Status Report

NASA Hubble Space Telescope Daily Report # 3594

By SpaceRef Editor
April 20, 2004
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NASA Hubble Space Telescope Daily Report # 3594

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




NIC3 9999

The COSMOS 2-Degree ACS Survey NICMOS Parallels

The COSMOS 2-Degree ACS Survey NICMOS Parallels. This program is a
companion to program 9822.

S/C/NIC1/NIC3 9994

NICMOS Focus Stability

The purpose of this activity is to determine if the best focus
determined in SMOV is stable. This program will execute in
approximately one month intervals starting about 1 month after the
last execution of proposal 8980.


Gravitational Microlensing in the NGC 3314A-B Galaxy Pair

Determining the composition of the dark matter that dominates the
masses of galaxies is an important unsolved problem, and the results
of the MACHO Collaboration suggest that some of Milky Way’s dark
matter may be in the form of very old white dwarfs. However, some have
argued that the excess of microlensing events seen by MACHO are due to
a larger than expected microlensing rate for lens stars in the LMC
itself or its tidal debris. We propose to address this question by
detecting microlensing events in the line-of-sight galaxy pair NGC
3314 A & B. The large line-of-sight distance between these galaxies
gives an optical depth that is 3-4 orders of magnitude larger than if
the source stars and lenses were in the same galaxy, and the fact that
the background galaxy is a spiral ensures that there will be a
sufficient number of bright, non-variable source stars. Our proposed
observations should have the sensitivity to detect microlensing by
both ordinary stars and dark matter in NGC 3314A {the foreground
galaxy}. If there are dark matter microlensing events to be found,
they can be clearly distinguished from stellar microlensing events
because they will occur outside the visible disk of NGC 3314A. If
baryonic dark matter is detected in NGC 3314A, we will be able to map
its radial density variation.

FGS 9972

Calibrating the Mass-Luminosity Relation at the End of the Main

We propose to use HST-FGS1R to calibrate the mass-luminosity relation
{MLR} for stars less massive than 0.2 Msun, with special emphasis on
objects near the stellar/brown dwarf border. Our goals are to
determine M_V values to 0.05 magnitude, masses to 5 than double the
number of objects with masses determined to be less than 0.20 Msun.
This program uses the combination of HST-FGS3/FGS1R at optical
wavelengths and ground-based infrared interferometry to examine
nearby, subarcsecond binary systems. As a result of these
measurements, we are deriving high quality luminosities and masses for
the components in the observed systems, and characterizing their
spectral energy distributions from 0.5 to 2.2 Mum. Several of the
objects included have M < 0.1 Msun, placing them at the very end of
the stellar main sequence. Three of the targets are brown dwarf
candidates, including the current low mass record holder, GJ 1245C,
with a mass of 0.062 +/- 0.004 Msun. The payoff of this proposal is
high because all 10 of the systems selected have already been resolved
with HST- FGS3/FGS1R during Cycles 5–10 and contain most of the
reddest objects for which masses can be determined.


A SNAPSHOT Survey of Sharp-Lined Early B-Type Stars

Although spectrum synthesis studies of the UV spectra of sharp-lined
main sequence B stars provide us with some our best determinations of
the abundances of the Fe group and neutron capture elements and the
chemical evolution in our galaxy and the Magellanic Clouds, the HST
archive is virtually devoid of high resolution spectra of the bright
nearby B stars that have become to be regarded as abundance standards.
For example, there are NO observations of HR 1886, iota Her, and tau
Her, the sharpest-lined representatives {V sin i < 5 km/s} of spectral
classes B1 V, B3 IV-V and B5 IV, and only a few tiny spectral
intervals of gamma Peg {B2 IV}. Information on the abundances of the
Fe group is important for computing opacities for stellar evolution
calculations and for determining astrophysical f-values. There are no
suitable galactic standards in the HST database to compare with recent
HST/STIS observations of B stars in the Magellanic Clouds and the
likely future observations of similar objects in M31 and other nearby
galaxies. To correct this deficiency, we propose SNAPSHOT observations
with the STIS E140M and E230M gratings of 33 of the best bright
abundance standards in nearby clusters and the galactic field. Using
this data we will determine the abundances of the Fe group and heavy
elements using the technique of spectrum synthesis with LTE and NLTE
treatments. We waive the proprietary period.


The COSMOS 2-Degree ACS Survey

We will undertake a 2 square degree imaging survey {Cosmic Evolution
Survey — COSMOS} with ACS in the I {F814W} band of the VIMOS
equatorial field. This wide field survey is essential to understand
the interplay between Large Scale Structure {LSS} evolution and the
formation of galaxies, dark matter and AGNs and is the one region of
parameter space completely unexplored at present by HST. The
equatorial field was selected for its accessibility to all
ground-based telescopes and low IR background and because it will
eventually contain ~100, 000 galaxy spectra from the VLT-VIMOS
instrument. The imaging will detect over 2 million objects with I> 27
mag {AB, 10 sigma}, over 35, 000 Lyman Break Galaxies {LBGs} and
extremely red galaxies out to z ~ 5. COSMOS is the only HST project
specifically designed to probe the formation and evolution of
structures ranging from galaxies up to Coma-size clusters in the epoch
of peak galaxy, AGN, star and cluster formation {z ~0.5 to 3}. The
size of the largest structures necessitate the 2 degree field. Our
team is committed to the assembly of several public ancillary datasets
including the optical spectra, deep XMM and VLA imaging, ground-based
optical/IR imaging, UV imaging from GALEX and IR data from SIRTF.
Combining the full-spectrum multiwavelength imaging and spectroscopic
coverage with ACS sub-kpc resolution, COSMOS will be Hubble’s ultimate
legacy for understanding the evolution of both the visible and dark

