Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.stsci.edu/institute/org/ins/files/DMMReports/2004DMMReports/Dec2004 Дата изменения: Mon Jan 10 19:19:31 2005 Дата индексирования: Sun Dec 23 22:06:34 2007 Кодировка: Поисковые слова: reflection nebula

Instruments Division


December 2004 Highlights



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JWST Branch

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JWST Science Instrument and ISIM Support Highlights for December 2004
* Jerry Kriss published "Recommendations for JWST FITS Formats and
Keywords", STScI-JWST-TM-2004-0025 A.
o The output FITS format will have 1 SCA per file, with multiple
frames in an exposure stored as planes in a data cube.
o Keywords corresponding to data in the science data header
packets are defined.
o Handling ancillary engineering data is still under discussion.
* Ed Nelan published "JWST Science Instrument Target Acquisition
Concepts", STScI-JWST-R-2005-0001 A.
o It allocates target acquisition functions to ISIM FSW and to
Activity Description scripts.
o Detailed requirements still need to be developed.
* Ed Nelan published "The Density of Stars in GSC-2 at High Galactic
Latitudes", STScI-JWST-TM-2004-0021 A.
o If only one guide channel is available, the 90% requirement (MR-
365) is met for all but a few small regions of the sky, provided
the FGS has the sensitivity to utilize GSC-2 to its full depth.
o It recommends an outline for a more thorough characterization of
GSC-2 for supporting JWST operations.
* The MIRI Operations Working Group held their first meeting.
o Margaret Meixner (STScI) leads this group. Vicki Balzano also
provides support.
o The process was discussed, and the charter was modified to
address concerns and confusions.
o The features list was discussed, and the group has taken an
action to prioritize the list by Jan. 6.
o Monthly telecons start Jan. 18 to begin work on the MIRI
features.
* The NIRCam Operations Working Group held their first meeting.
o John Stansberry (UA) leads this group. STScI representatives
include Peter McCullough and Vicki Balzano.
o A password-protected website and an email exploder have been set
up.
o Prioritization of the list of NIRCam features is the next task.
* Alex Fullerton completed an outline for an overview of the FGS-TF
calibration plan.
* The group reviewed Lionel Mitchell's draft Mission Efficiency Memo.
Biggest issues:
o Nelan corrected the formulation of the overhead due to guide
star acquisition failures.
o Meixner argued for a higher proportion of short MIRI
observations.
Plans for Next Month
* Valenti, Fullerton & Nelan will continue work on NIRSpec and FGS
calibration plans.
* Rhoads will continue examining cross-instrument calibration issues and
supporting HST and Spitzer observations for JWST.
* McCullough, Meixner, Regan, and Nelan will continue their support for
the NIRCam, MIRI, NIRSpec, and FGS Operations Working Groups.
* Valenti will start the JWST proposal planning tools study.
* Nelan will continue evaluation of the S&OC guide star catalog
requirements.


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ACS + WFPC2 Branch

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SELECTED HIGHLIGHTS


* The ACS suspended on 12/28/2004 due to a reset of the Main Electronics
Board, probably due to a particle impact during SAA passage. On
12/30/2004 the computer was reset and ACS was returned to normal
operations.

* All ACS+WFPC2 phase II proposals were submitted for the on-orbit two-
gyro tests in February 2005.

* Phase II reviews were completed for the majority of the ACS and WFPC2
Cycle 13 augmentation programs.

* An ISR was completed about the photometric stability of ACS. The
instrument is overall extremely stable, but there is evidence for a
very small decrease in the overall sensitivity of the ACS WFC at a
rate of 0.004 +/- 0.001 magnitudes per year.

* A detailed study of photometric transformations and zeropoints for the
ACS filters was completed by members of the ACS IDT and members of the
ACS+WFPC2 Branch at STScI, and submitted to PASP.



Observation Planning/Scheduling


* The ACS suspended on 12/28/2004 due to a reset of the Main Electronics
Board. A "suspend" state is one where the normal activity of the ACS
computer is halted and it is left running its boot code. This is the
first time since its installation that ACS has suspended. Analysis
suggested that the suspend was due to a particle impact during SAA
passage. On 12/30/2004 the computer was reset and ACS was returned to
normal operations. There were no anomalies during the recovery, the
computer is working normally, and ACS has resumed its normal observing
schedule.

* All ACS+WFPC2 phase II proposals were submitted for the on-orbit two-
gyro tests in February 2005. Program 10443 will observe a globular
cluster to quantify the properties of the PSF in two-gyro guiding
mode, as well as PSF repeatability, pointing and stability within the
orbit. Program 10444 will test similar issues during CVZ observations.
And Program 10445 will test the ACS coronagraphy mode.



Reference File Deliveries


* For ACS, 48 new dark frames and 12 bias frames were delivered to the
data reduction pipeline.

* For WFPC2, 114 new dark frames were delivered to the WFPC2 data
reduction pipeline.

