From ssm@latte.msfc.nasa.gov Wed Apr 9 19:05:54 1997 Received: from space.mit.edu by wiwaxia AA05991; Wed, 9 Apr 97 19:05:53 EDT Received: from head-cfa (head-cfa.harvard.edu) by space.mit.edu AA27937; Wed, 9 Apr 97 19:05:52 EDT Received: from latte.msfc.nasa.gov by head-cfa (SMI-8.6/SMI-SVR4) id TAA03747; Wed, 9 Apr 1997 19:04:26 -0400 Received: from latte.msfc.nasa.gov (ssm@localhost [127.0.0.1]) by latte.msfc.nasa.gov (8.7.5/8.7.3) with ESMTP id XAA15918 for ; Wed, 9 Apr 1997 23:05:03 GMT Message-Id: <199704092305.XAA15918@latte.msfc.nasa.gov> To: head@head-cfa.harvard.edu Subject: HRC Status Report #8 Date: Wed, 09 Apr 1997 23:05:03 +0000 From: "Stephen S. Murray" Status: R The HRC calibration is moving ahead rapidly. All of the EIPS tests are completed (with possible retesting at Mg-Ka being considered) and the HIREFS tests have been accelerated due to the deletion of a few tests at the higher energies that were not possible due to lack of flux. The Penning source tests have begun and there are some problems with the source that have been fixed, but the source flux is low and is diminishing as the testing proceeds. We expect to complete this phase of HRC testing about the end of the day on April 10-th! The hardware is functioning very well. A few highlights from the data analysis are that we have a very nice image of the PSF taken with C-Ka. The HRC can "see" the slight assymetry of the telescope as detected with the pinhole scans. Our FWHM radius for the PSF is about 0.4 arcsec which is basically the HRC resolution limit (FWHM 20 microns). We also have some impressive HRC-S/LETGS images that include easily seen high orders of the grating (I could count up to 13-th order on both sides). Peter P. tells me that the grating focus test data look very good and that the resolution of the grating at low energies is outstanding. Once we complete the final calibrations and bring the data and some of our analysis computers back to Cambridge we will be generating some of these images in a form suitable for general viewing - stay tuned. Overall the HRC measured performance is not terribly different from the expectations. We think that the Spectrometer efficiency is down slightly from the predictions, and is less than the Imager (perhaps 10-20%). There are also variations in the detective efficiency as a function of position which need to be dealt with using flat field data that we have not yet obtained. This may be greater than we had expected particularly at lower energies. The good news is that the HRC energy "resolution" may be better at lower energies that we expected (Lower energies mean below C-Ka). When the HRC calibration (with HRMA) is completed we will remain in the XRCF for a few days while the @C calibrations are completed. During that time we plan to take a long look at the on-board Fe-55 calibration source to have a good baseline for the on-orbit use of this function. When the XRCF is repress'ed, HRC will be removed (ACIS will be mounted) and we will begin work on some instrument refurbishment. A few corrections need to be made -e.g. the limit switches on the main door are wired backwards, and we want to replace the rather ugly "garage" (sheet metal section where the open door is "parked") with something more pleasing to the eye (and sturdier). During calibration we noticed a possible race condition in our command decoder, a simple electrical fix has been designed and tested, we will make that change on the flight unit. Following these repairs, we will begin the qualification environmental tests required of a flight instrument - EMC testing, Vibration, and Thermal Vacuum. These will all be doen at MSFC, so many of the HRC scientists and engineers will be traveling back and forth during the next two months. Finally we will go back to XRCF for flat field tests. We have 14 days of continuous operation planned to permit use to look at about 7 energies with each detector and accumulate about 10 million photons per flat field. That will give us a few percent statistics on about a 1mm x 1mm scale! It takes 50,000 seconds at the maximum HRC count rate to make these images, thus the 14 days. Then off to beautiful Boulder Co. and the ISIM! Steve Dr. Stephen S. Murray - Sr. Astrophysicist Associate Director - High Energy Astrophysics Division _______________________________________*_______________________________________ Smithsonian Astrophysical Observatory__| phone: (617) 495-7205 High Energy Astrophysics Division __| fax: (617) 495-7356 60 Garden Street, MS-2 __| email: ssm@head-cfa.harvard.edu Cambridge, MA 02138 __| http://hea-www.harvard.edu/~ssm/HomePage.html ___________________________|___________________________________________________