Status Report

NASA Hubble Space Telescope Daily Report # 3652

By SpaceRef Editor
July 13, 2004
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




ACS/HRC 10272

A Snapshot Survey of the Sites of Recent, Nearby Supernovae

During the past few years, robotic {or nearly robotic} searches for
supernovae {SNe}, most notably our Lick Observatory Supernova Search
{LOSS}, have found hundreds of SNe, many of them in quite nearby
galaxies {cz < 4000 km/s}. Most of the objects were discovered before
maximum brightness, and have follow-up photometry and spectroscopy;
they include some of the best-studied SNe to date. We propose to
conduct a snapshot imaging survey of the sites of some of these nearby
objects, to obtain late-time photometry that {through the shape of the
light and color curves} will help reveal the origin of their lingering
energy. The images will also provide high-resolution information on
the local environment of SNe that are far superior to what we can
procure from the ground. For example, we will obtain color-color and
color-magnitude diagrams of stars in these SN sites, to determine
their progenitor masses and constraints on the reddening. Recovery of
the SNe in the new HST images will also allow us to actually pinpoint
their progenitor stars in cases where pre-explosion images exist in
the HST archive. Use of ACS rather than WFPC2 will make our snapshot
survey even more valuable than our Cycle 9 survey. This Proposal is
complementary to our Cycle 13 archival proposal, in which we outline a
plan for using existing HST images to glean information about SN


ACS internal CTE monitor

The charge transfer efficiency {CTE} of the ACS CCD detectors will
decline as damage due to on-orbit radiation exposure accumulates. This
degradation will be closely monitored at regular intervals, because it
is likely to determine the useful lifetime of the CCDs. All the data
for this program is acquired using internal targets {lamps} only, so
all of the exposures should be taken during Earth occultation time
{but not during SAA passages}. This program emulates the ACS
pre-flight ground calibration and post-launch SMOV testing {program
8948}, so that results from each epoch can be directly compared.
Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}
data will be obtained over a range of signal levels for both the Wide
Field Channel {WFC}, and the High Resolution Channel {HRC}.


CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the
development of hot pixels and test for any source of noise in ACS CCD
detectors. This programme will be executed once a day for the entire
lifetime of ACS.

ACS/WFC 10181

ACS/NICMOS Imaging of Bright Lyman Break Galaxy Candidates from SDSS

The recent surprising discovery of six unusually bright {r~20 mag}
Lyman break galaxy {LBG} candidates with z=2.45-2.80 in the Sloan
Digital Sky Survey {SDSS} raises a number of questions. Specifically,
what is the true nature of these objects, and what role if any is
played by gravitational lensing? We propose to use the superior
resolution and sensitivity of ACS and NICMOS to obtain deep images of
these objects and their environments. Compared to SDSS images, HST
will allow us to determine their morphologies {extended, point-source,
or lensed}, the appearance of their environments {rich or poor}, and
to detect any faint foreground groups or clusters that might be
responsible for lensing these objects. All outcomes would be
intriguing. If the objects are lensed, it increases from 1
{MS1512-cB58} to 7 the number of normal LBGs bright enough to study
individually. If they are instead unlensed point sources, they will
represent a new class of previously unidentified absorption-line
quasars. Finally, if they are unlensed and extended star-forming
galaxies, they are at least 4mag brighter than L_* LBGs, thus making
them the most luminous star-forming objects yet seen, representing a
heretofore unknown extreme population of objects.

HST 9382

A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS
QSO MgII-FeII Systems.

We have searched the first public release of SDSS QSO spectra for
low-z {z<1.65} metal absorption lines and found over 200 large rest
equivalent width MgII-FeII systems. Previously, we empirically showed
that such systems are good tracers of large neutral gas columns, with
~50% being classical damped Lyman alpha {DLA} systems {N_HI>=2*10^20
cm^-2}. Here we propose to follow up a well-defined subset of 79 of
them to search for DLAs with 0.47<z<1.60. Only QSOs brighter than
g’=19 were selected. The QSO emission and DLA absorption redshifts
were constrained to virtually eliminate data loss due to intervening
Lyman limit absorption. Consequently, we expect to discover ~40 new
DLAs, which is a three-fold increase in this redshift interval. This
will significantly improve our earlier low-z DLA statistical results
on their incidence, cosmological mass density, and N_HI distribution.
The results will also allow us to better quantify the empirical DLA —
metal-line correlation. With this improved understanding, the need for
follow-up UV spectroscopy will lessen and, with the release of the
final database of SDSS QSO spectra {an ~25-fold increase}, the number
of low-z DLAs could be increased arbitrarily. Thus, the power of the
large and statistically-sound SDSS database in combination with a
proven technique for finding low-z DLAs will, over the next few years,
essentially solve the problem of making an accurate determination of
the cosmic evolution of the neutral gas component down to z~0.4.