* For WFPC2, a new IDCTAB was delivered to the reference file database.
This file contains filter dependent geometric distortion coefficients
for WFPC2. It can be used with the MultiDrizzle software for WFPC2
image combination.



User Support


* Phase II reviews were completed for the majority of the 71 proposals
accepted for ACS or WFPC2 as part of the Cycle 13 augmentation.

* New PSF sharpness tables were delivered to the ACS ETC, to fix an
error that occurred for relatively red sources observed with the SBC.



Documentation


* ACS/ISRs released:

04-17: The Photometric Stability of ACS: Revisiting the Hubble
Deep Field
Riess
http://www.stsci.edu/hst/acs/documents/isrs/isr0417.pdf

* Final modifications were submitted for a new version of the ACS Data
Handbook that fully describes the incorporation of MultiDrizzle into
the ACS pipeline. Release of the new document is expected in the
coming month.



Calibration


* Members of the ACS IDT, and members of the ACS+WFPC2 Branch at STScI
completed a detailed study of photometric transformations and
zeropoints for the ACS filters. The results are presented in a paper
(Sirianni et al.) submitted to PASP. The preprint is available through
the STScI and IDT web sites.

* Ten epochs of 15-tile ACS WFC mosaics imaging the HDFN in the F850lp
filter over two years, originally obtained for the science goal of
finding type Ia supernovae at z>1, were used to examine the
photometric stability of the WFC (with at least filter f850lp). Using
repeated measurements of 371 stars, a multi-variate linear regression
was performed to determine the dependence of photometric variations on
the time-dependent components of parallel and serial CTE degradation
as well as an overall time-dependence, which would indicate a change
in the WFC's sensitivity. Despite important differences between the
HDFN scenes and those in the original calibration field of 47 Tuc
(i.e., source crowding and sky level), the losses due to imperfect CTE
are consistent between the two independent calibrations.
Interestingly, there is also a decrease in the overall sensitivity of
the ACS WFC at a rate of 0.004 +/- 0.001 magnitudes per year
(consistent with findings based on 47 Tuc data from work in progress
by Mack et al. 2005, in prep.).

* The Phase II program was submitted for the last of the Cycle 13 ACS
calibration programs. Program 10378 will observe a highly polarized
reflection nebula to check for phase retardance effects in ACS
polarimetry.

* A study continues on the optimum and minimum length of ACS anneals. It
would be desirable to shorten the anneals to facilitate the building
of an efficient HST observing schedule. A shortened test anneal (6
hours, as compared to the present 12 hours) is being planned for
February 2005.

* A study is underway of the guiding performance of HST with three
gyroscopes, for comparison to the test data expected in February 2005
with two-gyro guiding.




Other


* An article about ACS and WFPC2 was submitted for the STScI Newsletter.

* Text about ACS and WFPC2 was submitted for inclusion in STScI Annual
Report over 2004.



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Spectroscopy Branch

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SELECTED HIGHLIGHTS


* A test to ensure that STIS can still provide sufficient load during
HST Battery Capacity Tests while in safe mode was successfully
executed on December 9th.

* A comprehensive STIS STAN (Space Telescope Analysis Newsletter) was
released to the HST community on December 15, 2004.



DETAILED ACTIVITIES



Instrument Health and Safety



* STIS remains in safe mode following the loss of 5-volt DC power in the
Side-2 electronics in August 2004. STIS heaters remain on, but the
instrument is otherwise inoperative.

* A test to ensure that STIS can still provide sufficient load during
HST Battery Capacity Tests while in safe mode was successfully
executed on December 9th. STIS commanding was rewritten to turn on the
STIS Control Electronics Box while keeping the other electric
components dormant. The current draw was as expected (about 0.7 Amps).




Pipeline


* The scripts for the revised STIS fringing tasks (prepspec,
mkfringeflat, normspflat, and defringe) in the STSDAS 3.3 release were
found to have been corrupted during the delivery process. New
corrected scripts were prepared and a patch was made available.

* Release notes for the new and modified STIS routines in calstis 2.17
were written and posted on the STIS web site.

* STAN articles were published describing the recently delivered changes
to the calstis and calhrs calibration pipelines.

* A script for fixing Doppler correction errors in early E140M TIME-TAG
data was released, along with instructions for using it.

* IDL routines developed by the STIS IDT were formally delivered on the
smalls domain of the SunFire. This software is used to create PHT
reference files. Archiving these routines on the SunFire gives a
permanent record of how these calibrations were done and will also
make it easier for us to revise these reference files in the future.



Calibration


* One Instrument Science Report was issued this period: ISR 2004-04,
"STIS Cycle 10 Calibration Close-out Report" by L. Dressel et al. This
report contains the status of all STIS Cycle 10 Calibration Programs,
including relevant results.



