CALDB Release Notes Version: 2.8 Effective CALDB Date: 2001-09-06T15:30:00 (11:28:54 EDT) Released publicly 2001-09-13 I. Summary of Changes: A. ACIS -120C OSIP files Filenames: acisD2000-01-29osipN0006.fits acisD2000-08-12osipN0006.fits Directory: $CALDB/data/chandra/acis/cpf/osip/ Derived from new ACIS-7 gain data released in CALDB 2.7; ACIS-5 N_sigma values adjusted to reduce clipping of events due to poor gain calibration; ACIS-4 energy range adjusted to accommodate LETG longer wavelength data, as was done with version N0005. Both the new files have identical data blocks. The only difference between them is their effective dates (as given in the filenames) which accommodates programmatic ACIS temperature changes during August 2000. Additional CALDB Changes: There are some changes to the PCAD CALDB branch coming in as well in this upgrade, just to keep the CIAO and Release CALDB's uniform in version number. None of these changes affect CIAO, but they are now present in the standard processing CALDB: B. Version 3 of the CALALIGN PCAD alignment and fid positions matrices. There are 31 new files being added, extending through 2001-06-01T00:00:00. Solves the 1.5 arcsecond ACIS-I DY coordinate offset problem reported in the Chandra Astrometric Accuracy monitor web page, at http://asc.harvard.edu/mta/ASPECT/celmon/index.html C. The FDC, RWA_BSPD, IRU_CHAR, and GYRO_SFMA effective dates have been extended backward from SSD opening to Launch date. This makes running pipelines on OAC phase I data possible with the release CALDB, wherein some of these files are used in processing, though the sunshade door was still closed at the time. II. Technical details A. -120C ACIS OSIP files The -120C FEFs and corresponding ACIS gains have been upgraded recently (CALDB 2.7). The only significant changes were in the data for chip S3. There are incumbent changes for the S3 chip order-sorting and integrated probability data (OSIP) used in grating processing (tg_resolve_events) and effective area analysis. Nominally one expects adjustments in OSIP every time there are any adjustments in gain. Because the files are used in processing, we have had to hold up upgrading the ACIS gains used in the pipelines. This upgrade eliminates that logjam. The file was built using the IDL routine acis_osip_ard_2.3.pro, with the input files acisD2000-01-29gainN0003.fits and acisD2000-01-29fef_phaN0002.fits. The S1 data were altered to eliminate clipping in the oscillating gain values that exist in that chip's current (inadequate) calibration. (S1 gains are about to be upgraded in the coming weeks.) S0 energy values were extended to lower energies to allow lambda > 40Angstroms for LETG/ACIS-S observations. File construction parameters (from the header): CCD_ID; N_sigma_lo; N_sigma_hi 4; -2.5; 5.0 5; -7.0; 5.0 6; -6.0; 6.0 7; -5.0; 5.0 8; -5.0; 5.0 9; -2.5; 2.5 Illustrations of the order-sorting are available at: 1. http://asc.harvard.edu/caldb/Illustrations/Osum_1703_full_003N002_LEG.gif (Obsid 1703, PKS 2155-304, LETG/ACIS-S) 2. http://asc.harvard.edu/caldb/Illustrations/Osum_57_full_003N002_MEG.gif http://asc.harvard.edu/caldb/Illustrations/Osum_57_full_003N002_HEG.gif (Obsid 57, Capella, HETG/ACIS-S) Threads affected: Apply an ACIS Gain Map http://asc.harvard.edu/ciao/threads/acisgainmap.thread.html What: The workaround here in the absence of the new OSIP files has been deleted. The OSIP and GAIN references have been updated in the following threads: Obtain Grating Spectra from HETG/ACIS-S Data http://asc.harvard.edu/ciao/threads/spectra.hetgacis.html Obtain Grating Spectra from LETG/ACIS Data http://asc.harvard.edu/ciao/threads/spectra.letgacis.html The specific -120C OSIP filename has been updated in the following threads: Compute HETG/ACIS-S Grating ARFs http://asc.harvard.edu/ciao/threads/mkgarf.hetgacis.html Compute LETG/ACIS-S Grating ARFs http://asc.harvard.edu/ciao/threads/mkgarf.letgacis.html