Daily Rpt #4985

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #4985

PERIOD COVERED: 5am December 3 - 5am December 4, 2009 (DOY 337/10:00z-338/10:00z)

OBSERVATIONS SCHEDULED

COS/NUV 11896

NUV Spectroscopic Sensitivity Monitoring

The purpose of this proposal is to monitor sensitivity of each NUV
grating mode to detect any changes due to contamination or other
causes.

COS/NUV/FUV 11531

COS-GTO: Brown Dwarf Activity

COS will obtain ultraviolet spectra of a representative sample of
brown dwarfs to study such questions as: (1) Is the hot gas in the
outer atmospheres of young brown dwarfs heated by accretion? (2) Is
the molecular hydrogen emission due to Lyman-alpha fluorescence or
collisional excitation? (3) Are the older brown dwarfs without disks
low mass analogs of active M dwarfs with flares and transient heating?
(4) Are young brown dwarfs with disks low mass analogs of classical T
Tauri stars?

FGS 11789

An Astrometric Calibration of Population II Distance Indicators

In 2002, HST produced a highly precise parallax for RR Lyrae. That
measurement resulted in an absolute magnitude, M(V)= 0.61+/-0.11, a
useful result, judged by the over ten refereed citations each year
since. It is, however, unsatisfactory to have the direct,
parallax-based, distance scale of Population II variables based on a
single star. We propose, therefore, to obtain the parallaxes of four
additional RR Lyrae stars and two Population II Cepheids, or W Vir
stars. The Population II Cepheids lie with the RR Lyrae stars on a
common K-band Period-Luminosity relation. Using these parallaxes to
inform that relationship, we anticipate a zero point error of 0.04
magnitude. This result should greatly strengthen confidence in the
Population II distance scale and increase our understanding of RR
Lyrae star and Pop. II Cepheid astrophysics.

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.

WFC3/ACS/UVIS 11360

Star Formation in Nearby Galaxies

Star formation is a fundamental astrophysical process; it controls
phenomena ranging from the evolution of galaxies and nucleosynthesis
to the origins of planetary systems and abodes for life. The WFC3,
optimized at both UV and IR wavelengths and equipped with an extensive
array of narrow-band filters, brings unique capabilities to this area
of study. The WFC3 Scientific Oversight Committee (SOC) proposes an
integrated program on star formation in the nearby universe which will
fully exploit these new abilities. Our targets range from the
well-resolved R136 in 30 Dor in the LMC (the nearest super star
cluster) and M82 (the nearest starbursting galaxy) to about half a
dozen other nearby galaxies that sample a wide range of star-formation
rates and environments. Our program consists of broad band
multiwavelength imaging over the entire range from the UV to the
near-IR, aimed at studying the ages and metallicities of stellar
populations, revealing young stars that are still hidden by dust at
optical wavelengths, and showing the integrated properties of star
clusters. Narrow-band imaging of the same environments will allow us
to measure star-formation rates, gas pressure, chemical abundances,
extinction, and shock morphologies. The primary scientific issues to
be addressed a (1) What triggers star formation? (2) How do the
properties of star-forming regions vary among different types of
galaxies and environments of different gas densities and compositions?
(3) How do these different environments affect the history of star
formation? (4) Is the stellar initial mass function universal or
determined by local conditions?

WFC3/IR 12044

DD Observations of the Coldest Brown Dwarf

We request DD observations of the SDWFS J1433+35, which is a strong
candidate for the coldest brown dwarf yet discovered and the first
example of the elusive "Y-dwarf" spectral class. This source was
discovered from a deep, wide-field survey of 10 square degrees with
the IRAC instrument on Spitzer, and is redder in both [3.6]-[4.5] and
H-[4.5] than any published brown dwarfs. The spectrum falls beyond 5
microns, strongly implying that the red mid-infrared colors are due to
methane absorption in the IRAC 3.6 micron channel rather than dust
obscuration. The source is undetected in deep, ground- based near-IR
images, with a H24.2 (Vega) limit derived from Keck AO imaging. The
proposed WFC3 imaging should provide detections in two near-infrared
bands. By showing the target is morphologically unresolved and that it
has the non-uniform spectral energy distribution of an ultracool brown
dwarf, the proposed observations will definitely show that (i) SDWFS
J1433+35 is the coldest brown dwarf known, (ii) test models of
ultracool, planet-like, brown dwarf atmospheres, and (iii) refine
predictions and strategies for the Wide-Field Infrared Survey Explorer
(WISE; planned to launch this December).

