CALDB Release Notes Version: 2.24 CALDB effective date: 2003-09-23T14:00:00 SDP (Internal) Release ONLY This CALDB version is to be released internally only, simultaneously with the installation of DS 7.0.0 in Operations, which requires the three new files included below. A later CALDB release with CIAO upgrades will include these files in a public release. I. Summary of Changes A. SIM positions file version N0002 Location: $CALDB/data/chandra/sim/bcf/pos/ FILENAME: simD1999-07-22posN0009.fits Description: The purpose of this change is to allow the obidet pipeline to correctly update the sim_z_offset value in the actual obspar. sim_z_offset is calculated according to sim_z_offset = SIM_TRANS_Z - SIM_Z where SIM_Z is the SIM translation stage position in the STF coordinate system (derived from SIM telemetry), SIM_TRANS_Z is the value from Table 1, recorded in the TRANS_Z_n columns of the SIM position ARD, and sim_z_offset is the SIM translation stage offset. For historical reasons, the sim_z_offset recorded in the ocat has the opposite sign for the SIM Z position when compared to the CXC standard STF coordinate system. To enable simple comparison between the actual obspar values and the ocat (and also all existing archived predicted obspars), we preserve this reversal of sign for the sim_z_offset (only) here. Affects: OBIDET L0.5 pipeline. Does not affect CIAO in any way. B. HRC Tapring Test Coefficients, version N0002 Location: $CALDB/data/chandra/hrc/bcf/tapring/ Filenames: hrciD1999-07-22tapringN0002.fits hrcsD1999-07-22tapringN0002.fits Description: HRC events processed on the lowest gain setting (AMP_SF=3) and which have an even number of amplifier tap values exceeding a threshold are subject to the tap-ringing problem (see http://cxc.harvard.edu/contrib/juda/memos/ring_evt_id/event_id.html) for a complete description of the problem). The problem is in determining when an even number of tap values are above threshold. At present, this is done by examining the ratio of tap values AU1/AU2 or AV1/AV2. Whenever these ratios exceed a constant, the event is corrected for tapringing. Values of the constants are contained in the current tapringtest files in CALDB. In October, 2000, an HRC operating parameter that determined when event widths were labelled as "wide" was set to a value that made it clear when events had an even number of tap values above threshold. This provided an independent, unambiguous means of identifying events subject to tapringing. Examination of events observed after this date indicate that a better test for identifying tapringing events prior to October, 2000 is a staright line, i.e., AU1 > A * AU2 + B, and similarly for the V axis. Thus two constants are now needed for each axis. The new constants are contained in the new versions of the tapringtest CALDB files. Affects: hrc_process_events (HRC L1 pipeline) Note: Affect on CIAO in the near term is that reprocessing data with CIAO 3.0.1 or earlier version will NOT include the new CALDB files OR the new software. Any HRC data process with DS 7.0.0 or later, and then reprocessed with CIAO 3.0.1 hrc_process_events or earlier version, will remove the PSF enhancement that these new files and software provide. A future release of CIAO (expected December 2003) will include these new CALDB data and the software in hrc_process_events.