HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #4959
PERIOD
COVERED: 5am October 26 - 5am October 27, 2009 (DOY 299/09:00z-300/09:00z)
OBSERVATIONS
SCHEDULED
ACS/WFC3
11879
CCD
Daily Monitor (Part 1)
This
program comprises basic tests for measuring the read noise and dark
current
of the ACS WFC and for tracking the growth of hot pixels. The
recorded
frames are used to create bias and dark reference images for
science
data reduction and calibration. This program will be executed
four
days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To
facilitate
scheduling, this program is split into three proposals. This
proposal
covers 352 orbits (22 weeks) from 31 August 2009 to 31 January
2010.
COS/FUV
11895
FUV
Detector Dark Monitor
The
purpose of this proposal is to monitor the FUV detector dark rate by
taking
long science exposures without illuminating the detector. The
detector
dark rate and spatial distribution of counts will be compared
to
pre-launch and SMOV data in order to verify the nominal operation of
the
detector. Variations of count rate as a function of orbital position
will
be analyzed to find dependence of dark rate on proximity to the
SAA.
Dependence of dark rate as function of time will also be tracked.
FGS
11704
The
Ages of Globular Clusters and the Population II Distance Scale
Globular
clusters are the oldest objects in the universe whose age can
be
accurately determined. The dominant error in globular cluster age
determinations
is the uncertain Population II distance scale. We propose
to
use FGS 1R to obtain parallaxes with an accuracy of 0.2
milliarcsecond
for 9 main sequence stars with [Fe/H] < -1.5. This will
determine
the absolute magnitude of these stars with accuracies of 0.04
to
0.06mag. This data will be used to determine the distance to 24
metal-poor
globular clusters using main sequence fitting. These
distances
(with errors of 0.05 mag) will be used to determine the ages
of
globular clusters using the luminosity of the subgiant branch as an
age
indicator. This will yield absolute ages with an accuracy of 5%,
about
a factor of two improvement over current estimates. Coupled with
existing
parallaxes for more metal-rich stars, we will be able to
accurately
determine the age for globular clusters over a wide range of
metallicities
in order to study the early formation history of the Milky
Way
and provide an independent estimate of the age of the universe.
The
Hipparcos database contains only 1 star with [Fe/H] < -1.4 and an
absolute
magnitude error less than 0.18 mag which is suitable for use in
main
sequence fitting. Previous attempts at main sequence fitting to
metal-poor
globular clusters have had to rely on theoretical
calibrations
of the color of the main sequence. Our HST parallax program
will
remove this source of possible systematic error and yield distances
to
metal-poor globular clusters which are significantly more accurate
than
possible with the current parallax data. The HST parallax data will
have
errors which are 10 times smaller than the current parallax data.
Using
the HST parallaxes, we will obtain main sequence fitting distances
to
11 globular clusters which contain over 500 RR Lyrae stars. This will
allow
us to calibrate the absolute magnitude of RR Lyrae stars, a
commonly
used Population II distance indicator.
FGS
11789
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 W Vir
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
11871
Long
Term Stability of FGS1R in Position Mode
This
proposal resumes the Long Term Monitoring of FGS1R in Position Mode
using
stars in M35 that are a subset of the FGS "OFAD catalog" using
both
the "fall" and "spring" seasons (the spring orient was not
available
under two gyro mode). The data acquired by this proposal are
used
to update the FGS1R "rhoA & kA" parameters that are associated
with
the
OFAD solution that is applicable at the observation's epoch. These
values
are critical to support sub-milli arcsecond astrometry with
FGS1R.
This
particular proposal also include a FGS3 visit to M35 for post SM4
verification
of its calibration status.
NIC2/WFC3/IR
11548
Infrared
Imaging of Protostars in the Orion A Cloud: The Role of
Environment
in Star Formation
We
propose NICMOS and WFC3/IR observations of a sample of 252 protostars
identified
in the Orion A cloud with the Spitzer Space Telescope. These
observations
will image the scattered light escaping the protostellar
envelopes,
providing information on the shapes of outflow cavities, the
inclinations
of the protostars, and the overall morphologies of the
envelopes.
In addition, we ask for Spitzer time to obtain 55-95 micron
spectra
of 75 of the protostars. Combining these new data with existing
3.6
to 70 micron photometry and forthcoming 5-40 micron spectra measured
with
the Spitzer Space Telescope, we will determine the physical
properties
of the protostars such as envelope density, luminosity,
infall
rate, and outflow cavity opening angle. By examining how these
properties
vary with stellar density (i.e. clusters vs. groups vs.
isolation)
and the properties of the surrounding molecular cloud; we can
directly
measure how the surrounding environment influences protostellar
evolution,
and consequently, the formation of stars and planetary
systems.
