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Daily Report #5161



 
 
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Old August 17th 10, 12:10 PM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report #5161

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5161

PERIOD COVERED: 5am August 16 - 5am August 17, 2010 (DOY 228/09:00z-229/09:00z)

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

12355 - GSAcq(1,2,1) at 228/11:51:32z, REAcq(1,2,1) at 228/13:04:36z,
228/14:44:47z and 228/16:23:51z all acquired fine lock backup on FGS 1
following scan step limit exceeded.

Observations possibly affected: WFC3 8-27, proposal ID#11671.


COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSAcq 5 5
FGS REAcq 9 9
OBAD with Maneuver 3 3

SIGNIFICANT EVENTS: (None)


OBSERVATIONS SCHEDULED:

ACS/WFC 11996

CCD Daily Monitor (Part 3)

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 308 orbits (19.25 weeks) from 21 June
2010 to 1 November 2010.

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 11900

NUV Internal/External Wavelength Scale Monitor

This program monitors the offsets between the wavelength scale set by
the internal wavecal versus that defined by absorption lines in
external targets. This is accomplished by observing two external
radial velocity standard targets: HD187691 with G225M and G285M and
HD6655 with G285M and G230L. The two standard targets have little flux
in the wavelength range covered by G185M and so Feige 48 (sdO) is
observed with this grating. Both Feige 48 and HD6655 are also observed
in SMOV. The cenwaves observed in this program are a subset of the
ones used during Cycle 17. Observing all cenwaves would require a
considerably larger number of orbits. Constraints on scheduling of
each target are placed so that each target is observed once every ~2-3
months. Observing the three targets every month would also require a
considerably larger number of orbits.

COS/NUV/FUV 11741

Probing Warm-Hot Intergalactic Gas at 0.5 z 1.3 with a Blind
Survey for O VI, Ne VIII, Mg X, and Si XII Absorption Systems

Currently we can only account for half of the baryons (or less)
expected to be found in the nearby universe based on D/H and CMB
observations. This "missing baryons problem" is one of the
highest-priority challenges in observational extragalatic astronomy.
Cosmological simulations suggest that the baryons are hidden in
low-density, shock-heated intergalactic gas in the log T = 5 - 7
range, but intensive UV and X-ray surveys using O VI, O VII, and O
VIII absorption lines have not yet confirmed this prediction. We
propose to use COS to carry out a sensitive survey for Ne VIII and Mg
X absorption in the spectra of nine QSOs at z(QSO) 0.89. For the
three highest-redshift QSOs, we will also search for Si XII. This
survey will provide more robust constraints on the quantity of baryons
in warm-hot intergalactic gas at 0.5 z 1.3, and the data will
provide rich constraints on the metal enrichment, physical conditions,
and nature of a wide variety of QSO absorbers in addition to the
warm-hot systems. By comparing the results to other surveys at lower
redshifts (with STIS, FUSE, and from the COS GTO programs), the
project will also enable the first study of how these absorbers evolve
with redshift at z 1. By combining the program with follow-up galaxy
redshift surveys, we will also push the study of galaxy-absorber
relationships to higher redshifts, with an emphasis on the
distribution of the WHIM with respect to the large-scale matter
distribution of the universe.

STIS/CCD/MA 11668

Cosmo-chronometry and Elemental Abundance Distribution of the Ancient
Star HE1523-0901

We propose to obtain near-UV HST/STIS spectroscopy of the extremely
metal-poor, highly r-process-enhanced halo star HE 1523-0901, in order
to produce the most complete abundance distribution of the heaviest
stable elements, including platinum, osmium, and lead. These HST
abundance data will then be used to estimate the initial abundances of
the long-lived radioactive elements thorium and uranium, and by
comparison with their observed abundances, enable an accurate age
determination of this ancient star. The use of radioactive
chronometers in stars provides an independent lower limit on the age
of the Galaxy, which can be compared with alternative limits set by
globular clusters and by analysis from WMAP. Our proposed observations
of HE1523-0901 will also provide significant new information about the
early chemical history of the Galaxy, specifically, the nature of the
first generations of stars and the types of nucleosynthetic processes
that occurred at the onset of Galactic chemical evolution.