User Support


* A STIS STAN (Space Telescope Analysis Newsletter) was released to the
HST community on December 15, 2004. The contents are listed below:

o Update on STIS Situation
o Calibration Close-out Highlights
o Doppler Correction Errors
o Cross-dispersion Plate Scale Corrections
o CALSTIS V2.17 Release Notes
o Support for STIS Imaging Data in Multidrizzle
o Recently published Instrument Science Reports (ISRs)
o Fix for CALHRS flux error



Management/Human Resources


* Management submitted a Newsletter article on the STIS situation for
publication in the Winter 2004 STScI Newsletter.

* Management provided input for the STScI Annual Report regarding STIS
Branch activities during 2004.







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Telescopes Branch

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SELECTED HIGHLIGHTS


* Russ Makidon and Stefano Casertano analyzed the December focus data
and determined that HST was still at negative focus, with an average
secondary position of -4 micron. Trending of focus data showed that
the negative focus position was not due to transitory effects, and
therefore a secondary mirror adjustment was appropriate. The
secondary mirror was moved by +4.16 micron in the positive direction
(away from the primary) at 23:12 on December 22, a date chosen because
of its relatively modest impact on GO programs. Initial analysis of
GO data obtained shortly before and after the move show the change in
the ellipticity pattern that is typical of in-focus images. The next
formal focus measurement will be taken on January 14.

* The Two-Gyro group discussed and approved the observing proposals
needed to carry out the Two-Gyro on-orbit test starting February 23.
The group discussed the planning and prioritization of the data
analysis after the test, with the goal of providing basic - and
limited - information to the Project within a week from the end of the
test.

* Tom Wheeler examined the historical data on ACS anneal cycles and
determined that the ACS anneal time can be reduced, probably to about
6 hours with a 1 hour stabilization, from the current 12+3 hours.
Wheeler also discussed ways to reduce power consumption during orbital
night; he is constructing a model to represent the expected change of
NICMOS temperatures if the set point is changed during the night.

* Wheeler analyzed the resolver characterization data for the WFC3 Filer
Select Mechanism. He will open appropriate flight software change
requests to update the home position for Side 2 and to implement a
correction algorithm similar to that used for ACS.

* Anand Sivaramakrishnan developed a detailed observing proposal to
carry out Coarse Phasing during JWST commissioning. The development
of the proposal showed the necessity to divide Coarse Phasing into
three separate visits, potentially requiring different target stars:
one for Pupil Imaging, one for Dispersed Hartmann Sensing (or the
alternative Dispersed Fringe Sensing), and one for out-of-focus phase
retrieval. Multiple procedures are needed to remove degeneracies
related to pupil alignment and secondary tilt from the Coarse Phasing
solution. The use of HST-style observing proposals proves to be a
powerful method to achieve detailed understanding of the sequence of
operations and observations required for commissioning activities.

* Babak Saif carried out an extensive work of characterizing the multi-
wavelength interferometer delivered by 4D Technology for the optical
test of the primary mirror, and currently at GSFC. Tests of the
interferometer have uncovered numerous anomalies that require
attention; it is expected that all outstanding issues will be resolved
by the end of January.

* Ernie Morse revised the JWST detector simulation code to include more
realistic PSFs as well as non-linearity effects in the detector.

* Larry Petro completed the development of the Science and Operations
Design Reference Mission, which contains a full year of observing
activity on the telescope, including a mixture of science programs and
calibration programs. Petro also developed the JWST Mission Simulator
to enable scheduling of the DRM, including observing links and
optimization of slews. Detailed reports can be obtained from the
Mission Simulator to apply other scheduling algorithms to the DRM
program. Petro also participated in the first meetings of the JWST
Orbit Trade study group, which will revisit the parameter space for
the orbit of JWST in view of the constraints posed by orbit
management, momentum management, scheduling efficiency, and scattered
light profile.

* George Hartig revisited the plans for integration and testing of
NIRCam, with special emphasis on its optical performance and
alignment, and attended the NIRCam Optics PDR where the optical design
developed for the full instrument PDR was reviewed in some detail.
The optical design is more stable and has better alignment tolerances
than previous versions; however, some concerns remain with the overall
plans for the alignment of the instrument.




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Data Analyst Branch

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SELECTED HIGHLIGHTS


. General
. Help desk statistics
. Appendix



DETAILED ACTIVITIES



General


Data Analysts (DAs) in the branch, besides supporting INS instrument teams,
also support other science and technical projects. 20 science and technical
projects are currently supported by 17 DAs. 2 future science projects and 2
functional projects are in the queue. The wait time for the queue is
approximately 2 months.




Help Desk Statistics


The general/instrument help desk (help@stsci.edu) received 70 calls last
month with the following distribution: 14 for General Help, 11 ACS, 4
NICMOS, 3 STIS, 35 STSDAS and 3 WFPC2 calls.
APPENDIX




Publications


Stability and Accuracy of the WFC3 UVIS Shutter
Hilbert, B. ISR WFC3 2004-14.