Notice: For the foreseeable future, the daily reports may
contain
apparent discrepancies between some
proposal descriptions and the listed
instrument usage. This is due to the
conversion of previously approved
ACS WFC or HRC observations into WFPC2,
or NICMOS observations
subsequent to the loss of ACS CCD science
capability in late January.
HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #
4330
PERIOD COVERED: UT March 29, 2007 (DOY 088)
OBSERVATIONS SCHEDULED
ACS/SBC 10810
The Gas Dissipation Timescale: Constraining Models of
Planet Formation
We propose to constrain planet-formation models by
searching for
molecular hydrogen emission around young
{10-50 Myr} solar-type stars
that have evidence for evolved dust
disks. Planet formation models show
that the presence of gas in disks is
crucial to the formation of BOTH
giant and terrestrial planets,
influences dust dynamics, and through
tidal interactions with giant planets
leads to orbital migration.
However, there is a lack of systematic information on the
presence and
lifetime of gas residing at
planet-forming radii. We will use a newly
identified broad continuum emission
feature of molecular hydrogen at
1600 Angstrom to search for residual gas within an orbital
radius of
5-10 AU around young stars that have evolved beyond the
optically thick
T Tauri
phase.
These observations will enable the most sensitive probe
to date of remant
gas in circumstellar disks, detecting surfaces
densites of ~0.0001 g/cm^2, or less than
10^-5 of the theoretical
"mininum
mass" solar nebula from which our solar system is thought to
have formed. Our observations are
designed to be synergistic with
ongoing searches for gas emission that
is being performed using the
Spitzer Space Telescope in that the proposed HST
observations are ~100
times more sensitive and will have 50
times higher angular resolution.
These combined studies will provide the most comprehensive
view of
residual gas in proto-planetary disks
and can set important constraints
on models of planet formation.
NIC2 10858
NICMOS Imaging of the z ~ 2 Spitzer Spectroscopic Sample
of
Ultraluminous Infrared Galaxies
We propose to obtain NICMOS images of the first large
sample of high-z
ultra-luminous infrared galaxies {ULIRGs} whose redshifts and
physical
states have been determined with
Spitzer mid-IR spectra. The detection
of strong silicate absorption
and/or PAH emission lines suggest that the
these sources are a mixture of highly
obscured starbursts, AGNs and
composite systems at z=2. Although some
of the spectra show PAH emission
similar to local starburst ULIRGs, their bolometric luminosities are
roughly an order of magnitude higher. One
important question is if major
mergers, which are the trigger for 95%
of local ULIRGs, also drive this
enormous energy output observed in our
z=2 sample. The NICMOS images
will allow us to {1} measure surface
brightness profiles of z~2 ULIRGs
and establish if major mergers
could be common among our luminous
sources at these early epochs, {2}
determine if starbursts and AGNs
classified based on their mid-IR spetra would have different
morphological signatures, thus different
dynamic state; {3} make
comparisons with the similar studies of ULIRGs at z ~ 0 - 1, thus infer
any evolutionary connections
between high-z ULIRGs and the formation of
normal, massive galaxies and quasars
observed today.
WFPC2 10886
The Sloan Lens ACS Survey: Towards 100 New Strong Lenses
As a continuation of the highly successful Sloan Lens ACS
{SLACS} Survey
for new strong gravitational
lenses, we propose one orbit of ACS-WFC
F814W imaging for each of 50 high-probability strong
galaxy-galaxy lens
candidates. These observations will
confirm new lens systems and permit
immediate and accurate photometry, shape
measurement, and mass modeling
of the lens galaxies. The lenses
delivered by the SLACS Survey all show
extended source structure, furnishing
more constraints on the projected
lens potential than lensed-quasar image positions. In addition, SLACS
lenses have lens galaxies that are
much brighter than their lensed
sources, facilitating detailed
photometric and dynamical observation of
the former. When confirmed lenses
from this proposal are combined with
lenses discovered by SLACS in Cycles
13 and 14, we expect the final
SLACS lens sample to number 80--100: an approximate
doubling of the
number of known galaxy-scale strong
gravitational lenses and an
order-of-magnitude increase in the number of
optical Einstein rings. By
virtue of its homogeneous selection
and sheer size, the SLACS sample
will allow an unprecedented
exploration of the mass structure of the
early-type galaxy population as a function
of all other observable
quantities. This new sample will be a
valuable resource to the
astronomical community by enabling
qualitatively new strong lensing
science, and as such we will waive all
but a short {3-month} proprietary
period on the observations.
