-------------+--------------------------------------------+--------------------- | FFFFFF OOOOOO SSS | STScI | FF OO OO SS | STAN - FOS Analysis | FFFF OO OO SS | Number 4 News | FF OO OO SS | January 1995 | FF OOOOOO SSS | -------------+--------------------------------------------+--------------------- CONTENTS: - HELP FOR PHASE II PROGRAM DEVELOPMENT AND IMPLEMENTATION - FOS NEWS + RE-ACQUISITION RESULTS + POST-COSTAR "FUDGE" FACTORS + FAINT LIMIT OF THE FOS + INSTRUMENT SCIENCE REPORTS - Target Acquisition Strategies - Location of FOS Spectra Cycle 4 - Cycle 3 FOS Red-side Superflats + LSF HEADER KEYWORDS - REORGANIZATION OF FOS SUPPORT - LATEST FOS PREPRINTS - APPENDIX: FOS CONTACTS ================================================================================ HELP FOR PHASE II PROGRAM DEVELOPMENT AND IMPLEMENTATION -------------------------------------------------------- Each cycle 5 PI has at their disposal two people, their Program Coordinator (PC) and Liaison Scientist (LS), dedicated to helping them develop and implement their phase II HST program. By now, all cycle 5 PIs should have been contacted by their PC/LS team, and received their preliminary phase II template, and a submission timeframe for their phase II program. Detailed instructions on the phase II submission were sent out to cycle 5 PIs in December. PIs should feel free to contact their PC or LS for help at any time up through the execution of their cycle 5 HST program. The PCs will maintain a file of advisories on RPS2, for example, so that known problems and recommended workarounds can be accessed easily. Look for this advisory list (and other Phase II documentation) in the World Wide Web page for Phase II Proposal Development: http://presto.stsci.edu/public/rps2home.html ================================================================================ FOS NEWS -------- RE-ACQUISITION RESULTS One can now re-use calculated coordinate offsets from multiple stage peak-ups. The procedure was tested in late December 1994, when a target was acquired and then re-acquired several days later, with the telescope in exactly the same orientation (roll angle) as before. The quality of the re-acquisition was better than 0.03" (and perhaps even better). The position was checked with a 4x4 peak-up, a saving in time. This procedure will be available for Cycle 5 proposals. For more information contact your Program Coordinator, or FOS Instrument Scientist. POST-COSTAR "FUDGE" FACTORS The new post-COSTAR SYNPHOT FOS "fudge factors" are now available in the HST Calibration Database system (CDBS). The purpose of these tables is to bring the total FOS sensitivity, as computed by multiplying the laboratory throughput data for all optical elements within the instrument, into agreement with the post_COSTAR sensitivity measurements derived from standard star observations. Similar pre-COSTAR fudge factors have been used in the past. The use of these factors leads to different count rate predictions with respect to the old version of SYNPHOT. Typically, the new predicted count rates range from about 0.7 of the old predictions at the blue extremes of each grating, to about 0.9 of the old predictions for the red extremes of each grating. The differences are larger in the vicinity of the 2000 A "dip" where the new values range between approximately 0.3 and 0.5 of the old values. The accuracy of count rate predictions for any given flux level should now be approximately 1% for the 1" aperture and roughly 5% for the 4.3" aperture. FAINT LIMIT OF THE FOS The paper "The Faint Limit of the Hubble Space Telescope Faint Object Spectrograph and Rejection of the Cosmic Ray Background" by David Tytler and Christopher Davis, is now in print (ApJ 438, 420). They demonstrate that the faintest object which the FOS can observe is determined by the cosmic ray, not the object flux. They show that 48% of the background counts are from cosmic rays, each of which generate a near instantaneous burst of two or more counts. INSTRUMENT SCIENCE REPORTS Instrument Science Report CAL/FOS-132 "Target Acquisition Strategies", provides a brief overview of the target acquisition strategies appropriate for Cycle 5 Phase II. For more detailed information on this topic, contact your Liaison Scientist, Program Coordinator, or an FOS Instrument Scientist. ``Location of FOS Spectra Cycle 4'' (CAL/FOS-133) outlines the types and amount of drift of spectra on the