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NICMOS STScI Analysis Newsletter 14

NICMOS STScI Analysis Newsletter 14

September 1998


        - NICMOS NEWS
          + New NICMOS Information on the WWW
	  + NICMOS Update


New NICMOS Information on the WWW
	by Doris Daou

Similar to all Space Telescope Instruments, the NICMOS home page on
the World Wide Web is updated with all instrument developments. The
NICMOS home page can be found by visiting the STScI WWW page
( and following Observing links to the NICMOS
Web pages.
Since last month, the following items have been newly posted:

	* NICMOS Photometry Update, Last Updated: 2 September 1998
	* NICMOS Parallel Program, Last Updated: 1 September 1998
	* NICMOS Calibration Resources, Last Updated: 6 August 1998
	* NICMOS Focus Update, Last Update: 17 September 98 
	* NICMOS PlateScale Update, Last Update: 25 August 98
	* NICMOS Coronographic Hole Update, Last Update: 25 August 98
	* NICMOS Unit Conversion Tool has been updated.
Since last month, the following Advisories have been posted:

	* The NICMOS "Pedestal" Effect.
	* NICMOS Camera 2 ACQ exposure times.
	* Rate for NICMOS time conversion in error.

Since last month, the following ISRs have been published:

	* Review of NICMOS Performance
	* NICMOS Focus and HST Breathing 
	* NICMOS Focus Data Reduction and Analysis Using Phase Retrieval


NICMOS operations have continued at a steady and high rate with the 
expected completion of nearly the entire NICMOS science program 
by November 15, 1998.  A very small number of programs with 
tightly constrained windows will be done after November 15 as long as 
cryogen remains.  In addition, a stepped up program of routine
monitoring will be conducted as described in detail below.  The
predicted date of exhaustion of cryogen is near the end of December
1998 with about a 30 day uncertainty.  Internal temperatures and
cryogen outflow rates continue to follow predicted curves.  The
focus in all three NICMOS cameras has remained stable despite some
small fluctuations in the best derived NIC3 focus. 

Planning for the end of NICMOS operations is nearly completed.  The 
overall goal of the end of life planning is to obtain data that will 
help characterize NICMOS in the temperature range likely 
to be achieved by the NICMOS Cryocooler and to leave the instrument 
in the safest possible configuration while warm.  Starting on 15 
October 1998 a dark current monitoring program will run several times 
per day during occultations when no other observations are possible. 
This will provide a source of data in the unlikely event that the 
cryogen runs out before 15 November.  Temperature data from thermal 
sensors will be monitored at an increased frequency to look for signs 
of cryogen exhaustion although models predict that a detectable 
change in temperature may occur only days in advance.   
Starting on 15 November, after the completion of most of the 
NICMOS science program, an increased calibration program will go 
into place.  Dark currents will be measured 12 - 14 times per day.  
Flat fields will be taken 4 times per day and focus sweeps will be 
obtained twice per week.  In addition, NIC3 generic parallel 
observations will be taken whenever possible.  This heightened 
monitoring will continue through cryogen exhaustion.   Once the 
onboard temperature sensors are no longer within their calibrated 
range (i.e. at temperatures of about 80K or higher), observations 
with NICMOS will be discontinued.  The NICMOS filter wheel will be 
stowed in the BLANK position as a hedge against additional 
contamination of the filters.  The Pupil Alignment Mechanism (PAM) 
Mirror will be moved to the NIC1/2 compromise focus.  No harm to 
either the filter wheel mechanism or the PAM is expected during warm 
up and subsequent cool down.  NICMOS will remain in this 
configuration until the Cryocooler is installed during the 
next servicing mission, now expected in the spring of year 2000.

                         RECENT PREPRINTS
We draw your attention to these papers, based on NICMOS 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.
"Characterization and Subtraction of Well-Exposed
HST/NICMOS Camera 2 Point Spread Functions for a Survey of
Very-Low-Mass Companions to Nearby Stars"  PASP 9-98


                     APPENDIX: NICMOS Contacts
Any questions about the scheduling of your observations should be
addressed to your Program Coordinator. Post-Observation questions can
be addressed to your Contact Scientist. If you do not know who these
persons are, you can find the information on the WWW at
Analysis, STSDAS or any other HST-related questions can also be
addressed to
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