l instrument. Dr. Walter Steiger of the U n i v e r s i t y of Hawaii Physics Department v i s i t e d HAO during the months of July and August 1956, and worked out the o p t i c a l and mechanical designs of the telescope i n c o l l a b o r a t i o n w i t h HAO s t a f f members. The HAO was able to supply a h e l i o s t a t and c e r t a i n components of a pho t o e l e c t r i c guidance system. An Acme 35 mm camera was provided through p r o j e c t 12.20 and a Halle narrow band pass f i l t e r was purchased under pr o j e c t 12.6. Dr. Steiger c a r r i e d out the assembly and alignment of the f l a r e p a t r o l a t the Makapuu Point Observa- t o r y w i t h assistance from HAO personnel. b. Sacramento Peak, New Mexico. A s p e c i a l l y modified Acme cinecamera was supplied to the Sacramento Peak Observatory. Other instrumentation f o r t h e i r f l a r e p a t r o l was provided under A i r Force auspices. c. High A l t i t u d e Observatory. Boulder. Colorado. A t h i r d f l a r e p a t r o l f o r the IGY was to be b u i l t f o r operation a t the Boulder Laboratories of the High A l t i t u d e Observa- t o r y . For t h i s purpose, an a d d i t i o n was made to the Sommers-Bausch Observatory of the Uni v e r s i t y of Colorado to house a ten-foot e q u a t o r i a l table upon which the f l a r e p a t r o l telescope was mounted. A l l of t h i s work was completed l a r g e l y by means of p r i v a t e funds of the Observatory. However, i t had been planned to incorporate a narrow band pass f i l t e r of unique design to permit r a p i d tuning over a wide range of wave-lengths to e i t h e r side of H-alpha. (Project 12.1) By t h i s means, solar features having high v e l o c i t i e s i n the l i n e of si g h t could be observed. However, t e c h n i c a l d i f f i c u l t i e s im- posed by the severe tolerances f o r the c a l c i t e elements prevented the completion of the Instrument. Instead, i t was decided to operate the Climax " f l a r e l o c a t o r " telescope on a r o u t i n e basis as part of the High A l t i t u d e Observatory's c o n t r i b u t i o n to the i n t e r n a t i o n a l net- work of solar p a t r o l s . This instrument then served the double purpose of p e r m i t t i n g the detection of solar events so tha t the observers could carry out t h e i r spectrographic programs as w e l l as serving as a photographic f l a r e p a t r o l . 3. Personnel. W.O. Roberts was the p r o j e c t supervisor; the p r i n c i p a l s c i e n t i s t s associated w i t h t h i s work were Gordon Newklrk, Donald B i l l i n g s , and Robert Lee. 4. Results. The three f l a r e p a t r o l s t a t i o n s (Sacramento Peak Observatory, Climax, and Hawaii) operated w i t h a high degree of e f f i c i e n c y during the IGY period, a f f o r d i n g es- s e n t i a l l y complete p a t r o l coverage during the d a y l i g h t hours between midwestern United States and Hawaii. Reports of f l a r e s and also prominences were submitted by a l l three observatories t o the World Data Centers and t h e i r data was also incorporated i n various intermediate solar p u b l i c a t i o n s . 5. Bibliography. Lowman, Karen and D. B i l l i n g s : "Study of the Flare-Surge Event of Sept. 7, 1958." A u s t r a l i a n Journal of Physics, 13, No. 3, 1960, pp. 606-609. R. Hansen, D. Gordon: "The Limb Flares of Oct. 13, 1958." Ast. Soc. of the P a c i f i c , v o l . 72, 1960, pp. 194-199. 526
