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Daily Report #4958



 
 
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Old October 26th 09, 04:20 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #4958

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #4958

PERIOD COVERED: 5am October 23 - 5am October 26, 2009 (DOY 296/09:00z-299/09:00z)

OBSERVATIONS SCHEDULED

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/UVIS 11924

WFC3/UVIS External and Internal CTE Monitor

CCD detector Charge Transfer Inefficiency (CTI)-induced losses in
photometry and astrometry will be measured using observations of the
rich open cluster NGC6791 and with the EPER (Extended Pixel Edge
Response) method using tungsten lamp flat field exposures. Although we
do not expect to see CTE effects at the outset of Cycle 17, this CTE
monitoring program is the first of a multi-cycle program to monitor
and establish CTE-induced losses with time. We expect to measure CTE
effects with a precision comparable to the ACS measurements.

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 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).

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.

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 11844

CCD Dark Monitor Part 1

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

ACS/SBC 11791

The Wavelength Dependence of Accretion Disk Structure

We can now routinely measure the size of quasar accretion disks using
gravitational microlensing of lensed quasars. The next step to testing
accretion disk models is to measure the size of accretion disks as a
function of wavelength, particularly at the UV and X-ray wavelengths
that should probe the inner, strong gravity regime. Here we focus on
two four-image quasar lenses that already have optical (R band) and
X-ray size measurements using microlensing. We will combine the HST
observations with ground-based monitoring to measure the disk size as
a function of wavelength from the near-IR to the UV. We require HST to
measure the image flux ratios in the ultraviolet continuum near the
Lyman limit of the quasars. The selected targets have estimated black
hole masses that differ by an order of magnitude, and we should find
wavelength scalings for the two systems that are very different
because the Blue/UV wavelengths should correspond to parts of the disk
near the inner edge for the high mass system but not in the low mass
system. The results will be modeled using a combination of simple thin
disk models and complete relativistic disk models. While requiring
only 18 orbits, success for one system requires observations in both
Cycles 16 and 17.

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/UVIS 11657

The Population of Compact Planetary Nebulae in the Galactic Disk

We propose to secure narrow- and broad-band images of compact
planetary nebulae (PNe) in the Galactic Disk to study the missing link
of the early phases of post-AGB evolution. Ejected AGB envelopes
become PNe when the gas is ionized. PNe expand, and, when large
enough, can be studied in detail from the ground. In the interim, only
the HST capabilities can resolve their size, morphology, and central
stars. Our proposed observations will be the basis for a systematic
study of the onset of morphology. Dust properties of the proposed
targets will be available through approved Spitzer/IRS spectra, and so
will the abundances of the alpha- elements. We will be able thus to
explore the interconnection of morphology, dust grains, stellar
evolution, and populations. The target selection is suitable to
explore the nebular and stellar properties across the galactic disk,
and to set constraints on the galactic evolutionary models through the
analysis of metallicity and population gradients.

COS/NUV 11601

UV Spectroscopy of the Hot Bare Stellar Core H1504+65

H1504+65 is the hottest known white dwarf (Teff=200, 000 K). It has an
extraordinary surface composition. The surface is devoid of hydrogen
and helium. It is mainly composed of carbon and oxygen (by equal
amounts) and neon (2%). We obviously see the exposed core of a former
red giant. The evolutionary history of this unique object is unknown.
We have identified magnesium absorption lines in the soft X-ray
photospheric Chandra spectrum, which suggests that H1504+65 may be an
O-Ne-Mg white dwarf. We will test this hypothesis by abundance
determinations of Mg and Na. If confirmed, then H1504+65 would be the
most compelling case for the existence of single O-Ne-Mg white dwarfs.

ACS/WFC3 11564

Optical and Ultraviolet Photometry of Isolated Neutron Stars

We propose ultraviolet and B-band observations of 5 nearby, thermally
emitting neutron stars. These data will measure the Rayleigh-Jeans
tails of their spectra, providing a vital complement to X-ray
spectroscopy and helping to constrain atmospheric models, working
toward the ultimate goal of unraveling the physics of neutron stars.
With these data we will have good-quality optical and UV data for the
full sample of these objects, allowing detailed comparisons between
them. Finally, the data should allow us to measure proper motions for
one or two objects, and will serve as the reference data for the
remaining objects; such proper motions allow ages to be determined for
these objects by tracing them back to likely birth locations.

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?

COS/NUV/FUV 11522

COS-GTO: STAR FORMATION/LYMAN-ALPHA

A sample of 20 star-forming galaxies will be observed with COS G130M.
The galaxies were selected from the Kitt Peak International
Spectroscopic Survey (KISSR) data release and cover a broad range of
luminosity, oxygen abundance, and reddening. The goal of the program
is to characterize the Lyman-alpha properties and establish
correlations with fundamental galaxy properties. Each galaxy will be
observed for one orbit.

NIC 11417

NICMOS Detector Read noise and Dark Current

The NICMOS detector characteristics will be monitored during the
entire extent of the SMOV4 through a set of dark exposures. This will
also allow a determination of the detector temperature from bias
measurements. The data should be obtained in SAA-free orbits,
approximately every 24 hours. In addition, the detector read noise and
the detector shading profiles will be measured once a week.

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?

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:

18734-1 - NCS CPL Restart (23 October 09) @ 296/2124z

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSAcq 22 21
FGS REAcq 20 20
OBAD with Maneuver 17 17

SIGNIFICANT EVENTS:

Flash Report: NCS CPL Restart

Ops Request 18734-1 to restart the NCS CPL has been successfully
completed.

The PCE was nominally commanded off at 296/14:29z UTC. The CPL was
transitioned from Standby to Pressure Prime at a reservoir setpoint of
+5 degC at 296/14:30z UTC. After achieving stability at the pressure
prime setpoint, the CPL was transitioned from Pressure Prime to
Startup at 296/16:41z UTC, enabling the 50 W Startup heater.

At this time, the +5 degC setpoint will be maintained until stable
operation at that temperature is confirmed.

Flash Report: SIs Recovered

ACS, STIS, COS, and WFC3 have all been recovered to their Operate
states via the intercept SMS, with WFC3 being the last to complete at
297/1329z. ACS and COS have resumed observations. WFC3 will spend
until ~297/2033z UTC going through its detector cooldowns with its
first observation beginning at 297/2203z.

 




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