Status Report

NASA Hubble Space Telescope Daily Report # 3729

By SpaceRef Editor
November 3, 2004
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




ACS/HRC 10137

Cluster Archeology: The Origin of Ultra-compact Dwarf Galaxies

Ultra-compact dwarf {UCD} galaxies are a new type of galaxy we have
discovered in the central regions of the Fornax and Virgo galaxy
clusters. Our most recent observations in the Fornax Cluster show that
UCDs outnumber normal galaxies in the centre of that cluster. Here we
propose snapshot imaging of UCDs in the Fornax and Virgo clusters to
test theories of how these fascinating objects formed. In particular
we wish to image Virgo cluster UCDs for which we have ground-based
Keck spectroscopy to test predictions that they formed more recently
than the Fornax UCDs.

ACS/HRC 10199

The Most Massive Galaxies in the Universe: Double Trouble?

We are proposing an HST snapshot survey of 70 objects with velocity
dispersion larger than 350 km/s, selected from the Sloan Digital Sky
Survey. Potentially this sample contains the most massive galaxies in
the Universe. Some of these objects may be superpositions; HST imaging
is the key to determining if they are single and massive or if they
are two objects in projection. The objects which HST imaging shows to
be single objects are interesting because they potentially harbor the
most massive black holes, and because their existence places strong
constraints on galaxy formation models. When combined with ground
based data already in hand, the objects which HST imaging shows are
superpositions provide valuable information about interaction rates of
early-type galaxies as well as their dust content. They also constrain
the allowed parameter space for models of binary gravitational lenses
{such models are currently invoked to explain discrepancies in the
distribution of lensed image flux ratios and separations}.

ACS/HRC 10377

ACS Earth Flats

High signal 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 used by the pipeline and will provide
a comparison with flats derived via other techniques: L-flats from
stellar observations, sky flats from stacked GO observations, and
internal flats using the calibration lamps. Weekly coronagraphic
monitoring is required to assess the changing position of the spots.

ACS/WFC 10006

Black Hole X-ray Novae in M31

During A01-3 we found 22 Black Hole X-ray Novae {BHXN} in M31 using
Chandra, and with HST {WFPC2} found two optical counterparts. Our
results suggest either a surprisingly high ratio of BH to NS binaries,
or a surprisingly high duty cycle for BHXN. We propose to continue
this program, with the goals of understanding the relative number of
BH vs. NS X-ray binaries in the M31 bulge, and determining the orbital
period distribution and duty cycles of these BHXN. Continued
observations can determine the duty cycle. The new ACS will allow us
to go 2 mags deeper than the WFPC2, and could triple the number of
optical counterparts and therefore orbital period estimates. M31 is
the only galaxy near enough to allow this extragalactic survey for

ACS/WFC 10118

Imaging the Chemical Distribution in Type Ia SN Ejecta

We know Type Ia supernovae are thermonuclear explosions of CO white
dwarfs, but we don’t know the specifics of how the nuclear burning
process proceeds from the core outward once it starts. The
thermonuclear instability is thought to start off as a subsonic,
turbulent deflagration or burning wave but then, at some point, may
transition into a blast or detonation wave. In such "delayed
detonation" models, differences between normal and subluminous Type Ia
SNe reflect differences in the amount of burning that has occurred in
the pre-detonation phase. More burning helps to pre-expand the WD
before passage of the detontation wave, which then results in
different final element abundances and internal Fe-rich ejecta
structure. Directly imaging the 2-D chemical distribution of ejecta
from a Type Ia SN is actually possible in the case of the subluminous
Type Ia SN 1885, which occurred on the near-side of M31’s central
bulge. This 119 year old remnant is visible — from its core to its
outer edge — via strong optical/UV Ca and Fe line absorptions.
Remarkably, the SNR appears to still be in a nearly free expansion
phase, meaning that the elemental stratification seen present today
accurately reflects SN Ia explosive nucleosynthesis physics. We
propose to obtain ACS WFC/HRC images of SN 1885 in order to take
advantage of this extraordinary situation: Having a young, nearby Type
Ia SN remnant visible in silhouette against a galaxy-size light table.
These unique observations will reveal a SN Ia’s Ca and Fe ejecta
distribution, density structure, sphericity, and ionization state as a
function of expansion velocity, thereby confronting various SN Ia
models with detailed ejecta stratification and expansion velocity

ACS/WFC 10135

Unveiling the Progenitors and Physics of Cosmic Explosions

GRBs and XRFs are clearly highly asymmetric explosions and require a
long-lived power source {central engine}. In contrast, nearby
core-collapse events are essentially spherical explosions. However,
the failure of spherical neutrino driven collapses has led to the idea
that asymmetric energy release is essential for the explosion. The
recent finding of a Type Ic SN in GRB 030329, the association of the
low energy event GRB 980425 with SN 1998bw, the theoretical
development discussed above and the rise of collapsar models make it
timely to consider whether all these explosions contain engines. Given
the uncertainties in theoretical modeling it is clear that
observations are needed to guide models. A priori there is little
reason to expect connection between the ultra-relativistic jet that
powers the GRB and the explosive nucleosynthesis of the ~0.5 solar
masses of Nickel-56 that powers the accompanying supernova. We propose
a comprehensive program of ACS photometric searches {and measurements}
for SNe associated with GRBs and XRFs. In concert, we will undertake
ground-based spectroscopy to determine velocity widths, and measure
engine parameters from pan-chromatic afterglow observations. Our goal
is to produce a comprehensive database of engine and SN physical
parameters against which theoretical modeling will be guided.

