HUBBLE SPACE TELESCOPE - Continuing to collect World Class
Science
DAILY REPORT #4662
PERIOD COVERED: 5am July 28 - 5am July 29, 2008 (DOY
210/0900z-211/0900z)
OBSERVATIONS SCHEDULED
NIC1/NIC2 11172
Defining Classes of Long Period Variable Stars in M31
We propose a thrifty but information-packed investigation {1440
exposures total} with NICMOS F205W, F160W and F110W providing crucial
information about Long Period Variables in M31, at a level of detail
that has recently allowed the discovery of new variable star classes in
the Magellanic Clouds, a very different stellar population. These
observations are buttressed by an extensive map of the same fields with
ACS and WFPC2 exposures in F555W and F814W, and a massive ground-based
imaging patrol producing well-sampled light curves for more than 400,000
variable stars. Our primary goal is to collect sufficient NIR data in
order to analyze and classify the huge number of long-period variables
in our catalog {see below} through Period-Luminosity {P/L} diagrams. We
will produce accurate P/L diagrams for both the bulge and a progression
of locations throughout the disk of M31. These diagrams will be similar
in quality to those currently in the Magellanic Clouds, with their lower
metallicity, radically different star formation history, and larger
spread in distance to the variables. M31 offers an excellent chance to
study more typical disk populations, in a manner which might be extended
to more distant galaxies where such variables are still visible, probing
a much more evenly spread progenitor age distribution than cepheids {and
perhaps useful as a distance scale alternative or cross-check}. Our data
will also provide a massive and unique color-magnitude dataset, and
allow us to confirm the microlensing nature of a large sample of
candidate lensed sources in M31. We expect that this study will produce
several important results, among them a better understanding of P/L and
P/L-color relations for pulsating variables which are essential to the
extragalactic distance ladder, will view these variables at a common
distance over a range of metallicities {eliminating the distance-error
vs. metallicity ambiguity between the LMC and SMC}, allow further
insight into possible faint-variable mass-loss for higher metallicities,
and in general produce a sample more typical of giant disk galaxies
predominant in many studies.
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA Calibration - CR Persistence Part 6
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 i
mages. Each observation will need its own CRMAP, as different SAA
passages leave different imprints on the NICMOS detectors.
WFPC2 11177
The Nature of z=3 Lyman-Alpha Emitters
The advent of large mosaic CCD cameras on 4 -- 8 m class telescopes has
recently led to a revolution in our ability to detect primordial
galaxies. Today, large numbers of strong Ly-alpha emitters (LAEs) are
being discovered between 2.4 < z < 6. These are important objects: not
only do they sample a part of the galaxy luminosity function that is
inaccessible to the Lyman-break technique, but they also tend to be
younger and less chemically evolved. In fact, the LAEs now being found
are currently our best candidates for galaxies in the act of formation.
To investigate the properties of this class of objects, we have
conducted an extremely deep narrow-band (5000 Angstrom; FWHM = 50
Angstrom) and broad-band (UBVRIzJK) survey of the Extended Chandra Deep
Field South, and have identified a homogeneous sample of strong Ly-
alpha emitters at z = 3.11. Twenty-seven of these objects are located
within the region surveyed by Great Observatories Origins Deep Survey
(GOODS) and have detailed morphological information available from the
rest-frame ultraviolet. We propose 0.2" resolution narrow-band imaging
of 11 of our LAEs using the F502N filter of WFPC2. By comparing the
Ly-alpha and rest-frame UV continuum morphologies of these galaxies, we
will be able to look for the presence of outflows, constrain their dust
content, and test whether these objects are truly primordial galaxies.
WFPC2 11206
At the Cradle of the Milky Way: Formation of the Most Massive Field Disk
Galaxies at z>1
We propose to obtain 2 orbit WFPC2 F814W images of a sample of the 15
most massive galaxies found at $1 < z < 1.3$. These were culled from
over 20,000 Keck spectra collected as part of DEEP and are unique among
high redshift massive galaxy samples in being kinematically selected.
Through a recent HST NICMOS-2 imaging program {GO-10532}, we have
confirmed that these galaxies have regular stellar disks, and their
emission line kinematics are not due to gradients from merging
components. These potentially very young galaxies are likely precursors
to massive local disks, assuming no further merging. The proposed WFPC2
and existing NIC-2 data provide colors, stellar masses, and ages of
bulge and disk subcomponents, to assess whether old stellar bulges and
disks are in place at that time or still being built, and constrain
their formation epochs. Finally, this sample will yield the first
statistically significant results on the $z > 1$ evolution of the
size-velocity-luminosity scaling relations, for massive galaxies at
different wavelengths, and constrain whether this evolution reflects
stellar mass growth, or passive evolution, of either bulge or disk
components.
WFPC2 11218
Snapshot Survey for Planetary Nebulae in Globular Clusters of the Local
Group
Planetary nebulae {PNe} in globular clusters {GCs} raise a number of
interesting issues related to stellar and galactic evolution. The number
of PNe known in Milky Way GCs, 4, is surprisingly low if one assumes
that all stars pass through a PN stage. However, it is likely that the
remnants of stars now evolving in Galactic GCs leave the AGB so slowly
that any ejected nebula dissipates long before the star becomes hot
enough to ionize it. Thus there should not be ANY PNe in Milky Way
GCs--but there are four! It has been suggested that these PNe are the
result of mergers of binary stars within GCs, i.e., that they are
descendants of blue stragglers. The frequency of occurrence of PNe in
external galaxies poses more questions, because it shows a range of
almost an order of magnitude. I propose a Snapshot survey aimed at
discovering PNe in the GC systems of Local Group galaxies more distant
than the Magellanic Clouds. These clusters, some of which may be much
younger than their counterparts in the Milky Way, might contain many
more PNe than those of our own galaxy. I will use the standard technique
of emission-line and continuum imaging, which easily discloses PNe.
WFPC2 11800
Hubble Heritage imaging of NGC 3324 in the Carina Nebula
An ACS H-alpha mosaic of NGC 3324 already exists (HST proposal 10475, PI
Nathan Smith). This program will use WFPC2 to obtain two more filters
for this field.
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: (None)
SCHEDULED
SUCCESSFUL
FGS GSacq
07
07
FGS REacq
06
06
OBAD with Maneuver 26
26
SIGNIFICANT EVENTS: (None)