Spacecraft and Other Technical Requirements for ASTROSAT

Power		:	420 watts (with UVIT)
			210 watts (X-ray payloads alone)
Weight		:	592 kg (X-ray payloads)
			782 kg (with UVIT)
Memory required onboard ASTROSAT		:	8 Gbits (X-ray payloads)
			2 Gbits (Housekeeping)
			50 Gbits (UVIT)
Tele-commands :
	Pulse commands	:	80 to 100
	16 bit data commands	:	100
	Time tagged commands	:	30 to 40

Telemetry bit rate to download the data once in 12 hours	105 Mbits per sec
Ground station support	Peenya, Lucknow, Car-Nicobar, Mauritius, also stations in Brunei & Indonesia. Support from Bears Lake and Wilheim needed in initial phases of ASTROSAT operations
Dedicated date links	Between ISTRAC-TIFR and ISTRAC-ISAC to transfer about 20 Gbytes of data per day.
Spacecraft	3-axes stabilized with pointing capability in any direction, having top deck of 1.8 m x 1.8 m and height (along roll axis) of not less than 3 m
Orbit	600 km altitude near circular orbit with inclination $\vert b\vert< 15^{\circ}$
Attitude control	Pointing accuracy of $10^{\prime\prime}$ to $20^{\prime\prime}$
Target acquisition accuracy	Within one arc minute
Jitter in Pointing	$\leq 20^{\prime\prime}$
Aspect Determination	Post-facto accuracy of $5^{\prime\prime}$ read out every 2 sec.
Slew rate	$5^{\circ}$ /min or better along any of the 3-axes.
Onboard Fuel for pointing	Should last at least for 5 years. Should cover at least 1000 different target sources in 5 years mission life, with requirement of multiple pointings at a give target at different times.
Star Sensor	2 Star Trackers needed for ASTROSAT with the capability to detect 8th magnitude stars in visible band. At least 3 stars in $6^{\circ} \times 6^{\circ}$ FOV of each target. Baffle design such that any source with sun angle $\geq 30^{\circ}$ is observable.
Thermal Control	LAXPC : $+10^{\circ}$ to $+30^{\circ}$ C.
	CZT : $0^{\circ}$ to $-20^{\circ}$ C
	SXT : CCD cooled by thermoelectric cooler to $\leq -60^{\circ}$ C
	SSM : $+10^{\circ}$ to $+30^{\circ}$ C