Daily Report #4915

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 (z1). 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)