HST Daily Report # 3303
HUBBLE SPACE TELESCOPE
DAILY REPORT # 3303
PERIOD COVERED: DOY 50
OBSERVATIONS SCHEDULED
NICMOS 8791
NICMOS Post-SAA calibration – CR Persistence Part 2
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 DARKSs. 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.
STIS/CCD 9066
Closing in on the Hydrogen Reionization Edge of the Universe.
The Space Telescope Imaging Spectrograph (CCD) was used in parallel
constrain
the Hydrogen reionization edge in emission that marks the transition from
a
neutral to a fully ionized IGM at a predicted redshifts.
HST 9382
A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS QSO
MgII-FeII Systems.
We have searched the first public release of SDSS QSO spectra for low-z
{z<1.65}
metal absorption lines and found over 200 large rest equivalent width
MgII-FeII
systems. Previously, we empirically showed that such systems are good
tracers of
large neutral gas columns, with ~50% being classical damped Lyman alpha
{DLA}
systems {N_HI>=2*10^20 cm^-2}. Here we propose to follow up a
well-defined
subset of 79 of them to search for DLAs with 0.47<z<1.60. Only QSOs
brighter
than g’=19 were selected. The QSO emission and DLA absorption redshifts
were
constrained to virtually eliminate data loss due to intervening Lyman
limit
absorption. Consequently, we expect to discover ~40 new DLAs, which is a
three-fold increase in this redshift interval. This will significantly
improve
our earlier low-z DLA statistical results on their incidence,
cosmological mass
density, and N_HI distribution. The results will also allow us to better
quantify the empirical DLA — metal-line correlation. With this improved
understanding, the need for follow-up UV spectroscopy will lessen and,
with the
release of the final database of SDSS QSO spectra {an ~25-fold increase},
the
number of low-z DLAs could be increased arbitrarily. Thus, the power of
the
large and statistically-sound SDSS database in combination with a proven
technique for finding low-z DLAs will, over the next few years,
essentially
solve the problem of making an accurate determination of the cosmic
evolution of
the neutral gas component down to z~0.4.
STIS 9398
Understanding Irradiation and Dipping Behaviour in Low Mass X-ray
Binaries
It is now clear that X-ray irradiation is the driving force behind many
of the
observed properties of accretion discs on a huge range of scales from
Galactic
interacting binaries to AGN. However to study the detailed physics of
this
process requires the accessible timescales and geometrical constraints
afforded
by Galactic low mass X-ray binaries {LMXBs}. The ideal object for this
study is
EXO 0748-676 {UY Vol} because of its high inclination and full spectrum
of LMXB
phenomenology: type I bursts, dips and total eclipses. It is also
remarkable as
it was designated a transient on its discovery in 1985, but remains X-ray
active
to this day, thereby providing a potential unifying link between
persistent and
transient systems. Its present high state is likely maintained by X-ray
heating;
hence we can learn about a disk strongly influenced by irradiation. STIS
TIMETAG
observations in the far-UV will eclipse map continuum and emission lines;
examine obscuration by the likely thick disk rim; and search for the UV
signatures of dips and bursts. This provides an unprecedented range of
techniques with which to probe the structure of an irradiated accretion
disk and
further our understanding of the irradiation of accretion flows in
general.
NICMOS 9414
Resolved halo stellar populations in the Milky Way analogue edge-on
galaxy NGC
891
The stellar halo is one of the fundamental building blocks of galaxies.
Although
ground-based surface photometry has shown that stellar halos exist in
some
spiral galaxies, with colours similar to those of the main disk, little
else is
known about their stellar populations. We propose to carry out a
systematic
study of the halo regions of the edge-on galaxy NGC 891. The resulting
deep
colour-magnitude diagrams will be used to infer the mean metallicity of
the
bright halo giants at the tip of the RGB and below, and its metallicity
spread.
Recently, Zepf et al. {2000} inferred that the halo metallicity of NGC
5907 has
to be low {Fe/H <= -1.7}, with a large stellar M/L ratio. We will be able
to
test this hypothesis with much better and deeper data. If we can confirm
a
similar halo composition in NGC 891, this would imply that the Milky Way
halo
might be very different from external halos. Since galactic halos trace
the
history of galaxy formation, this will have important implications for
our
understanding of galactic evolution on cosmological time scales. Using
these
survey data, we will be able to conclusively distinguish between genuine
halo
objects and merger remnants, without having to assume a scenario in which
the
halo field population is fully mixed. Surprisingly, such studies have not
yet
been undertaken for NGC 891, although the galaxy is a prime Milky Way
analogue.
