CALDB PUBLIC RELEASE NOTES Version: 3.0.1 CalDB Effective Date: 2005-02-08T14:00:00 CalDB 3.0.1 is a short patch to the basic 3.0.0 version released in December 2004. It brings CIAO HRC-S effective areas up to date with PIMMS and proposal planning files for Cycle 07. It also provides an improved energy scale for ACIS-S/Grating observations via slight ACIS-S chip corner position corrections to the PIXLIB GEOM file. I. Summary of Changes A. HRC-S QE/QE Unifomity (QEU) upgrades Location: $CALDB/data/chandra/hrc/bcf/qe/ Filenames: hrcsD1999-07-22qeN0007.fits hrcsD1999-07-22qeuN0004.fits These new files bring CIAO LETGS grating ARFs up to date with the new LETGS effective area calibrations posted in November 2004. (See "LETG Observer Information: LETG+HRC-S EA" http://cxc.harvard.edu/cal/Letg/Hrc_QE/ea_index.html. They also make CIAO ARFs consistent with the effective areas in PIMMS and in the Proposal Planning files for CY07. See the web pages for PIMMS and Proposal planning files: http://cxc.harvard.edu/caldb/prop_plan/index.html Related "Why" topic: "HRC-S QE and QEU" http://cxc.harvard.edu/ciao3.2/why/caldb3.0.1_hrc_qe.html Threads affected: Compute LETG/HRC-S Grating ARFs http://cxc.harvard.edu/ciao/threads/mkgarf_letghrcs/ B. PIXLIB geometry file: ACIS-S chip corners corrections; MEG period modification Location: $CALDB/data/chandra/tel/bcf/geom/ Filename: telD1999-07-23geomN0005.fits The HETG calibration and science planning teams have released corrected ACIS-S chip corner positions for chips ACIS-45689. (ACIS-7 is unchanged, as are all other corner positions.) These corrections, while having negligible affect on the imaging astrometry for ACIS-S, eliminate wavelength errors of the order .002 Anstroms in the HETG and LETG spectra with ACIS-S. In addition, a small correction to the MEG grating period has been included, which makes the HEG and MEG spectra more mutually consistent. Pipelines/tools affected: DS ACIS-S/Grating Level 1.5 processing / CIAO tool "tg_resolve_events" Related "Why" Topic: "PIXLIB Geometry File" http://cxc.harvard.edu/ciao3.2/why/caldb3.0.1_geom_v5.html Threads most significantly affected: "OBTAINING ACIS-S/Grating spectra with HETG or LETG" http://cxc.harvard.edu/ciao/threads/spectra_hetgacis/ http://cxc.harvard.edu/ciao/threads/spectra_letgacis/ There is a minor affect on the ACIS-S/Grating ARF threads, which also use the GEOM file: http://cxc.harvard.edu/ciao/threads/mkgarf_hetgacis/ http://cxc.harvard.edu/ciao/threads/mkgarf_letgacis/ C. PIXLIB aimpoint file: HRC-S imaging default aimpoint added Location: $CALDB/data/chandra/tel/bcf/aimpts/ Filename: telD1999-07-23aimptsN0002.fits This upgrade has no affect on CIAO software. "dmcoords" does access the aimpts file but does not use the aimpoints data within it in its calculations. For some time now the default HRC-S imaging aimpoint has been located differently from the LETG/HRC-S default position, so that in imaging mode sources would appear more near the center of the HRC-S2 plate. The default for LETGS is offset due to the presence of the HESF in the UV ion shield. The PIXLIB "aimpts" file stores these default positions for use by "obidet" in the pipelines. The new file includes an extra aimpoint designation for the HRC-S imaging mode. The change has no affect on the current software (DS 7.5) because the software will not look for the new configuration aimpoint; but in DS 7.6 and beyond, the new aimpoint position will be used by obidet. PIPES/TOOLS affected: OBIDET (L0.5) in the DS pipelines. Threads affected: NONE II. Technical Details A. HRC-S QE and QEU upgrades The LETGS/HRC-S calibration team has upgraded the HRC-S QE and QEU using observations of cosmic calibration sources PKS 2155-304, Mkn 421, and HZ 46. The procedure used involves taking ratios of positive and negative first order count spectra