Status Report

NASA Hubble Space Telescope Daily Report # 3773

By SpaceRef Editor
January 11, 2005
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HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT        # 3773



ACS/HRC 10377

ACS Earth Flats

High signal sky flats will be obtained by observing the bright Earth
with the HRC and WFC. These observations will be used to verify the
accuracy of the flats currently used by the pipeline and will provide
a comparison with flats derived via other techniques: L-flats from
stellar observations, sky flats from stacked GO observations, and
internal flats using the calibration lamps. Weekly coronagraphic
monitoring is required to assess the changing position of the spots.


ACS CCDs daily monitor- cycle 13 – part 1

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 programme will be
for the entire lifetime of ACS.


ACS Coronagraphic Imaging of Herbig Ae/Be Stars

We can indirectly learn about the planet formation process by studying
proto-planetary dust disks. In this proposed observational program, we
focus on Herbig Ae/Be stars which are pre-main sequence intermediate
mass stars {2-10 solar masses} thought to be immediate precursors to
the Vega-excess stars like Beta Pictoris. We propose to take ACS
coronagraphic images in the F606W filter of 6 Herbig Ae/Be stars, all
of which have well constrained spectral energy distributions and are
nearby {<200pc}, suggesting possible disk sizes of 3" or larger in radius. We use the recent ACS coronagraph image of Herbig Ae/Be star, HD 141569, which shows a spectacular circumstellar disk, as a template for observing strategy and exposure time estimates. Our observing program involves contemporaneous comparison stars that will be used to subtract the point spread function. These images will constrain the size and possibly, the morphology of the circumstellar dust that may have disk, envelope or disk+envelope geometries. We will analyze these images quantitatively using 2-Dust, an axisymmetric radiative transfer dust code, to derive basic physical parameters of the dusty circumstellar matter such as mass, size, geometry, inclination angle and grain properties.

ACS/WFC 10181

ACS/NICMOS Imaging of Bright Lyman Break Galaxy Candidates from SDSS

The recent surprising discovery of six unusually bright {r~20 mag}
Lyman break galaxy {LBG} candidates with z=2.45-2.80 in the Sloan
Digital Sky Survey {SDSS} raises a number of questions that only HST
can address. Specifically, what is the true nature of these objects,
and what role if any is played by gravitational lensing? We propose to
use the superior resolution and sensitivity of ACS and NICMOS to
obtain deep images of these objects and their environments. Compared
to SDSS images, HST will allow us to determine their morphologies
{extended, point-source, or lensed}, the appearance of their
environments {rich or poor}, and to detect any faint foreground groups
or clusters that might be responsible for lensing these objects. All
outcomes would be intriguing. If the objects are lensed, it increases
from 1 {MS1512-cB58} to 7 the number of normal LBGs bright enough to
study individually. If they are instead unlensed point sources, they
will represent a new class of previously unidentified absorption-line
quasars. Finally, if they are unlensed and extended star-forming
galaxies, they are at least 4mag brighter than L_* LBGs, thus making
them the most luminous star-forming objects yet seen, representing a
heretofore unknown extreme population of objects.


Pre-History of a Starburst: Deep Imaging of IC 10

The peculiar Local Group dwarf galaxy IC 10 is the nearest case of a
starburst in progress. Starburst galaxies are a prime laboratory for
studying the physical processes which regulate star formation in
galaxies; as the closest example, IC 10 is potentially the key galaxy
for understanding the starburst phenomenon. We propose to obtain deep
optical images of IC 10 with the ACS/WFC to achieve three main goals:
1} To make the first estimates of the pre-burst history of IC 10 based
on morphological and statistical analysis of its {V, I} color-
magnitude diagram; 2} to search for evidence of a past history of
burst-dormancy cycles; and 3} to explore the connection between the
ages and locations of bright stars and the large-scale structure of
the interstellar medium. The distance {0.8 Mpc}, extinction {2.5 mag},
and high surface brightness of IC 10 make these goals unobtainable
except with HST. The observations proposed here will yield far and
away the deepest images, in absolute magnitudes, ever obtained for any
starburst galaxy. Our photometry will reach to magnitudes {V, I} =
{28.5, 27.5}, which is below the level of the red clump/horizontal
branch and the location of the main-sequence turnoff of stars as old
as a billion years. For the first time, it will be possible to measure
the detailed history of a starburst host for the Gigayear time period
leading up to the burst. The horizontal branch morphology and colors
will provide new information on the metallicity and age distribution
of stars spanning the entire age of IC 10. Because of its close
distance, IC 10 is the ONLY starburst galaxy for which this type of
information is obtainable now or in the next decade. We propose to use
WFPC2 in parallel to search for a low-surface brightness population
associated with the neutral gas filaments surrounding IC 10.