ACS/HRC 9747

An Imaging Survey of the Statistical Frequency of Binaries Among
Exceptionally-Young Dynamical Families in the Main Asteroid Belt

We propose an ambitious SNAPSHOT program to determine the frequency of
binaries among two very young asteroid families in the Main Belt, with
potentially profound implications. These families {of C- and S-type}
have recently been discovered {Nesvorny et al. 2002, Nature 417, 720},
through dynamical modeling, to have been formed at 5.8 MY and 8.3 MY
ago in catastrophic impact events. This is the first time such
precise and young ages have been assigned to a family. Main-belt
binaries are almost certainly produced by collisions, and we would
expect a young family to have a significantly higher frequency of
binaries than the background, because they may not yet have been
destroyed by impact or longer-term gravitational instabilities. In
fact, one of the prime observables from such an event should be the
propensity for satellites. This is the best way that new numerical
models for binary production by collisions {motivated largely by our
ground-based discoveries of satellites among larger asteroids}, can be
validated and calibrated. We will also measure two control clusters,
one being an "old" family, and the other a collection of background
asteroids that do not have a family association, and further compare
with our determined value for the frequency of large main-belt
binaries {2%}. We request visits to 180 targets, using ACS/HRC.

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 1<z<1.7 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 8792

NICMOS Post-SAA calibration – CR Persistence Part 3

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.

WFPC2 10070

WFPC2 CYCLE 12 Supplemental Darks Part 2/3

This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot


CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the
development of hot pixels and test for any source of noise in ACS CCD
detectors. This programme will be executed once a day for the entire
lifetime of ACS.

STIS/CCD 10020

CCD Bias Monitor – Part 2

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/CCD 10018

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.


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

HSTAR 9380: During a successful GS Acquisition (1,2,1) @
107/10:39:37Z, during ZOE, the Saved FGS Error Null Bias (QSFGENB0)
flagged OOL with a value of -1007.212 arcsec. Under investigation.

HSTAR 9385: GS Acquisition (2,3,2) @ 110/07:33:05Z failed due to SRLE
on FGS 2 following a Type 2 slew @ 110/07:25:12Z. No FHST Full
Maneuver Updates were scheduled between the slew and the GS
acquisition. Search Radius of GS acquisition was 31 arcsec. FHST Map
@ 110/08:11:22Z showed vehicle errors of -5.354, 33.372, and -1.907
arcsec. The following GS Re-acquisitions @ 110/09:07:03Z and
110/10:43:01Z also failed due to SRLE on FGS 2. Under investigation.


  • 16618-2 – Contingency Activation of RTCS 21
  • 17098-2 – CONTINGENCY Bring +D SPA Back On-line


  • 17122-0 – FSW 2.5B On-Orbit Verification @ 107/2001z

                         SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq             33                        32             110/0733z 
(HSTAR # 9385)
FGS REacq             12                        10              110/0907z, 
FHST Update           47                        47


Continued FSW 2.5b on-orbit verification (OR 17122 with attached
script and COP 3.54). FHST 2 was placed in Rate Control during FGS
guiding from 107/13:00Z – 13:13Z and during RGA control from
107/13:13Z – 13:28Z.

An OBAD was performed on FHST 1 (4 stars found) with FHST 3 in Rate
Control from 107/1:50Z – 15:05Z. FHST 3 was placed into Rate Control
during FGS guiding from 107/16:13ZZ – 16:28Z.

All three FHSTs were placed in Rate Control during RGA control from
107/16:24Z – 16:39Z. An OBAD was performed on FHST 3 (6 stars found)
with FHST 2 in Rate Control from 107/16:40Z – 16:55Z.

An OBAD was performed on FHST 2 (7 stars found) with FHST 1 in Rate
Control from 107/18:02Z – 18:17Z.

An OBAD was performed on FHST 2 (6 stars found) with FHST 3 in Rate
Control from 107/19:46Z – 20:01Z.

SAC SE continues to evaluate the differences between the OBAD and SAC
star vectors. Additional Rate Control periods have been scheduled.

Solar Eclipse FDF 110/13:47:33Z – 14:04:38Z and 110/15:36:50Z –
15:46:06Z (OR 17126-1 with attached ROP PS-02A and MEGG timeline).
Expected darkness up to 30% of an Earth night period. This is the
first eclipse event with off-lining SPA configuration in place. ROP
PS-2A (Lunar Solar Eclipse Management) will be used to temporarily
disable both the Rate of Charge (SBATRTCE) and SA Cold Protection
(SCOLDSAE) test through the eclipse period and to re-enable the tests
after the event. Also, the CSS timer (FEWLIM), which defines when the
Sun is expected to be detected by the CSS at transitions into orbit
day, will be temporarily modified.

SpaceRef staff editor.