Notice: Due to the conversion of some ACS WFC or HRC
observations into
WFPC2, or NICMOS observations after
the loss of ACS CCD science
capability in January, there may be an
occasional discrepancy between a
proposal's listed (and correct) instrument
usage and the abstract that
follows it.
HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #
4438
PERIOD COVERED: UT August 30, 2007 (DOY 242)
OBSERVATIONS SCHEDULED
FGS 11211
An Astrometric Calibration of
Population II Distance Indicators
In 2002 HST produced a highly precise parallax for RR Lyrae. That
measurement resulted in an absolute
magnitude, M{V}= 0.61+/-0.11, a
useful result, judged by the over ten
refereed citations each year
since. It is, however, unsatisfactory
to have the direct,
parallax-based, distance scale of Population
II variables based on a
single star. We propose, therefore, to
obtain the parallaxes of four
additional RR Lyrae
stars and two Population II Cepheids, or
stars. The Population II Cepheids lie with the RR Lyrae
stars on a
common K-band Period-Luminosity
relation. Using these parallaxes to
inform that relationship, we
anticipate a zero-point error of 0.04
magnitude. This result should greatly
strengthen confidence in the
Population II distance scale and increase our
understanding of RR Lyrae
star and Pop II Cepheid
astrophysics.
FGS 11212
Filling the Period Gap for Massive Binaries
The current census of binaries among the massive O-type
stars is
seriously incomplete for systems in the
period range from years to
millennia because the radial velocity
variations are too small and the
angular separations too close for easy
detection. Here we propose to
discover binaries in this observational
gap through a Faint Guidance
Sensor SNAP survey of relatively bright targets listed in
the Galactic O
Star Catalog. Our primary goal is to
determine the binary frequency
among those in the
cluster/association, field, and runaway groups. The
results will help us assess the role of
binaries in massive star
formation and in the processes that lead
to the ejection of massive
stars from their natal clusters. The
program will also lead to the
identification of new, close binaries that
will be targets of long term
spectroscopic and high angular resolution
observations to determine
their masses and distances. The
results will also be important for the
interpretation of the spectra of suspected and
newly identified binary
and multiple systems.
NIC1/NIC2 11172
Defining Classes of Long Period Variable Stars in M31
We propose a thrifty but information-packed investigation
{1440
exposures total} with NICMOS F205W, F160W
and F110W providing crucial
information about Long Period Variables in
M31, at a level of detail
that has recently allowed the
discovery of new variable star classes in
the Magellanic
Clouds, a very different stellar population. These
observations are buttressed by an extensive
map of the same fields with
ACS and WFPC2 exposures in F555W and F814W, and a massive
ground-based
imaging patrol producing well-sampled
light curves for more than 400,000
variable stars. Our primary goal is to
collect sufficient NIR data in
order to analyze and classify the
huge number of long-period variables
in our catalog {see below} through
Period-Luminosity {P/L} diagrams. We
will produce accurate P/L diagrams
for both the bulge and a progression
of locations throughout the disk
of M31. These diagrams will be similar
in quality to those currently in
the Magellanic Clouds, with their lower
metallicity, radically different star
formation history, and larger
spread in distance to the variables.
M31 offers an excellent chance to
study more typical disk populations,
in a manner which might be extended
to more distant galaxies where
such variables are still visible, probing
a much more evenly spread
progenitor age distribution than cepheids {and
perhaps useful as a distance scale
alternative or cross-check}. Our data
will also provide a massive and
unique color- magnitude dataset, and
allow us to confirm the microlensing nature of a large sample of
candidate lensed
sources in M31. We expect that this study will produce
several important results, among them a
better understanding of P/L and
P/L-color relations for pulsating variables which are
essential to the
extragalactic distance ladder, will view
these variables at a common
distance over a range of metallicities {eliminating the distance-error
vs. metallicity
ambiguity between the LMC and SMC}, allow further
insight into possible faint- variable
mass-loss for higher
metallicities, and in general produce a
sample more typical of giant
disk galaxies predominant in many
studies.
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 DARKs. 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 11329
The Final SHOE; Completing a Rich Cepheid Field in NGC 1309
The Cycle 15 SHOES program {GO 10802} is a large HST
program allocated
186 orbits to rebuild the distance ladder using NGC 4258
as a new
anchor, a set of 6 recent, ideal type Ia supernovae and Cepheids in
their hosts, and NICMOS as a single,
homogeneous photometer of long
period Cepheids.
These tools provide the means to achieve a 4%
measurement of the Hubble constant, an
invaluable constraint for cosmic
concordance fits to dark energy models.
