From ssm@latte.msfc.nasa.gov Fri Mar 28 01:09:41 1997 Received: from space.mit.edu by wiwaxia AA15402; Fri, 28 Mar 97 01:09:40 EST Received: from head-cfa (head-cfa.harvard.edu) by space.mit.edu AA08660; Fri, 28 Mar 97 01:09:38 EST Received: from latte.msfc.nasa.gov by head-cfa (SMI-8.6/SMI-SVR4) id BAA18289; Fri, 28 Mar 1997 01:08:12 -0500 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 GAA20065 for ; Fri, 28 Mar 1997 06:08:34 GMT Message-Id: <199703280608.GAA20065@latte.msfc.nasa.gov> To: head@head-cfa.harvard.edu Subject: Return of the HRC Status Reports Date: Fri, 28 Mar 1997 06:08:34 +0000 From: "Stephen S. Murray" Status: R Having taken the time to get some sleep, I am happy to report that we had an exciting time watching the first images of X-rays being reflected off othe the flats formerly known as Drake! Last night (CST) the High Energy Suppresion Filters were tested using the C-Ka line source. While there are details to be worked out. It does appear that the flats are reflecting in the low energy region (recall that we had determined that there is little reflectivity at 2.56keV). This fifth first light experiment was very nice and Martin Weisskopf has lost a bet to Jeremy and me (he owes us both a large cup of coffee - we aren't sure if that is one cup to be split or one cup each). The sixth first light followed quickly with the LETGS being placed in the beam and aimed so that the spectrum fell on the HESF. We have a very interesting image to analyze from this experiment - hopefully there will some day be time to give it the attention it deserves. I does appear that the flats are working. WE need to better understand the geometry of the flats relative to the detector and the HRMA, and the gratings. Added to the night's (early morning) excitement was the dreaded molecular contamination test. In this measurement we aim the 0-th order of the LETGS on the boundary between HRC-S segments (to prevent over exposure on the MCPS) and then look at a high energy, hig intensity continuum source obtained using the Carbon anode running at 15keV with a boron filter to surpress the C-Ka line. The idea is to look for absorption features in this spectrum from contamination on the HRMA (or other elements in the optical path). We cautiously set up this observation to make sure the aim point was correct and that there were no unexpected bright lines in the spectrum due to conamination on the anode. I am happy to say the observation was made without any problems - again we have a very nice image that will require a lot of work to analyze. Following these C-Ka runs, and a ton of effective area and point spread measurements that have become more or less routine, we switched to the Be-Ka target. Fluxes from this source (108ev) are very low, observations take a long time (we can get about 1ct/sec in the HRC-I) which is very nice for the 2-nd floor teams. Martin W and Steve M (me) took some very nice grating spectra of the Be-Ka source at various voltages and filter combinations to make sure we could in fact use the planned data. Having the grating to analyze the source is a great tool - thanks to Peter P for his help. We are now on a series of Be-Ka effective area tests that will take up most of the next 12 hours before we look once again with the HESF to measure the refectivity at this energy. Overall the HRC-I and HRC-S are operating very well. There have been virtually no detector problems. We are stll concerned that there are areas of lower response on the HRC-S than expected - these variations can be calibrated out, but it means less throughput than we had hoped for. Other than this, the results are very close to what we had expected. 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 ___________________________|___________________________________________________