Status Report

NASA Hubble Space Telescope Daily Report # 3688

By SpaceRef Editor
September 4, 2004
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




ACS/HRC 10199

The Most Massive Galaxies in the Universe: Double Trouble?

We are proposing an HST snapshot survey of 70 objects with velocity
dispersion larger than 350 km/s, selected from the Sloan Digital Sky
Survey. Potentially this sample contains the most massive galaxies in
the Universe. Some of these objects may be superpositions; HST imaging
is the key to determining if they are single and massive or if they
are two objects in projection. The objects which HST imaging shows to
be single objects are interesting because they potentially harbor the
most massive black holes, and because their existence places strong
constraints on galaxy formation models. When combined with ground
based data already in hand, the objects which HST imaging shows are
superpositions provide valuable information about interaction rates of
early-type galaxies as well as their dust content. They also constrain
the allowed parameter space for models of binary gravitational lenses
{such models are currently invoked to explain discrepancies in the
distribution of lensed image flux ratios and separations}.

ACS/HRC 10255

A Never Before Explored Phase Space: Resolving Close White Dwarf / Red
Dwarf Binaries

We propose an ACS Snapshot imaging survey to resolve a well-defined
sample of highly probable white dwarf plus red dwarf close binaries.
These candidates were selected from a search for white dwarfs with
infrared excess from the 2MASS database. They represent unresolved
systems {separations less than approximately 2" in the 2MASS images}
and are distributed over the whole sky. Our HST+ACS observations will
be sensitive to a separation range {1-20 AU} never before probed by
any means. The proposed study will be the first empirical test of
binary star parameters in the post-AGB phase, and cannot be
accomplished from the ground. By resolving as few as 20 of our ~100
targets with HST, we will be able to characterize the distribution of
orbital semi-major axes and secondary star masses.


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.

ACS/WFC 10126

The 3-D Shape of the SMC: Is It Tidally Distorted?

We propose to exploit the exceptional spatial resolution of HST to
definitively show whether the SMC is tidally elongated along the
line-of-sight, and therefore the status of the Milky Way’s
interaction/destruction of the Magellanic Clouds. We use BVI ACS
images of several crowded SMC fields in the region predicted by models
of the orbit and tidal evolution of the Magellanic Clouds {and by
observations of Cepheids} to have a large depth. We exploit the red
clump feature {and the rarer true horizontal branch} to derive the
depth. Specifically, we will observe six fields along the predicted
region of maximum distance gradient of the SMC, along with two ACS
fields and several WFPC2 fields in the archives, to map out the depth
of the SMC in this region. We are searching for substructure, such as
a tidal tail, that may be present. Crowding in this region of the SMC
is so severe that this project cannot be done from the ground.

ACS/WFC 10178

Imaging Polarimetry of Young Stellar Objects with ACS and NICMOS: A
study in dust grain evolution

The formation of planetary systems is intimately linked to the dust
population in circumstellar disks, thus understanding dust grain
evolution is essential to advancing our understanding of how planets
form. By combining {1} the high resolution polarimetric capabilities
of ACS and NICMOS, {2} powerful 3-D radiative transfer codes, and {3}
observations of objects known to span the earliest stellar
evolutionary phases, we will gain crucial insight into the initial
phases of dust grain growth: evolution away from an ISM distribution.
Fractional polarization is a strong function of wavelength, therefore
by comparing polarimetric images in the optical and infrared, we can
sensitively constrain not only the geometry and optical depth of the
scattering medium, but also the grain size distribution. By observing
objects representative of the earliest evolutionary sequence of YSOs,
we will be able to investigate how the dust population evolves in size
and distribution during the crucial transition from a disk+envelope
system to a disk+star system. The proposed study will help to
establish the fundamental time scales for the initial depletion of
ISM-like grains: the first step in understanding the transformation
from small submicron sized dust grains, to large millimeter sized
grains, and untimely to planetary bodies.

NIC1 10179

A Coordinated NICMOS and XMM Experiment to Observe the Variability of
Sgr A*

The massive black hole Sgr A* at the Galactic center has recently
shown not only quiescent emission at near-IR wavelengths, but also
flare activity with quasi-periodicity of 17 minutes. Our research
group has been granted two blocks of observing time with XMM-Newton to
monitor the spectral and temporal properties of Sgr A*. Simultaneously
with these X-ray observations, we will also monitor Sgr A* at radio,
submillimeter, near-IR, and gamma-ray wavelengths. We propose to use
NICMOS in parallel with the XMM observations to provide evidence of a
well-defined minimum periodicity in the spectrum of flare
periodicities. This, combined with periodicity in the near-IR line
emission, would strengthen the claim that the emitting gas resides at
the innermost stable circular orbit around the GC black hole, thus
measuring the spin parameter of a massive black hole. Current
groundbased near-IR data suggest a spin parameter of ~0.5. In
addition, the correlation pattern of emission over a wide spectrum
would elucidate a key issue of how to explain the low luminosity of
Sgr A*. The NICMOS on HST is the only instrument that can accurately
measure the 17 minute quasi-periodic variability of Sgr A* because of
the long time baseline over which HST can observe Sgr A* in parallel
with XMM-Newton.

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.

NIC3 9846

The Origins of Sub-stellar Masses: Searching for the End of the IMF

Is there a preferred scale that defines the end of the IMF? We propose
to test this hypothesis by conducting a deep spectroscopic survey of
extremely low mass objects in the embedded young cluster associated
with NGC1333. At a distance of only 300pc, this cluster is one of the
nearest examples of a dense young cluster. We will be able to obtain
R=200 spectra and photometry for 40-60 cluster members with masses
between 5-40 Jupiter masses at an age of 1 Myr observed through
A{v}<10 mag. This will enable us to estimate temperatures and
luminosities for all sources detected in the survey. We will compare
their positions in an H-R diagram to PMS evolutionary tracks in order
to estimate their ages and masses. For a solar metallicity cloud at a
temperature of 10 K, the minimum mass for fragmentation is thought to
be 10 Jupiter masses. A statistically significant sample of objects
detected below this limit would challenge the role of hierarchical
fragmentation in limiting substellar masses. The proximity of this
cluster combined with the unique sensitivity, wavelength coverage, and
multi-object spectroscopic capability of NICMOS on HST make this
experiment possible.

S/C 4974


This program provides for the trending of FGS-2R coarse track to fine
lock transition performance.

WFPC2 10067

WFPC2 Cycle 12 Decontaminations and Associated Observations

This proposal is for the monthly WFPC2 decons. Also included are
instrument monitors tied to decons: photometric stability check, focus
monitor, pre- and post-decon internals {bias, intflats, kspots, &
darks}, UV throughput check, VISFLAT sweep, and internal UV flat

WFPC2 10071

WFPC2 CYCLE 12 Supplemental Darks Part 3/3

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

WFPC2 10080

Wavelength Stability of Narrow Band and Linear Ramp Filters

Verify the mapping of wavelength as a function of CCD position on
LRFs; check for changes in central wavelengths of narrow band filters.


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

HSTAR 9529: GS Acquisition (1,2,1) @ 246/18:50:47Z resulted in FL
backup (1,0,1) due to SSLE on FGS 1. Under investigation.

                           SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq                10                       10                            
FGS REacq                 5                         5                
FHST Update              19                       19 


Successfully completed TRTT 5th iteration, Run 1

SpaceRef staff editor.