HUBBLE
SPACE TELESCOPE - Continuing to collect World Class Science
DAILY
REPORT #4915
PERIOD
COVERED: 5am August 21 - 5am August 24, 2009 (DOY 233/09:00z-236/09:00z)
OBSERVATIONS
SCHEDULED
WFC3/UVI
11934
UVIS
G280 Flux Calibration
Flux
calibration, image displacement, and spectral trace of the UVIS
G280
grism will be established using observations of the HST flux
standard
start GD71. Accompanying direct exposures will provide the
image
displacement measurements and wavelength zeropoints for dispersed
exposures.
The calibrations will be obtained at the central position of
each
CCD chip and at the center of the UVIS field. No additional field-
dependent
variations will be derived.
WFC3/IR
11930
IR
Gain Measurement
The
gain of the IR channel of WFC3 will be measured using a series of
internal
flat fields. Using knowledge gained from ground testing, we
propose
to collect flat field ramps which will be used to create photon
transfer
curves and give a measure of the gain. By using two filters
centered
at similar wavelengths but differing bandwidths, we will be
able
to search for any flux-dependent changes in the the measure of the
gain.
WFC3/IR
11915
IR
Internal Flat Fields
This
program is the same as 11433 (SMOV) and depends on the completion
of
the IR initial alignment (program 11425). This version contains three
instances
of 37 internal orbits; to be scheduled early, middle, and near
the
end of Cycle 17, in order to use the entire 110-orbit allocation.
In
this test, we will study the stability and structure of the IR
channel
flat field images through all filter elements in the WFC3-IR
channel.
Flats will be monitored, i.e. to capture any temporal trends in
the
flat fields, and delta flats produced. High signal observations will
provide
a map of the pixel-to-pixel flat field structure, as well as
identify
the positions of any dust particles.
WFC3/UVI
11909
UVIS
Hot Pixel Anneal
The
on-orbit radiation environment of WFC3 will continually generate new
hot
pixels. This proposal performs the procedure required for repairing
those
hot pixels in the UVIS CCDs. During an anneal, the two-stage
thermo-electric
cooler (TEC) is turned off and the four-stage TEC is
used
as a heater to bring the UVIS CCDs up to ~20 deg. C. As a result of
the
CCD warmup, a majority of the hot pixels will be fixed; previous
instruments
such as WFPC2 and ACS have seen repair rates of about 80%.
Internal
UVIS exposures are taken before and after each anneal, to allow
an
assessment of the procedure's effectiveness in WFC3, provide a check
of
bias, global dark current, and hot pixel levels, as well as support
hysteresis
(bowtie) monitoring and CDBS reference file generation. One
IR
dark is taken after each anneal, to provide a check of the IR
detector.
WFC3/UVI
11908
Cycle
17: UVIS Bowtie Monitor
Ground
testing revealed an intermittent hysteresis type effect in the
UVIS
detector (both CCDs) at the level of ~1%, lasting hours to days.
Initially
found via an unexpected bowtie-shaped feature in flatfield
ratios,
subsequent lab tests on similar e2v devices have since shown
that
it is also present as simply an overall offset across the entire
CCD,
i.e., a QE offset without any discernable pattern. These lab tests
have
further revealed that overexposing the detector to count levels
several
times full well fills the traps and effectively neutralizes the
bowtie.
Each visit in this proposal acquires a set of three 3x3 binned
internal
flatfields: the first unsaturated image will be used to detect
any
bowtie, the second, highly-exposed image will neutralize the bowtie
if
it is present, and the final image will allow for verification that
the
bowtie is gone.
WFC3/UVI
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 (11909), will be
used
to generate the necessary superbias and superdark reference files
for
the calibration pipeline (CDBS).
ACS/SBC
11885
SBC
Dark Current Measurement
This
takes a series of SBC dark measurements over a continuous period of
about
6 hours (4 orbits). The aim is to collect dark images during an
extended
SBC on time. Earlier measurements indicate that the dark
current
increases with SBC on time and may also be increasing with
overall
SBC use. The 6-hour time matches the longest time used by any
observer.
