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ì ll! I L' I i: l r I ti m A PROGRAÃI FOR CONSTRUCTION OF OPTIUL TELESCOPES What types and sizes of optical telescopes should be built in the next ten years? The preceding sections have shown that observational astronomy is at a stage where more telescopes are urgently needed, both to increase the rate of acquisition of observational data and to enlarge the rather small circle of ast¡onomers who can now work on faint sources. This section of the report presents the specific recommendations of the Panel as to the telescopes that it believes represent a reasonable and prudent investment over the next decade. TYPES NEEDED The next generation of general-purpose resea¡ch telescopes will almost cer- tainly follow the over-all optical design of existing small-ffeld reflectors. This type of instrument has been shown to be extremely longJived anil versatile, and adaptable to changing astronomical problems through the ûtting of new analyzing instruments and detectors. The larger telescopes will ofier more tÏan one focal ratio through the use of secondary mirrors, and will provide for large and healy analyzing equipment at a ffxed coudé focus. Fields of view somewhat larger than the fraction of a degree previously customary can be achieved by slight deparhrre from conic seetions in the primary and secondary minors, or by improved correctol lenses placed a short distance ahead of the focal plane. But in inshtments that depend on the well-under- stood elements of geometrical optics, revolutionary changes in design are unlikely. 38 I I Copyright © National Academy of Sciences. All rights reserved.

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lli,- T el'e s coPes cial-PurPose Spe Special-purpose wide-ûeld telescopes will not, the Panel believes, become The 48-inch fraction of those built in the next few years' "i "ppå"iá¡U telescope has been a superb survey instrlrment' Experience Puloir-ar Schmidt since the completion of the Palomar Sþ Srirvey has shown trhat this one parts of the heav- ,"rve the neeils of u. s. astronomers for the ;rrroo*"rra ""r,to it. A similar instrument is urgentþ neeiled in the Southern ãrr, """urribl" ffã*irpfr"t". It could be identical, or it might be modiûecl-to give a larger plate Jcale at a price of reducecl angular feld-and,speed' For surveys to a il;htermag;tñde Limit, the smalier Schmidt telescopes (up to 24-ineh the nert ten I suãh as those at Michigan and Case, should sufice-for "pËt*" .,å"rr. Wid*-û"ld astrometric refractors, such as the twin Carnegie instnr- õUservatory and its counterpart being built for the Yale-Colum- i.f. í"*i ¡i" ,a"aio" in Argentina, will not need to be duplicated, since the "ripening ", plates is so much longer than the expos're cvele for ;ñJ;i;";*;otion coverage åf the sky and the subsequent evaluation period' ;"";;i"¿ fhe OO-inch astrometric reflector now being tested at the Flagstafi sta- tl.rat tion of the U. S. Naval Observatory is another special-purpose telescope r-,irfy U. S. demands in iis particular ffelcl for the next decade' rit""fa Solnr TelescoPes The completion of the McMath solar telescope at the Kitt Peak National of the country the largest such ô¡r"*"tärv f.". given the solar astrQnomers ;b.;;p; i Ur" i'o¡¿. The large aperture (60 inch) gives a brightgives an image' drermal controi of every part of the surroundings ^"JAä ""t"ruf high-resolution spectrcscopy of fine iletails of the solar sur- ;;;";,."1t for Peak Observatory is fååe. Still ánother facllity ât the Àtu Force-Sacramento stagås, and construction seems assured' The loss of reso- ì;;hJ¿;h""ing by tlo.boì"rrt air currents within the optical system (internal i"ri"" """*a¡"'.olvetl by placing the entire telescope and spectrogÉph in â r""ìîgiìt iå feels that it lrr"rliå. In view of thesL ma¡or ãdditions to facilities, the-PaneJ being techniques *o,,,1ã ¡" *ir" to await evaluãtion of the new instrumental employed before recommending construction of further solar telescopes' be vigorously sup- Thå Pánel believes, however, thai solar researchers shoulil p-iJ * the development of new auxiliary instruments an¿l in the testing of new methods Copyright © National Academy of Sciences. All rights reserved.

