CALDB Public Release Notes
Version 1.4
CALDB Date: TT=2000-08-17T18:00:00

I. New items:
1. ACIS: New position-dependent temperature-dependent order-sorting tables 
(Four OSIP files)
2. HRC:  LETG/HRC-S Bowtie region filter file (tgmask2 file).
3. PIXLIB (TEL branch): Change in the Rowland spacing value in the PIXLIB 
geometry file. (A temporary fix for the ACIS pixel size error, still under 
investigation.)

II. Effectivity:
All of these files will be used beginning with the release of R4CU5UPD8, on 
and after 2000-08-17T18:00:00. Any data processed with creation dates (FITS keyword "DATE") preceding this date and time will NOT be affected by this change. ACIS and HRC imaging observations will not be affected in any case. Only ACIS-S/grating and LETG/HRC-S observations *that have been processed after this date after this date* will be affected by these changes.

ACIS-S OSIP files:
The following calibration files have been added to the CALDB, for use in the 
TG_RESOLVE tool of standard
data processing:
See $CALDB/data/chandra/acis/cpf/osip/
acisD1999-07-22osipN0002.fits
acisD1999-08-13osipN0002.fits
acisD1999-09-16osipN0002.fits
acisD2000-01-29osipN0002.fits
These are position-dependent files, selectable by the observation dates, which 
correspond to the changes
in ACIS focal plane temperature. They replace the old "IRMF" file, and 
incorporate the CTI-affected response
and gain information for each acis chip, to allow more appropriate separation 
of overlapping orders.
The "IRMF" (integrated RMF table) will no longer be used.

LETG/HRC-S Bowtie region filter:
See $CALDB/data/chandra/hrc/bcf/tgmask2/letgD1999-07-22tgmask2N0001.fits
To reduce the background in LETGS observations, a bowtie-shaped region has been specified which adjusts the spatial window for the HRC-S. The LETG grating pattern is distorted due to astigmatism on the flat plates that make up HRC-S. Having this region specified allows more of the real counts to be admitted and fewer background counts, increasing the S/N.

PIXLIB geometry file: Rowland Spacing Keyword value changed.
See $CALDB/data/chandra/tel/bcf/geom/telD1999-07-23geomN0002.fits
Only the keyword for the Rowland Spacing has changed. This corrects the 
wavelengths (energies) assigned to positions along the detectors in the 
grating L1.5 and L2 analysis. This is a quick fix to allow more accurate 
results in reprocessing of previous observations, without waiting for the CAL 
and IPI teams to resolve the ACIS versus HRC pixel size discrepancy. Currently the issue of changing the relative pixel sizes between ACIS and HRC (by adjusting ACIS pixel size value) will probably occur on the January 2001 time frame.