Status Report

NASA Hubble Space Telescope Daily Report # 3610

By SpaceRef Editor
May 13, 2004
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




ACS 9476

Galaxy Evolution in the Richest Clusters at z=0.8: the EDisCS Cluster

The study of distant cluster galaxies requires two key ingredients:
{1} deep high-resolution imaging, to constrain galaxy structure; and
{2} 8m-class spectroscopy, to measure stellar content, star-formation
rates, dynamics, and cluster membership. We will reach both conditions
with the addition of HST/ACS imaging to our suite of VLT {36 nights}
and NTT {20 nights} observations of 10 confirmed clusters at z~0.8,
drawn from the ESO Distant Cluster Survey {EDisCS}. The proposed
HST/ACS data will complement our existing optical/IR imaging and
spectroscopy with quantitative measures of cluster galaxy morphologies
{i.e. sizes and shapes, bulge-disk decompositions, asymmetry
parameters}, and with measurements of cluster masses via weak lensing.
Major advantages unique to the EDisCS project include: {i} uniform
selection of clusters; {ii} large enough sample sizes to characterize
the substantial cluster-to-cluster variation in galaxy populations;
{iii} large quantities of high quality data from 8m telescopes; {iv}
uniform measurements of morphologies, spectroscopic and photometric
redshifts, SEDs, star-formation/AGN activities, and internal
kinematics; {v} optical selection of clusters to complement the X-ray
selection of almost all high-z clusters in the ACS GTO programs; {vi}
forefront numerical simulations designed specifically to allow
physical interpretation of observed differences between the high-z and
local clusters.

ACS/HRC 10050

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 coronographic
monitoring is required to assess the changing position of the spots.


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.


Galaxy Evolution During Half the Age of the Universe: ACS imaging of
rich galaxy clusters

Detailed studies of nearby galaxies {z<0.05} have shown that galaxies
have very complex histories of formation and evolution involving
mergers, bursts of star formation, and morphological changes. Even so,
the global properties of the galaxies {radii, luminosities, rotation
velocities, velocity dispersions, and absorption line strengths}
follow a number of very tight {empirical} scaling relations, e.g. the
Tully-Fisher relation and the Fundamental Plane. These relations place
constraints on models for galaxy evolution. The results for nearby
galaxies rely on high signal-to-noise spectroscopy and multi-color
photometry. With the Gemini Telescopes and the Hubble Space Telescope
{HST} it is possible to carry out similar detailed studies of galaxies
at much larger redshifts, up to z~1.0, equivalent to half the age of
the Universe. We have started a project using the scaling relations
and aimed at studying the galaxy evolution over the last half of the
age of the Universe. The project is based on a large database of
spectroscopy and photometry of galaxies in 15 X-ray selected clusters
of galaxies with redshifts between 0.15 and 1.0. Spectroscopic
observations are being obtained using both Gemini Telescopes; we have
observed 6 clusters so far, covering from z=0.18 to z=0.83. We propose
to use HST/ACS to image the clusters and determine the morphologies
and measure the sizes of the galaxies. At this time we ask for 26
orbits to image four of the clusters in our sample.

ACS/WFC 9727

Exploration of the SN Ia Hubble Diagram at z > 1.2

In the spirit of a Treasury proposal, we propose to organize, and
deliver to the astronomical community, non-proprietary follow-up
observations of ~10 Type Ia supernovae at 1<z<1.7 that are expected to
be discovered in a Cycle 12 Treasury proposal. Together with the
currently available sample, this would provide a Hubble diagram with
over 20 SNe Ia in this redshift range, where it is possible to test
the current cosmological model in the epoch of deceleration: If z ~
0.5 SNe Ia are fainter due to evolution rather than an accelerating
expansion, they should continue to get fainter at even higher
redshifts. This size sample will show trends and outliers, and permit
a more rigorous treatment of the asymmetric amplification distribution
from gravitational lensing. This is a key redshift range for the
studies of dark energy that will be done with future surveys {and
future instruments now being designed}; this dataset will lay the
ground-work for these studies by establishing the simple properties of
the supernovae in this redshift range, including magnitudes, colors,
and timescales.


The COSMOS 2-Degree ACS Survey

We will undertake a 2 square degree imaging survey {Cosmic Evolution
Survey — COSMOS} with ACS in the I {F814W} band of the VIMOS
equatorial field. This wide field survey is essential to understand
the interplay between Large Scale Structure {LSS} evolution and the
formation of galaxies, dark matter and AGNs and is the one region of
parameter space completely unexplored at present by HST. The
equatorial field was selected for its accessibility to all
ground-based telescopes and low IR background and because it will
eventually contain ~100, 000 galaxy spectra from the VLT-VIMOS
instrument. The imaging will detect over 2 million objects with I> 27
mag {AB, 10 sigma}, over 35, 000 Lyman Break Galaxies {LBGs} and
extremely red galaxies out to z ~ 5. COSMOS is the only HST project
specifically designed to probe the formation and evolution of
structures ranging from galaxies up to Coma-size clusters in the epoch
of peak galaxy, AGN, star and cluster formation {z ~0.5 to 3}. The
size of the largest structures necessitate the 2 degree field. Our
team is committed to the assembly of several public ancillary datasets
including the optical spectra, deep XMM and VLA imaging, ground-based
optical/IR imaging, UV imaging from GALEX and IR data from SIRTF.
Combining the full-spectrum multiwavelength imaging and spectroscopic
coverage with ACS sub-kpc resolution, COSMOS will be Hubble’s ultimate
legacy for understanding the evolution of both the visible and dark