As with all SBC observations this needs continuous SAA free
time.
FGS
11875
Monitoring
FGS2R2 Distortion and Alignment After SMOV4
This
proposal monitors changes in the FGS2R2 distortion and alignment
after
SMOV4 by observing selected stars in M35 in Position mode. Data
from
each epoch are compared to track changes in FGS2R2. When the rate
of
change becomes sufficiently slow, FGS2R2 will be cleared for a
mini-OFAD
and FGS-FGS alignment calibration (carried out in another
phase
2 proposal).
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.
STIS/MA1/MA2
11859
MAMA
Dispersion Solutions
Wavelength
dispersion solutions will be determined on a yearly basis as
part
of a long- term monitoring program. Deep engineering wavecals for
each
MAMA grating will be obtained at common cenwaves. Intermediate
settings
will also be taken to check the reliability of derived
dispersion
solutions. Final selection was determined on basis of past
monitoring
and C17 requirements. The internal wavelength calibrations
will
be taken using the LINE line lamp. Extra-deep wavecals are included
for
some echelle modes and first order modes to ensure detection of weak
lines.
STIS/CCD
11858
CCD
Spectroscopic Dispersion Solution
Constrain
wavelength and spatial distortion maps using internal wavecals
obtained
with all 6 gratings (G230LB, G230MB, G430L, G430M, G750L,
G750M)
supported for use with the CCD. Data will be obtained for the
nearly
identical set of 38 central wavelengths used in the 9617 and
10025
programs.
STIS/CCD
11846
CCD
Bias Monitor-Part 1
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
11844
CCD
Dark Monitor Part 1
Monitor
the darks for the STIS CCD.
WFC3/IR
11719
A
Calibration Database for Stellar Models of Asymptotic Giant Branch
Stars
Studies
of galaxy formation and evolution rely increasingly on the
interpretation
and modeling of near-infrared observations. At these
wavelengths,
the brightest stars are intermediate mass asymptotic giant
branch
(AGB) stars. These stars can contribute nearly 50% of the
integrated
luminosity at near infrared and even optical wavelengths,
particularly
for the younger stellar populations characteristic of
high-redshift
galaxies (z>1). AGB stars are also significant sources of
dust
and heavy elements. Accurate modeling of AGB stars is therefore of
the
utmost importance.
The
primary limitation facing current models is the lack of useful
calibration
data. Current models are tuned to match the properties of
the
AGB population in the Magellanic Clouds, and thus have only been
calibrated
in a very narrow range of sub- solar metallicities.
Preliminary
observations already suggest that the models are
overestimating
AGB lifetimes by factors of 2-3 at lower metallicities.
At
higher (solar) metallicities, there are no appropriate observations
for
calibrating the models.
We
propose a WFC3/IR SNAP survey of nearby galaxies to create a large
database
of AGB populations spanning the full range of metallicities and
star
formation histories. Because of their intrinsically red colors and
dusty
circumstellar envelopes, tracking the numbers and bolometric
fluxes
of AGB stars requires the NIR observations we propose here. The
resulting
observations of nearby galaxies with deep ACS imaging offer
the
opportunity to obtain large (100-1000's) complete samples of AGB
stars
at a single distance, in systems with well-constrained star
formation
histories and metallicities.
ACS/WFC3
11695
Searching
for the Bottom of the Initial Mass Function
The
measurement of the minimum mass of the IMF would provide a
fundamental
test of theories of star and planet formation. In a Cycle 13
program,
we used ACS and ground- based near-IR imaging and spectroscopy
to
measure the IMF down to a completeness limit of 10 M_Jup (i~24) in a
800"x1000"
area in the southern subcluster of the Chamaeleon I
star-forming
region (2 Myr, 160 pc). There is no sign of a low-mass
cutoff
in this IMF measurement. To provide a better constraint on the
minimum
mass of the IMF, we propose to obtain ACS images of this field
again
and use the two ACS epochs to identify substellar cluster members
down
to the detection limit of the data (i~27) via their proper motions.
