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Daily #4024

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Old January 10th 06, 03:13 PM posted to sci.astro.hubble
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Default Daily #4024

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science


PERIOD COVERED: UT January 09, 2006 (DOY 009)


ACS/HRC 10130

Systemic Proper Motions of the Magellanic Clouds from Astrometry with
ACS: II. Second Epoch Images

We request second epoch observations with ACS of Magellanic Cloud
fields centered on the 40 quasars in the LMC and SMC for which we have
first epoch Cycle 11 data. The new data will determine the systemic
proper motion of the Clouds. An extensive astrometric analysis of the
first epoch data shows that follow-up observations with a two year
baseline will allow us to measure the proper motion of the clouds to
within 0.022 mas/year in each of the two orthogonal directions
{assuming that we can image 25 quasars, i.e., with a realistic
Snapshot Program completion rate}. The best weighted combination of
all previous measurements has a seven times larger error than what we
expect. We will determine the proper motion of the clouds with 2%
accuracy. When combined with HI data for the Magellanic Stream this
will constrain both the mass distribution in the Galactic Halo and
theoretical models for the origin of the Magellanic Stream. Previous
measurements are too crude for such constraints. Our data will provide
by far the most accurate proper motion measurement for any Milky Way

ACS/HRC 10738

Earth Flats

Sky flats will be obtained by observing the bright Earth with the HRC
and WFC. These observations will be used to verify the accuracy of the
flats currently in the pipeline and to monitor any changes. Weekly
coronagraphic monitoring is required to assess the changing position
of the spots.


ACS CCDs daily monitor

This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in ACS CCD detectors. The files, biases and dark will be used to
create reference files for science calibration. This programme will be
for the entire lifetime of ACS. Changes from cycle 13:- The default
gain for WFC is 2 e-/DN. As before bias frames will be collected for
both gain 1 and gain 2. Dark frames are acquired using the default
gain {2}. This program cover the period Oct, 2 2005- May, 29-2006. The
second half of the program has a different proposal number: 10758.

ACS/WFC 10491

A Snapshot Survey of the most massive clusters of galaxies

We propose a snapshot survey of a sample of 124 high X-ray luminosity
clusters in the redshift range 0.3-0.7. Similarly luminous clusters at
these redshifts frequently exhibit strong gravitational lensing. The
proposed observations will provide important constraints on the nature
of the cluster mass distributions and a set of optically bright,
lensed galaxies for further 8-10m spectroscopy. We acknowledge the
broad community interest in this sample and waive our data rights for
these observations.

ACS/WFC 10543

Microlensing in M87 and the Virgo Cluster

Resolving the nature of dark matter is an urgent problem. The results
of the MACHO survey of the Milky Way dark halo toward the LMC indicate
that a significant fraction of the halo consists of stellar mass
objects. The VATT/Columbia survey of M31 finds a similar lens fraction
in the M31 dark halo. We propose a series of observations with ACS
that will provide the most thorough search for microlensing toward
M87, the central elliptical galaxy of the Virgo cluster. This program
is optimized for lenses in the mass range from 0.01 to 1.0 solar
masses. By comparing with archival data, we can detect lenses as
massive as 100 solar masses, such as the remnants of the first stars.
These observations will have at least 15 times more sensitivity to
microlensing than any previous survey, e.g. using WFPC2. This is due
to the factor of 2 larger area, factor of more than 4 more sensitivity
in the I-band, superior pixel scale and longer baseline of
observations. Based on the halo microlensing results in the Milky Way
and M31, we might expect that galaxy collisions and stripping would
populate the overall cluster halo with a large number of stellar mass
objects. This program would determine definitively if such objects
compose the cluster dark matter at the level seen in the Milky Way. A
negative result would indicate that such objects do not populate the
intracluster medium, and may indicate that galaxy harassment is not as
vigorous as expected. We can measure the level of events due to the
M87 halo: this would be the best exploration to date of such a lens
population in an elliptical galaxy. Star-star lensing should also be
detectable. About 20 erupting classical novae will be seen, allowing
to determine the definitive nova rate for this giant elliptical
galaxy. We will determine if our recent HST detection of an M87
globular cluster nova was a fluke, or indicative of a 100x higher rate
of incidence of cataclysmic variables and nova eruptions in globulars
than previously believed. We will examine the populations of variable
stars, and will be able to cleanly separate them from microlensing.

ACS/WFC 10615

Timing Studies of the X-ray Binary Populations in Globular Clusters

Close binaries are fundamental to the dynamical stability and
evolution of globular clusters, but large populations have been
extremely difficult to identify. Chandra X-ray images provide a
revolutionary resource, revealing a few to dozens of low-luminosity
X-ray sources in every cluster deeply examined; our own Chandra
programs uniformly study these ubiquitous X-ray sources {close
binaries and their progeny} in a dozen clusters. We have obtained
multicolor, single-epoch, ACS images, from which to obtain initial
optical counterparts, especially CVs {the dominant population in most
clusters}, BY Dra's, and qLMXBs. As HST capability for follow-on,
confirming, spectra of our multicolor-selected counterparts is now
severely curtailed, we propose an ACS time-series imaging program that
will yield equivalent follow-on information for 5 of our clusters. The
proposed ACS time-series data with 6 min resolution and 8 hr
time-span, will: provide variability information to secure our
suggested multicolor identifications; allow secure classifications of
the various X-ray subpopulations {e.g., CVs vs. BY Dra's}; yield
quality lightcurves, whose shape will help test the notion that
magnetic CVs are more common in globular clusters than the field; and,
provide interesting contraints on the period distributions of cluster
X-ray binaries.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