The Formation and Evolution of Spirals: An ACS and WFPC2 Imaging
Survey of Nearby Galaxies

Over 50% of galaxies in the local universe are spirals. Yet the star
formation histories and evolution of this crucial population remain
poorly understood. We propose to combine archival data with new
ACS/WFC and WFPC2 observations of 11 galaxies, to tackle a
comprehensive investigation of nearby spirals covering the entire
spiral sequence. The new observations will fill a serious deficiency
in HST’s legacy, and maximize the scientific return of existing HST
data. The filter combination of UBVI, and Halpha is ideal for studying
stellar populations, dust properties, and the ISM. Our immediate
scientific objectives are: {i} to use the resolved cluster
populations, both young massive clusters and ancient globular clusters
as a chronometer, to understand how spirals assembled as a function of
time; {ii} study the rapid disruption properties of young clusters;
and {iii} understand dust distributions in spirals from pc to kpc
scales. Each of these goals provides an important step towards
charting the evolution of galaxies, and an essential baseline for
interpreting the galaxy populations being surveyed in both the early
and present universe. The resolution of our survey, which exploits the
excellent imaging capabilities of HST’s two optical cameras, will
enable us to understand the record of star cluster, and galaxy
formation in a level of detail which is not possible for more distant
systems. Finally, the proposed observations will provide a key to
interpret an extensive, multiwavelength archive of space- and ground-
based data at lower spatial resolution {SPITZER, CHANDRA, GALEX,
NICMOS P alpha and H band imaging} for local spirals.

NIC3/WFPC2 10403

Ultraviolet Imaging of the UDF

The Hubble Deep Field North has uninterrupted observations at
wavelengths from Far-UV through NICMOS H- band, but the UDF goes no
bluer than B-band. We propose to complete the UDF coverage with deep
ultraviolet imaging of the Ultra-Deep Field {UDF} with the ACS-SBC in
the Far-UV {1500 Angstrom} and WFPC2 in the Near-UV {F300W}. We will
reach point source limits of ABmag=28.5, a factor of ten fainter than
the GALEX ultradeep surveys. Our dataset will add to the value of the
UDF legacy, and requires the unique capabilities of HST. In the spirit
of the UDF, we submit this proposal in the Treasury category. We
request a modest allocation of observing time for a Treasury program:
62 orbits. We will provide science quality images and photometric
catalogs to enable a range of research topics by the community. The
science goals of the team are to investigate the episode of strong
star formation activity in galaxies out to z=1, through the rest-frame
FUV luminosity function and the internal color structure of galaxies.
Far-UV number counts suggest that moderate redshift {z~0.5} starbursts
are undergoing a single, rapid burst of star-formation. We will
investigate this result by measuring the faint-end slope, alpha, of
the luminosity function. We will measure the star formation properties
of moderate redshift starburst galaxies and compare their morphologies
in the UV, optical, and near-IR. This catalog of starbursts will also
be important to the astronomical community in correlating unobscured
star-formation with the sources detected in the Spitzer Space
Telescope legacy observations of the field. With the high spatial
resolution data, will set strict limits on the flux escaping in
intermediate redshift {1 < z < 2} galaxies at wavelengths below the rest-frame Lyman limit, and thus infer the contribution of star forming galaxies at z~5 to the metagalactic ionizing radiation.


NICMOS Post-SAA calibration – CR Persistence Part 1.

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.

WFPC2 10359

WFPC2 CYCLE 13 Standard Darks

This dark calibration program obtains dark frames every week in order
to provide data for the ongoing calibration of the CCD dark current
rate, and to monitor and characterize the evolution of hot pixels.
Over an extended period these data will also provide a monitor of
radiation damage to the CCDs.


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

HSTAR 9653:  GS Acquisition (2,1,1) @ 011/08:14:11Z (during ZOE)
failed to RGA control due to SRLE on FGS 1 and 2.  Prior FM Updates
u1,3FM @ 011/07:53:46Z and 07:56:01Z had attitude errors V1 = 3.018,
V2 = 5.004, and V3 = 26.089 and V1 = 5.360, V2 = 9.079, and V3 = 2.637
arcsec.  Subsequent GS Reacquisition (2,1,1) @ 011/09:47:38Z failed to
RGA control. Under investigation.


17360-0 – Null Genslew for Proposal 10425 – Slot 4 & 5 (No Commands) @

17361-0 – Null Genslew for Proposal 10409 – Slot 6 & 7 (No Commands) @

1296-0 – Raise EAXLK1T Upper Temperature Limit @ 010/20:15z

                        SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq            08                        07             See Hstar # 9653
FGS REacq            06                        06
FHST Update          14                        14


SpaceRef staff editor.