NASA Hubble Space Telescope Daily Report # 3687
HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science
DAILY REPORT # 3687
PERIOD COVERED: DOY 245
OBSERVATIONS SCHEDULED
ACS/HRC 10050
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/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
Ia.
ACS/HRC 10198
Probing the Dynamics of the Galactic Bar through the Kinematics of
Microlensed Stars
The observed optical depths to microlensing of stars in the Galactic
bulge are difficult to reconcile with our present understanding of
Galactic dynamics. The main source of uncertainty in those comparisons
is now shifting from microlensing measurements to the dynamical models
of the Galactic bar. We propose to constrain the Galactic bar models
with proper motion observations of Bulge stars that underwent
microlensing by determining both the kinematic identity of the
microlensed sources and the importance of streaming motions. The
lensed stars are typically farther than randomly selected stars.
Therefore, our proper motion determinations for 36 targeted MACHO
events will provide valuable constraints on the dynamics of bulge
stars as a function of distance. The first epoch data for our proposed
events is already available in the HST archive so the project can be
completed within a single HST cycle. The exceptional spatial
resolution of HST is essential for completion of the project.
Constraints on the total mass in the bulge will ultimately lead to the
determination of the amount of dark matter in inner Galaxy.
ACS/HRC 10255
A Never Before Explored Phase Space: Resolving Close White Dwarf / Red
Dwarf Binaries
We propose an ACS Snapshot imaging survey to resolve a well-defined
sample of highly probable white dwarf plus red dwarf close binaries.
These candidates were selected from a search for white dwarfs with
infrared excess from the 2MASS database. They represent unresolved
systems {separations less than approximately 2" in the 2MASS images}
and are distributed over the whole sky. Our HST+ACS observations will
be sensitive to a separation range {1-20 AU} never before probed by
any means. The proposed study will be the first empirical test of
binary star parameters in the post-AGB phase, and cannot be
accomplished from the ground. By resolving as few as 20 of our ~100
targets with HST, we will be able to characterize the distribution of
orbital semi-major axes and secondary star masses.
ACS/HRC/WFC 10061
CCD Daily Monitor
This program consists of basic tests to monitor, the read noise, the
development of hot pixels and test for any source of noise in ACS CCD
detectors. This programme will be executed once a day for the entire
lifetime of ACS.
ACS/WFC 10049
ACS Internal Flat Field Stability
The stability of the CCD flat fields will be monitored using the
calibration lamps and a sub-sample of the filter set. High signal
observations will be used to assess the stability of the pixel-to-
pixel flat field structure and to monitor the position of the dust
motes. Shorter exposures will be used to identify charge traps and to
assess the stability of the DQ arrays. Only internal exposures with
the calibration lamps will be required.
ACS/WFC 10210
Groups of Dwarf Galaxies: Pools of Mostly Dark Matter?
Within 5 Mpc, there are 6 groups with well-known luminous galaxies but
there also appears to be a comparable number of groups containing only
dwarfs. If these dwarf entities are truly bound then M/L values are an
order of magnitude higher than values found for groups with luminous
spiral galaxies. There are theoretical reasons to anticipate that low
mass halos may frequently be mostly dark. The dynamical influence of
low mass halos is negligible in familiar groups with luminous members.
By contrast, a study of the dynamics of `groups of dwarfs’ may provide
direct evidence of the existence of dark matter potential wells with
few baryons. The goal of the present study is to gather detailed
information on the 3-D distribution of dwarf galaxies suspected to lie
within 7 groups of dwarfs within 5 Mpc. Distances with 7% relative
accuracy can be measured with the Tip of the Giant Branch method with
ACS and integrations within 1 orbit per target.
