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Daily 3691



 
 
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Old September 9th 04, 05:43 PM
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HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 3691

PERIOD COVERED: DOY 252

OBSERVATIONS SCHEDULED

ACS/HRC 10050

ACS Earth Flats

High signal sky flats will be obtained by observing the bright Earth
with the HRC and WFC. These observations will be used to verify the
accuracy of the flats currently used by the pipeline and will provide
a comparison with flats derived via other techniques: L-flats from
stellar observations, sky flats from stacked GO observations, and
internal flats using the calibration lamps. Weekly coronagraphic
monitoring is required to assess the changing position of the spots.

ACS/HRC/NIC1/WFC 10190

The Star Formation History and Metallicity Evolution of M33: A
Comprehensive Study of Disk Evolution

We will obtain deep, panchromatic imaging photometry of stellar
populations in four fields ranging from 0.5 to 4 scale lengths across
the disk of the Local Group spiral M33. The observations are designed
to detect the oldest main-sequence turnoffs in three outer disk
fields, and to reach the crowding limit in the innermost field. We
will combine the photometry data with information we already have
in-hand on abundances from stars and H II regions in M33 to derive the
star formation history and metallicity evolution of the M33 disk. The
information from our four fields will allow us to obtain {1} the ages
of the oldest disk stars and the radial variation of their ages; {2}
the radial variation of the star formation history and its nature
{e.g., constant, declining, or bursting}; and {3} the metallicity
distribution in each field and the time evolution of the metallicity
gradient. Our team, an experienced mix of photometrists,
spectroscopists, and galaxy evolution theorists, will use the results
from this program to construct a comprehensive chemo-dynamical model
for the M33 disk. This detailed study of M33 will be a key in
developing an understanding of the formation and evolution of disks
that can be applied to studies of disks at both low and high redshift,
and will also yield a wealth of information on stellar populations,
chemical evolution, and star clusters that will be of great value to
future investigators.

ACS/HRC/WFC 10061

CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the
development of hot pixels and test for any source of noise in ACS CCD
detectors. This programme will be executed once a day for the entire
lifetime of ACS.

ACS/SBC 10047

ACS UV Contamination Monitor

A standard star field {NGC6681} is observed every three months,
alternating between after and before annealing operations, through all
the ACS broad band UV filters. NGC6681 hosts several UV spectro -
photometric standard stars for which accurate spectra have been {and
will continue to be} measured with STIS. Two SBC dark current
exposures taken as the last exposure of each SBC sequence. Also, to
minimize SBS turn-on/turn-off cycles and in order to check the lab
flats for the SBC detector, internal observations using the deuterium
lamp with F125LP are being taken inflight, following the UV monitor
observations. The internal flats have been taken ~monthly since SMOV,
and the degradation of the lamp has been monitored. The total exposure
time to date is ~15 hours giving a total of 8600 counts/pixel. The
goal is 10, 000 counts/pixel such that the resulting pipeline flat has
uncertainties of ~1% due to poison counting statistics. Thus,
approximately 3 additional hours of observation are required.

ACS/WFC 10046

CCD Hot Pixel Annealing

Hot pixel annealing will be performed once every 4 weeks. The CCD TECs
will be turned off and heaters will be activated to bring the detector
temperatures to about +20C. This state will be held for approximately
12 hours, after which the heaters are turned off, the TECs turned on,
and the CCDs returned to normal operating condition. To assess the
effectiveness of this procedure, a bias and two dark images will be
taken after the annealing procedure for both WFC and HRC. The HRC
darks are taken in parallel with the WFC darks.

ACS/WFC 10248

Current star formation in young, compact clusters in the Small
Magellanic Cloud

The Small Magellanic Cloud {SMC} offers a deep, resolved stellar
population that leverages fundamental parameters {metallicity, dust
content} with respect to the Milky Way and to its most studied
counterpart, the LMC. Its subsolar metallicity makes it the best
analog to the large majority of dwarf irregulars, and gives us the
possibility to study star formation and evolution in an environment
with the closest {available} resemblance to the early universe. Young,
compact clusters are ideal laboratories to investigate how these
fundamental differences affect star and cluster formation and
evolution. We are therefore, proposing, to use ACS and NICMOS to
perform a in depth study of the "resolved" stellar population in the
four youngest compact clusters in the SMC. The observations, spanning
the UV to the near-IR, will reach the subsolar domain, and will
address the following fundamental questions: Does the IMF follow the
universal Salpeter's law? Is mass segregation prevalent in the SMC
clusters as in LMC clusters? Is on-going star formation present, where
and how? What is the role of massive star feedback? The four proposed
clusters span an age range from 3-20 Myr, and sample spatially
different regions of the SMC. The synergy with NICMOS will permit full
characterization of existing pre main sequence stars, if detected.
This proposal is part of a coordinated HST and ground-based study of
the stellar history and star formation processes in the SMC.

