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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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