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SIZE CATP.GOAIES The optical telescopes that could be built in the next ten years may be divided into the following arbitrary size categories: Giant: diameter larger than 250 inches Large: 100-20p inches fntermediate : 60-84 inches Small: 36-48 inches Except for tle giant class, the size ranges listed are those represented by existing U. S. telescopes. The gaps are not signi.ffcant, except in the sense that a ready-made, highly successful design cannot be taken over fo¡ the in-between sizes without some scaling up or down. PERF ORMAN CE V ERSUS SIZE The Panel's decision ón what telescopes to recommend for funding has re- quired balancing scientiffc obiectives against size, cost, and time for con- struction. A brief résumé of the interdependence of these factors is necessary to make clear the decisions Ênally taken. Faint star images must be detected against the unavoidable background of the Iight of the night sþ. Astronomical telescopes are normally built to optical and mechanical tole¡ances such that the tremor or seeing disk caused by atmospheric turbulence sets the limit of per{ormance; tlat is, the instru- mental blurríng of a point star image is less than the blurring caused by inllomogeneities in the earth's atmosphere above the telescope. Then the problem of registering a faint star image with a large telescope is one of contrast between the small angular patch representing the star (about 0.5 arc seconds in diameter ulder very good conditions ) and a simila¡ adjacent patch of blank night sky. Under these conditions the brightness of the faintest obiect detectable with a speciûed degree of certainty in a given time does not improve in pro- portion to the collecting area of the telescope obiective ( all dimensions of the telescope being scaled in the same proportion), as would be expected in the presence of negligible sþ background, but only in proportion to the square root of the area. (See, for example, Astronomi,cal Techniques, lJni- versity of Chicago Press, 1962, editecl by W. A. Hiltner, Chapter I by \M. A. Baum. ) The same rule applies to photoelectric photometry of faint obiects 40 L I I tu., Copyright © National Academy of Sciences. All rights reserved.

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spectroscopy anil through a focal plane cliaphragm, antl to low-dispersion ----In spectrophotometry. *ort of the frontier problems the aim is to reach out to the most reached each class' Êut fo¡ these faint obiects the ilistance ¿irt""i "Ui""tt "f assuming the of the telescope' varies only as the square root of the diameter space anil no redshift corrections; allow- inverse-souare law in transparent u"a.äa.UU, *ilt di-ioir' rhe clistance reached. The ;#;i"iilrr*r, lr"riu, tlre square of the diameter for the sizes alreaclv ;ilfä;""d. ", ;;ïr:it;;,h;'.,i"nt" t"l"."op"' oåt vet attempted' the cost mfav beincreasing expected because o the . varr, r"piilv as 2.5-3.0 po*"t oi thu iliameter' ä;í"t-;;i.É ã"rie" ^"å hig¡ ungineering costs' Thus' scince the nphoton umber "r u"-ãt"' Jqo"'"d, th" cost per ollected ;i;ffi;'u.J;î-it'" power of the diameter' from such telescopes varies only as ûte ó/4 or 6/4 and clistance' the But in view of the sqrra,e-'oot í"htio" b"t*""tt diameter reached' The cost varies ;;;;;;t"t ""ah" 5th'or 6th power of the clistancepened.to e(xploration')- ;;ä;5À;;61á power of tle volume of space o where the tight of the - -î;; l"ãi"-j""a high-rãsolution - 'p*åtto'"opy' the gain with tele- night sky does not enter as a backgrountl illumination' ao"' t'uty-"s the sq'are of the diameter' provided^ r"å"àt ìi rã.àåt "ti"*r.u L ptoportion to the iliameter of the collimator of he spectrographî"'"u'"' or.Bowen' Chapter 2 ,h;;"1**t" (See, e-.g., Bo:t"i, p'"'oiorr'- reference'emains unchanged' the É"tï th" "oú-"tot diameter r ;";;;;il;.