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Daily Report #5154



 
 
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Old August 6th 10, 04:26 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #5154

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5154

PERIOD COVERED: 5am August 5 - 5am August 6, 2010 (DOY 217/09:00z-218/09:00z)

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 8 8
FGS REAcq 6 6
OBAD with Maneuver 6 6

SIGNIFICANT EVENTS: (None)



OBSERVATIONS SCHEDULED:

ACS/WFC3 11670

The Host Environments of Type Ia Supernovae in the SDSS Survey

The Sloan Digital Sky Survey Supernova Survey has discovered nearly
500 type Ia supernovae and created a large, unique, and uniform sample
of these cosmological tools. As part of a comprehensive study of the
supernova hosts, we propose to obtain Hubble ACS images of a large
fraction of these galaxies. Integrated colors and spectra will be
measured from the ground, but we require high-resolution HST imaging
to provide accurate morphologies and color information at the site of
the explosion. This information is essential in determining the
systematic effects of population age on type Ia supernova luminosities
and improving their reliability in measuring dark energy. Recent
studies suggest two populations of type Ia supernovae: a class that
explodes promptly after star-formation and one that is delayed by
billions of years. Measuring the star-formation rate at the site of
the supernova from colors in the HST images may be the best way to
differentiate between these classes.

STIS/CCD 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CCD 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.

WFC3/ACS/IR 11563

Galaxies at z~7-10 in the Reionization Epoch: Luminosity Functions to
0.2L* from Deep IR Imaging of the HUDF and HUDF05 Fields

The first generations of galaxies were assembled around redshifts
z~7-10+, just 500-800 Myr after recombination, in the heart of the
reionization of the universe. We know very little about galaxies in
this period. Despite great effort with HST and other telescopes, less
than ~15 galaxies have been reliably detected so far at z7,
contrasting with the ~1000 galaxies detected to date at z~6, just
200-400 Myr later, near the end of the reionization epoch. WFC3 IR can
dramatically change this situation, enabling derivation of the galaxy
luminosity function and its shape at z~7-8 to well below L*,
measurement of the UV luminosity density at z~7-8 and z~8-9, and
estimates of the contribution of galaxies to reionization at these
epochs, as well as characterization of their properties (sizes,
structure, colors). A quantitative leap in our understanding of early
galaxies, and the timescales of their buildup, requires a total sample
of ~100 galaxies at z~7-8 to ~29 AB mag. We can achieve this with 192
WFC3 IR orbits on three disjoint fields (minimizing cosmic variance):
the HUDF and the two nearby deep fields of the HUDF05. Our program
uses three WFC3 IR filters, and leverages over 600 orbits of existing
ACS data, to identify, with low contamination, a large sample of over
100 objects at z~7-8, a very useful sample of ~23 at z~8-9, and limits
at z~10. By careful placement of the WFC3 IR and parallel ACS
pointings, we also enhance the optical ACS imaging on the HUDF and a
HUDF05 field. We stress (1) the need to go deep, which is paramount to
define L*, the shape, and the slope alpha of the luminosity function
(LF) at these high redshifts; and (2) the far superior performance of
our strategy, compared with the use of strong lensing clusters, in
detecting significant samples of faint z~7-8 galaxies to derive their
luminosity function and UV ionizing flux. Our recent z~7.4 NICMOS
results show that wide-area IR surveys, even of GOODS-like depth,
simply do not reach faint enough at z~7-9 to meet the LF and UV flux
objectives. In the spirit of the HDF and the HUDF, we will waive any
proprietary period, and will also deliver the reduced data to STScI.
The proposed data will provide a Legacy resource of great value for a
wide range of archival science investigations of galaxies at redshifts
z~2-9. The data are likely to remain the deepest IR/optical images
until JWST is launched, and will provide sources for spectroscopic
follow up by JWST, ALMA and EVLA.