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).

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the
UVIS detector (both CCDs) at the level of ~1%, lasting hours to days.
Initially found via an unexpected bowtie-shaped feature in flatfield
ratios, subsequent lab tests on similar e2v devices have since shown
that it is also present as simply an overall offset across the entire
CCD, i.e., a QE offset without any discernable pattern. These lab
tests have further revealed that overexposing the detector to count
levels several times full well fills the traps and effectively
neutralizes the bowtie. Each visit in this proposal acquires a set of
three 3x3 binned internal flatfields: the first unsaturated image will
be used to detect any bowtie, the second, highly exposed image will
neutralize the bowtie if it is present, and the final image will allow
for verification that the bowtie is gone.

WFC3/UVIS/IR 11570

Narrowing in on the Hubble Constant and Dark Energy

A measurement of the Hubble constant to a precision of a few percent
would be a powerful aid to the investigation of the nature of dark
energy and a potent "end-to end" test of the present cosmological
model. In Cycle 15 we constructed a new streamlined distance ladder
utilizing high-quality type Ia supernova data and observations of
Cepheids with HST in the near-IR to minimize the dominant sources of
systematic uncertainty in past measurements of the Hubble constant and
reduce its total uncertainty to a little under 5%. Here we propose to
exploit this new route to reduce the remaining uncertainty by more
than 30%, translating into an equal reduction in the uncertainty of
the equation of state of dark energy. We propose three sets of
observations to reach this goal: a mosaic of NGC 4258 with WFC3 in
F160W to triple its sample of long period Cepheids, WFC3/F160W
observations of the 6 ideal SN Ia hosts to triple their samples of
Cepheids, and observations of NGC 5584 the host of a new SN Ia, SN
2007af, to discover and measure its Cepheids and begin expanding the
small set of SN Ia luminosity calibrations. These observations would
provide the bulk of a coordinated program aimed at making the
measurement of the Hubble constant one of the leading constraints on
dark energy.

ACS/WFC3 11887

CCD Stability Monitor

This program will verify that the low frequency flat fielding, the
photometry, and the geometric distortion are stable in time and across
the field of view of the CCD arrays. A moderately crowded stellar
field in the cluster 47 Tuc is observed with the ACS (at the cluster
core) and WFC3 (6 arcmin West of the cluster core) using the full
suite of broad and narrow band imaging filters. The positions and
magnitudes of objects will be used to monitor local and large scale
variations in the plate scale and the sensitivity of the detectors and
to derive an independent measure of the detector CTE. The UV
sensitivity for the SBC and ACS will be addressed in the UV
contamination monitor program (11886, PI=Smith).

One additional orbit will be obtained at the beginning of the cycle
will allow a verification of the CCD gain ratios for WFC3 using gain
2.0, 1.4, 1.0, 0.5 and for ACS using gain 4.0 and 2.0. In addition,
one subarray exposure with the WFC3 will allow a verification that
photometry obtained in full-frame and in sub-array modes are
repeatable to better than 1%. This test is important for the ACS
Photometric Cross- Calibration program (11889, PI=Bohlin) which uses
sub-array exposures.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

#12112 GSAcq(2,1,1) @338/06:04:31z fails to gyro control due to search
radius limit exceeded on FGS-2 with Loss of Lock looping
@338/06:14:45z.

REAcq(2,1,1) @338/07:34:57z also failed to RGA Hold during LOS

Observations affected: ACS #77-88 Proposal ID#11887

COMPLETED OPS REQUEST:

#18562-1 CONTINGENCY Continuous FGS Loss Of Lock looping (Ref. HSTAR
#12112) @338/06:20z

COMPLETED OPS NOTES: (None)

SIGNIFICANT EVENTS: (None)