ACS 9427
Globular Cluster Systems in Supergiant E Galaxies
clusters {Brightest Cluster Galaxies}. It is among this BCG class that
the
characteristics of globular cluster systems display their widest range in
metallicity distribution and specific frequency and thus confront galaxy
formation models with their most varied challenges. Were these systems
built
primarily by early in situ conversion of gas clouds, by later mergers, or
by
ongoing accretions of dwarfs? Their extensive halo cluster systems
contain many
clues to these relic events. BCGs are the biggest and rarest type of
galaxy, and
to date the globular clusters in only two BCGs {M87, NGC 1399} are well
studied.
The ACS camera now brings many more such systems within reach. We propose
to
image the globular cluster systems in 13 BCGs in the distance regime cz
~eq
2000
– 5000 km s^-1. With deep {B, I} exposures we will measure the globular
cluster
metallicity distribution functions, specific frequency, radial
distributions,
and luminosity distributions, as well as correlations among these
quantities.
This work will be the first comprehensive, homogeneous deep survey of
globular
clusters in BCGs. The superior area and sensitivity of ACS will yield a
gain of
a factor of eight over previous WFPC2 studies for sample size and
metallicity
discrimination.
STIS 9441
Zinc Abundances in Damped Ly-Alpha Systems at z < 0.5: A Missing Link in
the
Chemical History of Galaxies
The evolution of metallicity in damped Lyman alpha {DLA} quasar
absorption
systems is an important constraint on the global star formation history
of the
universe, but remains a big puzzle at present. The H I column density
weighted
mean metallicity in DLAs is expected to rise to solar values at low
redshifts,
based on cosmic chemical evolution models, because the mass-weighted mean
metallicity of local galaxies is near- solar. However, current DLA
abundance
studies are highly uncertain and cannot distinguish between evolution and
no
evolution in the mean metallicity at redshifts 0.4 < z < 3.5. The
existing data
are particularly incomplete because no Zn measurements exist for z < 0.4,
and
only 2 exist for z < 0.5, which spans the past 35-45 % of the age of the
universe. To pin down the cosmic age-metallicity relation all the way to
the
present epoch, we propose to measure Zn abundances in five DLAs at 0.1 <
z <
0.5. We propose to use HST STIS because it is the only existing
instrument that
can measure the necessary UV lines. Our observations will clearly
distinguish
between no metallicity evolution vs. the predicted evolution. Our data
will
also
provide Cr measurements, which will help to estimate the dust abundance.
The
proposed observations are crucial for tying together the absorption and
emission
histories of gas and stars in galaxies and for clarifying the relation of
DLAs
to present-day galaxies.
NICMOS 9484
The NICMOS Parallel Observing Program
We propose to manage the default set of pure parallels with NICMOS. Our
experience with both our GO NICMOS parallel program and the public
parallel
NICMOS programs in cycle 7 prepared us to make optimal use of the
parallel
opportunities. The NICMOS G141 grism remains the most powerful survey
tool for
HAlpha emission-line galaxies at cosmologically interesting redshifts. It
is
particularly well suited to addressing two key uncertainties regarding
the
global history of star formation: the peak rate of star formation in the
relatively unexplored but critical 1<= z <= 2 epoch, and the amount of
star
formation missing from UV continuum-based estimates due to high
extinction. Our
proposed deep G141 exposures will increase the sample of known HAlpha
emission-
line objects at z ~ 1.3 by roughly an order of magnitude. We will also
obtain a
mix of F110W and F160W images along random sight-lines to examine the
space
density and morphologies of the reddest galaxies. The nature of the
extremely
red galaxies remains unclear and our program of imaging and grism
spectroscopy
provides unique information regarding both the incidence of obscured star
bursts
and the build up of stellar mass at intermediate redshifts. In addition
to
carrying
out the parallel program we will populate a public database with
calibrated
spectra
and images, and provide limited ground- based optical and near-IR data
for the
deepest parallel fields.
NICMOS 9485
Completing A Near-Infrared Search for Very Low Mass Companions to Stars
within
10 pc of the Sun
Most stars are fainter and less massive than the Sun. Nevertheless, our
knowledge of very low mass {VLM} red dwarfs and their brown dwarf cousins
is
quite limited. Unknown are the true luminosity function {LF},
multiplicity
fraction, mass function, and mass-luminosity relation for red and brown
dwarfs,
though they dominate the Galaxy in both numbers and total mass. The best
way to
constrain these relations is a search for faint companions to nearby
stars.
