Newsletter No. 99, December 2011

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6. Chandra X-ray Observatory Report
Roger Brissenden (SAO) & Martin C. Weisskopf (MSFC)

Chandra has carried out over 12 years of successful science operations. Chandra's overall observing efficiency has risen to the highest level of the mission, due to the evolution of Chandra's orbit, which has reduced the non-observing time spent in Earth's radiation belts. Science data processing, archiving, and distribution proceeded smoothly, with average time between
observation and data delivery remaining at about a day. In July Chandra carried out its first safemode in over 10 years, caused by a combination of increased gravity gradient torques due to the evolved orbit, and the timing of spacecraft activities near perigee. No hardware problems were involved and the recovery from safemode went smoothly, with no untoward effects.

We are nearing implementation of new on-board and ground-based procedures to adapt to increasing operational constraints and anticipated heightened solar activity. These actions will increase spacecraft safety margins and will in many cases speed up the return to observing after periods of solar activity, maximizing available observing time.

The Cycle 13 Chandra peer review, held in June, approved 199 proposals, out of 664 submitted by researchers worldwide who requested 142 Msec of observing time, ~5.4 times greater than the time available. The 26 Msec of total time allotted is about 6 Msec more than in earlier observing cycles. Among the approved proposals are four X-ray Visionary Projects (XVPs), which were allocated a total of 8 Msec. XVPs are longer observing programs intended to address major questions in astrophysics and to produce data sets of lasting value.

A small organizing committee, led by NASA Project Science put together "12 Years of Science with Chandra", held as part of the May AAS meeting in Boston. The Chandra X-ray Center conducted the workshop "Structure in Clusters and Groups of Galaxies in the Chandra Era" (July) and the X-ray Astronomy School and CIAO workshop (August).

In response to NASA's August Call for Proposals for the 2012 Senior Review of operating missions, CXC and Marshall Space Flight Center program staff are preparing the Senior Review proposal, due in January 2012.

The Chandra Press Office issued 6 image releases and 7 press releases (May-Oct 2011), including one resulting from a televised NASA news conference, and one at an AAS press event. A complete listing is available at http://chandra.harvard.edu/press/.

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