The Goal is to extract information on the HRC background when the detector is in the "stowed" position.
For our purposes the stowed position will be anytime that the SIM translation motor step position is greater than zero (TSCPOS > 0).
The detector MCP HV must be on and at the operational level
For the HRC-I, this means:
Some values of Hrc S parameters changed in April 2012.
The configuration of the HRC-I (or HRC-S) matters. Data from the
SI_MODE = DEFAULT configuration are the data of interest. For more
information on the HRC SI_MODEs (HRCMODE) see:
The DEFAULT configuration for each instrument has changed over time. Some of these changes are not expected to have an impact on the background (the WIDTH_THRESHOLD and RANGE_SWITCH_LEVEL parameters) but do have an impact on how the event data are processed.
The HRC-I has been operated in a non-DEFAULT configuration a few times, most notably when we are performing the ACIS undercover background. There can be times after these observations when the stowed background data would be collected in this configuration. these time intervals should not be included.
For the HRC-I the important configuration settings to satisfy are:
For the HRC-S the important configuration settings to satisfy are:
The third HRC "stowed" background to do is for the HRC-S high-precision timing configuration: For the HRC-S in the high-precision timing mode (HRCMODE S_TIMING) the important configuration settings to satisfy are:
SCIDPREN has a C-style bit numbering:
|11||2CLMDAST||CALIBRATION MODE ENABLE||10||2FIFOAVR||DATA FIFO ENABLE||9||2OBNLASL||OBSERVING/NEXT-IN-LINE MODE SELECT||8||2SPMDASL||SPECT DETECTOR SPECT/IMG MODE SELECT||5-7||SPARE|
|4||2EBLKAVR||EBLK VALIDITY ENABLE||3||2CBLKAVR||CBLK VALIDITY ENABLE||2||2ULDIAVR||ULD VALIDITY ENABLE||1||2WDTHAVR||WIDTH VALIDITY ENABLE||0||2SHLDAVR||SHIELD VALIDITY ENABLE|
The bit-mask filter SCIDPREN=0000xxxx000xxxxx requires the spare bits to be 0.
Given the time intervals when the SIM translation table has the HRC in the "stowed" position, the subset of times for which the HRC-I has the HV on and at the operational level and which satisfies the configuration settings can be found. Similar time intervals can be found for the HRC-S.
A complication in dealing with the HRC serial-digital housekeeping telemetry (the hrcf*_hk0.fits files) comes from "glitches". These can mark nominally good times as bad. There are three types of glitches:
In principle, the QUALITY bit-array flags the first type of glitch. The second can be at least partially identified by non-zero values to the spare bits in SCIDPREN. A bit-mask check of
should remove some of these second type of glitch. The third type are harder to spot but I have had some success with using MSID 2SMTRATM (the selected motor temperature). Normally, there is no motor selected and the value floats to some arbitrary value. The corruption of the data stems from bytes in the secondary science FIFO getting duplicated and the two bytes preceding 2SMTRATM are spares that stay at a "high" value. A reading of 55-56 for 2SMTRATM indicates corrupted data. For more information on this data corruption see:
For each interval the secondary science rate data should be extracted and merged into a single file for the interval. From each of these interval files the mean, sigma, min, and max of the total (TLEVART) and valid (VLEVART) MCP rates should be determined and incorporated into a table. This will permit investigation of the time history of the background and any potential changes in the valid/total ratio. It will probably be necessary to iteratively clip the rates when calculating the statistics to avoid outliers.
Processing the event data from each interval will require specifying the values for the keyword RANGELEV to do the AMP_SF correction. While earlier I described using time to divide between when it is appropriate to use 90 or 115 the automatic way to do it is to set the value based on MSID 2RSRFALV, which should be essentially constant over the interval. The prescription for the value of RANGELEV is:
RANGELEV = (int)((mean(2RSRFALV) - 127) * 2 + 0.5)
It is also necessary to specify the value of the keyword WIDTHRES to obtain the best tap-ringing correction. Its value is determined by the value of MSID 2WDTHAST, which should be constant during the interval. Its prescription is:
WIDTHRES = (int)(mean(2WDTHAST) + 0.5)
To run hrc_process_events, we also set following parameters.
|Parameters||HRC I||HRC S|
Hrc I uses a different gain file each year starting September of the year.
|Before Oct 30, 1999||hrciD1998-10-30sampgainN0001.fits|
|After Oct 30, 1999 Before Dec 11, 2000||hrciD1999-10-04sampgainN0001.fits|
|After Dec 11, 2000 Before Jan 25, 2002||hrciD2000-12-12sampgainN0001.fits|
|After Jan 25, 2002 Before Feb 21, 2003||hrciD2002-01-26sampgainN0001.fits|
|After Feb 21, 2003 Before Nov 24, 2004||hrciD2003-02-22sampgainN0001.fits|
|After Nov 24, 2004 Before Oct 17, 2005||hrciD2004-11-25sampgainN0001.fits|
|After Oct 17, 2005 Before Sep 06, 2006||hrciD2005-10-17sampgainN0001.fits|
|After Sep 06, 2006 Before Sep 17, 2007||hrciD2006-09-20sampgainN0001.fits|
|After Sep 17, 2007 Before Sep 07, 2008||hrciD2007-09-17sampgainN0001.fits|
|After Sep 07, 2008 Before Sep 09, 2009||hrciD2008-09-07sampgainN0001.fits|
|After Sep 09, 2009 Before Sep 24, 2009||hrciD2009-09-24sampgainN0001.fits|
|After Sep 24, 2009 Before Sep 25, 2010||hrciD2010-09-25sampgainN0002.fits|
|After Sep 25, 2010 Before Sep 27, 2012||hrciD2011-09-19sampgainN0001.fits|
|After Sep 27, 2012 Before Sep 16, 2013||hrciD2012-09-27sampgainN0001.fits|
|After Sep 16, 2013 Before Sep 16, 2014||hrciD2013-09-16sampgainN0001.fits|
|After Sep 16, 2014 Before Sep 27, 2015||hrciD2014-09-16sampgainN0001.fits|
|After Sep 27, 2015 Before Sep 20, 2016||hrciD2015-09-27sampgainN0001.fits|
|After Sep 20, 2016 Before Sep 17, 2017||hrciD2016-09-20sampgainN0001.fits|
|After Sep 17, 2017 Before Sep 17, 2018||hrciD2017-09-17sampgainN0001.fits|
|After Sep 17, 2018||hrciD2018-09-17sampgainN0001.fits|
For HRC S, there is only one gain file.
A separate level 1 type event file should be made for each of the stowed-background intervals. These can later be merged into larger data sets based on time or other discriminators.
Last modified: Mon, 14 Jan 2019 16:33:18