STIS/CCD 11721

Verifying the Utility of Type Ia Supernovae as Cosmological Probes:
Evolution and Dispersion in the Ultraviolet Spectra

The study of distant type Ia supernova (SNe Ia) offers the most
practical and immediate discriminator between popular models of dark
energy. Yet fundamental questions remain over possible
redshift-dependent trends in their observed and intrinsic properties.
High-quality Keck spectroscopy of a representative sample of 36
intermediate redshift SNe Ia has revealed a surprising, and
unexplained, diversity in their rest-frame UV fluxes. One possible
explanation is hitherto undiscovered variations in the progenitor
metallicity. Unfortunately, this result cannot be compared to local UV
data as only two representative SNe Ia have been studied near maximum
light. Taking advantage of two new `rolling searches' and the
restoration of STIS, we propose a non-disruptive TOO campaign to
create an equivalent comparison local sample. This will allow us to
address possible evolution in the mean UV spectrum and its diversity,
an essential precursor to the study of SNe beyond z~1.

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/IR 11671

Kinematic Reconstruction of the Origin and IMF of the Massive Young
Clusters at the Galactic Center

We propose to exploit the wide field capabilities of Wide Field Camera
3 to study star formation at the Galactic center. By studying young
stars located in the most physically extreme region of our Galaxy, we
can test star formation theories, which suggest that such environments
should favor high mass stars and, in extreme cases, should suppress
star formation entirely. Specifically, we will measure the proper
motions and photometry of stars over the full extent of the three
massive young clusters that have been identified at the Galactic
Center (Arches, Quintuplet, and the Young Nuclear Star Cluster). These
observations are a factor of ?2000 more efficient than what can be
done with ground-based adaptive optics. Our goals are two-fold. First,
we hope to establish the initial sites of star formation in order to
obtain an accurate estimate of the conditions that led to the stellar
populations within these clusters. Answering this question for the
Young Nuclear Star Cluster is particularly important as it establishes
whether or not star formation can indeed proceed within 0.1 pc of our
Galaxy's supermassive black hole. Second, we will measure the IMF in
the Arches and Quintuplet, where dynamical evolution is less severe,
using proper motions to determine membership and to reveal the tidal
radius. Probing how the properties of the emergent stellar populations
within our Galaxy may be affected by the physical environment in which
they arise is an important first step to understanding how they might
vary as a function of cosmic time and thereby affect our models of
galaxy formation and evolution.

WFC3/IR 11696

Infrared Survey of Star Formation Across Cosmic Time

We propose to use the unique power of WFC3 slitless spectroscopy to
measure the evolution of cosmic star formation from the end of the
reionization epoch at z6 to the close of the galaxy- building era at
z~0.3.Pure parallel observations with the grisms have proven to be
efficient for identifying line emission from galaxies across a broad
range of redshifts. The G102 grism on WFC3 was designed to extend this
capability to search for Ly-alpha emission from the first galaxies.
Using up to 250 orbits of pure parallel WFC3 spectroscopy, we will
observe about 40 deep (4-5 orbit) fields with the combination of G102
and G141, and about 20 shallow (2-3 orbit) fields with G141 alone.

Our primary science goals at the highest redshifts a (1) Detect Lya
in ~100 galaxies with z5.6 and measure the evolution of the Lya
luminosity function, independent of cosmic variance; 2) Determine the
connection between emission line selected and continuum-break selected
galaxies at these high redshifts, and 3) Search for the proposed
signature of neutral hydrogen absorption at re-ionization. At
intermediate redshifts we will (4) Detect more than 1000 galaxies in
Halpha at 0.5z1.8 to measure the evolution of the
extinction-corrected star formation density across the peak epoch of
star formation. This is over an order-of-magnitude improvement in the
current statistics, from the NICMOS Parallel grism survey. (5) Trace
``cosmic downsizing" from 0.5z2.2; and (6) Estimate the evolution in
reddening and metallicty in star- forming galaxies and measure the
evolution of the Seyfert population. For hundreds of spectra we will
be able to measure one or even two line pair ratios -- in particular,
the Balmer decrement and [OII]/[OIII] are sensitive to gas reddening
and metallicity. As a bonus, the G102 grism offers the possibility of
detecting Lya emission at z=7-8.8.

To identify single-line Lya emitters, we will exploit the wide
0.8--1.9um wavelength coverage of the combined G102+G141 spectra. All
[OII] and [OIII] interlopers detected in G102 will be reliably
separated from true LAEs by the detection of at least one strong line
in the G141 spectrum, without the need for any ancillary data. We
waive all proprietary rights to our data and will make high-level data
products available through the ST/ECF.

WFC3/IR/S/CCD 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 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.

 




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