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Daily Report #4385



 
 
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Old June 18th 07, 02:55 PM posted to sci.astro.hubble
Cooper, Joe
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Posts: 568
Default Daily Report #4385

Notice: For the foreseeable future, the daily reports may contain apparent
discrepancies between some proposal descriptions and the listed instrument
usage. This is due to the conversion of previously approved ACS WFC or HRC
observations into WFPC2, or NICMOS observations subsequent to the loss of
ACS CCD science capability in late January.


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4385

PERIOD COVERED: UT June 15,16,17, 2007 (DOY 166,167,168)

OBSERVATIONS SCHEDULED

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 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 images. Each observation will need its own CRMAP, as
different SAA passages leave different imprints on the NICMOS detectors.

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.

NIC3 11080

Exploring the Scaling Laws of Star Formation

As a variety of surveys of the local and distant Universe are approaching a
full census of galaxy populations, our attention needs to turn towards
understanding and quantifying the physical mechanisms that trigger and
regulate the large-scale star formation rates {SFRs} in galaxies.

FGS 10998

Exoplanet XO-1b: light curve and parallax

We propose to measure the radius of the recently-discovered transiting
extrasolar planet XO-1b. XO-1b's nominal radius is 1.30 times the radius of
Jupiter, which is nearly as large as HD 209458b {1.32 R_J}. We will use two
independent methods to measure XO-1b's radius: 1} precision light curve
analysis, and 2} measurement of its trigonometric parallax combined with its
spectroscopically-determined effective temperature and its apparent
magnitude.

NIC3 10908

Gotcha Using Swift GRBs to Pinpoint the Highest Redshift Galaxies

While there is convincing evidence that the Universe was reionized between
redshifts of 6.5 and 15, the role of galaxies in this process is still not
understood. Several star-forming galaxies at z~6 have been identified in
recent deep, narrow-field surveys, but the expensive observations along with
cosmic variance and contamination make it difficult to assess their
contribution to reionization, or to significantly increase the sample. It
has now been demonstrated that gamma-ray bursts {GRBs} exist at z6, and we
have already obtained HST and Spitzer observations of the host galaxy of
GRB050904 at z=6.295 using our Cycle 14 program. GRBs have the advantage of
being an uncontaminated signpost for star- formation, and their afterglows
are sufficiently bright even at z6 to allow photometric selection {via the
Ly-alpha drop out technique} with 2-5 meter telescopes. Spectroscopic
confirmation, including detailed information on the host ISM, is also likely
{as demonstrated in the case of GRB050904}. Using our approved TOO programs
at an extensive range of facilities {2-5 m telescopes up to
Keck/Magellan/Gemini}, we can rapidly find afterglows at z6 and easily
distinguish them from dusty low redshift bursts. This approach is highly
efficient compared to current techniques, especially at z7. Our large
allocation on Keck/Magellan/Gemini will also be used to obtain spectroscopy
of the afterglows and host galaxies. Here we request to continue our program
of imaging GRB-selected z6 galaxies with NICMOS {z6}, ACS {z~6}, and
Spitzer/IRAC to characterize their properties {SFR, age, morphology,
extinction}, and begin to address their role in reionization. These
observations are requested as 2 month TOOs, allowing flexibility of
scheduling and at the same time taking a unique and timely advantage of the
exquisite performance of three of NASA's premier missions.

