Daily #3945

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 3945

PERIOD COVERED: UT September 14, 2005 (DOY 257)

OBSERVATIONS SCHEDULED

ACS/HRC/WFC 10389

ACS CCDs daily monitor - Cycle 13 - Part 2

This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in ACS CCD detectors. The files, biases and dark will be used to
create reference files for science calibration. This program will be
for the entire lifetime of ACS.

ACS/HRS 10722

SBC geometric distortions and ACS UV L-flats

The primary goal of this calibration program is to improve the
accuracy of the geometric distortion solution for the ACS/SBC imaging
modes and to calculate the geometric solution for PR130L for the first
time. The secondary goals are to generate an L-flat for PR130L and to
provide independent checks for the L-flat and quantum efficiencies of
the SBC

ACS/WFC 10505

The Onset of Star Formation in the Universe: Constraints from Nearby
Isolated Dwarf Galaxies.

The details of the early star formation histories of tiny dwarf
galaxies can shed light on the role in galaxy formation of the
reionization which occured at high redshift. Isolated dwarfs are ideal
probes since their evolution is not complicated by environmental
effects owing to the vicinity of the Milky Way and M31. In addition,
dwarf galaxies are the most common type of galaxies, and potentially
the building blocks of larger galaxies. Since we can date the oldest
stars in them, their study represents a complementary approach to the
study of the formation and evolution of galaxies through high-z
observations. We propose to use the ACS to obtain a homogeneus dataset
of high-quality photometry, down to the old {13 Gyr} main-sequence
turnoffs, for a representative sample of 4 isolated Local Group dwarf
galaxies. These data are essential to unambiguously determine their
early star formation histories, through comparison with synthetic
color-magnitude diagrams, and using the constraints provided by their
variable stars. Parallel WFPC2 observations of their halos will allow
us to reveal the actual nature of their stellar population gradients,
providing important aditional constraints on their evolution. The
proposed observations are being complemented with ground-based
spectroscopy, to obtain metallicity and kinematic information. The
observations requested here, which must reach M_I=+3.5 {I=27.5- 28.2}
with S/N=10 in crowded systems, can only be achieved with HST using
ACS, and won't be possible with planned ground- or space-based
facilities such as JWST. Based on deep WFPC2 observations and ACS
image simulations, our team has designed an observational strategy
which carefully considers the optimal filter combination, the
necessary photometry depth and the effects of stellar crowding.

ACS/WFC 9727

Exploration of the SN Ia Hubble Diagram at z 1.2

In the spirit of a Treasury proposal, we propose to organize, and
deliver to the astronomical community, non-proprietary follow-up
observations of ~10 Type Ia supernovae at 1z1.7 that are expected to
be discovered in a Cycle 12 Treasury proposal. Together with the
currently available sample, this would provide a Hubble diagram with
over 20 SNe Ia in this redshift range, where it is possible to test
the current cosmological model in the epoch of deceleration: If z ~
0.5 SNe Ia are fainter due to evolution rather than an accelerating
expansion, they should continue to get fainter at even higher
redshifts. This size sample will show trends and outliers, and permit
a more rigorous treatment of the asymmetric amplification distribution
from gravitational lensing. This is a key redshift range for the
studies of dark energy that will be done with future surveys {and
future instruments now being designed}; this dataset will lay the
ground-work for these studies by establishing the simple properties of
the supernovae in this redshift range, including magnitudes, colors,
and timescales. If considered more appropriate, this proposal could be
treated as a part of a Treasury or Director's Discretionary program,
since the data would be available to everybody immediately, and we
would welcome others who would want to work with us on it.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

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.

NIC2/NIC1 10419

An in-depth analysis of a prototypical giant H II region: NGC 604

NGC 604 is, together with 30 Doradus, the extragalactic prototype
giant H II region. Its stellar content and mass {~200 O+WR stars,
~10**5 M_Sun}, age {~3.5 Myr}, proximity {840 kpc}, and low foreground
extinction {E{B-V} = 0.1} make it an ideal object to study the
massive stellar population of a scaled OB association, its interaction
with the surrounding medium, and the effects caused by the strong
differential extinction. We propose new HST observations which,
combined with existent ones, will provide the most thorough
multi-wavelength study of NGC 604 from the FUV to the NIR. We will
obtain spectral classifications for ~200 stars, measure their spectral
energy distributions from 1300 A to 2.2 microns, identify embedded
very-young stellar populations hidden inside dust clouds, measure the
extinction law and its possible variations as a function of
environmental conditions, and analyze the relationship between the hot
stars and the surrounding gas. The new data we are proposing is
divided into three parts: {a} slitless objective-prism FUV
spectroscopy using ACS/SBC, {b} multi-filter {6 broad-band and 2
narrow- band} NUV-optical imaging using ACS/HRC, and {c} HST/NICMOS
broadband imaging. Our final goal is to analyze in detail a
well-resolved giant H II region in order to understand the properties
of similar but unresolved objects located at cosmological distances.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTARS:

9949 - GSAcq(2,1,2) results in finelock backup (2,0,2) @ 258/06:34:51z
The GSAcq(2,1,2) scheduled at 258/06:34:51 - 06:42:55 Z resulted to
finelock backup (2,0,2) using FGS-2, due to scan step limit exceeded
on FGS-1 during acquisition walkdown. Prior FHST OBAD1 (with
maneuver) scheduled at 258/06:20:53 showed vehicle axis errors:
V1=138.48, V2=-271.07, V3=407.48 (arcsec). 3-axis (RSS) value =508.62
arcsec. Prior FHST OBAD2 (with maneuver) scheduled at 258/06:30:21
showed vehicle axis errors: V1=-6.69, V2=-3.15, V3=6.79 (arcsec).
3-axis (RSS) value =10.43 arcsec. Subsequent FHST OBAD (but no
maneuver) showed vehicle axis errors: V1=16.03, V2=-3.15, V3=6.79
(arcsec). 3-axis (RSS) value =17.69 arcsec.

9950 - ACS Target Acquisition Failed due to Guide Star Acq Failure ACS
target acquisition scheduled at 258/08:17:18 (BD+32D358) failed due to
GSacq scheduled at 258/08:10:00 failure to RGA Control The Take Data
Flag was down while ACS was executing its Target Acquisition Macro to
make a slew request.


COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL FAILURE TIMES
FGS Gsacq 10 09 Hstar
# 9950
FGS Reacq 05 05
OBAD with Maneuver 26 26


SIGNIFICANT EVENTS: (None)