Ultimately, this data will guide the development of a theory of
protostellar
evolution.
STIS/CCD
11844
CCD
Dark Monitor Part 1
The
purpose of this proposal is to monitor the darks for the STIS CCD.
STIS/CCD
11846
CCD
Bias Monitor-Part 1
The
purpose of this proposal is to monitor the bias in the 1x1, 1x2,
2x1,
and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up
high-S/N
superbiases and track the evolution of hot columns.
STIS/CCD/MA1
11525
COS-GTO:
STIS High Resolution Observations of the Local ISM
We
shall use bright early-type B stars located within 150pc of the Sun
to
probe the absorption properties of the interstellar gas associated
with
the local cavity. By utilizing the high sensitivity and high
spectral
resolution of the HST-STIS spectrograph we shall be able to
place
new detection limits on absorption occurring in any highly ionized
gas
associated with the lines of NV, SiIV and CIV that may be present
along
these sight-lines within the local cavity. These data will be used
to
test current theoretical models that generally predict far higher
absorption
column densities than have been previously found. Also, the
high
spectral resolution will enable far stricter limits to be placed on
the
thermal widths of such highly ionized absorption lines, which
previous
observations towards the Loop I region have suggested
anomalously
narrow profiles consistent with their formation by either
photo
ionization or highly non-equilibrium processes.
WFC3/ACS/UVIS
11360
Star
Formation in Nearby Galaxies
Star
formation is a fundamental astrophysical process; it controls
phenomena
ranging from the evolution of galaxies and nucleosynthesis to
the
origins of planetary systems and abodes for life. The WFC3,
optimized
at both UV and IR wavelengths and equipped with an extensive
array
of narrow-band filters, brings unique capabilities to this area of
study.
The WFC3 Scientific Oversight Committee (SOC) proposes an
integrated
program on star formation in the nearby universe which will
fully
exploit these new abilities. Our targets range from the
well-resolved
R136 in 30 Dor in the LMC (the nearest super star cluster)
and
M82 (the nearest starbursting galaxy) to about half a dozen other
nearby
galaxies that sample a wide range of star-formation rates and
environments.
Our program consists of broad band multiwavelength imaging
over
the entire range from the UV to the near-IR, aimed at studying the
ages
and metallicities of stellar populations, revealing young stars
that
are still hidden by dust at optical wavelengths, and showing the
integrated
properties of star clusters. Narrow-band imaging of the same
environments
will allow us to measure star-formation rates, gas
pressure,
chemical abundances, extinction, and shock morphologies. The
primary
scientific issues to be addressed are: (1) What triggers star
formation?
(2) How do the properties of star-forming regions vary among
different
types of galaxies and environments of different gas densities
and
compositions? (3) How do these different environments affect the
history
of star formation? (4) Is the stellar initial mass function
universal
or determined by local conditions?
WFC3/IR/S/C
11929
IR
Dark Current Monitor
Analyses
of ground test data showed that dark current signals are more
reliably
removed from science data using darks taken with the same
exposure
sequences as the science data, than with a single dark current
image
scaled by desired exposure time. Therefore, dark current images
must
be collected using all sample sequences that will be used in
science
observations. These observations will be used to monitor changes
in
the dark current of the WFC3-IR channel on a day-to-day basis, and to
build
calibration dark current ramps for each of the sample sequences to
be
used by GOs in Cycle 17. For each sample sequence/array size
combination,
a median ramp will be created and delivered to the
calibration
database system (CDBS).
WFC3/UV
11730
Continued
Proper Motions of the Magellanic Clouds: Orbits, Internal
Kinematics,
and Distance
In
Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in
the
Magellanic Clouds centered on background quasars. We used these data
to
determine the proper motions of the LMC and SMC to better than 5% and
15%
respectively. The results had a number of unexpected implications
for
the Milky Way-LMC-SMC system and received considerable attention in
the
literature and in the press. The implied three-dimensional
velocities
are larger than previously believed and close to the escape
velocity
in a standard 10^12 solar mass Milky Way dark halo. Our orbit
calculations
suggest the Clouds may not be bound to the Milky Way or may
just
be on their first passage, both of which are unexpected in view of
traditional
interpretations of the Magellanic Stream. Alternatively, the
Milky
Way dark halo may be a factor two more massive than previously
believed,
which would be surprising in view of other observational
constraints.
