A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Astronomy and Astrophysics » Hubble
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

Daily Report #4497



 
 
Thread Tools Display Modes
  #1  
Old November 30th 07, 03:52 PM posted to sci.astro.hubble
Cooper, Joe
external usenet poster
 
Posts: 568
Default Daily Report #4497

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****** # 4497

PERIOD COVERED: UT November 29 , 2007 (DOY 333)

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 11211

An Astrometric Calibration of Population II Distance Indicators

In 2002 HST produced a highly precise parallax for RR Lyrae. That
measurement resulted in an absolute magnitude, M{V}= 0.61+/-0.11, a
useful result, judged by the over ten refereed citations each year
since. It is, however, unsatisfactory to have the direct,
parallax-based, distance scale of Population II variables based on a
single star. We propose, therefore, to obtain the parallaxes of four
additional RR Lyrae stars and two Population II Cepheids, or W Vir
stars. The Population II Cepheids lie with the RR Lyrae stars on a
common K-band Period-Luminosity relation. Using these parallaxes to
inform that relationship, we anticipate a zero-point error of 0.04
magnitude. This result should greatly strengthen confidence in the
Population II distance scale and increase our understanding of RR
Lyrae star and Pop II Cepheid astrophysics.

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 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 11289

SL2S: The Strong Lensing Legacy Survey

Recent systematic surveys of strong galaxy-galaxy lenses {CLASS,
SLACS, GOODS, etc.} are producing spectacular results for galaxy
masses roughly below a transition mass M~10^13 Mo. The observed lens
properties and their evolution up to z~0.2, consistent with numerical
simulations, can be described by isothermal elliptical potentials. In
contrast, modeling of giant arcs in X-ray luminous clusters {halo
masses M ~10^13 Mo} favors NFW mass profiles, suggesting that dark
matter halos are not significantly affected by baryon cooling. Until
recently, lensing surveys were neither deep nor extended enough to
probe the intermediate mass density regime, which is fundamental for
understanding the assembly of structures. The CFHT Legacy Survey now
covers 125 square degrees, and thus offers a large reservoir of strong
lenses probing a large range of mass densities up to z~1. We have
extracted a list of 150 strong lenses using the most recent CFHTLS
data release via automated procedures. Following our first SNAPSHOT
proposal in cycle 15, we propose to continue the Hubble follow-up
targeting a larger list of 130 lensing candidates. These are
intermediate mass range candidates {between galaxies and clusters}
that are selected in the redshift range of 0.2-1 with no a priori
X-ray selection. The HST resolution is necessary for confirming the
lensing candidates, accurate modeling of the lenses, and probing the
total mass concentration in galaxy groups up to z~1 with the largest
unbiased sample available to date.

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************** 06****************** 06
FGS REacq************** 05****************** 05
OBAD with Maneuver **** 22****************** 22

SIGNIFICANT EVENTS: (None)


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Daily Report # 4338 Cooper, Joe Hubble 0 April 11th 07 04:13 PM
Daily Report # 4337 Cooper, Joe Hubble 0 April 10th 07 05:39 PM
Daily Report # 4336 Cooper, Joe Hubble 0 April 9th 07 04:16 PM
Daily Report [email protected] Hubble 0 October 29th 04 04:59 PM
HST Daily Report 131 George Barbehenn Hubble 0 May 11th 04 02:48 PM


All times are GMT +1. The time now is 12:20 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.