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OCR for page 218
Georgian Space Research Program
G . P. KAKHIDZE
Abastumani Astrophysical Observatory
ABSTRACT
This paper presents considerations of telescopes and spectrometers
planned to be designed and made by the Abastumani Astrophysical Ob-
senato~y of the Georgian SSR Academy of Sciences. The purpose of this
topic is to clarify actual scientific problems which are to be solved by using
telescopes. The experiments will begin in 1995.
INTRODUCTION
Telescopes and spectrometers are designed for mounting on the orbital
scientific station of the Mir type with the following characteristics (Orbital
Station Mir 1988~: inclination 51.6°; Bight altitude 3~0 km; orbit period
90 min. The total mass determined by the Georgian Academy of Sciences
Is 10,000 kg; telemetric information l.m bit/e; energy consumption 700 W.
Iblescopes and spectrometers can be mounted in a hermetic com-
partment in the station and on an independent platform enabling one to
carry out astrophysical observations not related to any problems of the
station. The independent platform provides pointing and stabilization not
worse than 1 min. The mass of scientific equipment is ~ 10,000 kg with
dimensions 5 x 5 x 3 me.
After consideration and determma~cion of the actual problems to be
solved, the telescopes and spectrometers will be improved according to
scien~c engineering offers.
Project Marina-3, consisdog of a complex of scientific equipment, has
been proposed for consideration.
218
OCR for page 219
HIGH-ENERGY ~TROP~ICS
219
Project Marina-3, consisting of a complex of scientific equipment, has
been proposed for consideration.
1. An omnidirectional telescope Marina-lM consisting of seven
module The telescope modulus is shown in Figure 1. The telescope is
designed for finding and localizing transient X-ray and gamma ray sources
for measurements of energy and temporal spectra and for determination
coordinates in the energy range from 2 keV to 10 MeV with the energy flux
1O-8 - 1o-4 er~cm2s. T=e resolution of X-ray and gamma ray bursts Is
0.1 msec.
1b measure energy spectra, proportional counters are used for detect-
ing X-rays in the energy range 2-30 keV with the sensitive surface 1.2 x
103 cm2, combined station detectors NaVCsI with the diameter of 200
mm are for detection of gamma radiation in the range 15 keV - 10 MeV,
and then sensitive surface is 1.2 x 103 cm2.
Bursts 1.5 · 10-6 erg/ s are registered by a scintillation detector
with the diameter 60 mm and with a semiconductor detector of mercury
diodide with a sensitive surface of 1 cm2.
The coordinates of X-ray and gamma bursts are determined by a single
coordinate chamber with a coded aperture (Horstman et al.; Bradt et al.
1988) with the field of view 6 x 60°, permitting observation of an image of
the celestial sphere with a transient X-ray source. The elected accuracy
of coordinate determination is of the order of 10 arc see for the energy flux
lO~8erg/cm2 s at the energy 20 keV
The telescope is mounted on a platform outside of the scientific
station, without orientation. Coordinates of transient sources obtained by
the telescope are corrected by a stellar sensor.
TELESCOPE-SPECTKOMETER TAMARA (FIGURE 2)
Scientific problems to be solved with a telescope-spectrometer are:
determination of coordinates of X-ray sources with the angular resolution
2s and measurements of energy and temporal spectra in the energy range
2-30 keV with the time resolution 0.1 m see, that can be obtained by
separate measurements of coordinates and energy and temporal spectra.
1b measure coordinates it is necessary to use a telescope with a mask
(Orbital Station Mir) in order to obtain an image of a region of the
celestial sphere in the energy range 2-30 keV with the energy resolution
of the order of 20%, field of view 8 x 8° with the angular resolution 2
see and the effective area 600 cm2 and time resolution required for image
construction 1 s.
Measurements of energy and temporal spectra in the energy range
2-50 keV are carried out with proportional counters (Bradt et al. 1988) with
OCR for page 220
220
AMERICAN AND SOVIET PERSPECTIVES
Nal/Csl detector array - 50/30nam
Nal scintillation detector 063 x 63mm
Nal/Csl detector array 20/20mm
Bee: Semiconductor detector 010 mm
Proportional counter 350 x 350 x 100 mm
Single coordinate chamber with coded aperture
Position of the detectors on a modulus
Id Coded mask
Collimator ~ ~
Position sensitive
~ proportional counter
Single coordinate chamber with a coded aperture
/Scintillation detector- 5 mm\ 0 2nD mm
-' . , 5mm thick
Ned
I:
_ _ _ ~
_
.
:~
collimator ~l IL I Al 1l 1
30mm thick
~ , ~cO~'~~=
Scintillation
detector 1 Omm thick
Nal/Csl detector
_ _ ~
__
FIGURE 1 Omidirectional Telescope Marina-lM. (a) Position of the omnidirectional
telescope on a platform. (b) Single coordinate chamber with a coded aperature. (c,d)
NaI/CsI detector.
OCR for page 221
HIGH-ENERGY ASTROPHYSICS
221
the angular resolution 2 x 2° and the sensitive area 105 cm2 enabling the
study of millisecond pulsars.
It was suggested that the NASA department of High-Energy Astro-
physics consider a possibility of construction of spectrometers with the
sensitive area 106 cm2 (Telebrpe 1989~.
A telescone-snectrometer is mounted on an independent platform with
orientation.
