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Daily Rpt #4619



 
 
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Old May 28th 08, 02:38 PM posted to sci.astro.hubble
Bassford, Lynn[_2_]
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Default Daily Rpt #4619

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT*** # 4619

PERIOD COVERED: 5am May 27 - 5am May 28, 2008 (DOY
148/0900z-149/0900z)

OBSERVATIONS SCHEDULED

ACS/SBC 11225

The Wavelength Dependence of Accretion Disk Structure

We can now routinely measure the size of quasar accretion disks using
gravitational microlensing of lensed quasars. The next step to testing
accretion disk models is to measure the size of accretion disks as a
function of wavelength, particularly at the UV and X-ray wavelengths
that should probe the inner, strong gravity regime. Here we focus on
two four-image quasar lenses that already have optical {R band} and
X-ray size measurements using microlensing. We will combine the HST
observations with ground-based monitoring to measure the disk size as
a function of wavelength from the near-IR to the UV. We require HST to
measure the image flux ratios in the ultraviolet continuum near the
Lyman limit of the quasars. The selected targets have estimated black
hole masses that differ by an order of magnitude, and we should find
wavelength scalings for the two systems that are very different
because the Blue/UV wavelengths should correspond to parts of the disk
near the inner edge for the high mass system but not in the low mass
system. The results will be modeled using a combination of simple thin
disk models and complete relativistic disk models. While requiring
only 18 orbits, success for one system requires observations in both
Cycles 16 and 17.

NIC1/NIC2/NIC3 11330

NICMOS Cycle 16 Extended Dark

This takes a series of Darks in parallel to other instruments.

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.

NIC2 11164

Molecular Hydrogen Disks Around T Tauri Stars

We propose to measure the properties of planetary system-sized disks
around Sun- like, pre-main sequence stars by imaging the inner parts
of these disks for the first time in gaseous emission from their most
dominant constituent, molecular hydrogen gas. Specifically, we will
use the F212N filter and NICMOS to determine the spatial distribution
of ro-vibrational H2 emission from protoplanetary disks around
selected classical and weak-lined T Tauri stars. The target stars are
among those detected by members of this team through high resolution,
ground-based infrared spectroscopy. The spectra reveal H2 emission at
the rest velocities of the stars and at positions spatially coincident
with the stars at the spatial resolution of the spectroscopic data.
This imaging experiment, which is impossible to do using ground- based
facilities, is possible using the NICMOS camera aboard the HST because
the point spread function of this system is extremely stable and can
be measured to a very high accuracy. This experiment is an important
test of the interpretation that the 2.122 micron H2 line emission seen
toward T Tauri stars is produced at distances of 10 to 30 AU from the
stars, the region in which giant planets are expected to form around
these stars. These observations will contribute toward developing a
better understanding of the process, likelihood, and timescale for the
formation of planets around Sun-like stars.

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.

WEPC2 11196

An Ultraviolet Survey 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 starbursts and creating/fueling
central AGN. We propose far {ACS/SBC/F140LP} and near {WFPC2/PC/F218W}
UV imaging of a sample of 27 galaxies drawn from the complete IRAS
Revised Bright Galaxy Sample {RBGS} LIRGs sample and known, from our
Cycle 14 B and I-band ACS imaging observations, to have significant
numbers of bright {23 B 21 mag} star clusters in the central 30
arcsec. The HST UV data will be combined with previously obtained HST,
Spitzer, and GALEX images to {i} calculate the ages of the clusters as
function of merger stage, {ii} measure the amount of UV light in
massive star clusters relative to diffuse regions of star formation,
{iii} assess the feasibility of using the UV slope to predict the
far-IR luminosity {and thus the star formation rate} both among and
within IR-luminous galaxies, and {iv} provide a much needed catalog of
rest- frame UV morphologies for comparison with rest-frame UV images
of high-z LIRGs and Lyman Break Galaxies. These observations will
achieve the resolution required to perform both detailed photometry of
compact structures and spatial correlations between UV and redder
wavelengths for a physical interpretation our IRX-Beta results. The
HST UV data, combined with the HST ACS, Spitzer, Chandra, and GALEX
observations of this sample, will result in the most comprehensive
study of luminous starburst galaxies to date.

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.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

#11319* Battery Temperature Out of Limits @ 147/18:20:37z

COMPLETED OPS REQUEST:

#18235-0* Off-Line +BB SPA Trim Relay @ 148/19:57z

COMPLETED OPS NOTES: (None)

************************ SCHEDULED***** SUCCESSFUL
FGS GSacq****************** 07************* 07
FGS REacq****************** 03************* 03
OBAD with Maneuver*** 18************* 18

SIGNIFICANT EVENTS:

Battery temperatures continue to cool following yesterday's action to
off-line the battery 3 +BB SPA. The peak module 1 (batteries 1-3)
temperature is now +2degC, down from its peak of +6.1degC yesterday.
The peak module 2 battery temperature remains at approximately -2degC.
Total system state of charge is 325 Ah (pressure based), down slightly
from its peak of 330 Ah. Sun-time duration is presently 63.5 minutes,
down from the DOY 142 peak of 67.6 minutes.


 




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