In
this way, we will improve the completeness limit of our IMF
measurement
to 3 M_Jup. In addition, to improve the number statistics of
our
measurement of the substellar IMF in Chamaeleon I, we propose to
double
the number of objects in the IMF sample by performing ACS imaging
of
a second field toward the northern subcluster.
WFC3/ACS/IR
11647
A
Deep Exploration of Classes of Long Period Variable Stars in M31
We
propose a thrifty but information-packed investigation with WFC3/IR
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 WFC3 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; 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. We
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.
WFC3/UVI
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/UVI/IR
11549
UVIS
and IR Pointing Stability
This
calibration proposal measures the pointing stability of the WFC3
UVIS
and IR channels.
Three
conditions will be tested: 1) 2-orbit stability after sitting at a
constant
thermal attitude for 10 orbits 2) 2-orbit stability after
sitting
at a hot thermal attitude for 10 orbits and then slewing to a
cold
attitude 3) 2-orbit stability after sitting at a cold thermal
attitude
for 10 orbits and then slewing to a hot attitude
Stability
measurements will be made by a series of short observations of
a
globular cluster.
COS/FUV
11492
FUV
Sensitivity
This
activity confirms COS sensitivity versus wavelength over the entire
observable
spectrum for all FUV gratings and central wavelength
settings.
Obtain quick look sensitivity visit early in SMOV. Later,
after
wavelength calibration is verified, perform a precise-centering
acquisition
and observe an appropriate HST flux standard star (chosen
from
the HST prime standard and FASTEX lists) with the PSA. (A limited
BOA
characterization is obtained in Visit 13 using primary standard
GD153.)
No off aperture- center observations are performed in this
activity
(see COS32, program 11490, for off- center characterizations).
Spectra
will be obtained to meet a Poisson S/N criterion of ~30 per
sensitivity
extraction bin or higher; substantially higher S/N
characterization
will be utilized in routine Cycle 17 calibration.
COS/NUV/FUV
11486
COS
FUV Target Acquisition Algorithm Verification
Verify
the ability of the COS FSW to place an isolated point source at
the
center of the aperture, both for the BOA and PSA, using dispersed
light
from the object using the FUV gratings. The various options for
target
centering should be exercised and shown to work properly. This
test
is for acquisitions in dispersed-light mode only. This program is
modeled
from SMOV activity summary COS28.
This
program should be executed two or more weeks after visit 12 of
11469,
and after the SIAF update, so that we have confirmed that NUV
imaging
acquisitions work properly with the BOA.
COS/NUV
11479
COS
NUV Spectroscopic Sensitivity
This
activity confirms COS sensitivity versus wavelength over the entire
observable
spectrum for all NUV gratings and central wavelength
settings.
Perform a precise- centering acquisition and observe an
appropriate
HST flux standard star (chosen from the HST prime standard
and
FASTEX lists) with the PSA. A limited BOA characterization is also
obtained
(see also program 11476, activity COS16). A quick spot check of
the
sensitivities with the PSA is also executed immediately after the
NUV
alignment (but at least 7 days after that). No off aperture-center
observations
are performed in this activity (see program 11477, activity
COS17,
for off-center characterizations). Spectra will be obtained to
meet
a Poisson S/N criterion of 20 per resolution element in the central
wavelength
of the setting; higher S/N characterization will be utilized
in
routine Cycle 17 calibration.
ACS/WFC3
11465
ACS
CCD Monitoring and Calibration for WFC3
This
program is a smaller version of our routine CCD monitoring program,
designed
to run throughout SMOV, after which our regular Cycle 17 CAL
proposal
will begin. This program obtains the bias and dark frames
needed
to generate reference files for calibrating science data, and
allows
us to monitor detector noise and the growth of hot pixels.
WFC3
11447
WFC3
IR Dark Current, Readnoise, and Background
This
proposal obtains full-frame, four-amp readout images.
Un-illuminated
internals are taken at regularly spaced intervals
throughout
SMOV in order to assess and monitor readnoise and dark
current
(of both light-sensitive pixels and reference pixels), and bad
(warm,
hot, dead, variable) pixels. In addition, externals aimed at
fields
with sparse stellar density are taken to measure diffuse
background
light.