FGS 9879

An Astrometric Calibration of the Cepheid Period-Luminosity Relation

We propose to measure the parallaxes of 10 Galactic Cepheid variables.
When these parallaxes {with 1-sigma precisions of 10% or better} are
added to our recent HST FGS parallax determination of delta Cep
{Benedict et al 2002}, we anticipate determining the Period-Luminosity
relation zero point with a 0.03 mag precision. In addition to
permitting the test of assumptions that enter into other Cepheid
distance determination techniques, this calibration will reintroduce
Galactic Cepheids as a fundamental step in the extragalactic distance
scale ladder. A Period-Luminosity relation derived from solar
metallicity Cepheids can be applied directly to extragalactic solar
metallicity Cepheids, removing the need to bridge with the Large
Magellanic Cloud and its associated metallicity complications.

FGS 9883

Parallaxes of Extreme Halo Subgiants: Calibrating Globular Cluster
Distances and the Ages of the Oldest Stars

The ages of the oldest stars are a key constraint on the evolution of
our Galaxy, the history of star formation, and cosmological models.
These ages are usually determined from globular clusters. However, it
is alternatively possible to determine ages of extreme Population II
subgiants in the solar neighborhood based on trigonometric parallaxes,
without any recourse to clusters. This approach completely avoids the
vexing issues of cluster distances, reddenings, and chemical
compositions. There are 3 known nearby, extremely metal-deficient Pop
II subgiants with Hipparcos parallax errors of 6-11% which are
available for such age determinations. At present, based on the latest
isochrones, the derived ages of these stars {HD 84937, HD 132475, and
HD 140283} are all close to 14 Gyr, uncomfortably close to or higher
than current estimates of the age of the universe. However, the errors
in the Hipparcos parallaxes imply uncertainties of at least 2 Gyr in
the ages of the 3 stars. We propose to measure parallaxes of these
three Pop II subgiants using HST’s Fine Guidance Sensor 1R. We expect
to reduce the Hipparcos parallax error bars by factors of 5-6,
providing the most stringent test yet of current theoretical stellar
models of Pop II stars and pushing the age uncertainties to below 0.5
Gyr. These data will also provide a major new constraint on the
distance scale of globular clusters, with wide implications for
stellar evolution and the calibration of Pop II standard candles.

NIC/NIC3 9865

The NICMOS Parallel Observing Program

We propose to continue managing the NICMOS pure parallel program.
Based on our experience, we are well prepared to make optimal use of
the parallel opportunities. The improved sensitivity and efficiency of
our observations will substantially increase the number of
line-emitting galaxies detected. As our previous work has
demonstrated, the most frequently detected line is Halpha at
0.7<z<1.9, which provides an excellent measure of current star
formation rate. We will also detect star-forming and active galaxies
in other redshift ranges using other emission lines. The grism
observations will produce by far the best available Halpha luminosity
functions over the crucial–but poorly observed–redshift range where
galaxies appear to have assembled most of their stellar mass. This key
process of galaxy evolution needs to be studied with IR data; we found
that observations at shorter wavelengths appear to have missed a large
fraction of the star-formation in galaxies, due to dust reddening. We
will also obtain deep F110W and F160W images, to examine the space
densities and morphologies of faint red galaxies. In addition to
carrying out the public parallels, we will make the fully reduced and
calibrated images and spectra available on-line, with some
ground-based data for the deepest parallel fields included.

NIC1/NIC2/NIC3 8792

NICMOS Post-SAA calibration – CR Persistence Part 3

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 9993

Cycle 12 NICMOS dark current, shading profile, and read noise
monitoring program

The purpose of this proposal is to monitor the dark current, read
noise, and shading profile for all three NICMOS detectors throughout
the duration of Cycle 12. This proposal is an essentially unchanged
continuation of PID 9636 which cover the duration of Cycle 11.

NIC2 9726

A NICMOS search for obscured supernovae in starburst galaxies

Recent near-IR monitoring campaigns were successful in detecting
obscured supernovae {SNe} in starburst galaxies. The inferred SN rate
is much higher than that obtained in previous optical campaigns, but
it is still significantly lower than expected by the high level star
formation of these systems. One possible explanation for the shortage
of SNe is that most of them occur in the nuclear region, where the
limited angular resolution of groundbased observations prevents their
detection. We propose NICMOS SNAP observations of a sample of
starburst galaxies already observed once by NICMOS, with the goal of
exploiting its sensitivity and angular resolution to detect nuclear
obscured SNe which might have been missed by groundbased surveys.
These observation will allow to assess the real SN rate in starbust
galaxies and deliver a sample of SN occurring in the extreme
environment of galactic nuclei. We expect to detect more than 55 SNe
{if the whole sample is observed}. If the number of SNe detected in
the program is much lower than expected it would prompt for a revision
of our understanding of the relation between the star formation rate
and the SN rate.