ACS/WFC 10217
The ACS Fornax Cluster Survey
The two rich clusters nearest to the Milky Way, and the only large
collections of early-type galaxies within ~ 25 Mpc, are the Virgo and
Fornax Clusters. We propose to exploit the exceptional imaging
capabilities of the ACS/WFC to carry out the most comprehensive
imaging survey to date of early-type galaxies in Fornax: the ACS
Fornax Cluster Survey. Deep ACS/WFC images — in the F475W {g’} and
F850LP {z’} bands — will be acquired for 44 E, S0, dE, dE, N and dS0
cluster members. In Cycle 11, we initiated a similar program targeting
early-type galaxies in the Virgo Cluster {the ACS Virgo Cluster
Survey; GO-9401}. Our proposed survey of Fornax would yield an
extraordinary dataset which would complement that already in hand for
Virgo, and allow a definitive study of the role played by environment
in the structure, formation and evolution of early-type galaxies and
their globular cluster systems, nuclei, stellar populations, dust
content, nuclear morphologies and merger histories. It would also be a
community resource for years to come and, together with the ACS Virgo
Cluster Survey, constitute one of the lasting legacies of HST.
ACS/WFC/WFPC2 10265
The Formation History of Andromeda
We propose deep observations of Andromeda’s outer disk and giant tidal
stream, to reconstruct their star formation histories. As the nearest
giant galaxy, Andromeda offers the best testing ground for
understanding galaxy formation and evolution. Given the dramatic
increase in sensitivity offered by the ACS, we can now resolve stars
on the old main sequence in the other giant spiral of the Local Group,
and employ the same direct age diagnostics that have been used for
decades in the study of Galactic globular clusters. In Cycle 11, we
successfully observed a field in the Andromeda halo and constructed a
deep color-magnitude diagram reaching well below the oldest main
sequence turnoff. In Cycle 13, we propose to extend these observations
to the outer disk and tidal stream of Andromeda, to constrain their
star formation histories and compare them to that of the halo. The
combined observations from these two programs will offer a dramatic
advance in our understanding of the overall evolution of spiral
galaxies.
NIC1 10179
A Coordinated NICMOS and XMM Experiment to Observe the Variability of
Sgr A*
The massive black hole Sgr A* at the Galactic center has recently
shown not only quiescent emission at near-IR wavelengths, but also
flare activity with quasi-periodicity of 17 minutes. Our research
group has been granted two blocks of observing time with XMM-Newton to
monitor the spectral and temporal properties of Sgr A*. Simultaneously
with these X-ray observations, we will also monitor Sgr A* at radio,
submillimeter, near-IR, and gamma-ray wavelengths. We propose to use
NICMOS in parallel with the XMM observations to provide evidence of a
well-defined minimum periodicity in the spectrum of flare
periodicities. This, combined with periodicity in the near-IR line
emission, would strengthen the claim that the emitting gas resides at
the innermost stable circular orbit around the GC black hole, thus
measuring the spin parameter of a massive black hole. Current
groundbased near-IR data suggest a spin parameter of ~0.5. In
addition, the correlation pattern of emission over a wide spectrum
would elucidate a key issue of how to explain the low luminosity of
Sgr A*. The NICMOS on HST is the only instrument that can accurately
measure the 17 minute quasi-periodic variability of Sgr A* because of
the long time baseline over which HST can observe Sgr A* in parallel
with XMM-Newton.
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.
WFPC2 10071
WFPC2 CYCLE 12 Supplemental Darks Part 3/3
This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot
pixels.
WFPC2 10080
Wavelength Stability of Narrow Band and Linear Ramp Filters
Verify the mapping of wavelength as a function of CCD position on
LRFs; check for changes in central wavelengths of narrow band filters.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)
HSTAR 9528: OTA SE review of PTAS processing log for SMS 236 revealed
LOL experienced in the GS Acquisition (1,3,1) @ 238/10:01:42Z. Both
FGSs were in FLDV @ 238/10:05:30Z, but @ 238/10:07:13Z, both returned
to SSM control and successfully re-achieved FLDV by 238/10:08:12Z.
The three GS Re-acquisition following the GS Acquisition were all
successful.
COMPLETED OPS REQs: None
OPS NOTES EXECUTED: None
SCHEDULED SUCCESSFUL FAILURE TIMES
FGS Gsacq 8 8
FGS Reacq 7 7
FHST Update 13 13
LOSS of LOCK
SIGNIFICANT EVENTS:
HST VEST Testing of Software Sunpoint Safemode recovery procedures.