A new procedure proposed to alleviate the CR-persistence problem of
NICMOS. Dark frames will be obtained immediately upon exiting the SAA
contour 23, and every time a NICMOS exposure is scheduled within 50
minutes of coming out of the SAA. The darks will be obtained in
parallel in all three NICMOS Cameras. The POST-SAA darks will be
non-standard reference files available to users with a USEAFTER
date/time mark. The keyword 'USEAFTER=date/time' will also be added to
the header of each POST-SAA DARK frame. The keyword must be populated
with the time, in addition to the date, because HST crosses the SAA ~8
times per day so each POST-SAA DARK will need to have the appropriate
time specified, for users to identify the ones they need. Both the raw
and processed images will be archived as POST-SAA DARKSs. Generally we
expect that all NICMOS science/calibration observations started within
50 minutes of leaving an SAA will need such maps to remove the CR
persistence from the science images. Each observation will need its
own CRMAP, as different SAA passages leave different imprints on the
NICMOS detectors.

NIC3 10538

Near-IR Spectrophotometry of 2MASSWJ 1207334-393254B - An Extra-Solar
Planetary Mass Companion

We propose to obtain "short" wavelength near-IR diagnostic and
characterizing spectra of the very high probability candidate
extra-solar giant planet {EGP} companion to 2MASSWJ 1207334- 393254
{2M1207}, a young brown dwarf and TW Hydrae Association member. Recent
NICMOS camera 1 multi-band photometric imaging of the companion
candidate, 0.77" {54 AU projected} from 2M1207 - initially detected at
longer wavelengths with VLT/NACO - implicate an object of several
Jupiter masses based on cooling models of EGPs and the likely age of
2M1207 {~ 8 Myr}. Physical companionship of the EGP candidate with
2M1207 has been established at the 99.1% level of confidence via
second-epoch NICMOS astrometric observations. Diagnostic spectra in
the 0.8 to 1.9 micron region {unobtainable from the ground and
overlapping the NICMOS imaging observations} will {a} critically
inform on the physical nature of the EGP, {b} provide currently
non-existing information to test/constrain theoretical models of EGP
properties and evolution, and {c} unequivocally confirm the imaging of
a bone fide EGP. Background light from 2M1207 would normally swamp the
EGP spectrum with direct spectral imaging. To obviate this, we propose
PSF-subtracted grism spectra of the EGP using 2M1207 as its own
spectral template via two- orientation high-contrast image
subtraction. The temporal stability of the HST+NICMOS PSF enables
self-subtractions of targets at different field orientations resulting
in contrast enhancements of 5 to 6 stellar magnitudes in the
circumstellar background at ~ 0.8" at these wavelengths. With the
grism field oriented to place the EGP "above" and "below" 2M1207 {at
two observational epochs} two independent spectra of the EGP will
emerge from a difference image. This prototypical spectrum will serve
to test and improve upon current models of young EGPs which predict
flux suppression by molecular absorption in their atmospheres.

NIC3/ACS/WFC 10404

The Nature of Protocluster Galaxies at z=2.16: Morphology-Density and
Color-Magnitude Relations

To establish the epoch when galaxy environment manifests itself as a
large-scale evolutionary process, we propose to extend the study of
galaxy colors and morphologies to a protocluster at z=2.16. Here the
universe is only 3 Gyrs old and significant differences are expected
between scenarios favoring a morphology-radius relation over a
morphology-density relation. In addition, because the fractional age
differences among cluster galaxies are larger, study of the color-
magnitude relation provides considerable leverage for determining the
epoch of early-type galaxy formation. To facilitate direct comparison
to studies at lower redshift, one must probe the same rest-frame
wavelengths with high photometric accuracy and at similar physical
scales. Its near-infrared photometric stability {low, constant
background} and ability to image large areas of sky at high
angular-resolution {compared to adaptive optics} makes HST/NICMOS
ideal for this program. Six pointings of NICMOS camera 3 will result
in rest-frame optical, high resolution images of 16 confirmed
protocluster members, and an additional 60 candidate protocluster
members including 29 EROs. These galaxies were selected with a variety
of techniques and span a range of projected radii within the
protocluster. The proposed observations constitute a unique
opportunity to extend the study of galaxies in overdense regions to an
early time in cosmic history.

WFPC2 10777

WFPC2 WF4 Bay 1 Temperature Reduction Test #1

A anomaly has been found in images from the WF4 CCD in WFPC2. The WF4
CCD bias level appears to have become unstable, resulting in sporadic
images with either low or zero bias level. The severity and frequency
of the problem is rapidly increasing, and it is possible that WF4 will
soon become unusable if no work-around is found. The other three CCDs
{PC1, WF2, and WF3} appear to be unaffected and continue to operate
properly. This proposal tests methods to fix the problem by adjusting
some temperatures inside WFPC2. 1 external and 24 internal orbits.


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

HSTARS: (None)

17618-0 - Patch WFPC2 UIDLE Replacement Heater Set Point (ARB OOT @ 009/12:27z


FGS GSacq 06 06
FGS REacq 09 09
OBAD with Maneuver 22 22


Ops request 17618-0 to patch WF-2 UIDLE replacement heater upper set
point to 12.2 degC was successfully completed at 009/12:28 the
replacement heater will be monitored to ensure that it cycles on and
off as expected.


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