Also, the relative velocity between the LMC and SMC was
larger
than expected, leaving open the possibility that the Clouds may
not
be bound to each other. To further verify and refine our results we
requested
an additional epoch data in Cycle 16 which is being executed
with
WFPC2/PC due to the failure of ACS. A detailed analysis of one LMC
field
shows that the field proper motion using all three epochs of data
is
consistent within 1-sigma with the two-epoch data, thus verifying
that
there are no major systematic effects in our previous measurements.
The
random errors, however, are only smaller by a factor of 1.4 because
of
the relatively large errors in the WFPC2 data. A prediction for a
fourth
epoch with measurement errors similar to epochs 1 and 2 shows
that
the uncertainties will improve by a factor of 3. This will allow us
to
better address whether the Clouds are indeed bound to each other and
to
the Milky Way. It will also allow us to constrain the internal
motions
of various populations within the Clouds, and to determine a
distance
to the LMC using rotational parallax. Continuation of this
highly
successful program is therefore likely to provide important
additional
insights. Execution in SNAPshot mode guarantees maximally
efficient
use of HST resources.
WFC3/UVIS
11565
A
Search for Astrometric Companions to Very Low-Mass, Population II
Stars
We
propose to carry out a Snapshot search for astrometric companions in
a
subsample of very low-mass, halo subdwarfs identified within 120
parsecs
of the Sun. These ultra-cool M subdwarfs are local
representatives
of the lowest-mass H burning objects from the Galactic
Population
II. The expected 3-4 astrometric doubles that will be
discovered
will be invaluable in that they will be the first systems
from
which gravitational masses of metal-poor stars at the bottom of the
main
sequence can be directly measured.
WFC3/UVIS
11905
WFC3
UVIS CCD Daily Monitor
The
behavior of the WFC3 UVIS CCD will be monitored daily with a set of
full-frame,
four-amp bias and dark frames. A smaller set of 2Kx4K
subarray
biases are acquired at less frequent intervals throughout the
cycle
to support subarray science observations. The internals from this
proposal,
along with those from the anneal procedure (Proposal 11909),
will
be used to generate the necessary superbias and superdark reference
files
for the calibration pipeline (CDBS).
WFPC2/NIC3/ACS/SBC
11144
Building
on the Significant NICMOS Investment in GOODS: A Bright,
Wide-Area
Search for z>=7 Galaxies
One
of the most exciting frontiers in observational cosmology has been
to
trace the buildup and evolution of galaxies from very early times.
While
hierarchical theory teaches us that the star formation rate in
galaxies
likely starts out small and builds up gradually, only recently
has
it been possible to see evidence for this observationally through
the
evolution of the LF from z~6 to z~3. Establishing that this build up
occurs
from even earlier times {z~7-8} has been difficult, however, due
to
the small size of current high-redshift z~7-8 samples -- now
numbering
in the range of ~4-10 sources. Expanding the size of these
samples
is absolutely essential, if we are to push current studies of
galaxy
buildup back to even earlier times. Fortunately, we should soon
be
able to do so, thanks to ~50 arcmin**2 of deep {26.9 AB mag at 5
sigma}
NICMOS 1.6 micron data that will be available over the two ACS
GOODS
fields as a result of one recent 180-orbit ACS backup program and
a
smaller program. These data will nearly triple the deep near-IR
imaging
currently available and represent a significant resource for
finding
and characterizing the brightest high-redshift sources -- since
high-redshift
candidates can be easily identified in these data from
their
red z-H colours. Unfortunately, the red z-H colours of these
candidates
are not sufficient to determine that these sources are at
z>=7,
and it is important also to have deep photometry at 1.1 microns.
To
obtain this crucial information, we propose to follow up each of
these
z-H dropouts with NICMOS at 1.1 microns to determine which are at
high
redshift and thus significantly expand our sample of luminous, z>=7
galaxies.
Since preliminary studies indicate that these candidates occur
in
only 30% of the NIC3 fields, our follow-up strategy is ~3 times as
efficient
as without this preselection and 9 times as efficient as a
search
in a field with no pre- existing data. In total, we expect to
identify
~8 luminous z-dropouts and possibly ~2 z~10 J- dropouts as a
result
of this program, more than tripling the number currently known.
The
increased sample sizes are important if we are to solidify current
conclusions
about galaxy buildup and the evolution of the LF from z~8.
In
addition to the high redshift science, these deep 1.1 micron data
would
have significant value for many diverse endeavors, including {1}
improving
our constraints on the stellar mass density at z~7-10 and {2}
doubling
the number of galaxies at z~6 for which we can estimate dust
obscuration.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
(None)
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSAcq
11
11
FGS
REAcq
05
05
OBAD
with Maneuver
07
07
SIGNIFICANT
EVENTS: (None)