HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4847
PERIOD COVERED: 5am May 4 - 5am May 5, 2009 (DOY
124/0900z-125/0900z)
OBSERVATIONS SCHEDULED
ACS/SBC 11980
Deep FUV Imaging of Cooling Flow Clusters
We propose to take deep ACS FUV images of a carefully
selected sample of
19 bright central galaxies in nearby galaxy clusters. This
program is
the last critical element of a comprehensive investigation
of the impact
of stellar and AGN feedback on the local galaxy cluster
environment. The
HST images will complement new, high-resolution, Halpha
images obtained
with the recently commissioned Maryland-Magellan Tunable
Filter (MMTF)
on the Baade 6.5m telescope, archival Chandra, VLA, and
GALEX data, and
on-going H2/NIR observations. The MMTF data have revealed
unsuspected
filamentary complexes in several systems. The GALEX data
often show
hints of extended NUV and FUV emission on a similar scale,
but their
poor spatial resolution prevents meaningful comparison
with the MMTF
data. The HST data will provide this much needed gain in
resolution. The
combined radio-H2-Halpha-FUV-X-ray dataset will allow us
to derive with
unprecedented precision the role of the AGN, hot stars,
shocks, and
relativistic particles on the excitation and
thermodynamics of the
multi-phase intracluster and interstellar media in these
systems. This
is an important question since the formation and evolution
of most
cluster galaxies have likely been affected by these
processes.
FGS 11704
The Ages of Globular Clusters and the Population II
Distance Scale
Globular clusters are the oldest objects in the universe
whose age can
be accurately determined. The dominant error in globular
cluster age
determinations is the uncertain Population II distance
scale. We propose
to use FGS 1r to obtain parallaxes with an accuracy of 0.2
milliarcsecond for 9 main sequence stars with [Fe/H] <
-1.5. This will
determine the absolute magnitude of these stars with
accuracies of 0.04
to 0.06mag. This data will be used to determine the
distance to 24
metal-poor globular clusters using main sequence fitting.
These
distances (with errors of 0.05 mag) will be used to
determine the ages
of globular clusters using the luminosity of the subgiant
branch as an
age indicator. This will yield absolute ages with an
accuracy 5%, about
a factor of two improvement over current estimates.
Coupled with
existing parallaxes for more metal-rich stars, we will be
able to
accurately determine the age for globular clusters over a
wide range of
metallicities in order to study the early formation
history of the Milky
Way and provide an independent estimate of the age of the
universe.
The Hipparcos database contains only 1 star with [Fe/H]
< -1.4 and an
absolute magnitude error less than 0.18 mag which is
suitable for use in
main sequence fitting. Previous attempts at main sequence
fitting to
metal-poor globular clusters have had to rely on
theoretical
calibrations of the color of the main sequence. Our HST
parallax program
will remove this source of possible systematic error and
yield distances
to metal-poor globular clusters which are significantly
more accurate
than possible with the current parallax data. The HST
parallax data will
have errors which are 10 times smaller than the current
parallax data.
Using the HST parallaxes, we will obtain main sequence
fitting distances
to 11 globular clusters which contain over 500 RR Lyrae
stars. This will
allow us to calibrate the absolute magnitude of RR Lyrae
stars, a
commonly used Population II distance indicator.
WFPC2 11302
WFPC2 CYCLE 16 Standard Darks - Part III
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.
WFPC2 11804
WFPC2 Closeout Calibration -- CTE Effects on Standard Star
Observations of the primary standard star GRW+70D5824 are
made at
several different places on the CCD to directly estimate
the impact of
CTE. All four CCDs are evaluated. Filters F170W and F555W
are used to
evaluate the effects of background and different PSF
shapes / sizes.
WFPC2 11956
Hubble Heritage: Side B
We propose a program of 39 orbits to observe 6 targets
with WFPC2
following a successful return to science using side B
electronics. These
observations will be used for Hubble Heritage releases in
the months
leading up to servicing mission 4. Because of launch
delays, our reserve
of releasable images is growing dangerously slim. We are
proposing here
to replenish one of our important lines of communication
with the
public.
