HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT    # 4620

PERIOD COVERED: 5am May 28 - 5am May 29, 2008 (DOY 149/0900z-150/0900z)

OBSERVATIONS SCHEDULED

FGS 11212

Filling the Period Gap for Massive Binaries

The current census of binaries among the massive O-type stars is
seriously incomplete for systems in the period range from years to
millennia because the radial velocity variations are too small and the
angular separations too close for easy detection. Here we propose to
discover binaries in this observational gap through a Faint Guidance
Sensor SNAP survey of relatively bright targets listed in the Galactic O
Star Catalog. Our primary goal is to determine the binary frequency
among those in the cluster/association, field, and runaway groups. The
results will help us assess the role of binaries in massive star
formation and in the processes that lead to the ejection of massive
stars from their natal clusters. The program will also lead to the
identification of new, close binaries that will be targets of long term
spectroscopic and high angular resolution observations to determine
their masses and distances. The results will also be important for the
interpretation of the spectra of suspected and newly identified binary
and multiple systems.

NIC1/NIC2 11155

Dust Grain Evolution in Herbig Ae Stars: NICMOS Coronagraphic Imaging
and Polarimetry

We propose to take advantage of the sensitive coronagraphic capabilities
of NICMOS to obtain multiwavelength coronagraphic imaging and
polarimetry of primordial dust disks around young intermediate-mass
stars {Herbig Ae stars}, in order to advance our understanding of how
dust grains are assembled into larger bodies. Because the polarization
of scattered light is strongly dependent on scattering particle size and
composition, coronagraphic imaging polarimetry with NICMOS provides a
uniquely powerful tool for measuring grain properties in spatially
resolved circumstellar disks. It is widely believed that planets form
via the gradual accretion of planetesimals in gas-rich, dusty
circumstellar disks, but the connection between this suspected process
and the circumstellar disks that we can now observe around other stars
remains very uncertain. Our proposed observations, together with
powerful 3-D radiative transfer codes, will enable us to quantitatively
determine dust grain properties as a function of location within disks,
and thus to test whether dust grains around young stars are in fact
growing in size during the putative planet-formation epoch. HST imaging
polarimetry of Herbig Ae stars will complement and extend existing
polarimetric studies of disks around lower-mass T Tauri stars and debris
disks around older main-sequence stars. When combined with these
previous studies, the proposed research will help us establish the
influence of stellar mass on the growth of dust grains into larger
planetesimals, and ultimately to planets. Our results will also let us
calibrate models of the thermal emission from these disks, a critical
need for validating the properties of more distant disks inferred on the
basis of spectral information alone.

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.

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.

NIC3 11333

NICMOS non-linearity tests

This program incorporates a number of tests to analyze the count rate
dependent non-linearity seen in NICMOS spectro-photometric observations.

We will observe a field with stars of a range in luminosity in NGC3603
with NICMOS in NIC1: F090M, F110W, F140W, F160W NIC2: F110W, F160W,
F187W, F205W, and F222M NIC3: F110W, F150W, F160W, F175W, and F222M. We
will repeat the observations with flatfield lamp on, creating
artificially high count-rates, allowing tests of NICMOS linearity as
function of count rate. We first take exposures with the lamp off, then
exposures with the lamp on, and repeat at the end with lamp off.
Finally, we continue with taking darks during occultation.

We will furthermore observe spectro-photometric standard P041C using the
G096, G141, and G206 grisms in NIC3, and repeat the lamp off/on/off test
to artificially create a high background.

WFPC2 11103

A Snapshot Survey of The Most Massive Clusters of Galaxies

We propose the continuation of our highly successful SNAPshot survey of
a sample of 125 very X-ray luminous clusters in the redshift range
0.3-0.7. As demonstrated by the 25 snapshots obtained so far in Cycle14
and Cycle15 these systems frequently exhibit strong gravitational
lensing as well as spectacular examples of violent galaxy interactions.
The proposed observations will provide important constraints on the
cluster mass distributions, the physical nature of galaxy-galaxy and
galaxy-gas interactions in cluster cores, and a set of optically bright,
lensed galaxies for further 8-10m spectroscopy. All of our primary
science goals require only the detection and characterization of
high-surface-brightness features and are thus achievable even at the
reduced sensitivity of WFPC2. Because of their high redshift and thus
compact angular scale our target clusters are less adversely affected by
the smaller field of view of WFPC2 than more nearby systems.
Acknowledging the broad community interest in this sample we waive our
data rights for these observations. Due to a clerical error at STScI our
approved Cycle15 SNAP program was barred from execution for 3 months and
only 6 observations have been performed to date - reinstating this SNAP
at Cycle16 priority is of paramount importance to reach meaningful
statistics.

