Daily Report #4766

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT****** #4766

PERIOD COVERED: 5am January 6 - 5am January 7, 2009 (DOY
*************************** 006/1000z-007/1000z)

OBSERVATIONS SCHEDULED

FGS 11789

An Astrometric Calibration of Population II Distance Indicators

In 2002 HST produced a highly precise parallax for RR Lyrae. That
measurement resulted in an absolute magnitude, M(V)= 0.61+/-0.11, a
useful result, judged by the over ten refereed citations each year
since. It is, however, unsatisfactory to have the direct,
parallax-based, distance scale of Population II variables based on a
single star. We propose, therefore, to obtain the parallaxes of four
additional RR Lyrae stars and two Population II Cepheids, or W Vir
stars. The Population II Cepheids lie with the RR Lyrae stars on a
common K-band Period-Luminosity relation. Using these parallaxes to
inform that relationship, we anticipate a zero-point error of 0.04
magnitude. This result should greatly strengthen confidence in the
Population II distance scale and increase our understanding of RR
Lyrae star and Pop II Cepheid astrophysics.

WFPC2 11966

The Recent Star Formation History of SINGS Galaxies

The Spitzer Legacy project SINGS provided a unique view of the current
state of star formation and dust in a sample of galaxies of all Hubble
types. This multi-wavelength view allowed the team to create current
star formation diagnostics that are independent of the dust content
and increased our understanding of the dust in galaxies. Even so,
using the SINGS data alone we can only make rough estimates of the
recent star formation history of these galaxies. The lack of high
resolution observations (especially U-band and H-alpha) means that it
is impossible to estimate the ages of young clusters. In addition, the
low resolution of the Spitzer and ground-based observations means that
what appear to be individual Spitzer sources can actually be composed
of many individual clusters with varying ages. We need to know the
ages, star formation histories, and extinction of these individual
clusters to understand how these clusters form and age and thus
influence the evolution of the galaxy. In this proposal we address
this missing area of SINGS by obtaining high-resolution WFPC2 UBVI &
H-alpha observations to not only accurately locate and determine the
ages of the young stellar clusters in the actively star forming SINGS
galaxies but to also address a variety of other scientific issues.
Over 500 HST orbits and 500 hours of Spitzter observing time have been
dedicated to observations of the SINGS sample. But the HST
observations have not been systematic. By adding a relatively small
fraction of this time for these requested observations, we will
greatly enhance the legacy value of the SINGS observations by creating
a uniform high resolution multi-wavelength HST archive that matches
the quality of the lower resolution SINGS archive.

WFPC2 11967

WFPC2 Imaging of the Lockman Hole

In order to understand galaxy evolution and constrain theoretical
models, we require both multiwavelength photometry (to robustly
determine physical parameters such as star formation rates and stellar
masses) and detailed morphological information. Galaxy morphology
encodes crucial information about galaxy formation history and the
physical processes that trigger star formation and AGN activity, and
high-resolution imaging for large samples of galaxies is currently
only obtainable with HST. The Lockman Hole has been the target of
extensive multi-wavelength observations from the X-ray to the radio,
and will be the target of the deepest wide-area blankfield thermal IR
observations with Herschel, but currently lacks comprehensive HST
imaging. We propose to obtain WFPC2 imaging of ~500 arcmin2 of the
central region of the Lockman Hole in F606W and F814W, to a depth of
V606~26.8 and I814~26. This imaging is crucial in order to
characterize the sources detected at other wavelengths.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11631 - REAcq(1,2,1) scheduled at 006/13:13:44 and at 006/14:49:42
failed. Initial GSACQ(1,2,1) at 006/11:47:12 was successful.

Observations affected: WFPC 50 to 53, proposal 11966.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

*********************** SCHEDULED***** SUCCESSFUL

FGS GSacq************** 05***************** 05
FGS REacq************** 10***************** 08
OBAD with Maneuver **** 28***************** 28

SIGNIFICANT EVENTS: (None)