HRC-S Degap Look-up Near the Aim-point

Introduction

The trend in shifting of the aim-point on the HRC-S has caused the dither-pattern for an on-axis source to range onto V-axis coarse positions that haven't been typical in the past. This has led to artifacts in the PSF that are caused by inadequacies of the event-position reconstruction due to the degapping corrections. I have investigated using the algorithms that I used for determining the HRC-I degapping correction for improving the degapping corrections near the HRC-S aim-point.

Data Sets

The table below lists the ObsIDs that I selected for use in the derivation. For each ObsID events were extracted for a 20-pixel radius centered on the on-axis source/zeroth-order.
ObsID SI/Grating Target Date SIM-Z Offset Y-Offset Z-Offset Number of Events
1166 HRC-S/NONE Capella 1999-09-05T21:50:43 0.010 0.000 0.000 10970
1300 HRC-S/NONE Capella 1999-09-05T22:29:57 0.010 0.000 0.000 4581
62435 HRC-S/LETG Capella 1999-09-06T00:27:21 0.010 0.000 0.000 64406
1167 HRC-S/LETG Capella 1999-09-09T12:55:30 0.010 0.000 0.000 30753
1244 HRC-S/LETG Capella 1999-09-09T17:28:18 0.010 0.000 0.000 24861
62410 HRC-S/LETG Capella 1999-09-09T23:43:55 0.010 0.000 0.000 23841
1246 HRC-S/LETG Capella 1999-09-10T02:54:57 0.010 0.000 0.000 30797
62426 HRC-S/NONE Capella 1999-09-12T10:48:28 0.010 0.000 0.000 358545
62422 HRC-S/LETG Capella 1999-09-12T18:22:37 0.010 0.000 0.000 23219
62423 HRC-S/LETG Capella 1999-09-12T23:37:38 0.010 0.000 0.000 29820
1420 HRC-S/LETG Capella 1999-10-29T22:31:27 0.010 0.000 0.000 62943
1248 HRC-S/LETG Capella 1999-11-09T13:28:25 0.010 0.000 0.000 180738
59 HRC-S/LETG HZ43 1999-11-12T04:32:08 0.010 0.000 0.000 351493
758 HRC-S/LETG CrabPulsar 2000-01-31T01:15:42 -1.599 0.000 0.000 651400
58 HRC-S/LETG Capella 2000-03-08T06:30:50 0.010 0.000 0.000 71134
998 HRC-S/NONE ArLac 2000-12-20T14:52:41 0.010 0.000 0.000 3922
1009 HRC-S/LETG Capella 2001-02-14T11:41:47 0.010 0.000 0.000 53979
997 HRC-S/NONE ArLac 2001-05-14T00:05:25 0.010 0.000 0.000 7435
2629 HRC-S/NONE ArLac 2002-01-26T15:54:51 0.010 0.000 0.000 6337
2650 HRC-S/NONE ArLac 2002-08-09T13:20:12 0.010 0.000 0.000 4676
2582 HRC-S/LETG Capella 2002-10-04T23:58:56 0.010 -1.500 0.000 60998
3479 HRC-S/LETG Capella 2002-10-06T10:03:02 0.010 1.500 0.000 53094
4336 HRC-S/NONE ArLac 2003-02-22T02:17:39 0.010 0.000 0.000 4821
4315 HRC-S/NONE ArLac 2003-09-01T11:46:53 0.010 0.000 0.000 3694
3675 HRC-S/LETG Capella 2003-09-28T04:23:10 0.010 0.000 0.000 51750
5081 HRC-S/NONE ArLac 2004-02-09T12:59:22 0.010 0.000 0.000 4224
4575 HRC-S/LETG LMCX-3 2004-04-20T01:52:07 -0.490 0.800 0.000 142658
5316 HRC-S/LETG LMCX-3 2004-05-04T09:26:23 0.010 -0.900 0.000 245135
5317 HRC-S/LETG LMCX-3 2004-05-08T15:22:16 0.493 0.900 0.000 223753
5102 HRC-S/NONE ArLac 2004-11-28T05:42:35 0.010 0.000 0.000 4973
6021 HRC-S/NONE ArLac 2005-02-10T10:38:01 0.010 0.000 0.000 16567
5956 HRC-S/LETG Capella 2005-03-31T08:09:53 0.010 0.000 0.000 84399
6000 HRC-S/NONE ArLac 2005-09-01T20:58:49 0.010 0.000 0.000 13427
6477 HRC-S/NONE ArLac 2006-03-20T05:05:39 0.010 0.000 0.000 20769
6624 HRC-S/NONE XTEJ1701-462 2006-03-27T03:29:48 0.008 0.000 0.000 71185
6472 HRC-S/LETG Capella 2006-04-23T23:31:29 0.010 1.500 0.000 75919
6498 HRC-S/NONE ArLac 2006-09-21T18:56:18 0.010 0.000 0.000 14330
8274 HRC-S/LETG HZ43 2007-03-14T16:15:38 0.010 0.000 0.000 162909
8320 HRC-S/NONE ArLac 2007-09-21T17:06:23 0.010 0.000 0.000 15268
9661 HRC-S/NONE ArLac 2008-09-02T02:37:56 0.010 0.000 0.000 12456
10622 HRC-S/LETG HZ43 2009-03-18T06:17:02 0.010 0.000 0.000 158227
10600 HRC-S/LETG Capella 2009-04-22T04:33:03 0.010 -1.500 0.000 83895
11932 HRC-S/LETG Capella 2009-11-19T20:15:58 0.010 0.000 0.000 77130
12101 HRC-S/LETG KTEri 2010-02-06T06:29:46 0.008 0.000 0.000 184713
10665 HRC-S/LETG Mkn421 2010-03-13T10:10:01 0.008 0.000 0.000 169678
12203 HRC-S/LETG KTEri 2010-04-21T10:46:09 0.010 0.000 0.000 343401
12122 HRC-S/LETG MKN421 2010-07-10T18:38:15 0.010 0.000 0.000 54785
11910 HRC-S/NONE ArLac 2010-09-25T15:05:53 0.010 0.000 0.000 17133
12324 HRC-S/LETG Pi3Ori 2010-11-09T12:17:00 0.010 0.000 0.000 13706
13184 HRC-S/LETG Pi3Ori 2010-11-21T19:23:36 0.010 0.000 0.000 4941
13090 HRC-S/LETG Capella 2010-11-29T14:39:23 0.010 -0.750 0.000 59268
12154 HRC-S/LETG NGC4593 2011-03-02T20:00:10 0.010 0.000 0.000 31753
13025 HRC-S/LETG HZ43 2011-03-16T02:34:32 0.010 0.000 0.000 152862
12915 HRC-S/LETG 1ES1553+113 2011-05-04T08:46:42 0.010 0.000 0.000 79638
12916 HRC-S/LETG 1ES1553+113 2011-06-18T05:50:38 0.010 0.000 0.000 38595
13068 HRC-S/NONE ArLac 2011-09-19T06:06:52 0.008 0.150 0.000 13934
14240 HRC-S/LETG Capella 2011-12-26T11:58:52 0.010 0.000 0.000 59472
14238 HRC-S/LETG HZ43 2012-03-18T05:17:06 0.010 0.700 0.000 80942

