HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5123
PERIOD
COVERED: 5am June 22 - 5am June 23, 2010 (DOY 173/09:00z-174/09:00z)
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
12310
- GSAcq(2,1,1) scheduled at 173/21:05:45z and REAcq scheduled at
173/22:00:26z both resulted in fine lock backup (2,0,2).
Observations possibly affected: STIS 23 - 27 Proposal ID#11693;
STIS 28 &29 Proposal ID#11857
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSAcq
5
5
FGS
REAcq
4
4
OBAD
with Maneuver 4
4
SIGNIFICANT
EVENTS: (None)
OBSERVATIONS
SCHEDULED:
COS/FUV
11619
Definitive
ISM Abundances through Low-mass X-ray Binaries as Lighthouses
We
propose observations of the UV spectra of two low-mass X-ray binaries
(Sco
X-1 and Cyg X-2) with existing Chandra X-Ray Observatory (CXO)
data.
From the X-ray data we will measure total (phase-independent)
column
densities of O, Ne, and Fe. From the UV data we will determine
gas-phase
column densities of H and O. The data in conjunction will
allow
us to make unique measurements of the total interstellar
abundances
of oxygen, neon, and iron, and direct measurements of the
dust-phase
abundances of O and Fe.
COS/FUV
11625
Beyond
the Classical Paradigm of Stellar Winds: Investigating Clumping,
Rotation
and the Weak Wind Problem in SMC O Stars
SMC
O stars provide an unrivaled opportunity to probe star formation,
evolution,
and the feedback of massive stars in an environment similar
to
the epoch of the peak in star formation history. Two recent
breakthroughs
in the study of hot, massive stars have important
consequences
for understanding the chemical enrichment and buildup of
stellar
mass in the Universe. The first is the realization that rotation
plays
a major role in influencing the evolution of massive stars and
their
feedback on the surrounding environment. The second is a drastic
downward
revision of the mass loss rates of massive stars coming from an
improved
description of their winds. STIS spectroscopy of SMC O stars
combined
with state-of-the-art NLTE analyses has shed new light on these
two
topics. A majority of SMC O stars reveal CNO- cycle processed
material
brought at their surface by rotational mixing. Secondly, the
FUV
wind lines of early O stars provide strong indications of the
clumped
nature of their wind. Moreover, we first drew attention to some
late-O
dwarfs showing extremely weak wind signatures. Consequently, we
have
derived mass loss rates from STIS spectroscopy that are
significantly
lower than the current theoretical predictions used in
evolutionary
models. Because of the limited size of the current sample
(and
some clear bias toward stars with sharp-lined spectra), these
results
must however be viewed as tentative. Thanks to the high
efficiency
of COS in the FUV range, we propose now to obtain
high-resolution
FUV spectra with COS of a larger sample of SMC O stars
to
study systematically rotation and wind properties of massive stars at
low
metallicity. The analysis of the FUV wind lines will be based on our
2D
extension of CMFGEN to model axi-symmetric rotating winds.
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.
STIS/CC
11693
Follow-up
Observations of Debris Disks around Two Solar-Type Stars
Circumstellar
debris disks offer direct views into the structure of
extrasolar
planetary systems. Their constituent dust, seen in scattered
light
and thermal emission, is created by the collisions of asteroidal
and
cometary parent bodies. The distribution of this dust provides
information
on the location of the parent bodies, and can be strongly
affected
by planetary perturbations. Dynamical signatures of planets can
include
asymmetries, warps, central clearings, and radial gaps in a
disk,
and thus are key features to search for in resolved images.
Following
up recent Spitzer measurements, we have now detected two new,
nearby
debris disks in scattered light. Our initial ACS F606W
coronagraphic
images show faint ringlike structures around the
solar-type
stars HD 10647 (F9V) and HD 207129 (G0V); both are also
spatially
resolved in Spitzer/MIPS 70 micron images. The HD 10647 disk,
seen
close to edge-on, represents the first disk ever imaged in
scattered
light around a star known to have a radial velocity planet.
The
inclined ring around HD 207129 is the faintest disk ever imaged in
scattered
light, and seems in the MIPS image to be asymmetric like the
eccentric
ring around Fomalhaut. We propose to obtain deep ACS
coronagraphic
images of these two disks. Our goals are to get definitive
measurements
of the dust spatial distributions (including disk
asymmetries
and sharpness of the ring edges), and measure the overall
F606W-F814W
color of each disk in order to constrain the dust
properties.
The results will be a definitive exploration of the Kuiper
belts
of two nearby, Sun-like stars. NOTE: HD 207129 was deleted from
this
program.
STIS/CC
11845
CCD
Dark Monitor Part 2
Monitor
the darks for the STIS CCD.
STIS/CC
11847
CCD
Bias Monitor-Part 2
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
11567
Boron
Abundances in Rapidly Rotating Early-B Stars
Models
of rotation in early-B stars predict that rotationally driven
mixing
should deplete surface boron abundances during the main-sequence
lifetime
of many stars. However, recent work has shown that many boron
depleted
stars are intrinsically slow rotators for which models predict
no
depletion should have occurred, while observations of nitrogen in
some
more rapidly rotating stars show less mixing than the models
predict.
Boron can provide unique information on the earliest stages of
mixing
in B stars, but previous surveys have been biased towards narrow-
lined
stars because of the difficulty in measuring boron abundances in
rapidly
rotating stars. The two targets observed as part of our Cycle 13
SNAP
program 10175, just before STIS failed, demonstrate that it is
possible
to make useful boron abundance measurements for early-B stars
with
Vsin(i) above 100 km/s. We propose to extend that survey to a large
enough
sample of stars to allow statistically significant tests of
models
of rotational mixing in early-B stars.
STIS/MA1/MA2
11857
STIS
Cycle 17 MAMA Dark Monitor
This
proposal monitors the behavior of the dark current in each of the
MAMA
detectors.
The
basic monitor takes two 1380s ACCUM darks each week with each
detector.
However, starting Oct 5, pairs are only included for weeks
that
the LRP has external MAMA observations planned. The weekly pairs of
exposures
for each detector are linked so that they are taken at
opposite
ends of the same SAA free interval. This pairing of exposures
will
make it easier to separate long and short term temporal variability
from
temperature dependent changes.
For
both detectors, additional blocks of exposures are taken once every
six
months. These are groups of five 1314s FUV-MAMA Time-Tag darks or
five
3x315s NUV ACCUM darks distributed over a single SAA-free interval.
This
will give more information on the brightness of the FUV MAMA dark
current
as a function of the amount of time that the HV has been on, and
for
the NUV MAMA will give a better measure of the short term
temperature
dependence.
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/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).
WFC3/UVIS
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/UVIS/IR
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.