HEAD High Energy Astrophysics Division

15. Suzaku
Koji Mukai (NASA/GSFC)

Suzaku entered into an automatic power-saving mode on January 24, 2012, and normal operations resumed only after several days of intensive effort by the Suzaku team in Japan. This incident was the result of the gradual degradation of the power-supply capability of the Solar Array Paddle (SAP) since launch in July, 2005 that reached a level at which operations are affected. Since then, all non-critical hardware has been turned off, and the Sun angle range for observations have been reduced to 70-110 deg (from the previous range of 65-110).

Currently, Suzaku continues to obtain scientific data using 3 units of XIS as well as the HXD, as before the January, 2012, incident. The team continues to monitor the SAP performance. Extrapolation of the recent rate of degradation suggests that we can maintain the current mode of operation through early 2014, but this depends on the actual radiation environment, such as the level of solar activity. The team will make every effort to continue Suzaku observations for as long as possible, which will likely involve a partial shut-down of the scientific instruments.

Suzaku AO-8 proposals are due on Friday, November 16, 2012 for observations during April 2013 through March 2014. Proposals should be submitted to ISAS/JAXA, NASA, or ESA, depending on the affiliation of the principal investigator. See the respective mission home pages for further details. Given the SAP situation, proposers should not assume that there will be an AO-9 call for proposals. Furthermore, we no longer solicit new Key Project proposals; completion of already accepted Key Projects remains a high priority for the mission, however. Also note the narrower Sun angle range for observations, principally affecting time-critical observations. Please note that the project may reduce the fraction of time available to time-critical and target-of-opportunity observations (currently 15%), based on an ongoing review of mission scheduling with the narrower Sun angle range.

The XIS team has released an updated calibration of the contaminant build-up, based partly on additional calibration observations, featuring a revised time-dependence of contaminant composition, and a new, time-dependent parametrization of the spatial dependence of the contaminant thickness. This new calibration can be applied by accessing the latest (20120902) version of the Suzaku CALDB, and re-generating the ARF files, using Suzaku FTOOLS newer than version 18. With this release, the low energy calibration of XIS data is significantly improved. There are two earlier calibration updates of note from the XIS team. In one, the increased non X-ray background for XIS1 with 6 keV charge injection is properly accounted for. The other provides an improved calibration of the Si and Al edges around 2 keV in XIS data. See the Suzaku GOF "Data Analysis" page for further details.

In other mission news, the US participation in Suzaku was assessed favorably by the 2012 NASA senior review of operating astrophysics missions. This ensures the continued funding for the US Suzaku GOF and the processing team. Dedicated funding for Suzaku guest observers were not restored, however, so successful US PIs of Suzaku AO-8 proposals will be directed to apply for funding through the ADAP program. We are now halfway through the AO-7 period, and Suzaku is performing a number of coordinated observations with NuSTAR, both for cross-calibration and scientific purposes. Finally, Suzaku continues to participate in joint Fermi-Suzaku and joint Chandra-Suzaku programs, allowing investigators to apply for Suzaku observing time as part of their Fermi or Chandra proposals. See the call for proposals of the respective missions for details.

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