FGS 10612
Binary Stars in Cyg OB2: Relics
of Massive Star Formation in a
Super-Star Cluster
We propose to make a high angular resolution SNAP survey
of the massive
stars in the nearby, super-star
cluster Cyg OB2. We will use FGS1r TRANS
mode observations to search for astrometric companions in the separation
range of 0.01 to 1.00 arcsec and in the magnitude difference range
smaller than 4 magnitudes. The
observations will test the idea that the
formation of very massive stars involves
mergers and the presence of
nearby companions. Discovery of
companions to massive stars in this
relatively nearby complex will provide
guidance in the interpretation of
apparently supermassive
stars in distant locations. The search for
companions will also be important for
verification of fundamental
parameters derived from spectroscopy,
adjustments to main sequence
fitting and distance estimations,
determining third light contributions
of eclipsing binaries, identifying
wide colliding wind binaries,
studying the relationship between orbital
and spin angular momentum, and
discovering binaries amenable to future
mass determinations. The massive
star environment in Cyg OB2 may be similar to the kinds found in the
earliest epoch of star formation, so
that a study of the role of
binaries in Cyg
OB2 will help us understand the formation processes of
the first stars in the Universe.
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA calibration - CR Persistence Part 6
A new proceedure proposed to
alleviate the CR-persistence problem of
NICMOS. Dark frames will be obtained
immediately upon exiting the SAA
contour 23, and everytime
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 i
mages. Each observation will need its
own CRMAP, as different SAA
passages leave different imprints on the
NICMOS detectors.
WFPC2 10869
The upper atmosphere and the escape state of the
transiting
very-hot-Jupiter HD189733b
The observation of the HD209458b transits in Lyman-alpha
revealed that
the atmosphere of this planet is
escaping. These observations raised the
question of the evaporation state of
hot-Jupiters. Is the evaporation
specific to HD209458b or general to hot-Jupiters? What is the
evaporation mechanism, and how does the
escape rate depend on the
planetary system characteristics? The
recent discovery of HD189733b, a
planet transiting a bright and nearby
K0 star {V=7.7}, offers the
unprecedented opportunity to answer these
questions. Indeed, among the
stars harboring transiting planets,
HD189733 presents the largest
apparent brightness in Lyman-alpha,
providing capabilities to constrain
the escape rate to high accuracy.
With ACS/PR110L we will observe
stellar emission lines to search for
atmospheric absorptions during the
transits. HD189733b being a very short
period planet orbiting a nearby
late type star with bright chromospheric emission lines, it is by far
the best target to make significant
progress in that field.
WFPC2 11030
WFPC2 WF4 Temperature Reduction #3
In the fall of 2005, a serious anomaly was found in images
from the WF4
CCD in WFPC2. The WF4 CCD bias level appeared
to have become unstable,
resulting in sporadic images with either
low or zero bias level. The
severity and frequency of the problem
was rapidly increasing, making it
possible that WF4 would soon become
unusable if no work-around were
found. Examination of bias levels
during periods with frequent WFPC2
images showed low and zero bias
episodes every 4 to 6 hours. This
periodicity is driven by cycling of the
WFPC2 Replacement Heater, with
the bias anomalies occurring at the
temperature peaks. The other three
CCDs {PC1, WF2, and WF3} appear to
be unaffected and continue to operate
properly. Lowering the Replacement
Heater temperature set points by a
few degrees C effectively eliminates
the WF4 anomaly. On 9 January 2006,
the upper set point of the WFPC2
Replacement Heater was reduced from
14.9C to 12.2C. On 20 February 2006, the upper
set point was reduced
from 12.2C to 11.3C, and the lower
set point was reduced from 10.9C to
10.0C. These changes restored the WF4 CCD bias level;
however, the bias
level has begun to trend downwards
again, mimicking its behavior in late
2004 and early 2005. A third temperature reduction
is planned for March
2007. We will reduce the upper set point of the heater
from 11.3C to
10.4C and the lower set point from
10.0C to 9.1C. The observations
described in this proposal will test the
performance of WFPC2 before and
after this temperature reduction.
Additional temperature reductions may
be needed in the future, depending
on the performance of WF4. Orbits:
internal 26, external 1
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal
performance that will be investigated.)
HSTARS:
10760 - GSAcq(1,2,2) failed to RGA Hold (Gyro Control
Upon
acquisition of signal at 088/09:59:55, the GSAcq(1,2,2) scheduled
at 088/09:39:54 - 09:47:59 had failed to RGA Hold due to
(QF1STOPF) stop
flag indication on FGS1. Pre-acquisition OBADs
(RSS) attitude correction
values not available due to LOS. Post-acq
OBAD/MAP had (RSS) of 7.58
arcseconds.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS GSacq 08
07
FGS REacq 02
02
OBAD with Maneuver 20 20
SIGNIFICANT EVENTS:
Flash Report:
WFPC2 WF4 post-temperature reduction early results:
The first internal images after reducing the WFPC2
Replacement Heater
temperature set points on Tuesday look
good. The WF4 CCD bias levels are
back in the 290 - 300 DN range and
very close to normal again. Changes
in optical alignment are very
small and in the expected range. All the
images so far look nominal.
____________________________________________________________
Lynn F. Bassford
Hubble Space Telescope
CHAMP
Lockheed Martin
NASA GSFC PH#: 301-286-2876
"The Hubble Space Telescope is
the astronomical observatory and key to unlocking the most cosmic mysteries of
the past, present and future." - 7/26/6