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Daily Rpt #4935



 
 
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Old September 22nd 09, 08:19 PM posted to sci.astro.hubble
Bassford, Lynn[_2_]
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Default Daily Rpt #4935

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #4935

PERIOD COVERED: 5am September 21 - 5am September 22, 2009 (DOY 264/09:00z-265/09:00z)

OBSERVATIONS SCHEDULED

ACS/WFC3 11879

CCD Daily Monitor (Part 1)

This program comprises basic tests for measuring the read noise and
dark current of the ACS WFC and for tracking the growth of hot pixels.
The recorded frames are used to create bias and dark reference images
for science data reduction and calibration. This program will be
executed four days per week (Mon, Wed, Fri, Sun) for the duration of
Cycle 17. To facilitate scheduling, this program is split into three
proposals. This proposal covers 352 orbits (22 weeks) from 31 August
2009 to 31 January 2010.

ACS/WFC3/STIS/CCD 11889

Photometric Cross-Calibration using Stellar Flux Standards

The purpose of this proposal is to: A) Verify the ACS HRC and WFC
photometric calibrations with a repeat visit to one of the three
primary WDs. B) Measure the change in sensitivity with time for bright
stars (which would include any small CTE contributions). C) Continue
to investigate the ~2% discrepancy between ACS flux calibration and
that of STIS (ACS ISR 2007-06). The goal is to measure any filter
bandpass shifts in ACS or rule out the possibility of shifts as the
primary contributors to the ACS/STIS discrepancy for cool stars.

COS/FUV 11895

FUV Detector Dark Monitor

The purpose of this proposal is to monitor the FUV detector dark rate
by taking long science exposures without illuminating the detector.
The detector dark rate and spatial distribution of counts will be
compared to pre-launch and SMOV data in order to verify the nominal
operation of the detector. Variations of count rate as a function of
orbital position will be analyzed to find dependence of dark rate on
proximity to the SAA. Dependence of dark rate as function of time will
also be tracked.

FGS 11704

The Ages of Globular Clusters and the Population II Distance Scale

Globular clusters are the oldest objects in the universe whose age can
be accurately determined. The dominant error in globular cluster age
determinations is the uncertain Population II distance scale. We
propose to use FGS 1R to obtain parallaxes with an accuracy of 0.2
milliarcsecond for 9 main sequence stars with [Fe/H] -1.5. This will
determine the absolute magnitude of these stars with accuracies of
0.04 to 0.06mag. This data will be used to determine the distance to
24 metal-poor globular clusters using main sequence fitting. These
distances (with errors of 0.05 mag) will be used to determine the ages
of globular clusters using the luminosity of the subgiant branch as an
age indicator. This will yield absolute ages with an accuracy of 5%,
about a factor of two improvement over current estimates. Coupled with
existing parallaxes for more metal-rich stars, we will be able to
accurately determine the age for globular clusters over a wide range
of metallicities in order to study the early formation history of the
Milky Way and provide an independent estimate of the age of the
universe.

The Hipparcos database contains only 1 star with [Fe/H] -1.4 and an
absolute magnitude error less than 0.18 mag which is suitable for use
in main sequence fitting. Previous attempts at main sequence fitting
to metal-poor globular clusters have had to rely on theoretical
calibrations of the color of the main sequence. Our HST parallax
program will remove this source of possible systematic error and yield
distances to metal- poor globular clusters which are significantly
more accurate than possible with the current parallax data. The HST
parallax data will have errors which are 10 times smaller than the
current parallax data. Using the HST parallaxes, we will obtain main
sequence fitting distances to 11 globular clusters which contain over
500 RR Lyrae stars. This will allow us to calibrate the absolute
magnitude of RR Lyrae stars, a commonly used Population II distance
indicator.

COS/NUV 11476

COS NUV External Spectroscopic Performance - Part 1

The goal of this project is to measure the spectral resolution of
absorption lines for each of the four COS NUV gratings. We will
acquire science data at the central wavelength of each grating through
both PSA and BOA apertures. We will also evaluate the effect of small
pointing errors on the spectral resolution by acquiring additional
spectra at spatially offset positions. The targets chosen for these
observations have sharp absorption lines and will be either unresolved
or marginally resolved at the COS resolution.

