News: As of May 2005, the implementation of the degap correction is being changed. Previously, the degap calibration product consisted of a set of coefficients for use with a fifth order polynomial. Now, the calibration product is a look-up table for each detector which gives the degap correction for each raw position. These FITS tables are available below (shift-click to download), and were included in CalDB version 3.0.4, released 14 June 2005, for standard data processing only (see release notes here). The tables were publicly released in CalDB version 3.1.0 (23 June 2005, notes here), for use with the new degap algorithm in hrc_process_events (CIAO version 3.3.2, also released 23 June 2005).
These v1 lookup tables are equivalent to the pre-existing coefficients tables (v3 for the HRC-I, and v4 for the HRC-S; see below). Analyses carried out using the new tables will result in data almost identical to that derived previously. Differences will exist between the analyses for coordinate locations that may spill over beyond the nominal tap boundaries.
Forthcoming updates to the HRC-S degap correction are described here.
The software for generating the degap coefficients has been developed by the HRC IPI team as part of their "unix" tools. In addition, Mike Juda has made modifications to the software (for example, to derive coefficients from 1 long HRC-S projection file and generate 1 complete HRC-S degap table, instead of 1 table for each segment).
Version 2 for the I and version 3 for the S did not run with the software available from this site. These versions have been replaced with versions 2.1 and 3.1 respectively. They derive from the same data, but are in standard CXC format.
Version 3 for the I was developed after applying the de-ringing software developed by the IPI team to the sub-assembly flat field data.
For instructions on making degap corrections, please see the appropriate CIAO analysis thread. There is one for the HRC-I and another for the HRC-S.
Information about recently addressed LETG and HRC-S data processing problems is available through the LETG Observer Information page.
|FITS Format (for ASCDS)|
The Chandra X-Ray
Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory.
60 Garden Street, Cambridge, MA 02138 USA. Email: firstname.lastname@example.org
Smithsonian Institution, Copyright © 1998-2004. All rights reserved.