To RHESSI collaborators:

RHESSI has been successfully operating in space for over 14 years now, and it is once again time to rejuvenate the detectors through an "anneal" procedure. RHESSI's germanium detectors will be heated up from their operating temperature of ~130 K to ~70 deg C (~343 K), held at that temperature for ten days, and then cooled back down. The detectors degrade steadily over time due to radiation damage from charged particles, and heating up the germanium restores lost sensitivity and resolution. These detectors have been previously annealed four times, most recently in 2014.

We plan to start the anneal on February 23 (UT), and the entire procedure is estimated to take about two months. During this time period, RHESSI will be unable to make X-ray or gamma-ray observations. If you have any questions about this anneal, please feel free to contact me.

Albert Shih

RHESSI Deputy Mission Scientist

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Albert Y. Shih

Solar Physics Laboratory, Code 671

NASA Goddard Space Flight Center

Greenbelt, MD 20771

Office: 301-286-1843