Chandra X-Ray Observatory

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Chandra Electronic Announcement #82

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1. HRC-S Event Position Errors Near the Current Aim Point
2. Chandra-Related PhD Theses

Item 1: HRC-S Event Position Errors Near the Current Aim Point

Recent observations using the HRC-S (whether using the LETG or not)
might be affected by an asymmetry and broadening of the PSF. Chandra aim
point drift over time has placed the aim point onto an area of the
detector that has not previously been subject to detailed PSF
calibration.  The observations falling on this detector "tap" have
revealed problems with photon event position calibration.

The document "HRC-S Event Position Errors Near the Aim Point"
explains all the details.

At least 10 GO/GTO point-source observations (listed in the document)
are known to have been affected. However, any observation made since
the beginning of 2010, or observations made since the beginning of the
mission - observing fields with multiple or extended sources that fall
onto the tap in question - might also be affected. Observers are
strongly advised to read the document which explains how to identify
the problem and outlines implications and remedies for past and future
observations. A revised HRC degap map to correct the problem will be
released in the near future with associated reprocessing
instructions. In the meantime observers with affected observations
should follow the instructions in the document or contact the CXC
Helpdesk. CIAO data analysis threads concerning HRC-S will be updated
in the next two weeks, with links to the document.

Item 2: Chandra-Related PhD Theses

If you or someone you know of has completed a PhD thesis with a
substantial Chandra component that is *not* already listed at

please let us know at, providing as much
information as you have: author, title, institution, year, abstract
and/or a link to the thesis.


Last modified: 02/27/12

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