Daily Rpt #5073

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5073

PERIOD COVERED: 5am April 12 - 5am April 13, 2010 (DOY 102/09:00z-103/09:00z)

OBSERVATIONS SCHEDULED

ACS/WFC 11995

CCD Daily Monitor (Part 2)

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 320 orbits (20 weeks) from 1 February
2010 to 20 June 2010.

ACS/WFC3 11882

CCD Hot Pixel Annealing

This program continues the monthly anneal that has taken place every
four weeks for the last three cycles. We now obtain WFC biases and
darks before and after the anneal in the same sequence as is done for
the ACS daily monitor (now done 4 times per week). So the anneal
observation supplements the monitor observation sets during the
appropriate week. Extended Pixel Edge Response (EPER) and First Pixel
Response (FPR) data will be obtained over a range of signal levels for
the Wide Field Channel (WFC). This program emulates the ACS pre-flight
ground calibration and post-launch SMOV testing (program 8948), so
that results from each epoch can be directly compared. The High
Resolution Channel (HRC) visits have been removed since it could not
be repaired during SM4.

This program also assesses the read noise, bias structure, and
amplifier cross-talk of ACS/WFC using the GAIN=1.4 A/D conversion
setting. This investigation serves as a precursor to a more
comprehensive study of WFC performance using GAIN=1.4.

COS/FUV 11895

FUV Detector Dark Monitor

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.

COS/NUV 11561

An Intensive COS Spectroscopic Study of the Planetary Debris Disks
Around two Warm White Dwarfs

It is very likely that the gas giants in our Solar system will survive
the evolution of the Sun into a white dwarf, and the same is thought
to be generally true for Jovian planets around solar-like stars if
their initial orbits are wider than ~3AU. Despite this prediction, no
unambiguous detection of a planet around a white dwarf has been
announced so far. However, over the past few years, about a dozen
white dwarfs have been identified which host metal-rich debris disks
that are thought to stem from the tidal disruption of asteroids. In
most cases the debris disks are observed in the form of an infrared
flux excess, and offer relatively little diagnostic potential for the
study of their structure. We have discovered three warm (T~20000K)
white dwarfs with metal-rich debris disks in a gaseous phase which
display strong double-peaked CaII emission lines in the I-band and
weak Fe 5169A emission. The line profiles can be modeled in terms of
Keplerian disks with an extension of ~1Rsun around the white dwarfs.
Photospheric MgII 4481A absorption demonstrates that the white dwarfs
are accreting from the debris disks. Besides these spectral features,
the optical wavelength range is devoid of other useful metal
transitions. Here, we propose an intensive spectroscopic ultraviolet
study of these systems, which will provide (a) ~1000 photospheric
absorption lines of 15 chemical elements, allowing an accurate
abundance study of the material accreted from the debris disks, and
(b) ~2 dozen additional emission lines of Mg, Cr, Ti, and Fe that will
provide detailed insight into the dynamical, thermal, and density
structure of these exo-planetary debris disks.

COS/NUV 11894

NUV Detector Dark Monitor

Measure the NUV detector dark rate by taking long science exposures
with no light on 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.

S/C 12046

COS FUV DCE Memory Dump

Whenever the FUV detector high voltage is on, count rate and current
draw information is collected, monitored, and saved to DCE memory.
Every 10 msec the detector samples the currents from the HV power
supplies (HVIA, HVIB) and the AUX power supply (AUXI). The last 1000
samples are saved in memory, along with a histogram of the number of
occurrences of each current value.

In the case of a HV transient (known as a "crackle" on FUSE), where
one of these currents exceeds a preset threshold for a persistence
time, the HV will shut down, and the DCE memory will be dumped and
examined as part of the recovery procedure. However, if the current
exceeds the threshold for less than the persistence time (a
"mini-crackle" in FUSE parlance), there is no way to know without
dumping DCE memory. By dumping and examining the histograms regularly,
we will be able to monitor any changes in the rate of "mini-crackles"
and thus learn something about the state of the detector.