TELESCOPE-SPECTROMETER NINO FIGURE 3)
Scientific problems to be solved with a telescope-spectrometer are:
determination of coordinates of X-ray sources with the angular resolution
6s and measurements of energy and temporal spectra in the energy range
15-200 keV, with temporal resolution 0.1 msec, it can be reached by separate
measurements of coordinates and energy spectra. It is suggested to use a
telescope with a mask to measure coordinates Curvier et al. 1982; Proposal
1982; Carter et al. 1982~. It allows construction of an image of the celestial
sphere in the energy range 20 to 2~)0 keV with the field of view 8 x 8° with
angular resolution 6s, and the effective area 104 cm2. A gamma chamber is
used in the telescope. The gamma chamber, unlike that of Anger (1958),
is constructed on NaVCsI combined detectors that decrease the registered
background in the image plane. The modulus construction of the telescope
allows construction of telescopes with the sensitive area 104 cm2 and to use
more effective methods (Ricker 1976) for the image reconstruction than
a two~imensional image construction. A stellar sensor operates coa~nal~y
with the telescope, which allows correction of the image at its construction.
The image is constructed in Is. Measurements of energy and temporal
spectra in the energy range 15 to 200 keV and the time resolution 0.1
msec is earned out using the combined NaVCsI detectors with an active
and passive collimator, with the angular resolution 2 x 2°, and with the
sensitive surface 2 x 104 cm2. Telescope-spectrometers are mounted on an
independent platform providing orientation not less than 1 min.
Construction of the celestial sphere image by telescopes in the energy
range of gamma-quanta Q2 - 0.66 MeV is difficult, since there is a Compton
effect in the Nat crystal leading to image defocusing. Combined detectors
BGO/CsI grve a possibility of increasing nnage brightness. The annihilation
line 511 keV will be registered with the efflmengy of 50%. A position
sensitive detector BGO/CsI can be used in telescope Nino.
This offer is based on the findings of the Abastumani Astrophysical
Observatory with the realization of proportional counters in ISZ Proton-l,
2, 3, 4, and of combined scintlllndon detectors in ISZ Cosmos ~56, 914,
1106 and in OS Mir.
OCR for page 222
222
--1
Position of the telescope-spectrometer on the independent platform
AMERICAN AND SOVIET PERSPECTIVES
Independent platform
Telescope with a coded
shadow mask
-
Modulus of proportional
counter
5000
' Coded mask
Stellar
photometer
_, ,
~Coordinate
prop rtional
n or
c~i:
Telescope with a coded shadow mask
Lid
~_~
,$~
Collimate
/~
Proportional
counter
Modulus of proportional counter F = 0.5m2
FIGURE 2 Telescope~pectrometer Armada. (a) Position of the telescope-spectrometer
on the independent platform, (b) Telescope with a coded shadow mask, (c) Modulus of
proportional counter F = 05 m .
OCR for page 223
HIGH-ENERGY ASTROPHYSICS
_
~OC]
OOLIann:~O
I 11 IL::O~aOO~ Telescope with a
non _~ coded mask
con: ore
loo on:
oc~oo~o~o::
00~10~0~
cotta
5000
-
_ Independent platform
-Nal/Csl detector
Position of the telescope-spectrometer on the independent platform
Plastic
detector
5mm thick /~'
~ // -
,~
-I
i
cat
Telescope with a coded mask
223
I= :ask
Passive collimator r Plastic scintillator
2° x 2° \ | 5mm thick
Csl active
collimator
lOmm thick I
f Nal/Csl detector
.; :~: .~25mm
Oo~~ 1Omm thick
Gamma-chamber
with Nal/Csl detector
/
P'~z ~ . ~
3
i\ , ,
Plastic scintillator
10mm thick
Nal/Csl detector
FIGURE 3 Telescope~pectrometer Nino. (a) Position of the telescope-spectrometer on
the independent platform, (by Telescope with a coded mask (c) NaI/CsI detector.
OCR for page 224
224
AMERICAN AND SOVIET PERSPECTIVES
RE~:RENCES
Anger, N.O. 1958. Rev. Sci. Instr. 29: 27.
An X-ray telescope with coded shadow mask TTM-Netherlands. Technical description of
the modulus "Quart" at the orbital Station "MIR."
Bradt, H.V., J.H. Swank, and R.E. Rothschild. 1988. Ihe X-ray timing explorer. Page 7,11.
Prepnot No. MIT-CSR-HEA 88-14.
Carter, J., P. Charalambous, AI. Dean, and J. Stephen. 198Z A Gamma-Ray Telescope for
the 1980's Journal of British Interplanetary Society. 35: 296 CIhe Zebra Telescope).
Horstman, H., E. Horstman Moretti, F. Fuligni, G. DiCocco, W. Dust, F. Forntera, E.
Morelli, and A Sp~chino. Performance of gamma ray camera for astrophysics.
Laboratona TE.S.R.E./CN.R., via De'Castagnoli 1, 40126 Bologna, Italy. Page 539.
Orbital Station MIR. 1988. Reference book for the user.
Proposal to the Science and Engineering Council for a Bntish-led Space Project in
Gamma-Ray Astronomy. November 198Z
Ricker, G.R 1976. A difEraction-limited X-ray shadow camera. Submitted for Publication
in the Astrophysics Journal (Letters).
Rivier, G., J. Paul, P. Manprue. 198Z Sigma: project of space observatory with high
angular resolution to study gamma-ray sources. 33rd Congress of the International
Astronautical Federation, Pans, France.
Teletype information to NASA Department of High Energy Astrophysics. 1989.
Representative terms from entire chapter:
energy range