NIC3 10014

Spectrophotometry of FAINT IR STANDARDS

Faint spectrophotometric standard stars required for the SBC channel
on ACS have been established via the STIS FASTEX program that has
executed over the last three cycles. Cycle 12 is an especially
opportune time to establish companion faint IR standards for WFC3,
because the NICMOS proposal 9998 includes observations in cycle 12 of
all 6 of the primary standard stars in order to establish the absolute
flux calibration of the three grism modes to 1%. In addition to WFC3,
these new faint secondary IR standards will be a significant step
towards establishing flux standards for JWST, as well as for SNAP,
SIRTF, and SOFIA. The 6 primary standards included in Propid=9998 are
in the range of V=11-13 and include three hot pure hydrogen WDs and 3
solar analogs. We propose to establish new IR faint standards in the
15-17 mag range. Appropriate spectral types for faint IR standards are
solar analogs and hotter WDs. Many M type and cooler stars are
variable, so that long term monitoring is required before committing
HST time to such cool stars. A few G type and WD faint stars will
provide a set of faint IR standards with minimal sky and color
coverage. Existing HST images of any candidates can provide
verification that there are no contaminating stars above the 1% level
within 2-3arcsec. However, the ACS calibration field in 47 Tuc is too
crowded for linking to ground based observations. If the other
candidates are selected from SDSS or other ground based data, then the
NICMOS and STIS acquisition images can provide this verification, as
well as correction factors for arbitrary photometric size apertures.
The SNAP team is providing the northern faint stars using unreleased
SDSS data. In addition, the extreme coolest types such as L and T
stars have proven essential to sorting out the long wavelength QE of
ACS; the ACS calibrations could be improved with knowledge of L and T
SEDs in the region beyond 0.95 microns. The brighter M, L, and T
standard stars will each require a NICMOS orbit, while each faint
standard requires two Nicmos orbits and one STIS orbit for complete
wavelength coverage. The STIS spectra of the M and L stars are done as
ACS calibrations in cycles 12 and 11, respectively. An additional
faint WD has already been proposed for 2 Nicmos and 4 STIS orbits in
their cycle 12 programs already. Bright stars in the V=0-6 mag range
would be useful for direct comparisons to NIST calibrated lamps. This
comparison would offer the opportunity to compare two fundamentally
different realms of physics: pure hydrogen stellar models and
laboratory black body physics. Unfortunately, the Nicmos bright limit
is V=~8 for a solar analog and a 1s exposure without defocussing the
OTA. The primary Sloan standard BD+17d4708 at V=9.9 is safely fainter
than this Nicmos limit.

NIC3 9999

The COSMOS 2-Degree ACS Survey NICMOS Parallels

The COSMOS 2-Degree ACS Survey NICMOS Parallels. This program is a
companion to program 9822.

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/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.

WFPC2 10070

WFPC2 CYCLE 12 Supplemental Darks Part 2/3

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


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

HSTAR 9415: GS Re-acquisition (2,1,1) @ 133/04:09:38Z failed to Gyro
control only with SSLE @ 133/04:14:19Z. Previous GS Acquisition @
133/02:41:16Z was successful. FGS 1 Attitude Error Vector (QDVEFGS1)
was OOL high with a value of 335.285 arcsec. Three 486 Status Buffer
messages ‘a0e’ were received @ 133/04:12:24Z, 04:13:36Z and 04:15:36Z,
indicating "FGS Sequential Attitude Update failed because error was
too large to correct". A real-time FHST Map was performed @
133/04:46Z, attitude errors were small: V1 = 8.440, V2 = -5.383, V3 =
7.259. An ARU/PRT was cancelled with agreement of PCS SE. Under


  • 17163-1 Real Time Map @ 133/04:47:41z


  • 1234-0 TDW Cross-support tracking (T77 CODE) @ 132/1936z
  • 1234-0 TDW Cross-support tracking (T77 CODE) @ 133/0419z
  • 0924-0 HSTAR Documentation for Guide Star Acq Failure/Loss of Lock @ 133/04:12:23z

                           SCHEDULED     SUCCESSFUL    FAILURE TIMES
GSacq               11                          11
REacq                07                          06               133/04:12:23z
FHST Update            15                           15


Internal Test Source (ITS) PLCP Validation, OAT scheduled 133/12:00Z –
23:00Z with GDOC, HITT, SE, and VEST using CCS "H" String with CCS
Release and PRD O06400ST. The purpose of this testing is to
verity FGS ITS PLCPs work in an operational scenario.

SpaceRef staff editor.