The distribution of events (black) and modeled locations (red) are shown in the following plot. Note that there is a lack of overlap between dither patterns near RAWY = 25100.

RawY vs RawX

We have different degapping corrections for each of the AMP_SF settings. However, since the gain has been changing with time the coverage is not the same for each of the AMP_SF sets as shown in the following figure.

RawY vs RawX for the different AMP_SF

The "holes" in the data sets may be filled by including additional observations.

Degapping Corrections

I applied the technique of using the aspect solution to predict the location of the aimpoint on the detector and find the mean RAW position of the events for a given modeled position for events in the combined data set. The figure below shows the result for modeled positions with CRSV = 99. The different colors for the data are for different AMP_SF (1-blue, 2-black, 3-red). the solid line is the CALDB degapping correction. The problem with sparse AMP_SF=3 data is obvious.

CRSV = 99 mean modeled-raw position vs modeled position

The figure below is similar but for CRSU = 8.

CRSU = 8 mean modeled-raw postion vs modeled position

Plots for other CRSU/V are at the following links: CRSV=95, CRSV=96, CRSV=97, CRSV=98, CRSV=100, CRSV=101, CRSV=102, CRSU=7, CRSU=9, CRSU=10.

Using these mean deviation between the modeled I derived an update to the degapping correction. in an effort to remove a bias from the initial CALDB degap, I iterated the process twice applying the newly updated degapping correction to the events at the start of each cycle. The following plots compare the final resulting degapping corrections (hrcs_gaplookup_test_f.fits) in the range of interest to the CALDB version. The CALDB version is shown by the dashed line; the solid colored lines are the updated corrections for various AMP_SF (1-blue, 2-black, 3-red).

Comparison of V-degapping corrections

Comparison of U-degapping corrections

Last modified: Wed Apr 18 14:42:56 EDT 2012

Dr. Michael Juda
Harvard-Smithsonian Center for Astrophysics
60 Garden Street, Mail Stop 70
Cambridge, MA 02138, USA
Ph.: (617) 495-7062
Fax: (617) 495-7356
E-mail: mjuda@cfa.harvard.edu