Daily Report #4596
Cooper, Joe
DAILY REPORT # 4596
PERIOD COVERED: UT April 23, 2008 (DOY 114)
OBSERVATIONS SCHEDULED
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 images. Each observation will need its own CRMAP, as
different SAA passages leave different imprints on the NICMOS detectors.
NIC2 10852
Coronagraphic Polarimetry with NICMOS: Dust grain evolution in T Tauri stars
The formation of planetary systems is intimately linked to the dust
population in circumstellar disks, thus understanding dust grain evolution
is essential to advancing our understanding of how planets form. By
combining {1} the coronagraphic polarimetry capabilities of NICMOS, {2}
powerful 3-D radiative transfer codes, and {3} observations of objects known
to span the Class II- III stellar evolutionary phases, we will gain crucial
insight into dust grain growth. By observing objects representative of a
known evolutionary sequence of YSOs, we will be able to investigate how the
dust population evolves in size and distribution during the crucial
transition from a star+disk system to a system containing planetesimals.
When combine with our previous study on dust grain evolution in the Class
I-II phase, the proposed study will help to establish the fundamental time
scales for the depletion of ISM-like grains: the first step in understanding
the transformation from small submicron sized dust grains, to large
millimeter sized grains, and untimely to planetary bodies.
NIC2/WFPC2 11142
Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3<z<2.7
Using HST and Spitzer
We aim to determine physical properties of IR luminous galaxies at
0.3<z<2.7 by requesting coordinated HST/NIC2 and MIPS 70um observations
of a unique, 24um flux-limited sample with complete Spitzer mid-IR
spectroscopy. The 150 sources investigated in this program have S{24um}
> 0.8mJy and their mid-IR spectra have already provided the majority
targets with spectroscopic redshifts {0.3<z<2.7}. The proposed 150~orbits of
NIC2 and 66~hours of MIPS 70um will provide the physical measurements of the
light distribution at the rest-frame ~8000A and better estimates of the
bolometric luminosity. Combining these parameters together with the rich
suite of spectral diagnostics from the mid-IR spectra, we will {1} measure
how common mergers are among LIRGs and ULIRGs at 0.3<z<2.7, and establish if
major mergers are the drivers of z>1 ULIRGs, as in the local Universe. {2}
study the co-evolution of star formation and blackhole accretion by
investigating the relations between the fraction of starburst/AGN measured
from mid-IR spectra vs. HST morphologies, L{bol} and z. {3} obtain the
current best estimates of the far-IR emission, thus L{bol} for this sample,
and establish if the relative contribution of mid-to-far IR dust emission is
correlated with morphology {resolved vs. unresolved}.
NIC3 11120
A Paschen-Alpha Study of Massive Stars and the ISM in the Galactic
Center
The Galactic center (GC) is a unique site for a detailed study of a
multitude of complex astrophysical phenomena, which may be common to nuclear
regions of many galaxies. Observable at resolutions unapproachable in other
galaxies, the GC provides an unparalleled opportunity to improve our
understanding of the interrelationships of massive stars, young stellar
clusters, warm and hot ionized gases, molecular clouds, large scale magnetic
fields, and black holes. We propose the first large-scale hydrogen Paschen
alpha line survey of the GC using NICMOS on the Hubble Space Telescope. This
survey will lead to a high resolution and high sensitivity map of the
Paschen alpha line emission in addition to a map of foreground extinction,
made by comparing Paschen alpha to radio emission. This survey of the inner
75 pc of the Galaxy will provide an unprecedented and complete search for
sites of massive star formation. In particular, we will be able to (1)
uncover the distribution of young massive stars in this region, (2) locate
the surfaces of adjacent molecular clouds, (3) determine important physical
parameters of the ionized gas, (4) identify compact and ultra-compact HII
regions throughout the GC. When combined with existing Chandra and Spitzer
surveys as well as a wealth of other multi-wavelength observations, the
results will allow us to address such questions as where and how massive
stars form, how stellar clusters are disrupted, how massive stars shape and
heat the surrounding medium, and how various phases of this medium are
interspersed.
WFPC2 11113
Binaries in the Kuiper Belt: Probes of Solar System Formation and Evolution
The discovery of binaries in the Kuiper Belt and related small body
populations is powering a revolutionary step forward in the study of this
remote region. Three quarters of the known binaries in the Kuiper Belt have
been discovered with HST, most by our snapshot surveys. The statistics
derived from this work are beginning to yield surprising and unexpected
results. We have found a strong concentration of binaries among
low-inclination Classicals, a possible size cutoff to binaries among the
Centaurs, an apparent preference for nearly equal mass binaries, and a
strong increase in the number of binaries at small separations. We propose
to continue this successful program in Cycle 16; we expect to discover at
least 13 new binary systems, targeted to subgroups where these discoveries
can have the greatest impact.