SOLAR ACTIVITY Project 12.19 - Solar A c t i v i t y Data Reduction and P u b l i c a t i o n 1. Objectives. This p r o j e c t a t the Central Radio Propagation Laboratory, Boulder Laboratories, National Bureau of Standards, provided f o r expansion of the format of the solar-geophysical data published by CRPL on an intermediate time schedule as w e l l as f o r reduction of new U.S. s o l a r . a c t i v i t y data and f o r the preparation of selected manuscripts, requested by CSAGI, f o r p u b l i c a t i o n . 2. Operations. The contents of the CRPL-F Part B "Solar-Geophysical Data" reports (also c a l l e d "Compilations of Solar-Geophysical Data") were expanded during the IGY by arranging f o r new data and by using data t h a t became av a i l a b l e i n the IGY World Data Center-A f o r Solar A c t i v i t y . These reports were issued monthly containing data from as recent as the month before issue. Included were: a. D a i l y Solar Indices ( i ) Relative Sunspot Numbers and 2800 Mc Solar Flux ( l i ) Graph of Sunspot Cycle i n c l u d i n g Predictions of Sunspot Numbers b. Solar Centers of A c t i v i t y ( i ) Calcium Plage and Sunspot Regions ( l i ) P r o v i s i o n a l Coronal Line Emission Indices c. Solar Flares Information on Op t i c a l Observations; Subflares; Solar P a t r o l Observations; and Ionospheric E f f e c t s ; Short-wave fadeouts (SWF), Sudden Enhancements of Atmospherics (SEA), Sudden Cosmic Noise Absorption (SCNA). The method of r e p o r t i n g SEA and SCNA and combining data from several sources was developed by t h i s p r o j e c t . d. Solar Radio Waves Daily Data and Outstanding Occurrences on Single Frequency Recordings (9530 Mc, 3200 Mc, 2800 Mc, 470 Mc, 200 Mc, 169 Mc, 167 Mc) and Spectrum Observations (100-580 Mc i n IGY expanded to 25-580 Mc i n IGC). e. Geomagnetic Indices ( i ) C, Kp, Ap and Selected Quiet and Disturbed Days ( i i ) Chart of Kp by Solar Rotations f . Radio Propagation Q u a l i t y Indices ( i ) North A t l a n t i c and North P a c i f i c ( i l ) Graphs of Useful Frequency Ranges - North A t l a n t i c g. AGIWARN Message Summaries A l e r t s and Special World I n t e r v a l Periods. 3. Personnel. J, V i r g i n i a L i n c o l n supervised t h i s work. D.B. Buckneun and O.E. Young- dahl assisted i n e d i t i n g the r e p o r t s . A. Blount, G. Otto and M. Moran helped prepare the data. 4. Results. Research workers throughout the world received these solar-geophyslcal data compilations which allowed them t o prepare prompt evaluations of t h e i r p r o j e c t s . The solar f l a r e data i n the WDC-A: Solar A c t i v i t y were placed on punch cards and were c o n t i n u a l l y r evised. These cards were used i n a high speed e l e c t r o n i c computer program to combine the m u l t i p l e reports of solar f l a r e s i n t o a s i n g l e , s t a t i s t i c a l l y weighted event. 527
SOLAR ACTIVITY "The McMath Working L i s t of IGY Flares" by Helen W. Dodson and E. Ruth Hedeman was placed on punch cards by t h i s p r o j e c t f o r p u b l i c a t i o n i n WDC-A IGY Solar A c t i v i t y Report Series as Number 12, June 25, 1960. A Calendar Record f o r the IGY of selected solar and geophysical events was prepared. I t was submitted to CSAGI f o r p u b l i c a t i o n i n the Annals of the IGY by A, H. Shapley as part of the World Days and Communications Program. A s i m i l a r Calendar Record f o r the IGC i s i n preparation. Progress was made on preparation of spe c i a l sunspot numbers by CRPL f o r the IGY period. This w i l l be a research r e p o r t . Using data a v a i l a b l e through the American Association of Variable Star Observers and reports to WDC-A f o r Solar A c t i v i t y , common observatory c o e f f i c i e n t s have been computed against the American r e l a t i v e sunspot numbers as a base. The reports have been grouped i n six-hour periods throughout the day and sunspot numbers f o r each of the four such periods a day are i n preparation. Such numbers should give a gross estimate of solar a c t i v i t y changes during a Greenwich day. 5. Bibliography. CRPL-F Ser-'.es Part B "Solar-Geophysical Data" Reports (155 through 172 f o r IGY, 173 through 184 f o r IGC). National Bureau of Standards. IGY Calendar Record, Vol. 16, Part I , Annals of the IGY. Pergamon Press. IGY Calendar Record, Vol. 16, Part I I , Annals of the IGY, Pergamon Press. 528
