Status Report

NASA Hubble Space Telescope Daily Report # 3793

By SpaceRef Editor
February 9, 2005
Filed under , ,
NASA Hubble Space Telescope Daily Report # 3793

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT       # 3793



ACS/HRC 10182

Towards a Comprehensive Understanding of Type Ia Supernovae: The
Necessity of UV Observations

Type Ia supernovae {SNe Ia} are very important to many diverse areas
of astrophysics, from the chemical evolution of galaxies to
observational cosmology which led to the discovery of dark energy and
the accelerating Universe. However, the utility of SNe Ia as
cosmological probes depends on the degree of our understanding of SN
Ia physics, and various systematic effects such as cosmic chemical
evolution. At present, the progenitors of SNe Ia and the exact
explosion mechanisms are still poorly understood, as are evolutionary
effects on SN Ia peak luminosities. Since early-time UV spectra and
light curves of nearby SNe Ia can directly address these questions, we
propose an approach consisting of two observational components: {1}
Detailed studies of two very bright, young, nearby SNe Ia with HST UV
spectroscopy at 13 epochs within the first 1.5 months after discovery;
and {2} studies of correlations with luminosity for five somewhat more
distant Hubble-flow SNe Ia, for which relative luminosities can be
determined with precision, using 8 epochs of HST UV spectroscopy
and/or broad-band imaging. The HST data, along with extensive
ground-based optical to near-IR observations, will be analyzed with
state-of-the-art models to probe SN Ia explosion physics and constrain
the nature of the progenitors. The results will form the basis for the
next phase of precision cosmology measurements using SNe Ia, allowing
us to more fully capitalize on the substantial past {and future}
investments of time made with HST in observations of high-redshift SNe

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/WFC 10420

The assembly of a massive galaxy cluster: The 4/h Mpc filament feeding

We propose a deep ACS/WFC F606W+F814W mosaic of the massive cluster
MACSJ0717.5+3745 at z=0.55 in order to obtain the first direct
detection of cluster evolution through infall of matter along
large-scale filaments. Existing optical, X-ray, and groundbased
weak-lensing data show strong evidence of galaxy groups and dark
matter in a coherent structure spanning at least 10 arcmin {4/h Mpc,
LCDM} in the plane of the sky. The size of this object rules out prior
interaction between the groups and the cluster, thus making it a prime
candidate for a genuine filament as opposed to a merger remnant. The
proposed observation will 1} allow the first direct measurement of the
dark matter content and mass distribution along a large-scale filament
via weak lensing, and 2} provide, through galaxy morphology and
resolved colour information, unprecedented insights into the physical
processes and environmental effects governing the transition from
field to cluster galaxies.


Resolving the Red Giant Population in Early Type Galaxies

This project addresses the fundamental issue of the age and abundance
of the stellar populations in early type galaxies. We propose deep
imaging observations with ACS/WFC in F606W, F814W, and NICMOS/NIC2 in
F110W, F160W to create optical/IR color-magnitude diagrams of the
upper red giant branch in the nearest example of a bona fide
elliptical galaxy, NGC3379, and simultaneously in the disk and halo of
its companion, the S0 galaxy NGC3384. These observations will build
upon the results from our NICMOS study of NGC3379, which produced the
first deep IR color-magnitude data for a normal, luminous elliptical
galaxy. This is the most direct way to establish the metallicity,
metallicity spread, and presence of intermediate age populations in
these representative Hubble types, exploring their star formation
histories and evolution. The data will enable comparison with M32, the
M31 halo, NGC5128, and other nearby galaxies similarly observed with

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 2

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 10360


This calibration proposal is the Cycle 13 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A
variety of internal exposures are obtained in order to provide a
monitor of the integrity of the CCD camera electronics in both bays
{gain 7 and gain 15}, a test for quantum efficiency in the CCDs, and a
monitor for possible buildup of contaminants on the CCD windows.


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

HSTAR 9700 :  ReAcq(2,1,1) enters CT 3 times before achieving FL-DV @
032/21:21:44z – OTA_SE review of PTAS processing log finds the
ReAcq(2,1,1) scheduled to begin at 2005.032/21:20:12 entered CT 3
different times on FGS 2, prior to achieving FineLock – DataValid. The
ultimate impact should have been no more than a slight delay in
SciInit and the P4TAKDAT flags.  Under investigation.


1296-0 Raise EAXLK1T Upper Temperature Limit @ 039/20:05z (Return to normal)

                           SCHEDULED     SUCCESSFUL    FAILURE TIMES 
 FGS Gsacq                04                        04 
 FGS Reacq                09                        09 
 FHST Update              06                        06 


SpaceRef staff editor.