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.

NIC1/NIC2/NIC3 9995

Photometric Stability

This NICMOS calibration proposal carries out photometric monitoring
observations during Cycle 12. The format of the program is identical
to that of the Cycle 11 program 9639, except that the frequency has
been reduced to bimonthly.

STIS/CCD 10018

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS/CCD 10020

CCD Bias Monitor – Part 2

Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1,
and 1×1 at gain = 4, to build up high-S/N superbiases and track the
evolution of hot columns.

STIS/CCD 10175

STIS Snapshot Survey of Boron Abundances in Early-B Stars

Boron abundances in massive stars provide a unique constraint for new
theoretical models of stellar evolution that include rotation. We
propose to use STIS to measure the B III doublet near 2066 Angstroms
in a large sample of early-B stars. A high priority will be placed on
obtaining abundances for several stars in each of a number of
different young clusters, associations, and star forming regions. This
will allow quantitative comparison with theoretical predictions of
rotationally driven mixing in early B stars as function of mass, age,
and rotation rate. Since boron abundance measurements are not possible
for large vsin{i} values, and sin{i} is not known for individual
stars, a large sample is required to statistically test the
predictions of boron depletion as a function of the true rotation
rate. For bright nearby stars {25 targets} we will use the G230MB
grating and obtain very high S/N {>200:1}. This avoids the need for an
ND filter which would discard 99% of the photons. Spectral synthesis
techniques will allow us to derive accurate abundances despite the
moderate resolution of this grating, even for stars with relatively
high vsin{i} values. This is especially important in testing
rotational models, as current abundance measurements are mostly for
stars with much lower than average rotation rates. For fainter, more
distant stars {27 targets} we will use the E230M or E230H grating with
the 0.2×0.2 aperture.

STIS/MA1 10034

Cycle 12 MAMA Dark Monitor

This test performs the routine monitoring of the MAMA detector dark
noise. This proposal will provide the primary means of checking on
health of the MAMA detectors systems through frequent monitoring of
the background count rate. The purpose is to look for evidence of
change in dark indicative of detector problem developing.

STIS/MA1/MA2 9739

Are We Missing the Dominant Sites of Star Formation in Local UV-Bright

We propose to explore the ages, extinctions, and masses of young
stellar clusters in four nearby dwarf starburst galaxies {He 2-10, NGC
5253, NGC 4214, and IIZw40}. We will combine available archival data
with new, high resolution HST observations from the ultraviolet to the
infrared. All four galaxies are known from ground based radio/infrared
observations to contain highly obscured, massive stellar clusters,
which dominate the far infrared flux. Despite the fact that almost all
of the infrared flux comes from regions which are obscured at UV and
optical wavelengths, these galaxies are consistent with the well known
correlation between the UV slope {beta} and the ratio of far infrared
flux to ultraviolet flux at 1600 Angstroms. Because the UV and IR
fluxes are decoupled, this observation implies that a simple
foreground screen model, where UV photons from hot stars are
reprocessed into the infrared by local dust, is not the proper
interpretation for why these galaxies follow the beta relation. We
propose to investigate the underlying mechanisms responsible for this
observed correlation in these UV bright galaxies, and explore the
implication for high redshift starbursts.

WFPC2 10067

WFPC2 Cycle 12 Decontaminations and Associated Observations

This proposal is for the monthly WFPC2 decons. Also included are
instrument monitors tied to decons: photometric stability check, focus
monitor, pre- and post-decon internals {bias, intflats, kspots, &
darks}, UV throughput check, VISFLAT sweep, and internal UV flat

WFPC2 10071

WFPC2 CYCLE 12 Supplemental Darks Part 3/3

This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot

WFPC2 9816

Proper motion kinematics in Galactic bulge/bar fields

With this proposal we continue a successful programme to measure
proper motions in fields in the galactic bulge. We are able to reach
accuracies of ca 10km/s in transverse motion at a distance of 8kpc,
for thousands of stars per WFPC2 field. In combination with VLT
spectroscopic radial velocities and metallicity indices, we will be
able to construct a full dynamical and stellar-population model for
our Bulge. Previous fields in this programme were on the minor axis;
the fields proposed here {using first epoch observations from
1995-1998 from the archive} lie in the first quadrant, on the near
side of the Galactic bar. We also wish to establish first-epoch
observations in the 4th quadrant, where no suitable data exist so far.


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.) None



                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq              11                           11
FGS REacq               6                             6
FHST Update           13                           13


SpaceRef staff editor.