Preface to the AO-7 Version

The AO-7 version of the ASCA Technical Description is organized in the same way as the AO-6 version and contains much of the same information. The performance of the SIS continues to suffer increasingly from the effects of radiation damage which is now so severe that 4-CCD mode observations have not been feasible for some time. Observations in 2-CCD mode are subject to restrictions in the choice of available modes due to the effect of hot pixels and the effect of RDD now becoming noticable for 2-CCD mode. 1-CCD mode observations still remain the least affected. However, even in 1-CCD mode, the energy resolution has now degraded to $\sim 4\%$ in the Fe K band, only a factor of $\sim 2$better than the GIS. The extent to which radiation damage will restrict observations, especially of extended objects, cannot be ignored and is discussed throughout this document, in particular the ``Performance Update'' chapter (Chapter 3).

As for AO-6, the anonymous FTP site for ASCA data and documentation is:

heasarc.gsfc.nasa.gov

Users should look in the directory asca/nra_info and its subdirectories. Each directory has an explanatory README file that appear on the screen when you first enter the directory.

In versions of this appendix prior to AO-6 an observation log was included in order to assist in finding out about any previous and/or already scheduled observations of your proposed object(s). This list of observations is rather large now so has been omitted since the AO-6 version. Observers are recommended to (1) check the ASCAMASTER catalog using the W3BROWSE facility on the World Wide Web (WWW) and (2) check the AO-6 timeline. W3BROWSE is accessible, for example, from the ASCA GOF page at the URL

http://heasarc.gsfc.nasa.gov/docs/asca/ascagof.html

(click on the W3BROWSE button at the bottom of the page). Once in W3BROWSE, click on a button to choose the required interface, click on ASCA, and then click on `Search By:' Coordinates or Object Name. Next, click on Begin Search, select the ASCAMASTER catalog and then enter the Object Name or coordinates, followed by a click on Submit Query. The AO-6 timeline is also accessible from the ASCA GOF page by clicking on the Timelines and Mission Info button.

The email address to which questions and comments about the NRA should be sent to:

ascanra@athena.gsfc.nasa.gov

Please remember that electronic submission of proposals is compulsory; in addition, we now require the PostScript files of the forms and the scientific justifications, to be uploaded via the RPS web interface or via anonymous ftp. Details are in Appendix C of the NRA.