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ASCA Guest Observer Facility

GOF Status Report

--by N. E. White, GSFC

There are 17 papers in the June issue (Vol 40, no 3) of the Publications of the Astronomical Society of Japan, PASJ, with more to appear in the following August issue. The November 10, 1994 issue of the Astrophysical Journal letters is dedicated to ASCA papers, and an additional 15-20 papers are expected. These early papers provide a quick sample of the depth of science the new capabilities of ASCA provide.

The first round of Guest Observer observations are now complete, and we are well into the AO2 program. A few AO1 observations did not accumulate their full allocation of time because of various operational factors and these are being rescheduled (see Petre's article, page 4). The deadline for AO3 proposals is August 30, and is for one full year of observations starting Dec 1, 1994. An observation log prepared by M. Itoh is given in this issue and provides an "as-flown" timeline. In the near future, the requested and obtained exposure times will be added to this log. It is planned to use the GIS as the determining factor for the observation time. The clean criteria for the SIS are more complex and sensitive to the requirements of the observation. Some SIS observations may lose time due to bright earth contamination and users should let the GOF know if they think their SIS time is under exposed.

A regular stream of first-time ASCA users are visiting the Guest Observer Facility here in building 2 at GSFC to learn the nuances of ASCA analysis from the expert support staff. While the analysis of ASCA data is relatively straightforward, and possible anywhere in the world, there are many new techniques to learn. The ASCA GOF has continued to expand its World Wide Web service to include the latest information (Smale, et al.) . This information includes calibration uncertainties, user guides, the observation program, status of the data processing and distribution, this newsletter, to name but a few. By using the Web, it is possible to disseminate information rapidly to ASCA users.

The next major event for ASCA will be the opening of the archive. By agreement between ISAS and NASA, the data taken during the performance verification phase will enter the public domain 18 months after the observation date. These data will be delivered in 1-month batches to the High Energy Astrophysics Science Archive Research Center, HEASARC, for public access. The first batch will cover PV data taken from April 15 to May 15, 1993 and will be available on November 15,1994. All US and US/J GO data delivered to prior to May 16, 1994 will be released one year after that date. For data deliveries after May 16, 1994, the data will enter the archive 1 year from the date of receipt for US and US/J data. All Japanese and J/US GO data will be delivered to the HEASARC 18 months after the data were received by the PI. In all cases, 2 weeks will be assumed for delivery of the data. The data will be accessible the same way ROSAT data currently is provided by the HEASARC. This will include the anonymous ftp area on, and via an e-mail request to the NSSDC Data Archiving and Distribution System, NDADS. The HEASARC Browse will be used to search the archive list and access the available data. More details about the archive structure and access will be contained in the next issue of ASCANews.

This issue of ASCANews provides several articles on the current understanding of the calibrations. The SIS and GIS background is described by Gendrau and Kubo, et al., respectively. The performance of the SIS and the predicted degradation due to radiation damage is discussed by Rasmussen, et al. This damage is now perceptable and is causing both a reduction in the detector resolution and the rate of hot and flickering pixels. Rasmussen, et al. show that this mostly affects operation of the full field of view (2222 arcmin) 4-CCD mode, and that the 1-CCD (1111 arcmin) performance is not significantly affected. Other articles summarize the GIS response calibration (Ishida, et al.), and explain the mysteries of the SIS Dark Frame Error/echo effect (Otani and Dotani). These articles demonstrate that the ASCA calibrations are well in hand.

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