We have carefully chosen targets that can efficiently use
single
pointings of WFPC2 to obtain images of visually striking
and
astrophysically interesting targets. Observations will
reach high S/N
and will be dithered and subsampled to improve the
resolution and pixel
scale to near ACS/WFC3 quality at a modest cost in
exposure time. Most
of the observations will schedule in the interim between a
return to
science and the availability of new science proposals that
may be
selected in response to an interim call for proposals.
WFPC2 11981
FUV Imaging Survey of Galactic Open Clusters
We propose a WFPC2 FUV imaging survey of 6 Galactic open
clusters with
ages ranging from 1 Myr to 300 Myr complemented with
NUV/optical imaging
of the same fields. No such survey has ever been attempted
before in the
FUV at the resolution of WFPC2 (indeed, no WFPC2 FUV
images of any
Galactic open cluster exist in the HST archive) and, since
WFPC2 will be
retired in SM4 and none of the other HST instruments can
do FUV imaging
of bright objects, this is the last chance to do such a
survey before
another UV telescope is launched. This survey will provide
a new
perspective on young/intermediate age Galactic clusters
and a key
template for the study of star formation at high redshift,
where the
intensity peak we observe in the optical/NIR from Earth is
located in
the FUV in its rest frame. For clusters still associated
with an H II
region, UV imaging maps the continuum emission of the
ionized gas and
the radiation scattered by background dust and, combined
with optical
nebular images, can be used to determine the 3-D structure
of the H II
region. For all young clusters, FUV+NUV+optical photometry
can be used
to study the UV excesses of T-Tauri stars. For clusters
older than ~40
Myr, the same photometric combination is the easiest
method to detect
companion white dwarfs which are invisible using only the
optical and
NIR. WFPC2 is also an excellent instrument to discover
close companions
around bright stars and improve our knowledge of their
multiplicity
fraction. Finally, for all clusters, the combination of
high-spatial-resolution UV and optical photometry can be
used to
simultaneously measure the temperature, extinction,
extinction law,
distance, and existence of companions (resolved and
unresolved) and,
thus, produce clean HR diagrams with resolved cluster
membership and
much-reduced systematic uncertainties.
WFPC2 11988
Searching for Intermediate Mass Black Holes in Globular
Clusters via
Proper Motions
The unambiguous detection of an intermediate mas black
hole (IMBH) in a
globular star cluster would be a major achievement for the
Hubble Space
Telescope. It is critical to know whether or not IMBHs
exist in the
centers of clusters in order to understand the dynamical
evolution of
dense stellar systems. Also, n IMBH detection would prove
the existence
of BHs in an entirely new mass range. Observationally, the
search has
been hampered by the low number of stars with known
velocities in the
central few arcseconds. This limits measurements of the
stellar velocity
dispersion in the region where the gravitational influence
of any IMBH
would be felt. Existing IMBH claims in the literature have
all been
called into question, and have all been based on
line-of-sight
velocities from spectroscopy. In cycle 13, we obtained
ACS/HRC
observations for 5 nearby Galactic globular clusters for a
new proper
motion study. Here, we request WFPC2/PC observations of
these clusters,
all of which are observable in Feb-May 2009. This 4 year
baseline will
allow us to measure the proper motions of stars into the
very center of
each cluster, and either detect or place firm constraints
on the
presence of an IMBH. In addition, we will determine
whether or not the
clusters rotate or show any anisotropy in their motions.
Our small (<75
orbit) program meets the criteria of addressing high
impact science
(IMBH detection) using innovative methods (proper
motions).
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are
preliminary reports
of potential non-nominal performance that will be
investigated.)
HSTARS:
11788 - GSAcq(1,2,1) scheduled at 124/14:09:59 resulted in
Fine Lock
Back Up 1,0,1 at 124/14:13:34.
Observation possibly affected: WFPC 33 - 36, Proposal ID# 11956.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS GSAcq
06
06
FGS REAcq
09
09
OBAD with Maneuver
30
30
SIGNIFICANT EVENTS: (None)