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Daily Rpt #4478



 
 
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Old October 30th 07, 04:04 PM posted to sci.astro.hubble
Bassford, Lynn
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Posts: 44
Default Daily Rpt #4478

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

DAILY REPORT*** # 4478

PERIOD COVERED: UT October 29, 2007 (DOY 302)

OBSERVATIONS SCHEDULED

ACS/SBC 10907

New Sightlines for the Study of Intergalactic Helium: A Dozen
High-Confidence, UV-Bright Quasars from SDSS/GALEX

The reionization of intergalactic helium is thought to have occurred
between redshifts of about 3 and 4. Detailed study of HeII Lyman-alpha
absorption toward a handful quasars at 2.7z3.3 demonstrates the
great potential of such probes of the IGM, but the current
critically-small sample limits confidence in resulting cosmological
inferences. The requisite unobscured quasar sightlines to
high-redshift are extremely rare, especially due to severe absorption
in random intervening Lyman-limit systems, but SDSS provides thousands
of z3.1 quasars potentially suitable for HeII studies. We have
cross-correlated SDSS quasars with GALEX UV sources to obtain a dozen
new, very high-confidence, candidate quasars/sightlines {z=3.1 to 4.1}
potentially useful for detailed HeII studies even with current HST
instruments. We propose brief, 2-orbit per target, reconnaissance
spectral exposures with the ACS SBC prism to definitively verify UV
flux down to the HeII break. Our combined SDSS/GALEX selection insures
a very high-yield of confirmations, as the quasars are already known
to be UV-bright from broadband GALEX images. The additional
sightlines, extending to very high-redshift, will directly enable
ensemble spectral stacks, as well as long exposure follow-up spectra,
at high S/N with the ACS/SBC ultraviolet prisms {or perhaps STIS or
COS later}, to confidently measure the spectrum and evolution of the
ionizing background radiation, the evolution of HeII opacity, and the
density of intergalactic baryons.

FGS 11213

Distances to Eclipsing M Dwarf Binaries

We propose HST FGS observations to measure accurate distances of 5
nearby M dwarf eclipsing binary systems, from which model-independent
luminosities can be calculated. These objects have either poor or no
existing parallax measurements. FGS parallax determinations for these
systems, with their existing dynamic masses determined to better than
0.5%, would serve as model-independent anchor points for the low-mass
end of the mass-luminosity diagram.

NIC1/NIC2/NIC3 11330

NICMOS Cycle 16 Extended Dark

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

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.

WFPC2 11079

Treasury Imaging of Star Forming Regions in the Local Group:
Complementing the GALEX and NOAO Surveys

We propose to use WFPC2 to image the most interesting star-forming
regions in the Local Group galaxies, to resolve their young stellar
populations. We will use a set of filters including F170W, which is
critical to detect and characterize the most massive stars, to whose
hot temperatures colors at longer wavelengths are not sensitive.
WFPC2's field of view ideally matches the typical size of the
star-forming regions, and its spatial resolution allows us to measure
individual stars, given the proximity of these galaxies. The resulting
H-R diagrams will enable studies of star-formation properties in these
regions, which cover largely differing metallicities {a factor of 17,
compared to the factor of 4 explored so far} and characteristics. The
results will further our understanding of the star-formation process,
of the interplay between massive stars and environment, the properties
of dust, and will provide the key to interpret integrated measurements
of star-formation indicators {UV, IR, Halpha} available for several
hundreds more distant galaxies. Our recent deep surveys of these
galaxies with GALEX {FUV, NUV} and ground-based imaging {UBVRI,
Halpha, [OIII] and [SII]} provided the identification of the most
relevant SF sites. In addition to our scientific analysis, we will
provide catalogs of HST photometry in 6 bands, matched corollary
ground-based data, and UV, Halpha and IR integrated measurements of
the associations, for comparison of integrated star-formation indices
to the resolved populations. We envisage an EPO component.

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.

WFPC2 11119

The Stellar Origins of Supernovae

Supernovae {SNe} have a profound effect on galaxies, and have been
used recently as precise cosmological probes, resulting in the
discovery of the accelerating Universe. They are clearly very
important events deserving of intense study. Yet, even with nearly
4000 known SNe, we know relatively little about the stars which give
rise to these powerful explosions. The main limitation has been the
lack of spatial resolution in pre-SN imaging data. However, since 1999
our team has been at the vanguard of directly identifying SN
progenitor stars in HST images. From this exciting new line of study,
the emerging trend from 5 detections for Type II-Plateau SNe is that
their progenitors appear to be relatively low mass {8 to 20 Msun} red
supergiants, although more cases are needed. Nonetheless, the nature
of the progenitors of Type Ib/c SNe, a subset of which are associated
with the amazing gamma-ray bursts, remains ambiguous. Furthermore, we
remain in the continually embarrassing situation that we still do not
yet know which progenitor systems explode as Type Ia SNe, which are
currently being used for precision cosmology. We propose to confirm
the identities of the progenitors of 4 SNe within 17 Mpc, which we
expect to occur during Cycle 16, through ToO observations using
WFPC2/PC.

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********************** 8************** 8
FGS REacq********************** 5************** 5
OBAD with Maneuver****** 24************* 24

SIGNIFICANT EVENTS: (None)


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