WFPC2 11227

The orbital period for an ultraluminous X-ray source in NGC1313

The ultraluminous X-ray sources {ULXs} are extragalactic point sources
with luminosities that exceed the Eddington luminosity for conventional
stellar-mass black holes by factors of 10 - 100. It has been hotly
debated whether the ULXs are just common stellar-mass black hole sources
with beamed emission or whether they are sub-Eddington sources that are
powered by the long-sought intermediate mass black holes {IMBH}. To
firmly decide this question, one must obtain dynamical mass measurements
through photometric and spectroscopic monitoring of the secondaries of
these system. The crucial first step is to establish the orbital period
of a ULX, and arguably the best way to achieve this goal is by
monitoring its ellipsoidal light curve. The extreme ULX NGC1313 X-2
provides an outstanding target for an orbital period determination
because its relatively bright optical counterpart {V = 23.5} showed a
15% variation between two HST observations separated by three months.
This level of variability is consistent with that expected for a tidally
distorted secondary star. Here we propose a set of 20 imaging
observations with HST/WFPC2 to define the orbital period. This would be
the first photometric measurement of the orbital period of a ULX binary.
Subsequently, we will propose to obtain spectroscopic observations to
obtain its radial velocity amplitude and thereby a dynamical estimate of
its mass.

WFPC2 11235

HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies
in the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared
selected galaxies exceeds that of optically selected galaxies. These
`luminous infrared galaxies' {LIRGs} are primarily interacting or
merging disk galaxies undergoing enhanced star formation and Active
Galactic Nuclei {AGN} activity, possibly triggered as the objects
transform into massive S0 and elliptical merger remnants. We propose
NICMOS NIC2 imaging of the nuclear regions of a complete sample of 88
L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised
Bright Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}.
This sample is ideal not only in its completeness and sample size, but
also in the proximity and brightness of the galaxies. The superb
sensitivity and resolution of NICMOS NIC2 on HST enables a unique
opportunity to study the detailed structure of the nuclear regions,
where dust obscuration may mask star clusters, AGN and additional nuclei
from optical view, with a resolution significantly higher than possible
with Spitzer IRAC. This survey thus provides a crucial component to our
study of the dynamics and evolution of IR galaxies presently underway
with Wide-Field, HST ACS/WFC and Spitzer IRAC observations of these 88
galaxies. Imaging will be done with the F160W filter {H-band} to examine
as a function of both luminosity and merger stage {i} the luminosity and
distribution of embedded star clusters, {ii} the presence of optically
obscured AGN and nuclei, {iii} the correlation between the distribution
of 1.6 micron emission and the mid- IR emission as detected by Spitzer
IRAC, {iv} the evidence of bars or bridges that may funnel fuel into the
nuclear region, and {v} the ages of star clusters for which photometry
is available via ACS/WFC observations. The NICMOS data, combined with
the HST ACS, Spitzer, and GALEX observations of this sample, will result
in the most comprehensive study of merging and interacting galaxies to
date.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports
of potential non-nominal performance that will be investigated.)

HSTARS:
11323 - GSaqc(2,1,2) failed to RGA control
           GSacq(2,1,2) scheduled at 149/1913:45 failed to RGA control at 19:17:11.
           There were no error flags. ESB message "a07" FGS Coarse Track failed
           -Timed out waiting for data valid. OBAD1 showed errors of V1=963.29,
           V2=1802.49, V3=-2686.73 and RSS=3375.71. ODAB2 showed errors of
           V1=-3.07, V2=-1.47, V3=19.89 and RSS=20.18. The Map at 19:21:00 showed
           errors of V1=-35.89, V2=-29.99, V3=-6.43 and RSS=47.21.

COMPLETED OPS REQUEST:
18237-0 - Execute ROP NS-11 Reset NICMOS Error Counter @ 149/22:06z

COMPLETED OPS NOTES: (None)

                      SCHEDULED      SUCCESSFUL
FGS GSacq               11                 10  
FGS REacq               02                 02                      
OBAD with Maneuver 26                 26                                 

SIGNIFICANT EVENTS: (None)