Our observations with the PSA will target the subdwarf B star Feige 48
(PG 1144+651). The observations with the BOA will be performed on the
bright O subdwarf BD+75D325, a bright (M_V = 9.6) HST calibration
standard.

COS/NUV 11477

COS NUV External Spectroscopic Performance - Part 2

The goal of this activity is to verify the spatial resolution of COS
in the NUV and to characterize the interdependence of the spatial and
spectral resolution of the instrument in that wavelength band. By
stepping the source along the cross-dispersion direction out to the
edge of the PSA, we will be able to quantify the variation of the
spatial profile of the source with off-axis position, both by
measuring the shape and width of the profile and by measuring the
amount of flux transmitted through the aperture as the source is
stepped past the edge of the aperture. Aside from measuring the
spatial resolution of COS spectra, this study will be particularly
useful for characterizing the contamination of sources near the
targeted object in crowded stellar fields.

This test is ideally performed with a spatially unresolved point
source with an emission line spectrum. Our observations with the PSA
will target the Galactic symbiotic stars AG Draconis and He 2-38.

Our observations with the BOA will target another Galactic symbiotic
star, RR Telescopii. This object exhibits similar line widths to AG
Dra, but includes a rich array of Fe II emission lines as well.

COS/NUV/FUV/WFC3/UVIS/IR 11520

COS-GTO: QSO Absorbers, Galaxies and Large-Scale Structures in the
Local Universe

This is a program to probe the large scale structure of baryons in the
universe, including addressing questions of baryon fraction, physical
conditions and relationships between absorbers and large-scale
structures of galaxies. Besides these specific goals, this proposed
GTO program also probes a large enough total path length in Ly alpha
and OVI to add significantly to what STIS/FUSE has already observed.
Several Galactic High Velocity Cloud Complexes also are probed by
these sightlines, particularly the M Complex. The total path length of
this proposed program for Ly alpha large-scale structure surveys is
delta_z~5.5.

We have selected a variety of targets to address these questions,
under the following subcategories:

1. Target 8 bright BL Lac objects to search for low contrast Ly alpha
absorbers from the warm-hot interstellar medium (WHIM).

2. Ly alpha cloud sizes: The targets are a bright AGN pair which yield
tangential distance separations of 100--500 kpc at z=0.01--0.05, where
galaxy surveys are excellent. This pair has two filaments and two
voids in this distance range.

3. Probes of starburst outflows: The targets are bright AGN, = 100
kpc in projection out of the minor axis of nearby starburst galaxies.

4. A large galaxy's gaseous halo: Three probes of the kinematics and
metallicity of a single L* galaxy halo. These observations includes
G130M, G160M exposures at SNR~20 and G285M at 2850A and SNR~10 for
MgII. The 2L* galaxy, ESO 157-G049 (cz=1678 km/s), being probed by
these sightlines has an available H I 21cm map from ATCA, H alpha
imaging from CTIO and long-slit spectra from MSSSO.

5. Dwarf galaxy winds: These targets probe the kinematics and
metallicities of outflows from active and inactive (in terms of star
formation) dwarfs.

NIC1/NIC2/NIC3 11947

Extended Dark Monitoring

This program takes a series of darks to obtain darks (including
amplifier glow, dark current, and shading profiles) for all three
cameras in the read-out sequences used in Cycle 17. A set of 12 orbits
will be observed every two months for a total of 72 orbits for a 12
month Cycle 17. This is a continuation of Cycle 16 program 11330
scaled down by ~80%.

The first orbit (Visit A0) should be scheduled in the NICMOS SMOV
after the DC Transfer Test (11406) and at least 36h before the Filter
Wheel Test (11407). Data download using fast track.

