HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4888
PERIOD COVERED: 5am July 15 - 5am July 16, 2009 (DOY
196/0900z-197/0900z)
OBSERVATIONS SCHEDULED
COS 11469
COS NUV Optics Alignment and Focus
This program has stringent guide star and timing
requirements. Refer to
the observing description section for complete details.
This program determines the fine focus using NUV MIRRORA
exposures of
the same target as COS08 (program 11468 -
This program must
commence execution approximately 48 hours after completion
of visit 1 of
COS08 and as soon as possible after the uplink in visit 2
of COS08.
Three fine focus visits are executed to establish on-orbit
nominal
focus. Two detailed verification visits are executed after
the three
focus-sweep visits. Approximately 48 hours after each
odd-numbered visit
an uplink of new information is required.
COS 11482
FUV Detector Dark
Measure the FUV detector dark rate by taking long science
exposures with
no light on the detector. The detector dark rate and
spatial
distribution of counts will be compared to pre-launch data
in order to
verify the nominal operation of the detector, and for use
in the CalCOS
calibration pipeline. Variations of count rate as a
function of orbital
position will be analyzed to find dependence of dark rate
on proximity
to the SAA.
This is SMOV Activity COS-24.
WFC3 11426
UVIS SMOV Contamination Monitor
The UV throughput of WFC3 during SMOV is monitored via
weekly standard
star observations in a subset of key filters (as many as
will fit into a
single orbit but to include at a minimum F218W, F225W,
F275W, and
F606W). The data will provide a
measure of throughput levels as a function of time and
wavelength,
allowing for detection of the presence of possible
contaminants. In
addition, a small set of internal exposures are included
with the
externals, to provide verification of detector stability.
This proposal corresponds to activity WFC3-13.
WFC3 11444
WFC3 UVIS Plate Scale
The geometric scale factors and distortion of the UVIS
detector will be
measured using multiple pointing observations of the
globular cluster 47
Tucanae (NGC 104) to image moderately dense stellar
fields. 24 pointings
will be used to sample a range of spatial scales. A
complementary
observation of a well studied field in the LMC will be
made in one
orbit.
Centroid position of stars will be used to tie down the
geometric
distortion to about 0.2 pixels across the field of each
detector. Well
measured distortion-corrected positions of stars
previously determined
for these fields will be used in the derivation of the
distortion
equation coefficients.
This proposal is activity ID WFC3-031
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 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 11452
UVIS Flat Field Uniformity
The stability and uniformity of the low-frequency flat
fields (L-flat)
of the UVIS detector will be assessed by using
multiple-pointing
observations of the globular clusters 47 Tucanae (NGC104)
and Omega
Centauri (NGC5139), thus imaging moderately dense stellar
fields. By
placing the same star over different portions of the
detector and
measuring relative changes in its brightness, it will be
possible to
determine local variations in the response of the UVIS
detector.
Based on previous experience with STIS and ACS, it is deemed
that a
total of 9 different pointings will suffice to provide
adequate
characterization of the flat field stability in any given
band. For each
filter to be tested, the baseline consists of 9 pointings
in a 3X3 box
pattern with dither steps of about 25% of the FOV, or
40.5", in either
the x or y direction (useful also for CTE measurements, if
needed in the
future). During SMOV, the complement of filters to be
tested is limited
to the following 6 filters: F225W, F275W, F336W, for Omega
Cen, and
F438W, F606W, and F814W for 47 Tuc. Three long exposures
for each target
are arranged such that the initial dither position is
observed with the
appropriate filters for that target within one orbit at a
single
pointing, so that filter-to-filter differences in the
observed star
positions can be checked.
In addition to the 9 baseline exposures, two sets of short
exposures
will be taken: a) one short exposure will be taken of
OmegaCen with each
of the visible filters (F438W, F606W and F814W) in order
to check the
geometric distortion solution to be obtained with the data
from proposal
11444; b) for each target, a single short exposure will be
taken with
each filter to facilitate the study of the PSF as a
function of position
on the detector by providing unsaturated images of
sparsely-spaced
bright stars.
This proposal corresponds to Activity Description ID WF39.
It should
execute only after the following proposal has executed:
WFC3 11808
WFC3 UVIS Bowtie Monitor
The UVIS detector was observed during ground testing to
occasionally
exhibit flat field and dark variations with a bowtie
pattern. These
variations are most significant as ~1% flat field (gain)
variations
across the field of view. It is believed that this represents
a state or
condition into which the detector can transition for
reasons and under
circumstances which are not currently understood. It is
also very
unlikely that most science observations will determine the
state (bowtie
or no-bowtie) of the detector. Ground test data indicates
that this
state is long lived (many hours to ~one day). Hysteresis
or memory of
past light exposure is also associated with this state.
Recent evidence suggests that exposing the detector to
~200k to 500k
electrons may quench this state. This proposal obtains an
internal flat
field sequence of three exposures: one at 10x full well
with two at 0.5x
full well immediately before and after. Each exposure is
3x3 binned to
reduce the data volume required.
These visits should be scheduled 2x per day until further
direction is
provided.
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
6
6
FGS
REAcq
13
13
OBAD with
Maneuver
6
6
SIGNIFICANT EVENTS: (None)