HRC-I In-flight Gain





date obsid target Gain maps Normalized Gain maps
mean
mean		 min max mean
mean		 min max
  09/03/99
 171 Cas A 139.2 23.94 0.17 73.79 207.5 177.0 22.02 0.12 106.5 309.1
  09/04/99
 1298 G21.5-0.9 137.0 21.87 0.16 50.40 216.6 175.5 28.33 0.16 73.54 298.7
10/04/99 HRC-I MCP HV final steps were lowered.
  10/23/99
 1409 Cas A 115.5 20.64 0.18 53.85 172.7 146.4 16.31 0.11 77.79 231.9
  10/25/99
 1406 G21.5-0.9 109.3 16.69 0.15 64.14 168.4 139.0 12.91 0.092 104.8 210.7
  11/12/99
 558/559 Coma Cluster 106.1 17.46 0.16 57.63 161.0 134.3 11.91 0.089 90.4 234.7
  12/19/99
 1505 Cas A 110.5 19.93 0.18 58.78 175.3 140.0 12.71 0.091 97.38 200.0
  02/14/00
 557/562 Coma Cluster 113.4 17.97 0.16 60.25 168.7 143.8 12.49 0.087 87.33 258.2
  02/16/00
 142 G21.5-0.9 107.9 16.37 0.15 58.53 169.0 137.5 15.77 0.11 91.57 209.7
SAC median gain map 0.7928 0.1376 0.17 0.4865 1.139

 

Level 1 event lists for HRC-I observations of selected extended sources were retrieved from the Chandra archive. Data were filtered though the "H test" and events from the first few minutes were deleted to eliminate events during HV ramp up.

A mean gain (PHA) map for each observation was created with a blocking factor of 128. These maps were normalized by dividing each map with a gain map generated by taking the median of gain maps (central regions were normalized to unity) from SAC "flight-settings" flat field measurements ["Flight median"].

The histograms and statistics above are for these 128 × 128 gain maps and ratio maps. The data for the two Coma Cluster observations on each of 12 Nov 1999 and 14 Feb 2000 are combined.

On 4 October 1999, the HRC-I MCP HV final steps were lowered. The top plate was taken from 79 to 77, and the bottom plate from 91 to 89. This lowered the overall gain of the detector.

Events from the latter half of the Cas A observation on 10/23/99 were ignored due to exceptionally high background, likely caused by solar flaring.