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Daily Report #5168

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Old August 26th 10, 01:24 PM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report #5168

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science


PERIOD COVERED: 5am August 25 - 5am August 26, 2010 (DOY 237/09:00z-238/09:00z)


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

HSTARS: (None)


18887-0 - Install COS CS FSW 4.11 @ 237/1542z


FGS GSAcq 05 05
FGS REAcq 10 10
OBAD with Maneuver 05 05


COS FSW 4.11 was successfully installed and verified by the FSW team
at 237/15:42.


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.

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.


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

WFC3/IR 11694

Mapping the Interaction Between High-Redshift Galaxies and the
Intergalactic Environment

With the commissioning of the high-throughput large-area camera
WFC3/IR, it is possible for the first time to undertake an efficient
survey of the rest-frame optical morphologies of galaxies at the peak
epoch of star formation in the universe. We therefore propose deep
WFC3/IR imaging of over 320 spectroscopically confirmed galaxies
between redshift 1.6 z 3.4 in well-studied fields which lie along
the line of sight to bright background QSOs. The spectra of these
bright QSOs probe the IGM in the vicinity of each of the foreground
galaxies along the line of sight, providing detailed information on
the physical state of the gas at large galactocentric radii. In
combination with our densely sampled UV/IR spectroscopy, stellar
population models, and kinematic data in these fields, WFC3/IR imaging
data will permit us to construct a comprehensive picture of the
structure, dynamics, and star formation properties of a large
population of galaxies in the early universe and their effect upon
their cosmological environment.

WFC3/IR 11708

Determining the Sub-stellar IMF in the Most Massive Young Milky Way
Cluster, Westerlund 1

Despite over 50 years of active research, a key question in galactic
astronomy remains unanswered: is the initial mass function (IMF) of
stars and sub-stellar objects universal, or does it depend on initial
conditions? The answer has profound consequences for the evolution of
galaxies as well as a predictive theory of star formation. Work to
date suggests that certain environments (high densities, e.g.
Elmegreen 2004; low metallicity, e.g. Larson 2005) should produce a
top-heavy IMF, and there are hints from unresolved star-bursts that
this might be the case. Yet, there is no clear evidence for an IMF
that differs from that characterizing the Galactic field stars in a
resolved stellar population down to one solar mass. Westerlund 1 is
the most massive young star cluster known in the Milky Way. With an
estimated mass of 5x10^4 Msun, an age of 3-5 Myr, and located at a
distance of 3-4 kpc, it presents a unique opportunity to test whether
the IMF in such a cluster deviates from the norm well down into the
brown dwarf regime. We propose WFC3 near-IR imaging to probe the IMF
down to 40 Jupiter masses. The data will enable use to: 1) provide a
stringent test of the universality of the IMF under conditions
approximating those of star-bursts; 2) search for primordial or
dynamic mass segregation in the clusters; and 3) assess whether the
cluster is likely to remain bound (as a massive open cluster) or
disperse into the field. We will obtain images in the F125W, F160W,
and F139M filters. The F139M filter covers a strong water absorption
feature and the color F125W/F139M is a powerful temperature diagnostic
in the range 2800-4000 K. This information will enable us to: a)
confirm membership for low mass stars suspected on the basis of their
position in the color-magnitude diagram; b) place the members in the
HR diagram; and c) estimate the masses and ages of cluster members for
low-mass stars and sub-stellar objects. This new capability offered
with the WFC3 (through a novel combination of filter complement, high
spatial resolution, and large field of view) will enable us to make a
fundamental test of whether the IMF is universal on a unique resolved
stellar population, as well as assess the clusters structure,
dynamics, and ultimate fate.

WFC3/IR 11926

IR Zero Points

We will measure and monitor the zeropoints through the IR filters
using observations of the white dwarf standard stars, GD153, GD71 and
GD191B2B and the solar analog standard star, P330E. Data will be taken
monthly during Cycle 17. Observations of the star cluster, NGC 104,
are made twice to check color transformations. We expect an accuracy
of 2% in the wide filter zeropoints relative to the HST photometric
system, and 5% in the medium- and narrow-band filters.

WFC3/IR 11928

WFC3/IR Low-Frequency Flat and Geometric Distortion

Multiple observations of globular cluster Omega Cen at multiple
infrared wavelengths of IR detector will be used to derive filter
dependency of low-frequency sensitivity (L_flat fields) across of IR
detector and its time variation. Additionally, the same data will be
also used to derive filter-dependant geometric distortion of the
detector and its time-dependency.

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 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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