STIS/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CC 11847

CCD Bias Monitor-Part 2

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 11855

STIS/CCD Spectroscopic Sensitivity Monitor for Cycle 17

Monitor sensitivity of each CCD grating mode to detect any change due
to contamination or other causes.

WFC3/ACS/IR 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/IR 11838

Completing a Flux-limited Survey for X-ray Emission from Radio Jets

We will measure the changing flow speeds, magnetic fields, and energy
fluxes in well-resolved quasar jets found in our short-exposure
Chandra survey by combining new, deep Chandra data with radio and
optical imaging. We will image each jet with sufficient sensitivity to
estimate beaming factors and magnetic fields in several distinct
regions, and so map the variations in these parameters down the jets.
HST observations will help diagnose the role of synchrotron emission
in the overall SED, and may reveal condensations on scales less than
0.1 arcsec.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more
reliably removed from science data using darks taken with the same
exposure sequences as the science data, than with a single dark
current image scaled by desired exposure time. Therefore, dark current
images must be collected using all sample sequences that will be used
in science observations. These observations will be used to monitor
changes in the dark current of the WFC3-IR channel on a day-to-day
basis, and to build calibration dark current ramps for each of the
sample sequences to be used by Gos in Cycle 17. For each sample
sequence/array size combination, a median ramp will be created and
delivered to the calibration database system (CDBS).

WFC3/IR/S/C 12093

IR Non-linearity Calibration using Subarrays

The purpose of this proposal is to measure the non-linearity in
subarray internal flatfields. The results will be compared to the
current non-linearity correction based on full-frame data, to
determine whether the current calibration is appropriate for the
significantly faster readouts in subarrays.

WFC3/UV/IR 11620

A Quasar Light Echo in the Local Universe?

The time history and duty cycle of individual AGN is an important part
of their evolution and the growth history of massive black holes, but
almost unconstrained on scales between galaxy-interaction timescales
(hundreds of Myr) and the scales of years probed by variability
measurements. We propose a detailed study of an object which seems to
be a large-scale light echo from a QSO-level episode in a nearby
galaxy. The Galaxy Zoo morphological survey of SDSS objects has
uncovered a peculiar emission-line structure whose spectrum matches
the narrow-line region of AGN, despite lying at least 20 kpc from a
galaxy whose activity is currently very weak. This is best explained
if the nucleus has faded dramatically on time scales of several tens
of thousands of years. We propose a suite of imaging and spectroscopic
observations to probe its properties, and the time history of this
episode of nuclear activity, measuring time scales hitherto
unavailable.

WFC3/UVI/IR 11557

The Nature of Low-Ionization BAL QSOs

The rare subclass of optically-selected QSOs known as low-ionization
broad absorption line (LoBAL) QSOs show signs of high-velocity gas
outflows and reddened continua indicative of dust obscuration. Recent
studies show that galaxies hosting LoBAL QSOs tend to be ultraluminous
infrared systems that are undergoing mergers, and that have dominant
young ( 100 Myr) stellar populations. Such studies support the idea
that LoBAL QSOs represent a short- lived phase early in the life of
QSOs, when powerful AGN-driven winds are blowing away the dust and gas
surrounding the QSO. If so, understanding LoBALs would be critical in
the study of phenomena regulating black hole and galaxy evolution,
such as AGN feedback and the early stages of nuclear accretion. These
results, however, come from very small samples that may have serious
selection biases. We are therefore taking a more aggressive approach
by conducting a systematic multiwavelength study of a volume limited
sample of LoBAL QSOs at 0.5 z 0.6 drawn from SDSS. We propose to
image their host galaxies in two bands using WFC3/UVIS and WFC3/IR to
study the morphologies for signs of recent tidal interactions and to
map their interaction and star forming histories. We will thus
determine whether LoBAL QSOs are truly exclusively found in young
merging systems that are likely to be in the early stages of nuclear
accretion.

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: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSAcq 10 10
FGS REAcq 6 6
OBAD with Maneuve 8 8

SIGNIFICANT EVENTS: (None)