To: sot_shift
Subject: B-1 shift report
Date: Sat, 24 Jul 1999 00:22:50 -0400
From: Tom Aldcroft <aldcroft@head-cfa.harvard.edu>

** Day 204 ** B1 shift report

This was another great day for Chandra science.  Both ACIS and HRC were
successfully activated according to plan, with no issues.

Prior to ACIS activation, trending of the cold radiator temperature showed
an interesting profile, starting off as an exponential decay, and then
appearing to go linear for about an hour.  The assumption was that this
was due to the changing thermal environment as Chandra ascended in orbit.
A worst case linear extrapolation showed a potential thermal issue if
activation were at the nominal time, although the ACIS thermal model 
indicated no problem.  Fortunately this never became an issue, because
a timeline reschedule moved ACIS activation forward by several hours.  Then
the problem was getting Paul out of the shower in time.

ACIS activation began at about 20:07 GMT.  The DPA's and DEA-A were switched 
on, then focal plane temperature setpoint was set at -120 C, detector
housing heater set at -60 C, and pressure transducers were turned on.
ACIS is currently operating with a nominal thermal profile.  The CCD 
temperature was last measured at -118.9 C.  The housing has stabilized
at -60 C, whereas the CCD has not yet reached its setpoint.

For HRC activation, Steve Murray reported (flight notes 32 & 33):

"The HRC-I was activated this evening with low voltage turn on and an internal
 pulse generator test.  The analysis of these data indicate that the
 detector is working very well and is essentially unchanged in its response 
 to test pulses from the integration of the ISIM at TRW about two years
 ago.  This is an excellent indicator that the HRC-I readout system has
 survived launch and is ready for full operation when the high voltage is 
 turned on."

"The HRC-S was activated this evening with low voltage turn on and an internal 
 pulse generator test.  The analysis of these data indicate that the detector
 is working very well.  However, the pulser amplitude used for this test was 
 set low resulting in somewhat noiser data than desired for obtaining a better 
 baseline for HRC-S.  None-the-less, this is an excellent indicator that the 
 HRC-S readout system has survived the launch and is ready for full operation
 when the high voltage is turned on."

On a different note, telemetry dropouts continue to be an issue.  This is
especially a problem for ACIS.  At times there were dropped minor frames
for each ~few major frames. 

-Tom