WFC3/ACS/IR 11677

Is 47 Tuc Young? Measuring its White Dwarf Cooling Age and Completing
a Hubble Legacy

With this proposal we will firmly establish the age of 47 Tuc from its
cooling white dwarfs. 47 Tuc is the nearest and least reddened of the
metal-rich disk globular clusters. It is also the template used for
studying the giant branches of nearby resolved galaxies. In addition,
the age sensitive magnitude spread between the main sequence turnoff
and horizontal branch is identical for 47 Tuc, two bulge globular
clusters and the bulge field population. A precise relative age
constraint for 47 Tuc, compared to the halo clusters M4 and NGC 6397,
both of which we recently dated via white dwarf cooling, would
therefore constrain when the bulge formed relative to the old halo
globular clusters. Of particular interest is that with the higher
quality ACS data on NGC 6397, we are now capable with the technique of
white dwarf cooling of determining ages to an accuracy of +/-0.4 Gyrs
at the 95% confidence level. Ages derived from the cluster turnoff are
not currently capable of reaching this precision. The important role
that 47 Tuc plays in galaxy formation studies, and as the metal-rich
template for the globular clusters, makes the case for a white dwarf
cooling age for this metal-rich cluster compelling.

Several recent analyses have suggested that 47 Tuc is more than 2 Gyrs
younger than the Galactic halo. Others have suggested an age similar
to that of the most metal poor globular clusters. The current
situation is clearly uncertain and obviously a new approach to age
dating this important cluster is required.

With the observations of 47 Tuc, this project will complete a legacy
for HST. It will be the third globular cluster observed for white
dwarf cooling; the three covering almost the full metallicity range of
the cluster system. Unless JWST has its proposed bluer filters (700
and 900 nm) this science will not be possible perhaps for decades
until a large optical telescope is again in space. Ages for globular
clusters from the main sequence turnoff are less precise than those
from white dwarf cooling making the science with the current proposal
truly urgent.

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/ACS/UVIS 11613

GHOSTS: Stellar Outskirts of Massive Spiral Galaxies

We propose to continue our highly successful GHOSTS HST survey of the
resolved stellar populations of nearby, massive disk galaxies using
SNAPs. These observations provide star counts and color-magnitude
diagrams 2-3 magnitudes below the tip of the Red Giant Branch of the
outer disk and halo of each galaxy. We will measure the metallicity
distribution functions and stellar density profiles from star counts
down to very low average surface brightnesses, equivalent to ~32 V-mag
per square arcsec.

This proposal will substantially improve our unique sampling of galaxy
outskirts. Our targets cover a range in galaxy mass, luminosity,
inclination, and morphology. As a function of these galaxy properties,
this survey provides: - the most extensive, systematic measurement of
radial light profiles and axial ratios of the diffuse stellar halos
and outer disks of spiral galaxies; - a comprehensive analysis of halo
metallicity distributions as function of galaxy type and position
within the galaxy; - an unprecedented study of the stellar metallicity
and age distribution in the outer disk regions where the disk
truncations occur; - the first comparative study of globular clusters
and their field stellar populations.

We will use these fossil records of the galaxy assembly process to
test halo formation models within the hierarchical galaxy formation
scheme.

WFC3/UVIS 11630

Monitoring Active Atmospheres on Uranus and Neptune

We propose Snapshot observations of Uranus and Neptune to monitor
changes in their atmospheres on time scales of weeks and months, as we
have been doing for the past seven years. Previous Hubble Space
Telescope observations (including previous Snapshot programs 8634,
10170, 10534, and 11156), together with near-IR images obtained using
adaptive optics on the Keck Telescope, reveal both planets to be
dynamic worlds which change on time scales ranging from hours to
(terrestrial) years. Uranus equinox occurred in December 2007, and the
northern hemisphere is becoming fully visible for the first time since
the early 1960s. HST observations during the past several years
(Hammel et al. 2005, Icarus 175, 284 and references therein) have
revealed strongly wavelength-dependent latitudinal structure, the
presence of numerous visible-wavelength cloud features in the northern
hemisphere, at least one very long- lived discrete cloud in the
southern hemisphere, and in 2006 the first clearly defined dark spot
seen on Uranus. Long term ground-based observations (Lockwood and
Jerzekiewicz, 2006, Icarus 180, 442; Hammel and Lockwood 2007, Icarus
186, 291) reveal seasonal brightness changes that seem to demand the
appearance of a bright northern polar cap within the next few years.
Recent HST and Keck observations of Neptune (Sromovsky et al. 2003,
Icarus 163, 256 and references therein) show a general increase in
activity at south temperate latitudes until 2004, when Neptune
returned to a rather Voyager-like appearance with discrete bright
spots rather than active latitude bands. Further Snapshot observations
of these two dynamic planets will elucidate the nature of long-term
changes in their zonal atmospheric bands and clarify the processes of
formation, evolution, and dissipation of discrete albedo features.

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).

 




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