¡ aperture, and gain with telescope size varies at best as the square r-oot of the gratings large ffä;ä;;;ã tñt " th"," i' tto gain at all' Savailable even for the existing ingle-difiraction are not ;;;;;;;;;;.',he desireil condíIion 24 to 30 inches in ãöó-ii"r.i"r"t-pe' For a 400-inch telescopø a grating-area a size is beyoncl ãi"*ì,"t *""r¿ Ue re(uired for proper eåi"i"ticy' a"ã srrch to these conclusions is that ;"ä;;;;;h-tog'v. dTht ob''"ioi'o"o'ollutvlarger glatings would be i,r"""rrfot iogi.reerin-g evelopment f much -as of the obiectivã'even with existing tele- ;äl-J;; inL""rinittt" "puit"" Such .^,,.,hêc âc is iliscusseil furthår in the section ãn auxiliary instr.ments. still larger instruments' ;;:";'p*;. ;; "" essential preliminary to buildingto ofier in extending the have something Other factors b"ria", "fi'tu'" T onger er(posure times will' for a linear *"tú; ilï;f "1"rg" t"lã'"ope' root of the time detector, pro'drr"" a gain that ia¡esãs the square """","i" iä;ä; ;,h;;tãgraphic pìátes the situation is complicated bv saturation to- tÏe il;;þ;;"ìÉ fail;e. The'u;it """ b" extendeil igainroportionrealizecl np may be Such a square root of the gain i" qi'"n-t"* "ffi"i"o"y' photogrãphic emulsions; the from a practical itn"g" uoåî ito*-improuåd Copyright © National Academy of Sciences. All rights reserved.

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efficiency is-low,enough at present so that there is room for a gain at least as gleât as tliat from doubling the telescope aperture. Better avetage seeing through the discovery of superior sites, or through treatment of the immedil ate surroundings of the telescope, is another obvious possibility. Here the gain is in direct proportion to the reduction in image diamete¡. HOW BIG? An-y rational,ten-year plan to provide facilities for the optical astronomers will inevitably put the major share of the funds into b;il¿ling large tele_ scopes; partþ because tÏey are needed for frontier problem{ anJ partly because experíence has shown t}rat the record of reseãrch yierd froni sucÍr telescopes over tfre whole range of observational astronomy has been an excellent return on the investment. LARGE TELESCOPES The Panel concluded that ffrst priority should go to telescopes in the large_ size c_atego-ry. Three large telescopes in the l50-200-inch aperture range shor'1¿ 6u funded as rapidly as meritorious proposals fo¡ their construction and operation are put forward. proven designi should be used wherever possible, a¡d at least one of the three should be located in the Southern Hemisphere. Each of the large telescopes placed at a new site should include a_ supporting auxiliary telescope. For the Southern Hemisphere site, this should be a 4S-inch Schmidt-type survey instrument. This conclusion was based in the main on the consideration of urgency versus the long time-scale for the "giant x-inch." fn view of the rather slow gain in per{ormance with size, an increase in apertu-re from the Iargest existing instrument (200 inches) to anything less than 350 or 400 inches would hardly be worth the inveitment needed to produce a new engineering design. If ffrst priority were to be given to a "giant x-inch" in tle 350-400-inch aperture range, the cost wodJbe of the order of $100 million, and the time-scale would be ffve to seven years longer þ1r for the straightfor-ward construction of a proven design, iuóh as ùat of the 200-inch Palomar telesc OCR for page 45
the neecl for access to large tele- À seconil important consideration was .";;;;;-;*h 1urser number of astronomers than isnumberossibls and ttlat he now p or fronts advances on a ;""iå:ïä#äåi'itv "o"'""t"ã access' It should be emphasizeil that the "lp-"uel would come with such i will not deny îT9h'": this timethe creation of "giant ¿lecision âgainst consbuction of a to ;.H;"ï":ä; Jdd*lv u'"""n"itrtt"tttold analogousanv large telescope the cutofi or ;:iöffitr';;;;;r";"""b"tor, since is not a suilden one' telescopes wa-s dictated in part The ilecision to recommend thtee s¡ch on faint obiects' outlinetl neeJfor acceleration of research .il;;;;;it b" i-ge telescopes has not in recent vears kept üJi;"ti;í .il" ;id """'l'"' u't'o"i*lcal wãrk force-in the country' Three "i oace wit}r the grovrth of r¡" large tele- *o"r¿ ¿ãï¡i" the number of u' s'-controlled #; ffi äåÇ", mentioneil tu"g" roõ t" zóo it"rt"s' since' as hasleen ::"*ïrh;;tJo'" Uniteil States is in the' in earlier discussion, tf'" outnt"' of astronomershe-number should not be ilecaile' t the r'"xt exnected to double, at te"st, itt of experiencetl operating groups that t¡" ò;;ilio" ;.T""1"* ""-tãt "p'oi""'t'îiul r'i"¿lpr"' tle size of the burden that f äîîï;d"";"i;-riÀr" astronomers' sets an upper î'är¿ be lr-""¿ on thJinstrumentaþ-inclinedhree' of the Panel' this limit is t l" ,f" ü-ir. "p-ron LOCATION OF LARGE TELESCOPES should certainly be located in the At least one of the three large telescopes have three large instr-uments makes Soutlerl Hemisphere' Th" ilÀi* ¿ them at three difier- i"ö;i" ;;ä" *o*tr''I "'ã ob¡""tu"'{iot putting design can- shorten uv ã ptou"o ent sites. And the immedí"t" -r"tto"tio" in telescope of maiol size can bring the interval until a U. S.*""ttåU"¿ sky: riches of the southern observations of the unique ää ""a"t"tpf"it"il Clo'ds ) , the center of our own Mage[ånic the nèarest extemal galuxies lthe "nearest globular clusters' The existing th" .t"u'-th" ;;îC;;itg "enìrh' t"l"t"op"t ii the all in the Northem imbalance, wíth the sete" l;;;;'t 'wor]d ;;ã .h' t*" 7l-i;;i' ;'i'o-u"o in the- southern ausplces t"Ï:*': iï"-öil; in palt under European at infeúor sites, may soon be redresse'l seem logical for the united whatever other countries ;;;;;l;;;"id tul""op" that will bring to the States to set up a So"tft"* ï"-l'ph"t" tltut ttte Ïigtrly suecessful 200- skies the t"-" n";t;;;ã tãtt"tifity southern Hemisphgre' aaescope hìs provicletl in the Northern îJi"-"t i""rt l¡- Copyright © National Academy of Sciences. All rights reserved.

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lliili Unless telescopes in the 150-200 inch aperture range are located at the most favorable sites, their potential usefuIness can be seriously degraded. In the United States, climatological factors make it imperative that large telescopes be located in the soutlwestem part of the country. Thorough lltl investigation of temperaturg wind, clear night hours, Eansparency, ilarkneìs of the sþ, and especially seeing is required before a new site is occupied, il in the United States as elsewhere. Considerations o{ convenience or prox- imity to urban centers are secondary tb ûnding a site of superior quality. UNDER WHAT AUSPICES? The Panel has not attempted to select speciffc institutions for each optical telescope that it recommends to be built. Such designations by the panel could have created conflict-of-interest situations tìat would have prevented qualiûed astronomers from se¡ving on the Panel. For each class of ínstuument, proposals will undoubtedly be put forward ll by universities, research institutions, or associations of universities. For the larger instruments at leas! and particularly in cases where a choice must be made, ad, hoc evaltation panels should be established to review proposals. l,l The Panel has given thought to the general principles to be followed in selecting the organization to build and operate the telescopes of largest li aperture. ll l.i Preaíous PetJormnnce Competence, demonstrated by building a telescope of lesser aperfure and lri producing research results with it, constitutes an essential qualiffiation. The alertness and breadth of experience of the astronomers ässociated with the ltl organization must be weíghed. The group must have shown itselÍ capable of ilt developing auxiliary instruments that work well and of maintaining tlem in optimum condition. Tgpe of Instítutìon There is no single answer as to the type of organization best suited to be the builder and custodian of a large optical telescope. In this, as in quite a num- ber of thÍs country's other educational, cultural, and scientiffc enterprises, ti the strength tåat comes from diversity and friendly rivalry would appear to i,t give the best guarantee of outstanding achievement. ii !ll lji 44 ,ii J ! L+. Copyright © National Academy of Sciences. All rights reserved.

