Piplines/Tools affected:
DS 7.6.11.2 ACIS L1 pipeline and CIAO 3.4/4.0 tool acis_process_events,
parameter "tgainfile", L1 Event File Keyword "TGAINFIL".
Analysis threads affected:
"Create a New Level=2 Event File"
http://asc.harvard.edu/ciao/threads/createL2/index.html#acis
"Apply the Time-Dependent ACIS Gain Correction"
http://asc.harvard.edu/ciao/threads/acistimegain/
CIAO Information Pages:
Please refer to the web page "How CalDB 3.4.2 Affects Your Analysis"
http://cxc.harvard.edu/ciao/releasenotes/ciao_3.4_release.html#HowCALDB3.4.2AffectsYourAnalysis
See also the ACIS Time-dependent Gain "why" page:
http://cxc.harvard.edu/ciao/why/acistgain.html
B. Chandra Proposal Cycle 10 "PIMMS" effective areas
Location: $CALDB/data/chandra/acis/cpf/pimms/
Filenames: acisiD2007-11-04pimmsN0010.fits
acissD2007-11-04pimmsN0010.fits
Location: $CALDB/data/chandra/hrc/cpf/pimms/
Filenames: hrciD2007-11-04pimmsN0010.fits
hrcsD2007-11-04pimmsN0010.fits
Location: $CALDB/data/chandra/tel/grating/hetg/cpf/pimms/
Filenames: acisihetg0D2007-11-04pimmsN0010.fits
acissheg1D2007-11-04pimmsN0010.fits
acisshegmeg1D2007-11-04pimmsN0010.fits
acisshetg0D2007-11-04pimmsN0010.fits
acissmeg1D2007-11-04pimmsN0010.fits
Location: $CALDB/data/chandra/tel/grating/letg/cpf/pimms/
Filenames: acisiletg0D2007-11-04pimmsN0010.fits
acissleg1D2007-11-04pimmsN0010.fits
acissletg0D2007-11-04pimmsN0010.fits
hrciletg0D2007-11-04pimmsN0010.fits
hrcsleg1D2007-11-04pimmsN0010.fits
hrcsleghiD2007-11-04pimmsN0010.fits
hrcsletg0D2007-11-04pimmsN0010.fits
Tools affected:
PIMMS effective area viewer, and count rate estimator.
III. TECHNICAL DETAILS
A. ACIS T_GAIN updates (Epoch 31)
Four files are included in the upgrade because 1) we are maintaining two different T_GAIN sets, one with BI chip T_GAIN corrections for the non-CTI corrected case, and one with
the appropriate corrections for the BI chips when the BI CTI correction IS applied, and 2) we provide a flat file to cover the final available epoch so that no long-term extrapolations are calculated in the absence of the next-in-line T_GAIN corrections, in this case the TBD Epoch 32 corrections (Nov 2007-Jan 2007).
Table 1: New T_GAIN files and components, with the files
being replaced. The EPOCH1 and EPOCH2 values given
are for the NEW files.
|
NEW FILENAME (*.fits) |
OLD FILENAME (*.fits) |
EPOCH1 (UTC date in sec) |
DELTPHA1 INPUT (*.fits) |
EPOCH2 (UTC date in sec) |
DELTPHA2 INPUT
(*.fits)
|
CVSD0001 |
| acisD2007-05-01t_gainN0005 |
acisD2007-05-01t_gainN0002 |
298339265.184 | corrgain2007-05-01.v4 |
306288065.184 | corrgain2007-08-01.v4 |
2007-05-01 |
| acisD2007-05-01t_gainN0006 |
acisD2007-05-01t_gain_biN0002 |
298339265.184 | corrgain2007-05-01.v4 (FI only), corrgain2007-05-01.v5 (BI only) |
306288065.184 | corrgain2007-08-01.v4 (FI only), corrgain2007-08-01.v5 (BI only) |
2007-05-01 |
| acisD2007-08-01t_gainN0002 |
none; new "flat" file |
306288065.184 | corrgain2007-08-01.v4 |
314236865.184 |
corrgain2007-08-01.v4 |
2007-08-01 |
| acisD2007-08-01t_gain_biN0002 |
none; new "flat" file |
306288065.184 | corrgain2007-08-01.v4 (FI only), corrgain2007-08-01.v5 (BI only) |
314236865.184 |
corrgain2007-08-01.v4 (FI only), corrgain2007-08-01.v5 (BI only) |
2007-08-01 |
The EPOCH1 value is the midpoint between the CVSD value of the given file and the CVSD of the NEXT file in the series. The EPOCH2 value is the midpoint (numerical average) of the CVSD values from the next TWO files in the sequence. For the last two files in the table, EPOCH2 is the midpoint time between 2007-11-01T00:00:00 and 2008-02-01T00:00:00.
The files tagged as version N0002 above have the same data in DELTPHA2 as in DELTPHA1, and hence the file interpolates over two identical data values, and so the result is an identical value. Hence such a file is known as a "flat file", preventing two-point trends from being extrapolated too far into the future.
Graphical presentation of the effects of the new T_GAIN data versus the existing data (to be replaced):
Fig 1: I3 aimpoint, version N0005 files. Click to see a larger image.
Fig 2: I3 Aimpoint, version N0006 files. These should appear the same as in Fig 1, as they are in fact the same data, in different files.
In both of the above figures we can see that the T_GAIN correction at the I3 aimpoint is currently dimishing with time over Epochs 28 - 30.
Fig. 3: S3 aimpoint, NO CTI CORRECTION APPLIED!:
Fig. 4: S3 Aimpoint, for events WITH CTI correction applied:
In general, then, the changes introduced by these new data are quite small, namely less than a few percent of the
value of Photon Energy for each event to which they are applied, relative to the existing data. However, these
new data will be the standard going forward, until the version N0002 files are updated by the next Epoch's release.
B. CY10 PIMMS Effective Areas
The PIMMS Effective Areas for Proposal Cycle 10 are included in the release of CalDB 3.4.2. These files are virtually ineffectual as CalDB files in the Chandra/CIAO proposal planning software, as they are read in during the building process at the CXC, and are essentially never read from the CalDB by CIAO.
However, users may find techinical details and support information for PIMMS EA's for CY10 at the following posted locations:
"Cycle 10 PIMMS Effective Areas" at http://cxc.harvard.edu/caldb/prop_plan/pimms/index.html
and input data information at
"Cycle 10 PIMMS Effective Area Public Information," http://cxc.harvard.edu/caldb/prop_plan/pimms/pimms.html