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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
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
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.
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.
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 .
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.
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.