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Since optical astronomy requires a gooil climate, there were strong th" Kitt Peak National Observatory, a national cen- reasons for "ìtubüthlog ter operated by an association of u¡riversities' Such an organization can eogale in actiuities u¡suited to the clouily surroundings of excellent univer- for any one of them to part of the country, and too large ,iuiJlt ttt" ""tt"* nationwicle character of such a center, anil its status as a The manage alone. f"a".ãty ffnancecl facility open to aII qualiÊed applicants, combine to guar- to its telesãopes will be granteil to the less-v/ell-established alr"t ^"""r. center must, of course, have a large telescope' and until jt ".ri"" workers. Such a à*r,lt""tt* *mpleteþ {tllll its objectives' The 150-inch reflector alreaily at the ;ñ;Jby the Kiti Peai National Observatory shouldttre completeil cience be ã".Ii".t pá"ti""l date. This enterprise, approvetl by National S of ìhe thrãã hrge telescopes recommended F;;á"ai"", is counteil as one by the Panel. Certain single universities witlr experience in the operation of an ob- ,u*",ory ,rtqi* Ïkely to ask to be asilgneil the resp-onsibility of building ;il;;i"b;"å;". wháe the qualiûcatiðns -can be demonstrated bevond iolrti tft"." ""ãcl be no hesitatiãn about singling out a particular university i" ifrií *"y. When the funds of the feileral government go into such a proi- but must ect, the oierating instituuon cannot have sole proprietary rights' granting a por- ttt" nÃv astronomical resource as a national asset' "dáitrirt"i ii* of obr"rui.g time to qualified observers from other institutions' Never- theless, the morã intimate association of such a telescope with an astronomi- the plannìng of a with a single instituiion could favor .t"ÍI Ñ;;J;"á concentrated relear"h campaign, when such ismembers Anil ""i "ooo""ted needed' in a ihe fact that tÏe home team of observers would be faculty woultl give a chance ,rniversity, who taught cou¡ses and had thesis students, fo, th" Iarge telescãpe to exert its maximum influence on the educational pro""rr, u,rätt though the graduate students ditl not themselves have access to the insûument. universi- Decisions between competing universities, or between single commitlee t}l':at ties anJ associations, must be grappled with by the ad' hoc facility' The most important require- all the factors for each large "onside.sthe Panelis view, is {ree and open competition' T}ie inter-university ment, in or national center is a valuable device for enabling universities by itself' to clo collectiveþ what no one of them can do as well, or at all' "r.o"iutlon preemption by such But there should not be any automatic, unreviewed Ín the universi- centers of functions that can be carried out as well or better ties. Each assignment should be maile on the merits' 45 Copyright © National Academy of Sciences. All rights reserved.

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Tha Pri.mnrg Goal The decisions to be taken in locating ttre largest and most expensive optical telescopes must be clirectecl to the primary goal-acceleration of astronomi- cal research on the most dificult frontier problems. The quality of the people who builit and administer the new facilities, and particularly the quality of the observers selecteil to use them-seasoned veterans, young developing asùonome.rs, and promising postdoctoral fellows-are more important tìan the organizational structure or tle management scheme. More than one arrangáment has been made to work well by the nuclear physicists in tÏe opurutiott of particle accelerators. But whatever schemes are adopteil to bimg the nation's Iargest telescopes and talented astronomers together, the prinãiple of equality of opportunity must, at this level, be subordinated to ãn insistence on performance-to the requirement of excellence at the top' A GIANT TELESCOPE ENGINEEAING STUDT FOR The Panel recommends that as soon as tlle three large telescopes for the next decade are ulder way, a representative stuily group be assembleil to con- sider the problems of buildÍng a telescope of the largest feasible size, to decide on practícal design concepts, and to prepare a cost estimate for the design adopted. Th"r"ìutt hardly be any doubt of the ultimate desirability of planning for an optical telescope larger than any yet built. Yet, for the reasons given in our discussion of performance and size (p. 40), the next upward step cannot be a small one if a sizable gain in depth-penetrating power is to be realized. A tholoughgoing engineering design study to determine the feasi- bilíty anil cost of a 400-inch or possibly 600-inch telescope ought -to b-e undårtaken before any proposal to start such a project is seriousþ considered' The problems to be consideretl are both optical and mechanical What material tho"ld bu used for the mirror and what technique for fabrication and for producing the ûnal precise shape? What focal ratio is practical anil how shall the enormous surface be supporteil so as to hold its proper shape at all pointing angles? \Mill transportation problems preclude making the mi..oifrom the raw material at any other place than the observing site? Can the mechanically desirable shift to an alt-azimuth mounting-no\¡/ standard for large ¡adio telescopes-be made without loss of following antl pointing u""*Jry? Can the flexure in the very heary mounting be balanced out, or 46 Copyright © National Academy of Sciences. All rights reserved.