This
program corresponds to WFC3-34.
WFC3
11446
WFC3
UVIS Dark Current, Readnoise, and CTE
This
proposal obtains full-frame, four-amp readout bias and dark frames
at
regularly- spaced intervals throughout SMOV in order to assess and
monitor
dark current, bad (warm, hot, dead) pixels, and readnoise. In
addition,
a set of internals using the WFC3 calsystem are taken to
provide
a baseline CTE measurement. WFC3-33
WFC3
11432
UVIS
Internal Flats
This
proposal will be used to assess the stability of the flat field
structure
for the UVIS detector. Flat fields will be obtained for all
filters
using the internal D2 and Tungsten lamps.
This
proposal corresponds to Activity Description ID WF19. It should
execute
only after the following proposals have executed: WF08 - 11421
WF09
- 11422 WF11 - 11424 WF15 - 11428
STIS20
11402
STIS-20
NUV MAMA Dark Monitor
The
STIS NUV-MAMA dark current is dominated by a phosphorescent glow
from
the detector window. Meta-stable states in this window are
populated
by cosmic ray impacts, which, days later, can be thermally
excited
to an unstable state from which they decay, emitting a UV
photon.
The equilibrium population of these meta-stable states is larger
at
lower temperatures; so warming up the detector from its cold safing
will
lead to a large, but temporary, increase in the dark current.
To
monitor the decay of this glow, and to determine the equilibrium dark
current
for Cycle 17, four 1380s NUV-MAMA ACCUM mode darks should be
taken
each week during the SMOV period. Once the observed dark current
has
reached an approximate equilibrium with the mean detector
temperature,
the frequency of this monitor can be reduced to one pair of
darks
per week.
STIS26
11395
STIS-26
MAMA Image Stability
The
maximum thermal motion of the MAMA detectors occurs in the first
portion
of the orbit immediately following a large angle maneuver
leading
to maximum external changes on the portion of axial bay closest
to
the STIS instrument. By the second orbit on the same target, the
thermal
motions settle down to a significant displacement right after
target
rise, a possible change later in the orbit due to sun/bright
earth/dark
earth/ deep space. We will follow these changes for two
orbits
with each MAMA with internal lamp and the medium dispersion
echelle
formats in order to obtain a two-dimension series of reference
points
on the 2-dimensional detector format. Exposures will be done
using
the 0.1X0.03 aperture and medium resolution echelle gratings, and
will
have exposure times of 120 seconds for deep, sharp spectral line
images.
For
each orbit, six spectral line images will follow each other, then
dark
frames are interposed with exposure times extending from 300
seconds
to 600 seconds. This provides frequent sampling in the portion
of
the orbit where thermal flexure is largest, while avoiding excessive
lamp
use when shifts are expected to be slower. The dark frames will
also
provide a useful addition to the calibration of the MAMA detector
dark
current.
Note
that E140M test is from hot to cold and the E230M test is from cold
to
hot. If noticeable changes are measured, the complimentary test pair
should
be considered at a later date.
ACS/WFC3
11343
Identifying
the Host Galaxies for Optically Dark Gamma-Ray Bursts
We
propose to use the high spatial resolution capabilities of Chandra to
obtain
precise positions for a sample of Gamma-ray bursts (GRBs) with no
optical
afterglows, where the optical light is suppressed relative to
the
X-ray flux. These bursts are likely to be highly obscured and may
have
different environments from the optically bright GRBs. Our Chandra
observations
will (unlike Swift-XRT positions) allow for the unique
identification
of a host galaxy. To locate these host galaxies we will
follow
up our Chandra positions with deep optical and IR observations
with
HST. The ultimate aim is to understand any differences between the
host
galaxies of optically dark and bright GRBs, and how these affect
the
use of GRBs as tracers of star formation and galaxy evolution at
high
redshift.
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
20
20
FGS
REAcq
39
39
OBAD
with Maneuver
12
12
SIGNIFICANT
EVENTS: (None)