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Operations CXO Status Report

Friday 18 May 2001 10.00am EDT

During the last week, Chandra completed the observing schedule as planned.

Recent real-time activities included a commanded CTI measurement at 8am EDT on May 6. This measurement and others taken through April show that no significant degradation in the ACIS energy resolution was sustained during April. This is excellent news given the extreme levels of solar radiation experienced during the month, and provides confidence in the monitoring systems and safing thresholds in place. Also, a routine update of the Ephemeris was completed on May 14.

Of note last week was the approval of a new solar torque ground software model used to determine the timing and magnitude of momentum dumps. The momentum builds each orbit due principally to solar pressure and gravity gradient through perigee. The momentum is unloaded by firing the Momentum Unloading Propulsion System (MUPS). The new model is based on actual on-orbit data from the first 18 months of the mission, and is expected to significantly reduce the number MUPS firings.

Two Chandra press releases were issued last week, the first on May 14 presented a new view of the Circinus Galaxy's central supermassive black hole and a host of potential smaller black holes sprinkled throughout its spiral arms. The second release on May 17 reported on the first complete census of compact binary systems in the core of the globular cluster 47 Tucanae. For the full stories and pictures see, and

The planned observations for the coming week are shown below and include an observation of the Gamma-ray source GRS 1915+105 coordinated with RXTE and the VLA.

Q1422+231               ACIS-S       May 21 
Centaurus A             ACIS-S/HETG
Radiation Belts                      May 22 
4U 0142+61              ACIS-S/HETG
GRS 1915+105            ACIS-S/HETG  May 23 
AO PSC                  ACIS-S/HETG
A3112                   ACIS-S       May 24 
Radiation Belts
CAS A                   ACIS-S/HETG  May 25
Cartwheel               ACIS-S       May 26 
NGC4111                 ACIS-S       May 27 
2MASSJ130700+2338       ACIS-I
Radiation Belts
UGC 05101               ACIS-S NONE  May 28


All spacecraft subsystems continued to operate nominally.

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