CALDB Public Release Notes Version 1.2 CALDB Date=2000-06-12T15:25:00 RE: New -110C and -120C ACIS gain files added! I. UPDATE INFORMATION: The Chandra CALDB has been updated to version 1.2, with the inclusion of two new ACIS position-dependent gain files, active for -110C and -120C operating temperatures, respectively. Names and effective observation dates on the files are: -110C (acisD1999-09-16gainN0004.fits) CVSD0001 1999-09-16T00:00:00 Obs date after which file should be used -120C (acisD2000-01-29gainN0001.fits) CVSD0001 2000-01-29T20:00:00 Obs date after which file should be used You will find the files in the Release CALDB, under /data/CALDB/data/chandra/acis/bcf/gain/ and indexed in the new index file caldbN0002.indx under /data/CALDB/data/chandra/acis/index/ The files will also be released on the CIAO web page for calibration data files, and announced to users by the CDO, as soon as possible. The effective CALDB, AP, and CP dates are all the same in this case, specifically at TT= 2000-06-12T15:25:00. This means ACIS obsid files processed in real-time AP, and in CP, after the above date and time, will have used these new gain files, provided that the were observed with -120C or -110C ACIS focal plane temps. The effective observation dates above indicate the date and time of the operational ACIS temperature changes. Users should check the DATE keyword and the GAINFILE keyword to determine whether or not the new gain maps have already been used in processing of their data. All data processed between Jan 2, 2000 and June 12, 2000 would have been processed using the old -110C file, regardless of the operating temperature. The old file is acisD1999-09-16gainN0003.fits. II. TECHNICAL INFORMATION: -110C: This is the second -110C map to be used in SDP and in CIAO. It replaces version N0003, derived from the old, discarded -110C FEF's. However, this update will NOT affect any FI chips. The N0004 gain map is the same as the N0003 for all of ACIS-0,1,2,3,4,6,8, and 9. There is a modification (significant improvement) in the gain maps for the BI chips, ACIS-5 and ACIS-7. Evaluation of ACIS-S3 imaging data should be significantly improved using this file. -120C: This is the first -120C map to be released or used in SDP. By lowering the temperature, we reduce the CTI effect, but the change from -110C is not very linear in chip position or in energy, so it is difficult to give global estimates of the effect on the calibration. However, the -120C file shows the expected trends in the reduced CTI versus distance from the readout on the FI chips. The BI data were recently improved also via modification of the not-ready-for-prime-time -120C FEF's. Final release of the FEF's awaits analysis of recent E0102 observations, to optimize the low-E calibration. This may have zero affect on the -120C gain map. It should also be noted that the performance of the BI chips at -120C is slightly degraded compared with -110 or -100 (optimal for BI's), and the new gains, among other coming items (FEF's, QEU) will reflect this. Comparing ACIS-0, quadrant C0 gains between -110C and -120C, we have: Energy ADU(-110C) ADU(-120C) (eV) at ysub=31 at ysub=31 277 16.87 22.95 392 43.93 50.71 525 75.44 83.03 548 80.93 88.66 553 82.12 89.88 930 171.01 181.07 1.487 301.80 315.23 1.830 382.52 398.04 1.860 390.62 406.34 1.940 409.53 425.74 3.314 734.09 758.68 4.510 1016.04 1047.91 5.898 1343.62 1383.95 8.048 1851.67 1905.10 9.886 2284.52 2349.12 TABLE 1: Gain chart showing the affect of the CTI versus FP_TEMP for the most extreme case, y=31, the farthest cell from the readout, of ACIS-I0, quadrant 0 (FI chip). The relative affect of lowering the temp to -120 C decreases with increasing energy, and so high-E photons are not as much affected.