NIC1 10143

Ultracool companions to the nearest L dwarfs

We propose to conduct the most sensitive survey to date for low mass
companions to nearby L dwarfs. We will use NICMOS to image targets
drawn from a volume-complete sample of 70 L dwarfs within 20 parsecs.
The combination of infrared imaging and proximity will allow us to
search for T dwarf companions at separations as small as 1.6 AU. This
is crucial, since no ultracool binaries are currently known with
separations exceeding 15 AU. Only 10 dwarfs in this sample have
previous HST observations primarily at optical wavelengths. With the
increased sensitivity of our survey, we will provide the most
stringent test to date of brown dwarf models which envisage formation
as ejected stellar embryos. In addition, our observations will be
capable of detecting binaries with mass ratios as low as 0.3, and will
therefore also test the apparent preference for equal-mass ultracool
binaries. Finally, our observations offer the best prospect to date of
detecting companions significantly cooler than the coolest t dwarf
currently known.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

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 USEAFTER
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 DARKSs. 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.

NIC1/NIC2/NIC3 9995

Photometric Stability

This NICMOS calibration proposal carries out photometric monitoring
observations during Cycle 12. The format of the program is identical
to that of the Cycle 11 program 9639, except that the frequency has
been reduced to bimonthly.

NIC2 10169

Star Formation in Luminous Infrared Galaxies: giant HII Regions and
Super Star Clusters

Luminous Infrared Galaxies {LIRGs, LIR = 10^11-10^12Lsol} and
Ultraluminous Infrared Galaxies {LIR10^12Lsol} account for
approximately 75% of all the galaxies detected in the mid-infrared in
the redshift range z=0-1.5. In the local universe it is found that
LIRGs are predominantly powered by intense star formation {SF}.
However, the physical conditions and processes governing such dramatic
activity over scales of tens to a few hundred parsecs are poorly
known. In the last decade HST has been playing a significant role,
mainly with the discovery of super star clusters {SSCs}, and more
recently, giant HII regions. Based on observations of a few LIRGs, we
found that these giant HII regions and associated SSCs appear to be
more common in LIRGs than in normal galaxies, and may dominate the
star formation activity in LIRGs. A larger sample is required to
address fundamental questions. We propose an HST/NICMOS targeted
campaign of a volume limited sample {v5200km/s} of 24 LIRGs. This
proposal will probe the role of giant HII regions in the overall
energetics of the current star formation, their relation to SSCs, and
the dependence of star formation properties on other parameters of
LIRGs. Such detailed knowledge of the SF properties of LIRGs in the
local universe is essential for understanding galaxies at high
redshift.

NIC2 10176

Coronagraphic Survey for Giant Planets Around Nearby Young Stars

A systematic imaging search for extra-solar Jovian planets is now
possible thanks to recent progress in identifying "young stars near
Earth". For most of the proposed young {~ 30 Myrs} and nearby {~ 60
pc} targets, we can detect a few Jupiter-mass planets as close as a
few tens of AUs from the primary stars. This represents the first time
that potential analogs of our solar system - that is planetary systems
with giant planets having semi-major axes comparable to those of the
four giant planets of the Solar System - come within the grasp of
existing instrumentation. Our proposed targets have not been observed
for planets with the Hubble Space Telescope previously. Considering
the very successful earlier NICMOS observations of low mass brown
dwarfs and planetary disks among members of the TW Hydrae Association,
a fair fraction of our targets should also turn out to posses low mass
brown dwarfs, giant planets, or dusty planetary disks because our
targets are similar to {or even better than} the TW Hydrae stars in
terms of youth and proximity to Earth. Should HST time be awarded and
planetary mass candidates be found, proper motion follow-up of
candidate planets will be done with ground-based AOs.

WFPC2 10071

WFPC2 CYCLE 12 Supplemental Darks Part 3/3

This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot
pixels.

WFPC2 10075

WFPC2 CYCLE 12 Intflat and Viflat Sweeps and Filter Rotation Anomaly
Monitor

Using intflat observations, this WFPC2 proposal is designed to monitor
the pixel-to-pixel flatfield response and provide a linearity check.
The intflat sequences, to be done once during the year, are similar to
those from the Cycle 11 program 9597. The images will provide a backup
database in the event of complete failure of the visflat lamp as well
as allow monitoring of the gain ratios. The sweep is a complete set of
internal flats, cycling through both shutter blades and both gains.
The linearity test consists of a series of intflats in F555W, in each
gain and each shutter. As in Cycle 11, we plan to continue to take
extra visflat, intflat, and earthflat exposures to test the
repeatability of filter wheel motions.

FLIGHT OPERATIONS SUMMARY:

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

HSTAR 9531: The GSacq(2,3,3) at 253/02:56:36 - 253/03:03:54 resulted
in finelock backup(2,0,2)due to scan step limit exceeded on FGS 3. The
Map at 03:04:33 shows vehicle errors of 20.133, -5.487, 1.595.
Possible observations affected: NIC 56, WFPC 74 - 83, ACS 99. Under
investigation.

COMPLETED OPS REQs: None

OPS NOTES EXECUTED: None

SCHEDULED SUCCESSFUL FAILURE TIMES
FGS Gsacq 11 11
FGS Reacq 09 09
FHST Update 10 10
LOSS of LOCK

SIGNIFICANT EVENTS: None


 




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