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| GGGGGGG HH HH RRRRR SSS |
STScI | GG HH HH RR R SS | STAN - GHRS
Analysis | GG GGG HHHHHH RRRRR SS | Number 7
News | GG GG HH HH RR R SS | April 1995
| GGGGGGG HH HH RR R SSS |
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CONTENTS:
- GHRS NEWS
+ "Timeout Fix"
+ Another noisy Diode
+ Cycle 6
+ Incorrect Count Rates Using Synphot
+ Changes in the GHRS WWW pages
- SCIENCE WITH THE HUBBLE SPACE TELESCOPE - II
- RECENT GHRS PREPRINTS
- APPENDIX: GHRS CONTACTS
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GHRS NEWS
---------
by D. Soderblom
GHRS Group Lead
Timeout Fix
-----------
In the past month, the "timeout fix" for the GHRS has been installed as part of
the flight software and it has been shown to work properly in several real
instances of carrousel resets. The fix is necessary because once in a while
the grating carrousel takes a little too long to get to its proper position and
locked into place. In the past, this delay caused the subsequent observation
to be dropped entirely so that the overall schedule after that would not be
disrupted. In some cases these data losses could be serious and at the least
were a nuisance.
The "fix" causes the current observation to be terminated a little
early so that the overall schedule is maintained with minimal data loss. In
nearly all cases we expect this scheme to result in negligible loss of data or
quality of science. However, data reduction will be complicated somewhat
because portions of observations will have slightly different integration times
than other portions. We are checking the reduction system to ensure that this
situation is handled properly.
Another noisy diode
------------------
Diode number 237 (counting the first science diode as #1) has been occasionally
noisy. Rather than risk corrupting your observations, we have elected to turn
this one off. There are only about half a dozen GHRS diodes that have shown
similar problems and have had to be turned off, so this is a minor problem.
Use of COMB addition when in ACCUM mode gets around dead diodes by displacing
the spectrum (see the Instrument Handbook).
Cycle 6
-------
The Cycle 6 Call for Proposals and associated documentation will soon be
issued, including a new GHRS Instrument Handbook. You may have to specifically
request a copy of the Instrument Handbook, but we urge you to do so when
writing your proposals because it contains much new information.
We anticipate that Cycle 6 will be the last for the GHRS and it will be a short
one besides. There are many things the GHRS does that STIS will be able to do
at least as well, but also some things STIS is not as good at. Cycle 6 will be
your last chance to use the GHRS for such science.
Incorrect Count Rates Using Synphot
-----------------------------------
by Steve Hulbert
It has recently been discovered that count rate calculations for the GHRS
spectral modes using SYNPHOT are incorrect. The errors do not affect target
acquisition count rate calculations. The problem has been traced to incorrect
throughput tables for the GHRS gratings.
Count rates calculated with the incorrect throughput tables are systematically
too low by a factor of 10-100. Consequently, exposure times based on these
calculations will be too long. If you have used SYNPHOT to make such
calculations for your proposals please send email to hulbert@stsci.edu so that
we can double check your exposure times and avoid any potential problems.
Changes in the GHRS WWW pages
-----------------------------
by Lisa E. Sherbert
A new User Support section has been added to the GHRS Instrument Page. It will
lead you to information about visits and STScI contacts. More documentation is
accessible from the Documents anchor (formerly Manuals and Reports), including
links to the HST Data Handbook, GHRS STAN. Calibration questions were added to
the Frequently Asked Questions file. There is also a pointer to the Instrument
Definition Team's Web page.
Dates are listed next to the topics on the top GHRS page to let you know when
something underneath has been updated. Please remember to always check the
Advisories section, especially if the date is more recent than the last time
you looked.
Also, to make moving around a little easier, the top page now has a button to
take you back to the Instruments Page and buttons to the top GHRS page have
been added to the bottoms of the lower pages.
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SCIENCE WITH THE HUBBLE SPACE TELESCOPE - II
by Ethan Schreier and F. Duccio Macchetto
A Scientific Conference co-organized by the ST ScI and ST-ECF
Paris (UNESCO Buildings) December 4-8, 1995
During the two years following the Maintenance & Refurbishment Mission which
restored the full capabilities of HST, this orbiting Observatory has produced
very impressive scientific results, many of which have opened new insights into
our understanding of the Universe.
The aim of this Conference is to present and discuss these results in all areas
of astronomy. It will consist mainly of invited reviews. A limited number of
contributed papers and posters will be possible. The program will include
reviews of future HST Instruments, plans for future maintenance missions, and a
Special Session on "Education and HST."
The Scientific Organizing Committee consists of P. Benvenuti, J. Bergeron, R.
Fosbury, H. Hammel, R. Kirshner, R. Kudritzki, D. Macchetto, G. Miley, V.
Rubin, and E. Schreier.
A Second Announcement, including a Registration Form and hotel information,
will be distributed in June. The deadline for submission of titles and
abstracts for contributed papers and posters will be in September 1995.
Please return the information below, preferably by e-mail, to:
Cheryl Schmidt at the STScI (schmidt@stsci.edu) or
Britt Sjoberg at the ST-ECF (bsjoeber@eso.org).
------------------------------------------------------------------------------
Science with the Hubble Space Telescope - II
O I intend to participate in the Conference
O I intend to submit a Paper/Poster
Preliminary Title:
O Please include my name in the distribution list
------------------------------------------------------------------------------
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RECENT GHRS PREPRINTS
---------------------
We draw your attention to these papers, based on GHRS 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 distribution of metal-absorbing high velocity clouds in the galaxy"
Bowen, D.V.; Blades, J.C.; Pettini, M.; ApJ 8-1-95
"Interstellar Mg II absorption lines from low-redshift galaxies"
Bowen, D.V.; Blades, J.C.; Pettini, M.; ApJ 8-1-95
"Interpretation of anomalous UV transitions of Fe II observed in laboratory FTS
and stellar HST and IUE spectra"
Johansson, S.; Brage, T.; Leckrone, D.S.; Nave, G.; Wahlgren, G.M.; ApJ 6-10-95
"Deuterium and the Local Interstellar Medium Properties for the Procyon and
Capella Lines of Sight"
Linsky, J.L., Diplas, A., Wood, B.E., Brown, A., Ayres, T.A., and Savage, B.D.
1995, ApJ, in press.
"An HST archival study of galactic interstellar zinc and chromium"
Roth, K.C.; Blades, J.C.; ApJ accepted
"The local Ly alpha forest: association of clouds with superclusters and voids"
Stocke, J.T.; Shull, J.M.; Penton, S.; Donahue, M.E.; Carilli, C.
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APPENDIX: GHRS 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
contains that information.
Post-Observation questions should be addressed to the GHRS Team, or
help@stsci.edu (410-338-1082).
GHRS TEAM
---------
Instrument Scientists:
Steve Hulbert hulbert@stsci.edu 410-338-4911
Claus Leitherer leitherer@stsci.edu 410-338-4425
Al Schultz schultz@stsci.edu 410-338-5044
David Soderblom soderblom@stsci.edu 410-338-4543 Group Lead
Technical Assistants:
Anne Gonnella gonnella@stsci.edu 410-338-4584
Lisa E. Sherbert lisa@stsci.edu 410-338-5036
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Comments about this newsletter, questions, requests for issues, addition or
deletions to the mailing list, etc. can be e-mailed to help@stsci.edu.
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The Space Telescope Science Institute is operated by the Association of
Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.
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