obtained by summing the data from several observations of these sources. The corrections to the original QEU as derived from flat field measurements of the HRC-S array are derived from the slope of the curve which is the deviation of the counts ratio from the ratio of the original QEU. (By taking the ratios, other model components cancel out, leaving the counts ratio versus the QEU ratio.) Once the QEU has been corrected, an iteration of the QE versus wavelength with the LETGS effective area is necessary. The procedure is reviewed in the 2004 CCW paper "Improvements to the HRC-S QE uniformity and LETGS effective area" located at: http://asc.harvard.edu/ccw/proceedings/index.html/presentations/pease/index.html The new MCP QE is Cal's "version 4," and may be seen on the HRC QE web page at http://cxc.harvard.edu/cal/Hrc/mcp_qe.html The QEU is posted at "HRC-S Flat field map": http://cxc.harvard.edu/cal/Hrc/flatfield.html#hrc-s The new HRC-S QEU is calibration version 3 on that page. B. PIXLIB geometry file: ACIS-S chip corners corrections; MEG period modification The gratings CAL and SDS teams have identified very small changes to the ACIS chip corner positions which are insignificant in the astrometry calculations, but are meaningful to grating spectral wavelength calculations. In addition, a slight refinement to the MEG period has been included. These values are stored in the PIXLIB GEOM file in the CalDB, and hence a new version of this file has been built and tested, and is ready for installation in the CalDB. The new corner positions are presented and justified in the posted memorandum "Update on ACIS-S detector corner positions; MEG period" http://space.mit.edu/ASC/docs/docs.html#acis_s_geom The new MEG grating period is also to be found on the Cal web page http://space.mit.edu/HETG/technotes/chip_gaps04/chip_gaps04.html. The value has been modified from 4001.41 to 4001.95. In addition, M. Markevitch, who maintains the calibration of ACIS sky coordinates, reports that the new file leaves image coordinates well within astrometry uncertainties for ACIS, and indicates the file is good to go. C. PIXLIB AIMPTS version 2 Purpose: Add a new aimpoint HS2 to differentiate HRC-S imaging SIM focus position from HRC-S spectroscopy SIM focus position. The new aimpoint will be used only by obspar_upd to ensure that the nominal SIM positions are correct in the obspar for HRC-S imaging, to eliminate a SIM focus mismatch warning in the new V&V software in this circumstance (the actual SIM position is determined from telemetry and is not affected by this change). Also cleaned up (unused) ACIS-I1 aimpoint (AI1) that must be present in the file to have same SIM focus position as the ACIS-I3 aimpoint (AI2). There are also small numeric changes in the precision of each aimpoint position, as in this version these are computed using the conversions from SIM motor steps using transform coefficients provided by Eric Vrem (May 1999). The following SIM motor step positions were used: AIMPOINT_NAME SIM_X SIM_Z ------------- ----- ----- AI1 -536 94459 (Unused; chosen to give same SIM_Z as previous ARD version) AI2 -536 92905 AS1 -468 75620 HI1 -716 -50505 HS1 -991 -99612 HS2 -1065 -99612 NEW FILE DATA DUMP: dmlist telD1999-07-23aimptsN0002.fits data --------------------------------------------------------------------------- Data for Table Block AIMPOINTS --------------------------------------------------------------------------- ROW AIMPOINT_NAME AIMPOINT[3] DESC 1 AI1 [-0.78234819833843 0 -237.4997090701] ACIS-I1 aimpoint 2 AI2 [-0.78234819833843 0 -233.5924630914] ACIS-I3 aimpoint 3 AS1 [-0.68426746699586 0 -190.1325231040] ACIS-S aimpoint 4 HI1 [-1.0402925884 0 126.9854943053] HRC-I aimpoint 5 HS1 [-1.4295857921 0 250.4559758190] HRC-S spect aimpoint 6 HS2 [-1.5333365632 0 250.4559758190] HRC-S imag aimpoint