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introduce¿l tlrough a com-puter? compensated by corrections ----'SJ"" be one of national dre ånterpríse would, in the enil' uniloubtedly (AURA) in .""pãlaU" ¡tr""i"tiän of Univársities for Research 'A'stronomy organíze.the study' The would be an appropriate agency under which to ;"'ä;;;;tËir¿'¡"Lrd"-o¡tárvational asbonomers' optical experts' and structural engineers of the highest competence' rn""ú"ii""i ""¿ TELESCOPES OF MODERATE SIZE telescopes of ap:rture The Panel recommends rheLt lour general-purpose tä" ão ," Sa.ches be built in the-next ten years'telescopes melf-suficient These are s entioned as ;:iä"ö;, ;J"'" i" "Jalti"" to the suppoiting 42' page to th" large instruments discussetl on - "rr*iüu¡u"same consitlerations àf performance veisui size-that create difficul- The telescopes larger than d", f;;;J;;;;ers contemplatirìg the constr"ction of ,"rì"i¡"tfa are favorable^to thã users of telescopes of i:rtermediate size, instruments ilí"i";ûneã-;¿0 to 84 inches aperture' Experience with such McDonalil (such as the Moo"i \Milson oiservatory and the ;;";l;il research on öUiããi"w l .ho*, th"* to be capable of tuming out first-ratehat from the t t"," ot prtoton collectÍon mav be less ,t}''n iå;il;;il;it page 17' Such telescopes " i"rfJ "*irai"g aelescopes; e*amoL' were cited on of anaþzing insbuments' to support thå complete range rrJi"rg" {or-observational work that would other- "rroigh th"m àin be \iih;;;;"";f "sed latg"st telescopes' the opportunities for wise consume time on one of the developments may be tested access to the latter are multçiieã. Insämental their ù""rt"rreil to the'largest telescope after they have proven ""Ji"i* worth. ""-îrou"n exist' but' where designs for telescopes of intermediate size engineering costs' Instru- ,"q"o¿ *ãitû-ed clesign wouid not involve high tlreir capabilities- are " and' ments,ft*f this size cost a gfeat d.eal, however, -o at good-sites' The conditions need not ,ft"t .lt"old be loJat"d only ,"ät for the wL*t Lí""Jp"s' bul. universíties in the clouclv ;;;';ü;; strong astonomy "s which have, eastern or ãidwestern parts ãf the country' proiluctÍve operators of intermediate-size deoartments anil could qualifu as observatiorial prosrarns' must consider ät:ä#ï""ä"';;;T;i"td Often this coulcl Duttins them at olrr"*i"g tüioot L th" W"'t ot So:uthwest' ^b" on ãt atllacent to an already-occupiecl- site' '.ooth*"rt"- part of the country with universities t trr" *"rt""o o. _À Copyright © National Academy of Sciences. All rights reserved.