ACS/WFC 10361

Earth Flats

This proposal monitors flatfield stability. This proposal obtains
sequences of Earth streak flats to construct high quality flat fields
for the WFPC2 filter set. These flat fields will allow mapping of the
OTA illumination pattern and will be used in conjunction with previous
internal and external flats to generate new pipeline superflats. These
Earth flats will complement the Earth flat data obtained during cycles

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.

NIC2 10173

Infrared Snapshots of 3CR Radio Galaxies

Radio galaxies are an important class of extragalactic objects: they
are one of the most energetic astrophysical phenomena and they provide
an exceptional probe of the evolving Universe, lying typically in high
density regions but well-represented across a wide redshift range. In
earlier Cycles we carried out extensive HST observations of the 3CR
sources in order to acquire a complete and quantitative inventory of
the structure, contents and evolution of these important objects.
Amongst the results, we discovered new optical jets, dust lanes,
face-on disks with optical jets, and revealed point-like nuclei whose
properties support FR-I/BL Lac unified schemes. Here, we propose to
obtain NICMOS infrared images of 3CR sources with z<0.3 as a major
enhancement to an already superb dataset. We aim to deshroud dusty
galaxies, study the underlying host galaxy free from the distorting
effects of dust, locate hidden regions of star formation and establish
the physical characteristics of the dust itself. We will measure
frequency and spectral energy distributions of point-like nuclei,
expected to be stronger and more prevalent in the IR, seek spectral
turnovers in known synchrotron jets and find new jets. We will
strongly test unified AGN schemes and merge these data with existing
X-ray to radio observations. The resulting database will be an
incredibly valuable resource to the astronomical community for years
to come.

NIC2 10176

Coronagraphic Survey for Giant Planets Around Nearby Young Stars

A systematic imaging search for extra-solar Jovian planets is now
possible thanks to recent progress in identifying "young stars near
Earth". For most of the proposed young {<~ 30 Myrs} and nearby {<~ 60
pc} targets, we can detect a few Jupiter-mass planets as close as a
few tens of AUs from the primary stars. This represents the first time
that potential analogs of our solar system – that is planetary systems
with giant planets having semi-major axes comparable to those of the
four giant planets of the Solar System – come within the grasp of
existing instrumentation. Our proposed targets have not been observed
for planets with the Hubble Space Telescope previously. Considering
the very successful earlier NICMOS observations of low mass brown
dwarfs and planetary disks among members of the TW Hydrae Association,
a fair fraction of our targets should also turn out to posses low mass
brown dwarfs, giant planets, or dusty planetary disks because our
targets are similar to {or even better than} the TW Hydrae stars in
terms of youth and proximity to Earth. Should HST time be awarded and
planetary mass candidates be found, proper motion follow-up of
candidate planets will be done with ground-based AOs.

WFPC2 10360


This calibration proposal is the Cycle 13 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A
variety of internal exposures are obtained in order to provide a
monitor of the integrity of the CCD camera electronics in both bays
{gain 7 and gain 15}, a test for quantum efficiency in the CCDs, and a
monitor for possible buildup of contaminants on the CCD windows.

WFPC2 10363

WFPC2 CYCLE 13 Intflat and Visflat Sweeps and Filter Rotation Anomaly

Using intflat observations, this WFPC2 proposal is designed to monitor
the pixel-to-pixel flatfield response and provide a linearity check.
The intflat sequences, to be done once during the year, are similar to
those from the Cycle 12 program 10075. The images will provide a
backup database in the event of complete failure of the visflat lamp
as well as allow monitoring of the gain ratios. The sweep is a
complete set of internal flats, cycling through both shutter blades
and both gains. The linearity test consists of a series of intflats in
F555W, in each gain and each shutter. As in Cycle 12, we plan to
continue to take extra visflat, intflat, and earthflat exposures to
test the repeatability of filter wheel motions.


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

HSTAR 9579 GSAcq (1,2,2) Loss of Lock. OTA SE review of PTAS
processing revealed GSAcq(1,2,2) required two attempts to successfully
achieve fine lock. Fine Lock was originally achieved on FGS1 at
299/03:43:05 and on FGS2 at 03:43:49. Both FGSs returned to SSM
control at 03:45:20 and the acquisition was ultimately successful at

17299-0 – Null genslew for proposal 10398 (slot 13) @ 307/1811z


                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS Gsacq               8                          8
FGS Reacq               9                          9
FHST Update            10                        10


SpaceRef staff editor.