Daily Report #4971

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #4971

PERIOD COVERED: 5am November 12 - 5am November 13, 2009 (DOY 316/10:00z-317/10:00z)

OBSERVATIONS SCHEDULED

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/IR/ACS/WFC 11731

Studying Cepheid Systematics in M81: H-band Observations

The local value of the Hubble Constant remains one of the most
important constraints in cosmology, but improving on the 10% accuracy
of the HST Key Project is challenging. No improvements will be
convincing until the metallicity dependence is well constrained and
blending effects are fully understood. M81 and its dwarf companion
Holmberg IX are superb laboratories for studying Cepheid systematics
because they contain large numbers of bright Cepheids with a good
spread in metallicity lying at a common, relatively close distance. We
have identified 180 12P 70 day Cepheids in these two galaxies using
the Large Binocular Telescope (compared to 30 in total by the KP), and
will expand the sample further in 2008-2009. We will use 10 orbits
with WFC3/IR to obtain H-band images of 100 Cepheids in M81 to add to
the ACS/BVI calibrations we will obtain from archival data and 1 orbit
with WFC3/UVIS to add B-band data for Holmberg IX. Four band BVIH
photometry will allow us to flux calibrate, estimate extinction,
measure metallicity effects and then check the results in detail. We
can also examine blending effects on WFC3/IR data in a relatively
nearby galaxy before it is applied to more distant galaxies. Our M81
sample is three times larger than the next best sample, that of
NGC4258, and suffers less from blending because M81 is at half the
distance, so it is an excellent laboratory for studying Cepheid
systematics even if it lacks as precise a geometric distance as
NGC4258.

WFC3/UV 11643

A Timeline for Early-Type Galaxy Formation: Mapping the Evolution of
Star Formation, Globular Clusters, Dust, and Black Holes

While considerable effort has been devoted to statistical studies of
the origin of the red sequence of galaxies, there has been relatively
little direct exploration of galaxies transforming from late to early
types. Such galaxies are identified by their post-starburst spectra,
bulge-dominated, tidally-disturbed morphologies, and current lack of
gas. We are constructing the first detailed timeline of their
evolution onto the red sequence, pinpointing when star formation ends,
nuclear activity ceases, globular clusters form, and the bulk of the
merging progenitors' dust disappears. Here we propose to obtain HST
and Chandra imaging of nine galaxies, whose wide range of
post-starburst ages we have precisely dated with a new UV-optical
technique and for which we were awarded Spitzer time. We will address
1) whether the black hole-bulge mass relation arises from nuclear
feedback, 2) whether the bimodality of globular cluster colors is due
to young clusters produced in galaxy mergers, and 3) what happens to
the dust when late types merge to form an early type.

WFC3/UV 11646

Light Echoes as Probes of Supernova Type Ia Environments

Environmental factors of Type Ia supernovae are key in understanding
their nature, lightcurve evolution, and utility as cosmological
standard candles. The progenitor ages (and many other properties) are
bimodal, differing by roughly an order of magnitude. Is this reflected
as well in the differences in their immediate surroundings in terms of
gas and dust? The most powerful and direct way to address this issue
is by imaging the reflected light from the dust itself via a light
echo. In order for this approach to work, however, one must start
imaging the vicinity of the supernova frequently and soon after the
explosion is seen. We propose to maintain the imaging sequences
crucial for understanding the three-dimensional dust distribution of
two recent and key Type Ia supernovae, in a timely manner that will
prevent otherwise significant holes in our knowledge. These
observations are likely to be important in determining if the
interstellar versus the circumstellar environments are more important
in determining the appearance of Type Ia explosions, and thereby offer
a clue as to the poorly-understood mass-loss history of SN Ia
progenitors.

WFC3/UV 11730

Continued Proper Motions of the Magellanic Clouds: Orbits, Internal
Kinematics, and Distance

In Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields
in the Magellanic Clouds centered on background quasars. We used these
data to determine the proper motions of the LMC and SMC to better than
5% and 15% respectively. The results had a number of unexpected
implications for the Milky Way-LMC-SMC system and received
considerable attention in the literature and in the press. The implied
three-dimensional velocities are larger than previously believed and
close to the escape velocity in a standard 10^12 solar mass Milky Way
dark halo. Our orbit calculations suggest the Clouds may not be bound
to the Milky Way or may just be on their first passage, both of which
are unexpected in view of traditional interpretations of the
Magellanic Stream. Alternatively, the Milky Way dark halo may be a
factor two more massive than previously believed, which would be
surprising in view of other observational constraints. Also, the
relative velocity between the LMC and SMC was larger than expected,
leaving open the possibility that the Clouds may not be bound to each
other. To further verify and refine our results we requested an
additional epoch data in Cycle 16 which is being executed with
WFPC2/PC due to the failure of ACS. A detailed analysis of one LMC
field shows that the field proper motion using all three epochs of
data is consistent within 1-sigma with the two-epoch data, thus
verifying that there are no major systematic effects in our previous
measurements. The random errors, however, are only smaller by a factor
of 1.4 because of the relatively large errors in the WFPC2 data. A
prediction for a fourth epoch with measurement errors similar to
epochs 1 and 2 shows that the uncertainties will improve by a factor
of 3. This will allow us to better address whether the Clouds are
indeed bound to each other and to the Milky Way. It will also allow us
to constrain the internal motions of various populations within the
Clouds, and to determine a distance to the LMC using rotational
parallax. Continuation of this highly successful program is therefore
likely to provide important additional insights. Execution in SNAPshot
mode guarantees maximally efficient use of HST resources.

WFC3/UV 11801

Black Holes in Globular Clusters

Search for 3000 solar mass black holes at the centers of three
Galactic globular clusters using stellar proper motions.

WFC3/UV/IR 11573

Investigating Post-Equinox Atmospheric Changes on Uranus

Uranus is now past its 7 December 2007 equinox. The large seasonal
phase shift expected from its long radiative time constant implies
that it should now be in the process of reversing its hemispheric
asymmetries in cloud band structure and zonal circulation. Many
changes already observed -- the development of the first
visible-wavelength dark spot, discovered in Cycle 15, the fading of
the south polar cap, and the development of a new northern bright band
while the southern band fades -- may all be indicative of the expected
reversal. We propose a detailed characterization of Uranus' current
seasonal response with a 9-orbit program consisting of 3 orbits of
WFC3 imaging of cloud bands and dark spots, and 6 orbits of high
signal-to-noise imaging using the F845M filter, capable of tracking
bright discrete cloud features. Filters between 0.467 and 1.7 microns
will provide vertical sensing depths scanning through the pressure
range where the putative methane and deeper H2S clouds might plausibly
exist and provide strong constraints on their contributions and parent
gas mixing ratios. These observations have unique combinations of
spectral range and resolution with needed temporal sampling and
spatial resolution not available from groundbased observations.

WFC3/UV/S/S 11938

UVIS Stray Light

Structures outside the optical path of the detector FOV and the
surfaces of optical elements could scatter significant light from
bright sources onto the UVIS CCD. Such structures are oversized by
typically a few mm relative to the FOV?s beam. The beam footprint of a
source outside the FOV can overlap the edges of those structures,
which will cause light to be scattered onto the detector. This on
orbit test will: 1) verify that release of gravitational stress has
not changed the detector mask by comparison with similar ground tests,
2) assess the far wing stray light from a sources outside the CCD FOV,
3) note any sources of stray light in the near and far field that were
not noted during ground test, and 4) assess the surface brightness of
the off-chip target PSF relative to the on-chip PSF.

WFC3/UVIS 11732

The Temperature Profiles of Quasar Accretion Disks

We can now routinely measure the size of quasar accretion disks using
gravitational microlensing of lensed quasars. At optical wavelengths
we observe a size and scaling with black hole mass roughly consistent
with thin disk theory but the sizes are larger than expected from the
observed optical fluxes. One solution would be to use a flatter
temperature profile, which we can study by measuring the wavelength
dependence of the disk size over the largest possible wavelength
baseline. Thus, to understand the size discrepancy and to probe closer
to the inner edge of the disk we need to extend our measurements to UV
wavelengths, and this can only be done with HST. For example, in the
UV we should see significant changes in the optical/UV size ratio with
black hole mass. We propose monitoring 5 lenses spanning a broad range
of black hole masses with well-sampled ground based light curves,
optical disk size measurements and known GALEX UV fluxes during Cycles
17 and 18 to expand from our current sample of two lenses. We would
obtain 5 observations of each target in each Cycle, similar to our
successful strategy for the first two targets.

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: (None)

COMPLETED OPS REQUEST:

18755-0 - Execute TimeTag GenSlew (ROP NS-08) for prop 11572 @
317/0000z

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSAcq 10 10
FGS REAcq 04 04
OBAD with Maneuver 06 06

SIGNIFICANT EVENTS: (None)