Re: AXAF Burn Visibility?

Philip Chien (
Mon, 12 Jul 1999 22:58:25 -0400

>>> Has anyone here started to look into the potential of viewing some of
>>> the insertion burns for the upcoming Chandra (formerly AXAF) X-Ray
>>> observatory deployment on STS-93?
>>> Bill Moore

Ron Lee <> said:

>Here is where I am at a loss.  I have ZERO data on the orbit and ZERO
>info on the burn times.  That adds up to almost no chance to tell
>people when and where to look.   Perhaps Mr Chien can correct the
>lack of info.

Well, I would if people would still call it AXAF instead of Chandra ...
(Who me bitter that they didn't select the name I proposed - nah!)

>The IUS was under investigation due to failure placing a DSP into orbit.
>I have not seen anything that clears the IUS for flight.  If it is not
>cleared, I suspect the Chandra flight will be delayed.

While the Air Force investigation on DSP-19/IUS-21 is ongoing the IUS-27
for AXAF has been cleared for flight with launch planned for July 20th at
12:36 am EDT.  (4:36 UT).

Here's the predicted shuttle orbit for the AXAF/IUS deploy -

STS-93 OMS-2
1 99993P          99201.22870020  .00018250  13934-8  44256-4 0    14
2 99993  28.4662 199.3456 0003191 302.7331 301.7244 15.95038814    15

Here's the key events -

07 h 17 m	AXAF deploy from the shuttle
08 h 17	m	IUS stage 1 ignition
08 h 19 m	IUS stage 1 burnout

320 x ??? km. orbit - I can probably figure this out based on the amount of
propellant in the first IUS stage

08 h 22	m	IUS stage separation
08 h 23 m	IUS stage 2 ignition
08 h 24	m	IUS stage 2 shutdown

320 x 64000 km. orbit, 28.5 degree inclination

Surprisingly the online shuttle press kit at
actually has a decent amount of information.

With a bit of effort I could probably precess the orbits and determine
where the burns take place.

Philip Chien, KC4YER
Earth News
world (in)famous writer, science fiction fan, ham radio operator,
all-around nice guy, etc.