SOLAR ACTIVITY Project 12.20 - Hawaii Flare P a t r o l - HAO Assistance 1. Objectives. This p r o j e c t a t the High A l t i t u d e Observatory, U n i v e r s i t y of Colorado, was organized to provide f o r close c o l l a b o r a t i o n between personnel from the U n i v e r s i t y of Hawaii and HAO i n order to e s t a b l i s h an o p t i c a l f l a r e p a t r o l i n Hawaii. 2. Operations. Dr. Walter Steiger, U n i v e r s i t y of Hawaii, v i s i t e d HAO i n July and August 1956 t o work out w i t h HAO personnel aspects o f the instrumentation; f i l t e r design, c o n s t r u c t i o n , operation, r e d u c t i o n , and analysis of r e s u l t s . A t e n t a t i v e o p t i c a l layout was also worked out. When the instrument was ready to i n s t a l l , HAO personnel v i s i t e d Hawaii to a s s i s t . 3. Personnel. W.O. Roberts was supervisor of t h i s work, R.J. Low, Gordon Newkirk, and Donald B i l l i n g s were also associated w i t h t h i s p r o j e c t . 4. Results. See p r o j e c t 12.13 f o r d e t a i l s . Project 12.21 - I n d i r e c t Solar Flare Detection, New York - Instrumentation 1. Objectives. This p r o j e c t a t the Observatory of Rensselaer Polytechnic I n s t i t u t e provided f o r the c o n s t r u c t i o n of a cosmic noise receiver to monitor atmospheric absorp- t i o n as an i n d i c a t o r of f l a r e occurrence. 2. Operations. A f i x e d broadside-array antenna (two half-wave dlpoles) was constructed a t the RPI radio astronomy s i t e at Grafton, New York. A receiver followed by a detector c i r c u i t f o r recording minimum s i g n a l noise l e v e l i n a 50 kc band (by sweeping over the band and e l i m i n a t i n g w i t h a noise r e j e c t o r "spikes" due to fixed-frequency broadcast signals) and a recorder were provided to monitor noise a t a frequency near 18 Mc. 3. Personnel. Robert Fleischer was p r o j e c t d i r e c t o r ; Robert W. Redlich, Pearl Lichten- s t e i n and Alan S. Meltzer were associated w i t h the p r o j e c t . 4. Data. The data were d i s t r i b u t e d monthly t o other workers and to the IGY World Data Centers i n tabular form. I n a d d i t i o n , reproductions of the recorder tapes w i t h comments, were published, usually monthly, beginning w i t h March 1958. 5. Results. I n a d d i t i o n to the i n d i r e c t d e t e c t i o n of solar f l a r e s , v a r i a t i o n s i n r e - ceived cosmic noise were detected which were c o r r e l a t e d w i t h a u r o r a l i o n i z a t i o n and w i t h l o c a l tropospherlc phenomena. The analysis of the observations was pursued under pro- j e c t 22.2. 6. Bibliography. R. Fleischer, P.R. L i c h t e n s t e i n , N. Carragan, and R.E, Falconer: "18-Megacycle Cosmic Noise I n t e n s i t i e s . " Publications No. 1 through 18, 1958 to 1960. R. Fleischer; "Variations i n 18-Megacycle Solar and Cosmic Noise." Proc. of the Paris Symposium on Radio Astronomy, Bracewell, R.N., e d i t o r , Stanford U n i v e r s i t y Press, 1959, p. 208. R. Fleischer: "Auroral Absorption of 18-Mc/s Cosmic Radio Waves on Feb. 11, 1958." Nature. 181, A p r i l 19, 1958. R. Fleischer, R.W. Redlich: "Cosmic-Noise Absorption a t 18.2 Megacycles." Astronomical Journal, v o l . 62, 1957, p. 243. 529