Unfortunately, the SHOES NICMOS
integrations of long period Cepheids in the last and most recent nearby
type Ia
supernova host, NGC 1309, are too short because the preliminary
estimate of its distance, 30 Mpc, was too low. Our refined estimate now
based on the full reduction of both
our Cycle 14 and 15 ACS data is 36
Mpc, or 0.4 mag farther. Fortunately, Nature was extremely kind
providing a single rich NIC2 field in
which we can fully make up for the
shortfall due to its abundance of Cepheids. We are expensing our final 4
orbits on this field of a dozen
P>30 day Cepheids and seek an additional
5 orbits to reach the depth for measuring the mean F160W
magnitudes of
the long-period Cepheids
with the necessary signal-to-noise ratios of
better than 10.
WFPC2 10789
The Role of Environment in the Formation of Dwarf Galaxies
Clusters of galaxies contain an overdensity
of dwarfs compared to the
field. Within galaxy clusters there
is also a correlation between the
overdensity of dwarfs and local galaxy
density, such that areas of lower
galaxy density contain more dwarfs per
giant. The origin of these
'extra' dwarfs is unknown, but a
large fraction of them did not form
through standard collapses early in the
universe. Some dwarf ellipticals
in clusters have metal rich and
young {< 6 Gyr} stellar populations
while others contain old metal poor
populations, suggesting multiple
formation mechanisms and time scales. We
propose to test the idea that
dwarfs descend from galaxies accreted
into clusters during the past 8
Gyr by correlating ages and metallicities of dwarfs with their internal
structures - spiral arms, bars, and disks.
If dwarfs originate from more
massive galaxies then these features
should be common in metal rich and
young dwarfs. On the other hand, if
no correlation is found it would
suggest that dwarfs form through
in-situ collapses of gas in the
intragalactic medium after the universe was reionized.
WFPC2 10915
ACS Nearby Galaxy Survey
Existing HST observations of nearby galaxies comprise a
sparse and
highly non-uniform archive, making
comprehensive comparative studies
among galaxies essentially
impossible. We propose to secure HST's
lasting impact on the study of nearby
galaxies by undertaking a
systematic, complete, and carefully
crafted imaging survey of ALL
galaxies in the Local Universe outside
the Local Group. The resulting
images will allow unprecedented
measurements of: {1} the star formation
history {SFH} of a >100 Mpc^3 volume
of the Universe with a time
resolution of Delta[log{t}]=0.25; {2} correlations
between spatially
resolved SFHs
and environment; {3} the structure and properties of thick
disks and stellar halos; and {4} the
color distributions, sizes, and
specific frequencies of globular and
disk clusters as a function of
galaxy mass and environment. To reach
these goals, we will use a
combination of wide-field tiling and
pointed deep imaging to obtain
uniform data on all 72 galaxies within
a volume-limited sample extending
to ~3.5 Mpc,
with an extension to the M81 group. For each galaxy, the
wide-field imaging will cover out to ~1.5
times the optical radius and
will reach photometric depths of at
least 2 magnitudes below the tip of
the red giant branch throughout the
limits of the survey volume. One
additional deep pointing per galaxy will reach
SNR~10 for red clump
stars, sufficient to recover the
ancient SFH from the color-magnitude
diagram. This proposal will produce
photometric information for ~100
million stars {comparable to the number
in the SDSS survey} and uniform
multi- color images of half a square
degree of sky. The resulting
archive will establish the fundamental
optical database for nearby
galaxies, in preparation for the shift
of high- resolution imaging to
the near-infrared.
WFPC2 11039
Polarizers Closeout
Observations of standard stars and a highly polarized
reflection nebula
are made as a final calibration for
the WFPC2 polarizers. VISFLATS are
also obtained.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal
performance that will be investigated.)
HSTARS:
10967 - GSacq(2,3,2) failed, Search Radius Limit exceeded on FGS 2
GSacq(2,3,2)
at 243/05:47:45 failed at 05:53:54 with search radius limit
exceeded on FGS 2. OBADs prior to
GSACQ had RSS errors of 5692.67 and
7.42 arcseconds
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 10 09
FGS REacq 05 05
OBAD with Maneuver 28 28
SIGNIFICANT EVENTS: (None)
-
____________________________________________________________
Lynn F. Bassford
Hubble Space Telescope
CHAMP
CHAMP Flight Operations Team Manager
Lockheed Martin
NASA GSFC PH#: 301-286-2876
"The Hubble Space Telescope is the
astronomical observatory and key to unlocking the most cosmic mysteries of the
past, present and future." - 7/26/6