HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT # 4298
PERIOD COVERED: UT February 12, 2007 (DOY 043)
OBSERVATIONS SCHEDULED
NIC2 10798
Dark Halos and Substructure from Arcs & Einstein Rings
The surface brightness distribution of extended
gravitationally lensed
arcs and Einstein rings contains super-resolved
information about the
lensed object, and, more excitingly, about the smooth and
clumpy mass
distribution of the lens galaxies. The source and lens
information can
non-parametrically be separated, resulting in a direct
"gravitational
image" of the inner mass-distribution of
cosmologically-distant galaxies
{Koopmans 2005; Koopmans et al. 2006 [astro-ph/0601628]}.
With this goal
in mind, we propose deep HST ACS-F555W/F814W and
NICMOS-F160W WFC
imaging of 20 new gravitational-lens systems with
spatially resolved
lensed sources, of the 35 new lens systems discovered by
the Sloan Lens
ACS Survey {Bolton et al. 2005} so far, 15 of which are
being imaged in
Cycle-14. Each system has been selected from the SDSS and
confirmed in
two time- efficient HST-ACS snapshot programs {cycle
13&14}.
High-fidelity multi-color HST images are required {not
delivered by the
420s snapshots} to isolate these lensed images {properly
cleaned,
dithered and extinction-corrected} from the lens galaxy
surface
brightness distribution, and apply our "gravitational
maging" technique.
Our sample of 35 early-type lens galaxies to date is by
far the largest,
still growing, and most uniformly selected. This minimizes
selection
biases and small-number statistics, compared to smaller,
often
serendipitously discovered, samples. Moreover, using the
WFC provides
information on the field around the lens, higher S/N and a
better
understood PSF, compared with the HRC, and one retains
high spatial
resolution through drizzling. The sample of galaxy mass
distributions -
determined through this method from the arcs and Einstein
ring HST
images - will be studied to: {i} measure the smooth mass
distribution of
the lens galaxies {dark and luminous mass are separated
using the HST
images and the stellar M/L values derived from a joint
stellar-dynamical
analysis of each system}; {ii} quantify statistically and
individually
the incidence of mass-substructure {with or without
obvious luminous
counter- parts such as dwarf galaxies}. Since dark-matter
substructure
could be more prevalent at higher redshift, both results
provide a
direct test of this prediction of the CDM hierarchical
structure-formation model.
WFPC2 10918
Reducing Systematic Errors on the Hubble Constant:
Metallicity
Calibration of the
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
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.
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 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
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
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
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.
WFPC2 10913
The Light Echoes around V838 Monocerotis
V838 Monocerotis, which burst upon the astronomical scene
in early 2002,
is a completely unanticipated new object. It underwent a
large-amplitude
and very luminous outburst, during which its spectrum
remained that of
an extremely cool supergiant. A rapidly evolving set of
light echoes
around V838 Mon was discovered soon after the outburst,
and quickly
became the most spectacular display of the phenomenon ever
seen. These
light echoes provide the means to accomplish four unique
types of
measurements based on continued HST imaging during the
event: {1} Study
effects of MHD turbulence at high resolution and in 3
dimensions; {2}
Construct the first unambiguous and fully 3-D map of a
circumstellar
dust envelope in the Milky Way; {3} Study dust physics in
a unique
setting where the spectrum and light curve of the
illumination, and the
scattering angle, are unambiguously known; and {4}
Determine the
distance to V838 Mon through direct geometric techniques.
Because of the
extreme rarity of light echoes, this is almost certainly
the only
opportunity to achieve such results during the lifetime of
HST. We
propose two visits during Cycle 15, in order to continue the
mapping of
the circumstellar dust and to achieve the other goals
listed above.
WFPC2 11095
Hubble Heritage Observations of NGC 6050
The Hubble Heritage team will use a single pointing of
WFPC2 to obtain
F450W, F555W, F656N, and F814W images of NGC 6050 as part
of a public
release image.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
10684 - GSacq(2,3,3) resulted in Fine Lock Backup
GSacq(2,3,3) scheduled at 043/15:18:56 resulted
in Fine Lock Backup
(2,0,2). Stop flags QF3STOPF and QSTOP were
received for FGS 3. OBAD2 at
1513:40 showed errors of V1= -1.15, V2=-2.29,
V3=5.64 and RSS=6.19. The
Map at 15:26:04 showed error of V1=-0.76,
V2=-12.39, V3=-2.54 and RSS
=12.67.
10685 - OBAD Failed Identification
At 043/18:29:14 OBAD1 scheduled at 18:26:19
failed. The second OBAD and the
Reacq was successful.
10686 - OBAD Failed Identification
At 043/23:36:38, OBAD1 using trackers FHST-1 and
FHST-2 failed. OBAD
success flag (mnemonic GCHACL09) returned to the
"no success" state (a
value of 1). OBAD1 had (RSS) value of 192464.25
arcseconds. Subsequent
GSAcq was successful.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 07 07
FGS REacq 07 07
OBAD with Maneuver 28 26
SIGNIFICANT EVENTS: (None)