Such
a search has several advantages over field surveys, including greater
sensitivity to VLM objects and the availability of precise parallaxes
from
which
luminosities and masses can be derived. We propose to complete our
four-filter
NICMOS snapshot search for companions to stars within 10 pc. With a 10
sigma
detection limit of M_J ~ 20 at 10 pc, we can detect companions between 10
and
100 AU that are at least 9 mag fainter than the empirical end of the main
sequence and at least 6.5 mag fainter than the brown dwarf Gl 229B. When
completed, our search will be the largest, most sensitive, volume-limited
search
for VLM companions ever undertaken. Our four-filter search will permit
unambiguous identification of VLM-companion candidates for follow-up
observation. Together with IR speckle and deep imaging surveys, our
program
will
firmly establish the LF for VLM companions at separations of 1-1000 AU
and the
multiplicity fraction of all stars within 10 pc.
ACS/WFPC2 9488
Cosmic Shear – with ACS Pure Parallel Observations
The ACS, with greater sensitivity and sky coverage, will extend our
ability to
measure the weak gravitational lensing of galaxy images caused by the
large
scale distribution of dark matter. We propose to use the ACS in pure
parallel
{non- proprietary} mode, following the guidelines of the ACS Default Pure
Parallel Program. Using the HST Medium Deep Survey WFPC2 database we have
measured cosmic shear at arc-min angular scales. The MDS image
parameters, in
particular the galaxy orientations and axis ratios, are such that any
residual
corrections due to errors in the PSF or jitter are much smaller than the
measured signal. This situation is in stark contrast with ground-based
observations. We have also developed a statistical analysis procedure to
derive
unbiased estimates of cosmic shear from a large number of fields, each of
which
has a very small number of galaxies. We have therefore set the stage for
measurements with the ACS at fainter apparent magnitudes and smaller, 10
arc-second scales corresponding to larger cosmological distances. We will
adapt
existing MDS WFPC2 maximum likelihood galaxy image analysis algorithms to
work
with the ACS. The analysis would also yield an online database similar to
that
in archive.stsci.edu/mds/
ACS/WFC 9575
Default {Archival} Pure Parallel Program.
The Advanced Camera for Surveys (WFC) was used to test ACS pure parallels
in
POMS.
WFPC2 9594
WFPC2 CYCLE 11 SUPPLEMENTAL DARKS pt2/3
This dark calibration program obtains 3 dark frames every day to provide
data
for monitoring and characterizing the evolution of hot pixels
STIS 9605
CCD Dark Monitor-Part 1
Monitor the darks for the STIS CCD
STIS 9607
CCD Bias Monitor – Part 1
Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1,
and 1×1
at gain = 4, to build up high-S/N superbiases and track the evolution of
hot
columns.
STIS 9615
Cycle 11 MAMA Dark Monitor
This test performs the routine monitoring of the MAMA detector dark
noise. This
proposal will provide the primary means of checking on health of the MAMA
detectors systems through frequent monitoring of the background count
rate. The
purpose is to look for evidence of change in dark indicative of detector
problem
developing.
ACS 9655
ACS Post-SMOV UV Contamination Monitor
A standard star field {NGC6681} is observed about once a month through
all the
ACS broad band UV filters. NGC6681 hosts several UV spectro – photometric
standard stars for which accurate spectra have been {and will continue to
be}
measured with STIS. The target cannot be observed for three months from
mid
november through to mid february, so the standard star GRW+70 will be
observed
twice in its stead. This programme continues the UV sensitivity
monitoring
campaign {ACS SMOV proposal 9010} of the HRC and SBC after the end of the
SMOV
period. An SBC dark current measurement is taken as the last exposure of
each
SBC sequence.
ACS 9673
CCD Daily Monitor
for any source of noise in ACS CCD detectors. This programme will be
executed
once a day for the entire lifetime of ACS
WFPC2 9676
POMS Test Proposal: WFII parallel archive proposal
This is the generic target version of the WFPC2 Archival Pure Parallel
program.
The program will be used to take parallel images of random areas of the
sky,
following the recommendations of the 2002 Parallels Working Group.
WFPC2 9699
POMS Test Proposal: WFII backup parallel archive proposal
This is a POMS test proposal designed to simulate scientific plans.
STIS 9706
STIS Pure Parallel Imaging Program: Cycle 10
This is the default archival pure parallel program for STIS during cycle
10.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.) None
SCHEDULED SUCCESSFUL FAILURE TIMES FGS GSacq 8 8 FGS REacq 8 8 FHST Update 21 21 LOSS of LOCK
SIGNIFICANT EVENTS:
The FGS Scattered Light test was successfully completed from 045/22:32 –
046/00:10. During the
Dark Earth grazing occultation, the FGSs saw a small increase in the
background light but
maintained lock throughout the entire pass. During the Bright Earth
grazing
occultation, the
background counts increased until all of the FGSs eventually lost lock,
but
this occurred well
inside of the current scheduling limits. There were no other Out Of
Limits
observed during the
test.
