Daily # 4277

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4277

PERIOD COVERED: UT January 11, 2007 (DOY 011)

OBSERVATIONS SCHEDULED

ACS/HRC/WFPC2/NIC3 10842

A Cepheid Distance to the Coma Cluster

We propose to use the Advanced Camera for Surveys to search for
Cepheid variables in two spiral galaxies in the core of the Coma
cluster. A direct application of the canonical primary distance
indicator at 100 Mpc will measure the far-field Hubble constant free
of many of the systematic uncertainties which beset current
determinations relying on secondary indicators. Establishing the
far-field H_o with Cepheids will provide one of the strongest links in
the extragalactic distance scale and will directly calibrate the
fiducial fundamental plane of elliptical galaxies in Coma. With
ACS/HRC, S/N=5 to 10 or better can be reached for Cepheids with
periods of 40d to 70d at mean light in 5 orbits with the F606W filter
if H_o=72 km/s/Mpc. Efficient detection and phasing can be done with
twelve epochs optimally spaced for periods of 40-70d.

ACS/WFC 10882

Emission Line 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. We
discovered new optical jets, dust lanes, and revealed point-like
nuclei whose properties support AGN unified schemes. Here, we propose
to obtain ACS emission line images at low and high excitation of 3CR
sources with z0.3, both low- and classical high- power radio
galaxies, as a major enhancement to an already superb dataset. We aim
to probe fundamental relationships between warm optical line-emitting
gas, radio source structure {jets and lobes} and X-ray coronal halos.
We will combine our existing UV images with new emission- line images
to establish quantitative star formation characteristics and their
relation to dust and merging, and with emission-line excitation maps,
test theories on ionization beam patterns and luminosities from active
nuclei. We will seek jet induced star formation and knowing optical
emission-line physics, investigate quantitative jet physics. The
nuclear emission line properties of the galaxies will themselves be
established and used as ingredients in continuing tests of unified AGN
theories. The resulting database will be an incredibly valuable
resource to the astronomical community for years to come.

ACS/WFC 10918

Reducing Systematic Errors on the Hubble Constant: Metallicity
Calibration of the Cepheid PL Relation

Reducing the systematic errors on the Hubble constant is still of
significance and of immediate importance to modern cosmology. One of
the largest remaining uncertainties in the Cepheid- based distance
scale {which itself is at the foundation of the HST Key Project
determination of H_o} which can now be addressed directly by HST, is
the effect of metallicity on the Cepheid Period-Luminosity relation.
Three chemically distinct regions in M101 will be used to directly
measure and thereby calibrate the change in zero point of the Cepheid
PL relation over a range of metallicities that run from SMC-like,
through Solar, to metallicities as high as the most metal- enriched
galaxies in the pure Hubble flow. ACS for the first time offers the
opportunity to make a precise calibration of this effect which
currently accounts for at least a third of the total systematic
uncertainty on Ho. The calibration will be made in the V and I
bandpasses so as to be immediately and directly applicable to the
entire HST Cepheid-based distance scale sample, and most especially to
the highest-metallicity galaxies that were hosts to the Type Ia
supernovae, which were then used to extend the the distance scale
calibration out to cosmologically significant distances.

ACS/WFC 11052

Internal Flat Fields

The stability of the CCD P-flat fields will be monitored using the
calibration lamps and a sub- sample of the filter set. High signal
observations will be used to assess the stability of the pixel-
to-pixel flat field structure and to monitor the position of the dust
motes.

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration - CR Persistence Part 5

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, ACS/WFC 10802

SHOES-Supernovae, HO, for the Equation of State of Dark energy

The present uncertainty in the value of the Hubble constant {resulting
in an uncertainty in Omega_M} and the paucity of Type Ia supernovae at
redshifts exceeding 1 are now the leading obstacles to determining the
nature of dark energy. We propose a single, integrated set of
observations for Cycle 15 that will provide a 40% improvement in
constraints on dark energy. This program will observe known Cepheids
in six reliable hosts of Type Ia supernovae with NICMOS, reducing the
uncertainty in H_0 by a factor of two because of the smaller
dispersion along the instability strip, the diminished extinction, and
the weaker metallicity dependence in the infrared. In parallel with
ACS, at the same time the NICMOS observations are underway, we will
discover and follow a sample of Type Ia supernovae at z 1. Together,
these measurements, along with prior constraints from WMAP, will
provide a great improvement in HST's ability to distinguish between a
static, cosmological constant and dynamical dark energy. The Hubble
Space Telescope is the only instrument in the world that can make
these IR measurements of Cepheids beyond the Local Group, and it is
the only telescope in the world that can be used to find and follow
supernovae at z 1. Our program exploits both of these unique
capabilities of HST to learn more about one of the greatest mysteries
in science.

NIC3 10861

An ACS Treasury Survey of the Coma cluster of galaxies

We propose to use the unique spatial resolution of HST and ACS to
construct a Treasury imaging survey of the core and infall region of
the richest local cluster, Coma. We will observe samples of thousands
of galaxies down to magnitude B=27.3 with the aim of studying in
detail the dwarf galaxy population which, according to hierarchical
models of galaxy formation, are the earliest galaxies to form in the
universe. Our initial scientific objectives a 1} A study of the
structure of the dwarf galaxies, including scaling laws, nuclear
structure and morphology, to compare with hierarchical and
evolutionary models of their formation. 2} A study of the stellar
populations from colors and color gradients, and how the internal
chemical evolution of galaxies is affected by interaction with the
cluster gaseous and galaxy environment. 3} To determine the effect of
the cluster environment upon morphological features, disks, bulges and
bars, by comparing these structure in the Coma sample with field
galaxy samples. 4} Identification of dwarf galaxy samples for further
study with the new generation of multi-object and integral-field
spectrographs on 8-10 metre class telescopes such as Keck, Subaru,
Gemini, and GTC. This is the first such survey of a nearby rich
cluster. It will provide a key database for studies of galaxy
formation and evolution, and a very needed reference for comparison
with similar galaxy surveys both in lower density environments in the
nearby universe, and in high density environments at high redshifts.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10618 - GSAcq (1,0,1) failed due to Search Radius Limit Exceeded on FGS 1

At AOS (011/18:30:16) GSAcq (1,0,1)scheduled for 011/17:32:53-17:38:46
failed due to Search Radius Limit Exceeded on FGS 1. Received 486 ESB
a05 "Exceeded SRL". This is a single FGS acquisition. OBAD #1: V1
212.31, V2 1759.02, V3 -80.22, RSS 1773.60 OBAD #2: unavailable due to
LOS OBAD MAP: V1 -0.17, V2 -7.12, V3 -6.14, RSS 9.40

At AOS (011/19:22:26) REAcq (1,0,1) failed due to Search Radius Limit
Exceeded on FGS 1. Received 486 ESB a05 "Exceeded SRL" and 1808 "TxG
FHST Sanity Check Failed". OBAD #1: V1 -63.71, V2 1005.84, V3 -36.33,
RSS 1008.51 OBAD #2: unavailable due to LOS OBAD MAP: V1 1.00, V2
5.27, V3 -2.92, RSS 6.11

10619 - REacq (1,0,1) failed due to Search Radius Limit Exceeded

REaca(1,0,1) scheduled at 011/20:50:24 failed due to search radius
limit exceeded on FGS 1. OBAD1: V1=-71.20,V2=356.46,V3=-43.69,
RSS=366.121 OBAD2: V1=2.21, V2=-3.39, V3=1.23, RSS=4.22

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSacq 07 06
FGS REacq 08 06
OBAD with Maneuver 30 30

SIGNIFICANT EVENTS: (None)