DAILY REPORT #3907

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT #3907

PERIOD COVERED: UT July 21, 2005 (DOY 202)

OBSERVATIONS SCHEDULED

ACS/HRC/NIC3 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
Ia.

ACS/HRC/WFC 10411

Catching optical emission from the first discovered double-pulsar
system: J0737-3039

This proposal is aimed to detect optical emission from one of the most
intriguing astronomical object ever found in the sky: the newly
discovered binary system harbouring two pulsar {PSR J0737-3039A and
PSR J0737-3039B}. This is the first double- pulsar system ever
detected {Burgay et al. 2003; Lyne et al. 2004} and it provides a
wonderful laboratory for the study of relativistic gravity and
gravitational radiation. Moreover, for the first time, it offers the
opportunity to probe the magnetosphere and the local environment of a
neutron star. There is indeed evidence of strong interactions between
the energy released by one pulsar and the magnetosphere of the other.
Our team is now carrying out a multi-wavelength project to understand
the nature of the occurring interactions and the energy budget of the
system. In particular, while radio observations will continue to
survey the object, X-ray observations with Chandra have been already
allocated. Here we ask for deep ACS-HR observations to catch the
optical emission from the system. These observations will firstly
estimate the optical nonthermal flux, and, once combined with radio
and X-ray fluxes, will give us unique insights into the physics of the
relativistic wind interactions within the system.

ACS/HRC/WFC/NIC2 10399

Accurate and Robust Calibration of the Extragalactic Distance Scale
with the Maser Galaxy NGC4258 II

The extragalactic distance scale {EDS} is defined by a comparison of
Cepheid Period- Luminosity {PL} relations for nearby galaxies and the
LMC, whose uncertain distance is thereby the SOLE anchor. Studies of
masers orbiting the central black hole in NGC4258 have provided the
most accurate extragalactic distance ever {7.2+/-0.5 Mpc}, and new
radio data and analysis techniques will reduce the uncertainty to
3.5% {0.07 mag} by 2005. Since this distance is well determined and
based on geometric arguments, NGC4258 can provide a much needed new
anchor for the EDS. Ultimately, the combination of an independent
measurement of H0 and measurements of CMB fluctuations {e.g., WMAP}
can be used to directly constrain cosmological parameters including
the equation of state of dark energy. In our Cycle 12 proposal, we
defined a program spanning two cycles. The Cycle 12 portion was
accepted. We have acquired WFC images and are constructing well
sampled PL relations in 3 colors {BVI}. The purpose of the Cycle 13
observations is to address systematic sources of error and is crucial
for the success of the entire program. To disentangle the effects of
reddening and metallicity, and to characterize the effects of
blending, we require 50 orbits to obtain H-band photometry
{NICMOS/NIC2} and high resolution images {ACS/HRC}.

ACS/WFC/WFPC2 10394

Deep imaging of newly discovered globular clusters in the outer halo
of M31

Globular clusters {GCs} are fossil relics with which we can
investigate the processes of galaxy formation and growth. We have
recently discovered a sample of GCs, as part of a very wide area CCD
survey of M31. These clusters span a range in projected galactocentric
distance of 20 - 80 kpc, more than double the radii of the previous
most remote known GC. Here we apply for deep ACS images of 13 GCs,
which will allow us to study their stellar populations, line-of-sight
distances and structural parameters. These will be used to: a}
Investigate the merger history of M31, through an examination of
variations in the RGB and HB morphologies, particularly to obtain
metallicities and check for the presence of any second parameter
effect in the HB. d} Determine, in conjuction with ground-based
spectroscopy, the dynamical mass of M31 at large radius, providing a
direct probe of the mass distribution of its dark halo.

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.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES:
1357-0 HST486 Full EEPROM Memory Dump @ 202/16:35z
1356-0 HST486 Full RAM Memory Dump @ 202/22:56z

SCHEDULED SUCCESSFUL
FGS Gsacq 06 06
FGS Reacq 11 11
FHST Update 07 07