HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4810
PERIOD COVERED: 5am March 12 - 5am March 13, 2009 (DOY
071/1000z-072/1000z)
OBSERVATIONS SCHEDULED
FGS 11785
Trigonometric Calibration of the Distance Scale for
Classical Novae
The distance scale for classical novae is important for
understanding
the stellar physics of their thermonuclear runaways, their
contribution
to Galactic nucleosynthesis, and their use as
extragalactic standard
candles. Although it is known that there is a relationship
between their
absolute magnitudes at maximum light and their subsequent
rates of
decline--the well-known maximum-magnitude rate-of-decline
(MMRD)
relation--it is difficult to set the zero-point for the
MMRD because of
the very uncertain distances of Galactic novae.
We propose to measure precise trigonometric parallaxes for
the quiescent
remnants of the four nearest classical novae. We will use
the Fine
Guidance Sensors, which are proven to be capable of
measuring parallaxes
with errors of ~0.2 mas, well below what is possible from
the ground.
WFPC2/ACS/SBC 11975
UV Light from Old Stellar Populations: a Census of UV
Sources in
Galactic Globular Clusters
In spite of the fact that HST has been the only operative
high-resolution eye in the UV-window over the last 18
years, no
homogeneous UV survey of Galactic globular clusters (GGCs)
has been
performed to date. In order to fill this gap in the
stellar population
studies, we propose a program that exploits the unique
capability of the
WFPC2 and the SBC in the far-/mid- UV for securing deep UV
imaging of 46
GGCs. The proposed observations will allow to study with
unprecedented
accuracy the hottest GGC stars, comprising the extreme
horizontal branch
(HB) stars and their progeny (the so-called AGB-manque',
and Post-early
AGB stars), and "exotic stellar populations"
like the blue straggler
stars and the interacting binaries. The targets have been
selected to
properly sample the GGC metallicity/structural parameter
space, thus to
unveil any possible correlation between the properties of
the hot
stellar populations and the cluster characteristics. In
addition, most
of the targets have extended HB "blue tails",
that can be properly
studied only by means of deep UV observations, expecially
in the far-UV
filters like the F160BW, that is not foreseen on the WFC3.
This data
base is complemented with GALEX observations in the
cluster outermost
regions, thus allowing to investigate any possible trend
of the
UV-bright stellar types over the entire radial extension
of the
clusters. Although the hottest GGC stars are just a small
class of
"special" objects, their study has a broad
relevance in the context of
structure formation and chemical evolution in the early
Universe,
bringing precious information on the basic star formation
processes and
the origin of blue light from galaxies. Indeed, the
proposed
observations will provide the community with an
unprecedented data set
suitable for addressing a number of still open
astrophysical questions,
ranging from the main drivers of the HB morphology and the
mass loss
processes, to the origin of the UV upturn in elliptical
galaxies, the
dating of distant systems from integrated light, and the
complex
interplay between stellar evolution and dynamics in dense
stellar
aggregates. In the spirit of constructing a community
resource, we
entirely waive the proprietary period for these
observations.
WFPC2 11987
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 U-band
observations
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. In
this proposal we plan to address this missing area in
SINGS by obtaining
high-resolution WFPC2 UBVI observations to accurately find
and determine
the ages of the young stellar clusters in a subset of the
SINGS
galaxies. These observations will greatly enhance the
legacy value of
the SINGS observations while also directly answering
questions
pertaining to star formation in galaxies.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
11720 - At 071/23:03:36, GSAcq(1,0,1) scheduled from
071/23:00:00 -
23:06:24 failed to RGA Hold due to (QF1STOPF) and (QSTOP) stop flag
indications on FGS-1.
Observations affected: WFPC 136-140, Proposal ID# 11975
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSAcq
08
07
FGS REAcq
06
06
OBAD with Maneuver
28
27
SIGNIFICANT EVENTS: (None)