HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5086
PERIOD
COVERED: 5am April 29 - 5am April 30, 2010 (DOY 119/09:00z-120/09:00z)
OBSERVATIONS
SCHEDULED
COS/FUV
11687
SNAPing
Coronal Iron
This
is a Snapshot Survey to explore two forbidden lines of highly ionized
iron
in late-type coronal sources. Fe XII 1349 (T~ 2 MK) and Fe XXI 1354
(T~
10 MK) -- well known to Solar Physics -- have been detected in about a
dozen
cool stars, mainly with HST/STIS. The UV coronal forbidden lines are
important
because they can be observed with velocity resolution of better
than
15 km/s, whereas even the state-of-the-art X-ray spectrometers on
Chandra
can manage only 300 km/s in the kilovolt band where lines of highly
ionized
iron more commonly are found. The kinematic properties of hot
coronal
plasmas, which are of great interest to theorists and modelers,
thus
only are accessible in the UV at present. The bad news is that the UV
coronal
forbidden lines are faint, and were captured only in very deep
observations
with STIS. The good news is that 3rd-generation Cosmic Origins
Spectrograph,
slated for installation in HST by SM4, in a mere 25 minute
exposure
with its G130M mode can duplicate the sensitivity of a landmark
25-orbit
STIS E140M observation of AD Leo, easily the deepest such exposure
of
a late-type star so far. Our goal is to build up understanding of the
properties
of Fe XII and Fe XXI in additional objects beyond the current
limited
sample: how the lineshapes depend on activity, whether large scale
velocity
shifts can be detected, and whether the dynamical content of the
lines
can be inverted to map the spatial morphology of the stellar corona
(as
in "Doppler Imaging''). In other words, we want to bring to bear in the
coronal
venue all the powerful tricks of spectroscopic remote sensing, well
in
advance of the time that this will be possible exploiting the corona's
native
X-ray radiation. The 1290-1430 band captured by side A of G130M also
contains
a wide range of key plasma diagnostics that form at temperatures
from
below 10, 000 K (neutral lines of CNO), to above 200, 000 K
(semi-permitted
O V 1371), including the important bright multiplets of C
II
at 1335 and Si IV at 1400; yielding a diagnostic gold mine for the
subcoronal
atmosphere. Because of the broad value of the SNAP spectra,
beyond
the coronal iron project, we waive the normal proprietary rights.
ACS/WFC
11715
The
Luminous Galactic Cepheid RS Puppis: A Geometric Distance from its
Nested
Light Echoes
RS
Puppis is one of the most luminous Cepheids in the Milky Way (P =
41.4
days) and an analog of the bright Cepheids used to measure
extragalactic
distances. An accurate distance would help anchor the
zero-point
of the bright end of the period-luminosity relation, but at a
distance
of about 2 kpc it is too far away for a trigonometric parallax
with
existing instrumentation.
RS
Pup is unique in being surrounded by a reflection nebula, whose
brightness
varies as pulses of light from the Cepheid propagate
outwards.
Members of our team have used ground-based imaging of the
nebula
to derive phase lags in the light variations of individual
features
in the nebula, and have inferred a seemingly very precise
geometric
distance to the star. However, there is an unavoidable
ambiguity
involving the cycle counts, which was resolved by assuming
that
the features lie in the plane of the sky. If this assumption is
incorrect,
a large systematic error would be introduced into the
distance
measurement.
We
show that polarimetric imaging using the high spatial resolution of
ACS/WFC
and its ability to image close to the star can resolve this
ambiguity
and yield a reliable geometric distance to RS Pup. We will
also
obtain a wide-field multicolor image of the nebula, in order to
study
its morphology and the mass-loss history of the Cepheid.
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/CCD
11852
STIS
CCD Spectroscopic Flats C17
The
purpose of this proposal is to obtain pixel-to-pixel lamp flat
fields
for the STIS CCD in spectroscopic mode.
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
11911
UVIS
L-Flats and Geometric Distortion
Multiple
pointing observations of the globular cluster Omega Centauri
(NGC
5139) will be used to measure the filter-dependent low frequency
flat
field (L-flat) corrections and stability for a key set of 10
broadband
filters used by GO programs. The selected filters are F225W,
F275W,
F336W, F390W, F438W, F555W, F606W, F775W, F814W and F850LP. By
measuring
relative changes in brightness of a star over different
portions
of the detector, we will determine local variations in the UVIS
detector
response.
The
broad wavelength range covered by these observations will allow us
to
derive the L-flat correction for the remaining wide, medium and
narrow-band
UVIS filters. The same data will also be used to determine
and
correct the geometric distortion that affects UVIS data. The broad
wavelength
range covered by these observations will allow us to measure
the
geometric distortion dependence with wavelength and filters and to
provide
the most appropriate correction over the entire wavelength range
provided
by UVIS.
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.
ACS/WFC
11995
CCD
Daily Monitor (Part 2)
This
program comprises basic tests for measuring the read noise and dark
current
of the ACS WFC and for tracking the growth of hot pixels. The
recorded
frames are used to create bias and dark reference images for
science
data reduction and calibration. This program will be executed four
days
per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To
facilitate
scheduling, this program is split into three proposals. This
proposal
covers 320 orbits (20 weeks) from 1 February 2010 to 20 June
2010.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
12259
- GSAcq(2,3,3) at 119/10:11:22z was successful. REAcqs(2,3,3) scheduled at
119/11:36:48z, 1312z, 1451z,
1633z, and 1815z all failed.
Observations affected: WFC3 111-130, proposal ID#11911.
12263
- GSAcq(1,2,1) results in fine lock backup (2,0,2) using FGS-2 @ 120/0323z
Observations Possibly affected: COS 34-38 Proposal ID#11687, ACS
115-116
Proposal ID#11995, STIS 47 Proposal ID#11845
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS
GSAcq
07
07
FGS
REAcq
11
06
OBAD
with Maneuver 05 05
SIGNIFICANT
EVENTS: (None)