WFPC2 11160
Escape fraction and stellar populations in a highly magnified
Lyman-Break Galaxy
Understanding how star-forming galaxies contribute to cosmic reionization is
one of the frontiers of observational cosmology. A key ingredient in this
issue is measuring the escape fraction of Lyman-continuum photons in high
redshift galaxies (z>3). Gravitationally lensed Lyman-break galaxies (LBGs)
act as important laboratories for studying the resolved physical properties
at sub-kpc scales with high signal-to-noise. Correlating the local escape
fraction with physical parameters derived from stellar population modeling
(such as the star formation rate, age and reddening) will offer new insights
into understanding the physical processes involved with the production of
ionizing photons. We propose here follow-up observations of the "Cosmic
Eye", a remarkable, highly magnified (x 30), Lyman-break galaxy at z~3.07
using WFPC2 and NICMOS. Deep ultraviolet WFPC2 imaging will provide a
detailed study of variations in the escape fraction, while WFPC2 and
NICMOS/NIC2 imaging will complement the current broad-band detections to
allow a precise modeling of the spatially-dependent spectral energy
distribution. This will allow the first comprehensive analysis between the
escape fraction, the local SED and the dynamics of a distant galaxy.
WFPC2 11201
Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images
In Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in the
Magellanic Clouds centered on background quasars. We used these data to
determine the proper motions of the LMC and SMC to better than 5% and 15%
respectively. These are by far the best determinations of the proper motions
of these two galaxies. The results have a number of unexpected implications
for the Milky Way-LMC-SMC system. The implied three-dimensional velocities
are larger than previously believed, and are not much less than the escape
velocity in a standard 10^12 solar mass Milky Way dark halo. Orbit
calculations suggest the Clouds may not be bound to the Milky Way or may
just be on their first passage, both of which would be unexpected in view of
traditional interpretations of the Magellanic Stream. Alternatively, the
Milky Way dark halo may be a factor of two more massive than previously
believed, which would be surprising in view of other observational
constraints. Also, the relative velocity between the LMC and SMC is larger
than expected, leaving open the possibility that the Clouds may not be bound
to each other. To further verify and refine our results we now request an
epoch of WFPC2/PC data for the fields centered on 40 quasars that have at
least one epoch of ACS imaging. We request execution in snapshot mode, as in
our previous programs, to ensure the most efficient use of HST resources. A
third epoch of data of these fields will provide crucial information to
verify that there are no residual systematic effects in our previous
measurements. More importantly, it will increase the time baseline from 2 to
5 yrs and will increase the number of fields with at least two epochs of
data. This will reduce our uncertainties correspondingly, so that we can
better address whether the Clouds are indeed bound to each other and to the
Milky Way. It will also allow us to constrain the internal motions of
various populations within the Clouds, and will allow us to determine a
distance to the LMC using rotational parallax.
WFPC2 11231
Calibration of the WFPC2 HeII and [SII] Filters.
Observations of NGC 6720 (the Ring Nebula) will be used to determine the
calibration constants for the important emission-line filters that isolate
nebular HeII (F469N) and [SII] (F673N) emission. The pre-launch calibrations
are inadequate because of possible temporal changes and the fact that these
interference filters are used in a different configuration from that of the
ground calibration. The Ring Nebula is a nearly ideal reference source as
multiple 2.4"x4.0" samples have been accurately measured
spectro-photometrically and five of the six samples can be imaged with one
pointing of the HST. The method of derivation of the calibration constants
will be the same as previously employed to calibrate the primary
emission-line filters for the WFPC2 (F487N, F502N, F656N, F658N) and ACS
(F502N, F658N, F660N) using the Orion Nebula as a reference source. However,
Orion cannot be used for this calibration because the targeted lines are
weak ([SII]) or absent (HeII) and the scattered-light continuum is strong.
The Ring Nebula has strong HeII emission in its middle, strong [SII]
emission in its main ring, and a weak (atomic only) continuum.
WFPC2 11233
Multiple Generations of Stars in Massive Galactic Globular Clusters
This is a follow-up to recent HST imaging of NGC 2808, which discovered that
its main sequence is triple, with three well-separated parallel branches
{Fig.~1}. Along with the double MS of Omega Centauri, this challenges the
long-held paradigm that globular clusters are simple, single stellar
populations. The cause of this main sequence multiplicity in both clusters
is likely to be differences in helium abundance, which could play a
fundamental role in the understanding of stellar populations. We propose to
image seven more of the most massive globular clusters, to examine their
main sequences for indications of splitting.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of
potential non-nominal performance that will be investigated.)
HSTARS:
11268 - GSACQ(1,2,1) failed, scan step limit exceeded on FGS 1
GSACQ(1,2,1) at 114/18:16:55 failed due to scan step limit exceeded on FGS
1. No ESB messages were received, NICMOS 705 status buffer message (TDF down
when a target acquisition SAM request is made) was posted at 18:26:36.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 08 07
FGS REacq 06 06
OBAD with Maneuver 28 28
SIGNIFICANT EVENTS: (None)