photocathodes up to Cycle 4 observations. FOS/BLUE shows a drift of roughly 90 YBASES (~ 0.45 arc-seconds) from the Cycle 1 locations, and is seen in all gratings. The FOS/RED showed no obvious trend. New calibration files were delivered to the Archive and have been used in data deliveries from November 1994. ``Cycle 3 FOS Red-side Superflats'' ( CAL/FOS-134) describes the method for constructing the superflats and their recommended usage. Tests indicate that all single-aperture data for the G190H, G270H and G160L gratings taken AFTER 7 August 1992, and single-aperture data for the G190H, G270H, G650L and the PRISM taken AFTER 18 June 1992, should be reprocessed with these new flats. These reports can be downloaded from the FOS' Documents page http://www.stsci.edu/ftp/instrument_news/FOS/fos_bib.html Paper copies can be requested at etkins@stsci.edu. HEADER KEYWORDS: The units of the CDELT1 keyword in the Line Spread Functions header files (.r7h) are wrong. It says "Angstrom per pixel" it should be "Microns (in image space) per pixel". The files will be modified and redelivered in the near future. ================================================================================ REORGANIZATION OF THE FOS GROUP ------------------------------- The groups that are responsible for user and instrument support are being reorganized at STScI. Perhaps the most obvious change for the FOS is the departure of Anne Kinney who has moved from the FOS Team Lead to the Office of Public Affairs. This change is effective immediately. Sherie Holfeltz will be leaving the group on 4 February to take over as the FGS contact person. On the same date the A-Team for the FOS will be integrated into the FOS group. All Cycle 4 proposals that the A-Teams were supporting will continue to be supported as before, and all of the group is committed to provide the best and most timely technical and analysis information on the FOS. ================================================================================ LATEST FOS PREPRINTS -------------------- We draw your attention to these papers, based on FOS data, that will appear in the next few months. This list includes all preprints received by the STScI Library not yet published in the journals. Please remember to include our Library in your preprint distribution list. "The ultraviolet emission properties of quasars" Laor, A.; Bahcall, J.N.; Jannuzi, B.T.; Schneider, D.P.; Green, R.F.; ApJS accepted. "The ultraviolet spectrum of Triton from HST: first results" Stern, S.A.; Trafton, L.M.; Icarus 112 accepted "Rotationally-resolved studies of the mid-ultraviolet spectrum of Triton II: HST surface and atmospheric results" Stern, S.A.; Trafton, L.M.; Flynn, B.; AJ in press. "The physics of massive OB stars in different parent galaxies. I. Ultraviolet and optical spectral morphology in the Magellanic clouds" Walborn, N.R.; Lennon, D.J.; Haser, S.M.; Kudritzki, R.-P.; Voels, S.A.; PASP 2/95 ================================================================================ APPENDIX: FOS contacts ----------------------- Any questions about the scheduling of your observations should be addressed to your PRESTO contact. If you do not know who this person is, PRESTO's Mosaic page (http://presto.stsci.edu/public/propinfo.html) contains that information. Post-Observation questions should be addressed to the FOS Analysis Team, if your program is covered by this pilot project (see article above) or analysis@stsci.edu (410-338-1082). FOS Analysis Team: ------------------ Analysis Scientist: Jeffrey Hayes - hayes@stsci.edu - 410-338-4936 Analysis Specialist: Jennifer Christensen - christen@stsci.edu - 410-338-1265 Analysis Specialist: Stephan Martin - smartin@stsci.edu - 410-338-4724 http://www.stsci.edu/observer/ateam.html FOS Instrument Scientists: -------------------------- Michael Dahlem dahlem@stsci.edu 410-338-4733 Anuradha Koratkar koratkar@stsci.edu 410-338-4470 Tony Keyes keyes@stsci.edu 410-338-4975 http://www.stsci.edu/ftp/instrument_news/FOS/topfos.html ================================================================================ Comments, questions, requests for issues, additions or deletions to the mailing list, etc. can be e-mailed to analysis@stsci.edu ================================================================================ The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. ================================================================================