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Daily Rpt #4452

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Old September 21st 07, 08:18 PM posted to sci.astro.hubble
Bassford, Lynn
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Posts: 44
Default Daily Rpt #4452

Notice: Due to the conversion of some ACS WFC or HRC observations into
WFPC2, or NICMOS observations after the loss of ACS CCD science capability
in January, there may be an occasional discrepancy between a proposal's
listed (and correct) instrument usage and the abstract that follows it.

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science


PERIOD COVERED: UT September 20, 2007 (DOY 263)


ACS/SBC 10840

The FUV fluxes of Tauri stars in the Taurus molecular cloud

Present and forthcoming ground-based and space surveys of the T Tauri stars
in the Taurus molecular cloud will provide information from high energy
stellar and accretion radiation to low energy solid state and molecular
emission from the disk, making those stars perfect laboratories to carry out
self-consistent studies of disk physics and evolution. We propose to
complete this wealth of information by obtaining ACS/FUV spectra for a
significant sample of Taurus T Tauri stars, covering a range of accretion
properties and dust evolutionary stages. FUV fluxes carry ~ 10 - 100 more
energy than X-rays into these disks and are thus crucial gas heating agents
and key to disk dispersal by photoevaporation. These observations are a
pre-requisite to interpret observations with Spitzer, SOFIA, Herschel, and
ALMA, and will become one of the important legacies of HST to the star
formation community.

ACS/SBC 10872

Lyman Continuum Emission in Galaxies at z=1.2

Lyman continuum photons produced in massive starbursts may have played a
dominant role in the reionization of the Universe. Starbursts are important
contributors to the ionizing metagalactic background at lower redshifts as
well. However, their contribution to the background depends upon the
fraction of ionizing radiation that escapes from the intrinsic opacity of
galaxies below the Lyman limit. Current surveys suggest escape fractions of
a few percent, up to 10%, with very few detections {as opposed to upper
limits} having been reported. No detections have been reported in the epochs
between z=0.1 and z=2. We propose to measure the fraction of escaping Lyman
continuum radiation from 15 luminous z~1.2 galaxies in the GOODS fields.
Using the tremendous sensitivity of the ACS Solar- blind Channel, we will
reach AB=30 mag., allowing us to detect an escape fraction of 1%. We will
correlate the amount of escaping radiation with the photometric and
morphological properties of the galaxies. A non-detection in all sources
would imply that QSOs provide the overwhelming majority of ionizing
radiation at z=1.3, and it would strongly indicate that the properties of
galaxies at higher redshift have to be significantly different for galaxies
to dominate reionization. The deep FUV images will also be useful for
extending the FUV study of other galaxies in the GOODS fields.

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration - CR Persistence Part 5

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 DARKs. 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 11016

NICMOS Flats: narrow and broad filters for NIC1 {+ NIC2, NIC3 in

This proposal obtains sequences of NICMOS narrow band filter flat fields for
camera 1. In cameras 2 and 3, parallel observations will allow us to obtain
high S/N flats for all spectral elements.

NIC3 11064


Now that the spectrophotometric capabilities of the NICMOS grism have been
established, cycle 15 observations are needed to refine the sensitivity
estimates, to check for sensitivity loss with time, to improve the accuracy
of the linearity correction, to improve the secondary flux standards by
re-observation, and to expand the G206 data set now that the sky subtraction
technique has been shown to produce useful fluxes for some of the fainter
secondary standards. These faint secondary IR standards will be a
significant step towards establishing flux standards for JWST, as well as
for SNAP, Spitzer, and SOFIA. 1.Re- observe the 3 primary WDs GD71, G191B2b,
& GD153 twice each, once at the beginning and once near the end of the 18
month cycle. To date, we have only 2 observation of each star, while the
corresponding STIS data set for these primary standards ranges from 6 to 23
obs. No observations exist for GD71 or GD153 with G206, so that the current
G206 sensitivity is defined solely by G191B2B. Purposes: Refine
sensitivities, measure sens losses. Orbits: 2 for each of 6 visits = 12 2.
Re-observe WD1057 & WD1657 plus another P041C lamp-on visit to improve the
scatter in the non-lin measurements per Fig. 8 of NIC ISR 2006-02. The WD
stars require 2 orbits each, while the lamp-on test is done in one. The very
faintest and most crucial standard WD1657 has 2 good visits already, so to
substantially improve the S/N, two visits of two orbits are needed. Include
G206 for P041C in the lamp-off baseline part of that orbit. Orbits:
WD1057-2, WD1657-4, P041C-1 -- 7 3. Re-observe 9 secondary standards to
improve S/N of the faint ones and to include G206 for all 9. BD+17 {3 obs}
is not repeated in this cycle. Four are bright enough to do in one orbit:
VB8, 2M0036+18, P330E, and P177D. Orbits:2*5+4=14 Grand Total orbits over 18
month cycle 15 is 12+6+14=32 {Roelof will submit the P041C lamp-on visit in
a separate program.}

WFPC2 10915

ACS Nearby Galaxy Survey

Existing HST observations of nearby galaxies comprise a sparse and highly
non-uniform archive, making comprehensive comparative studies among galaxies
essentially impossible. We propose to secure HST's lasting impact on the
study of nearby galaxies by undertaking a systematic, complete, and
carefully crafted imaging survey of ALL galaxies in the Local Universe
outside the Local Group. The resulting images will allow unprecedented
measurements of: {1} the star formation history {SFH} of a 100 Mpc^3 volume
of the Universe with a time resolution of Delta[log{t}]=0.25; {2}
correlations between spatially resolved SFHs and environment; {3} the
structure and properties of thick disks and stellar halos; and {4} the color
distributions, sizes, and specific frequencies of globular and disk clusters
as a function of galaxy mass and environment. To reach these goals, we will
use a combination of wide-field tiling and pointed deep imaging to obtain
uniform data on all 72 galaxies within a volume-limited sample extending to
~3.5 Mpc, with an extension to the M81 group. For each galaxy, the
wide-field imaging will cover out to ~1.5 times the optical radius and will
reach photometric depths of at least 2 magnitudes below the tip of the red
giant branch throughout the limits of the survey volume. One additional deep
pointing per galaxy will reach SNR~10 for red clump stars, sufficient to
recover the ancient SFH from the color-magnitude diagram. This proposal will
produce photometric information for ~100 million stars {comparable to the
number in the SDSS survey} and uniform multi- color images of half a square
degree of sky. The resulting archive will establish the fundamental optical
database for nearby galaxies, in preparation for the shift of high-
resolution imaging to the near-infrared.

WFPC2 11084

Probing the Least Luminous Galaxies in the Local Universe

We propose to obtain deep color-magnitude data of eight new Local Group
galaxies which we recently discovered: Andromeda XI, Andromeda XII, and
Andromeda XIII {satellites of M31}; Canes Venatici I, Canes Venatici II,
Hercules, and Leo IV {satellites of the Milky Way}; and Leo T, a new
"free-floating" Local Group dwarf spheroidal with evidence for recent star
formation and associated H I gas. These represent the least luminous
galaxies known at *any* redshift, and are the only accessible laboratories
for studying this extreme regime of galaxy formation. With deep WFPC-2 F606W
and F814W pointings at their centers, we will determine whether these
objects contain single or multiple age stellar populations, as well as
whether these objects display a range of metallicities.


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

HSTARS: (None)




FGS GSacq 04 04
FGS REacq 06 06
OBAD with Maneuver 20 20



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