SOLAR ACTIVITY Project 12.22 - Solar H-alpha and Radio Noise P a t r o l , Washington, D.C. 1. Objectives. This p r o j e c t a t the Naval Research Laboratory was part of the Radio Astronomy Branch program and the observations covered by NRL support. The f l a r e p a t r o l instrument was provided f o r under p r o j e c t 12.17. Observations on the east coast of North America s u b s t a n t i a l l y completed U.S. p a t r o l coverage from sunset i n Europe to sunset i n Hawaii. 2. Operations. The observation, recording, measurement, and analysis of solar o p t i c a l phenomena were to be cor r e l a t e d w i t h events observed simultaneously i n the r a d i o f r e - quency spectrum. For t h i s reason, the o p t i c a l and radio (3200, 9530 Mc) equipment were located as close to each other as p r a c t i c a l . The observations of the solar d i s k were made on a continuous minute-by-minute basis, i n l i g h t of the H-alpha emission, to detect solar f l a r e s . The goal of a cooperative program on continuous cinematic recording had been set f o r t h i n the f o l l o w i n g suggestions and recommendations of the I n t e r n a t i o n a l Astronomical Union sub-commission on cinematography of chromospheric phenomena: a. To produce a documentary record a t a c e n t r a l observatory t h a t w i l l permit r e c o n s t r u c t i o n , as l a t e r studies may r e q u i r e , of the state of the chromosphere f o r any s p e c i f i c time. b. To produce s t a t i s t i c s of f l a r e s , surges, sudden prominence disappearances, and other chromospheric phenomena from time-analysis and photometric study of the f i l m s . An H-alpha solar heliograph was b u i l t a t NRL f o r observations p r i o r to the d e l i v e r y of the SECASI instrument. The f l a r e p a t r o l observations during the f i r s t year of the IGY were made w i t h the NRL instrument. Radio observations a t 3200 Mc were s t a r t e d l a t e i n 1957 and were f u l l y o p erational as a solar p a t r o l i n e a r l y 1958. P a t r o l observations at 9530 Mc and 70,000 Mc were added l a t e r t o the program. 3. Personnel. Robert J. Coates was p r o j e c t d i r e c t o r f o r t h i s work. 4. Data. A l l f l a r e data were tabulated and sent to HAO f o r i n c l u s i o n i n the solar a c t i v i t y summaries. Radio observations began i n February 1958 and a l l data were tabu- lated f o r submission to HAO. 5. Results. H-alpha Flare data published i n NBS B u l l e t i n s CRPL F156, August 1957 through CRPL F175, March 1959 i n c l u s i v e . H-alpha Report of Surges, and Active Prominences appear i n the IGY Solar A c t i v i t y Report Series of the HAO, U n i v e r s i t y of Colorado, Boulder, Colorado, Nos. 3, 5, 6, 7, and 8 of January 1958 - March 1959. Radio data on 3200 and 9530 Mc published i n the CRPL B u l l e t i n s , Part B, from March 1958 through A p r i l 1959 i n c l u s i v e . 6. Bibliography. R. Coates, S. Edelson, T. McCullough, N. S a n t i n i : "IGY Solar Flare Studies." NRL Report 5203 (Abstract i n Transactions of the I.A.U., v o l . X, 1960, p. 656. Robert J. Coates, S. Edelson, N.J. S a n t i n i , and T.P. McCullough: " C o r r e l a t i o n of H-alpha Flares w i t h lO-cm Radio Bursts." URSI-IRE Meet., May 1959. Robert J. Coates: "The Observation of a Solar Flare a t 4.3-inm Wavelength." Nature, v o l . 162, Sept. 27, 1958, p. 861. 530
SOLAR ACTIVITY Robert J. Coates, A.E. Covington and S. Edelson: "The 4.3 mm and 10.7 cm Outbursts of June 9, 1959." Astronomical J., v o l . 64, Oct. 1959, p. 1273. Robert J, Coates, S. Edelson, N. S a n t i n i , and T.P. McCullough: "Time Relations Between Centimeter Wavelength Burst and Solar H-a Flares." Astronomical J., v o l . 64, Oct. 1959, p. 1273. 531