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well-established astronomy departrnents can put forward a strong case for intenneiliate-size telescopes. He¡e suitable nearby sites can be found, and the easy integration of the telescopes into graaluate-student thesis problems can be a very important part of tle development and training of new astrono- me¡s. Universities or research instífutions already operating good telescopes of intermediate size or larger should not be excluded from consiileration for an additional telescope ín the 60-84-inch range if the entire case, based on site, productivity, and educational beneffts, is a strong one. The recommendation ol four telescopes is dictated again by the number of institutions with the proper capability anil background. There are now ûve U. S. telescopes in thís aperture range at goorl-climate sites. SMALL TELESCOPES The Panel recommends that eight telescopes of 36 to 48 inches aperture be built in the next decade. These should be fully equipped ¡esearch instru- ments located at dark-sþ sites near universities with active gtaduate depart- ments. Climatic conditions need be given little weight. The case for modern telescopes of research quality as an integral part of the basic local equipment of an ínstitution maintaining a graduate-level astronomy department has been set forth in Section II. The efiectiveness of the concept has been demonstrated at several institutions ín relatively poor or mediocre climates, of which Wisconsin, Michigan, and Case Institute have been cited as examples. While tle 36-to-48-inch aperture range is given, the most useful design thus far has been a 36-inch Cassegrain reflector, equipped with a photoelectric photometer, a low-dispersion spectrograph, and possibly a spectrum scanner. Telescopes in this category are now almost "ofi-the-shelf" items, and need not be re-engineered in each case. Some of the institutions acquiring these telescopes may be acquiring their ffrst instruments with research capabilities. The qualiûcation should be an existing graduate department of demonstrated vitality; at least one faculty member in it should have some aptitude and experience in observa- tional astronomy anil the use of instruments. The ¡ecommend ation of eight such telescopes is based on the number already existing and an estimate of the number of astronomy depârtments that are likely to come forwar¿l with meritorious proposals. The recent rapid development of graduate study in astronomy in universities that previously had only small programs or did not awarcl tlre Ph.D. degree in astronomy at 48 I Copyright © National Academy of Sciences. All rights reserved.

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at the decade ahead will see similar- developments all makes it probable that wilt rilt p"*i¡le that øi*hf such telescopes several more institutions. rn"t ¿"""¿", p'*"'to b" too few' If the sufÊcient number äïåil;"d;tl" set forth here the qualiffcations of small telescopes for insututiã"s meeting oriven a- Iarger number' the should prove to be tweloe t'üJth;; 'dltt' päce"tage of the total expeniliture ,tilt t" ooti" ìä"d:; ä'ãã '-"uwithin the margin ot Panel, and well ä;"-;;Jüthe ^error' in the.36 to 48 inches It should be emphasized inlt '¡" instruments teaching telescopes of' ¡'aáltional aperture range are research tä[t""p"t' gradu- befuncleil from p::llttott for sav. 16 to 30 inch", *"v "pn'åi'tåi"iv *r'l"r' are not within the province of thís Panel' ;îå'l'joî^ö;;úprrrétt, FOR SUMMARY OF RECAMMENDA?IONS OPTICAL TELESCOPES class' The Kitt Peak pro- Thrae Iargetelescopes o{ the 150-to-200-inch I tft" tttt'uments The other two should iecteil 150¡inch is included "t "i" "f be located in the southern ffîitäffift;-"t"', ""i*ì"* o"" 't'outd sites can be considered for Hemisphere. only the t"ty ;"';;;;oi"ltop location. Cost: $60 millíon' three large telescopes are gtå,,p to be formeil as soon as the î*"ît,ö feasible optical reflec- *ell rrnder wav, to considerä" a"ttg";f th-e largest four vears' $1 0 million sptead over .;:'ö;i;áe: aperture to be located 3 Fourmoderate-size t"Ëö;sî;b-io-s+--i""ntrong astronomy depart- with s in above-average 'ä-ü"jásities "fi-"tt mentsorresearchinstitutions'withexceptionalpromiseorpâstachievement îã"iã t" .ft" t""ipients' Cost: $4 0 million' telescopes of 36 to 48 inches 4 Eís,ht fuIly "q"ipp"a äoÏ"'ïï"Sã"i'"e good universities' *"1t-o'g"tti""ã;;;";;ty tlJpartm"nts at to be located "t studv program' baseil or this rour-part construction and fii;lüf#::;t VI¿nil the Appenclix' is thus on the detailed ",tgin""'ioiäiu*"ìi;;tt"" expense incìuded' õä4.ä*inioo, *ith ì'to ope'ii'-'g 49 Copyright © National Academy of Sciences. All rights reserved.