The following 28 orbits (visit A1-N2) should be scheduled AFTER the
SMOV Proposal 11407 (Filter Wheel Test). This is done in order to
monitor the dark current following an adjustment of the NCS set-point.
These visits should be executed until the final temperature is reached
during SMOV.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA Calibration - CR Persistence Part 6

This is a new procedure proposed to alleviate the CR-persistence
problem of NICMOS. Dark frames will be obtained immediately upon
exiting the SAA contour 23, and every time a NICMOS exposure is
scheduled within 50 minutes of coming out of the SAA. The darks will
be obtained in parallel in all three NICMOS cameras. The post-SAA
darks will be non-standard reference files available to users with a
'Use After' date/time mark. The keyword 'UseAfter=date/time' will also
be added to the header of each post-SAA dark frame. The keyword must
be populated with the time, in addition to the date, because HST
crosses the SAA ~8 times per day, so each post-SAA dark will need to
have the appropriate time specified, for users to identify the ones
they need. Both the raw and processed images will be archived as
post-SAA darks. Generally we expect that all NICMOS
science/calibration observations started within 50 minutes of leaving
an SAA will need such MAPs to remove the CR persistence from the
science images. Each observation will need its own CRMAP, as different
SAA passages leave different imprints on the NICMOS detectors.

STIS/CCD 11844

CCD Dark Monitor Part 1

The purpose of this proposal is to monitor the darks for the STIS CCD.

STIS/CCD 11846

CCD Bias Monitor-Part 1

The purpose of this proposal is to monitor the bias in the 1x1, 1x2,
2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up
high-S/N superbiases and track the evolution of hot columns.

STIS/CCD 11852

STIS CCD Spectroscopic Flats C17

The purpose of this proposal is to obtain pixel-to-pixel lamp flat
fields for the STIS CCD in spectroscopic mode.

STIS/CCD 11853

Cycle 17 STIS CCD Imaging Flats

This program periodically monitors the STIS CCD imaging mode flat
fields by using the tungsten lamps.

STIS/MA1/MA2 11857

STIS Cycle 17 MAMA Dark Monitor

This proposal monitors the behavior of the dark current in each of the
MAMA detectors.

The basic monitor takes two 1380s ACCUM darks each week with each
detector. However, starting Oct 5, pairs are only included for weeks
that the LRP has external MAMA observations planned. The weekly pairs
of exposures for each detector are linked so that they are taken at
opposite ends of the same SAA free interval. This pairing of exposures
will make it easier to separate long and short term temporal
variability from temperature dependent changes.

For both detectors, additional blocks of exposures are taken once
every six months. These are groups of five 1314s FUV-MAMA Time-Tag
darks or five 3x315s NUV ACCUM darks distributed over a single
SAA-free interval. This will give more information on the brightness
of the FUV MAMA dark current as a function of the amount of time that
the HV has been on, and for the NUV MAMA will give a better measure of
the short term temperature dependence.

WFC3/ACS/UVIS 12007

Supernova Follow up

This proposal is one orbit to follow up discovery of a supernova.

WFC3/IR 11936

IR Grism Flux Calibration

This program will determine image displacement, spectral trace and
flux calibration for the IR G102 and G141 grisms as a function of
spatial position within the field of view. The HST flux standard GD71
will be observed in a 9-point pattern in the IR field of view, which
will provide the necessary image displacement, spectral trace, and
throughput measurements.

WFC3/UVIS 11565

A Search for Astrometric Companions to Very Low-Mass, Population II
Stars

We propose to carry out a Snapshot search for astrometric companions
in a subsample of very low-mass, halo subdwarfs identified within 120
parsecs of the Sun. These ultra-cool M subdwarfs are local
representatives of the lowest-mass H burning objects from the Galactic
Population II. The expected 3-4 astrometric doubles that will be
discovered will be invaluable in that they will be the first systems
from which gravitational masses of metal-poor stars at the bottom of
the main sequence can be directly measured.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set
of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K
subarray biases are acquired at less frequent intervals throughout the
cycle to support subarray science observations. The internals from
this proposal, along with those from the anneal procedure (Proposal
11909), will be used to generate the necessary superbias and superdark
reference files for the calibration pipeline (CDBS).

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

12017 - GSAcq (2,3,3), scheduled from 265/07:54:41z - 265/08:01:24z,
failed due to Search Radius Limit Exceeded on FGS3.

Observations affected: COS 117 & 118, Proposal ID# 11895 & Astrometry
Proposal ID# 11704

COMPLETED OPS REQUEST:

18562-1 - Continuous FGS Loss Of Lock looping @ 265/0825z

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSAcq 7 6
FGS REAcq 7 7
OBAD with Maneuver 6 6

SIGNIFICANT EVENTS: (None)

 




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