WFPC2 10902

The Nearest Luminous Blue Compact Galaxies: A Window on Galaxy Formation

As we move to intermediate and high redshifts, Luminous Blue Compact
Galaxies {LBCGs} become increasingly common. The nearest LBCGs, with their
violent starbursts and rich populations of super star clusters {SSCs} and
globular clusters {GCs}, thus provide ideal laboratories for studying galaxy
evolution. Many LBCGs appear to be involved in mergers between dwarf
galaxies, triggering their starbursts. The starburst regions in LBCGs
consist of numerous young star clusters, whose populations are both easily
measurable with HST and easily modelled. Studying cluster populations
provides a powerful probe of the starburst and merger history which is
possible neither for closer objects {of which there are too few} or for
those at high redshift {which are too far away}. We have previously studied
the closest LBCG with WFPC2 and found hundreds of bright compact SSCs and
GCs. In particular, we found a population of intermediate-age {~2 Gyr} GCs,
indicating a past event of massive cluster formation. We now propose a
multi-wavelength study of the three other LBCGs with the highest known
number of SSCs. The extinction is small in these galaxies and age estimates
robust. The age distribution of GCs and SSCs will be used to study the past
evolution of the galaxies. For each LBCG, we will map its cluster formation
history, unveiling its merger and starburst history, and thereby shed light
on some of the processes involved in galaxy evolution at high redshift.

WFPC2 10890

Morphologies of the Most Extreme High-Redshift Mid-IR-Luminous Galaxies

The formative phase of the most massive galaxies may be extremely luminous,
characterized by intense star- and AGN-formation. Till now, few such
galaxies have been unambiguously identified at high redshift, restricting us
to the study of low-redshift ultraluminous infrared galaxies as possible
analogs. We have recently discovered a sample of objects which may indeed
represent this early phase in galaxy formation, and are undertaking an
extensive multiwavelength study of this population. These objects are bright
at mid-IR wavelengths {F[24um]0.8mJy}, but deep ground based imaging
suggests extremely faint {and in some cases extended} optical counterparts
{R~24-27}. Deep K-band images show barely resolved galaxies. Mid-infrared
spectroscopy with Spitzer/IRS reveals that they have redshifts z ~ 2-2.5,
suggesting bolometric luminosities ~10^{13-14}Lsun! We propose to obtain
deep ACS F814W and NIC2 F160W images of these sources and their environs in
order to determine kpc-scale morphologies and surface photometry for these
galaxies. The proposed observations will help us determine whether these
extreme objects are merging systems, massive obscured starbursts {with
obscuration on kpc scales!} or very reddened {locally obscured} AGN hosted
by intrinsically low-luminosity galaxies.

WFPC2 10870

The Ring Plane Crossings of Uranus in 2007

The rings of Uranus turn edge-on to Earth in May and August 2007. In
between, we will have a rare opportunity to see the unlit face of the rings.
With the nine optically thick rings essentialy invisible, we will observe
features and phenomena that are normally lost in their glare. We will use
this opportunity to search thoroughly for the embedded "shepherd" moons long
believed to confine the edges of the rings, setting a mass limit roughly 10
times smaller than that of the smallest shepherd currently known, Cordelia.
We will measure the vertical thicknesses of the rings and study the faint
dust belts only known to exist from a single Voyager image. We will also
study the colors of the newly-discovered faint, outer rings; recent evidence
suggests that one ring is red and the other blue, implying that each ring is
dominated by a different set of physical processes. We will employ near-
edge-on photometry from 2006 and 2007 to derive the particle filling factor
within the rings, to observe how ring epsilon responds to the "traffic jam"
as particles pass through its narrowest point, and to test the latest models
for preserving eccentricities and apse alignment within the rings. Moreover,
this data set will allow us to continue monitoring the motions of the inner
moons, which have been found to show possibly chaotic orbital variations; by
nearly doubling the time span of the existing ACS astrometry, the details of
the variations will become much clearer.

WFPC2 10841

A Proper Motion Search for Intermediate Mass Black Holes in Globular
Clusters {2nd Epoch Observations}

Establishing the presence or absence of intermediate-mass black holes {IMBH}
in globular clusters is crucial for understanding the evolution of dense
stellar systems. Observationally, this search has been hampered by the low
number of stars with known velocities in the central few arcseconds. This
limits our knowledge of the velocity dispersion in the region where the
gravitational influence of any IMBH would be felt. In Cycle 13, we
successfully obtained ACS/HRC images of the centers of five carefully chosen
Galactic globular clusters {GO-10401} for a new proper motion study.
Although the science case was approved and the first epoch images obtained,
the requested future cycle observations were not granted {due to a general
policy decision based on the strong uncertainties at the time concerning the
immediate future of HST}. We have now assessed the quality of the first
epoch observations. The HRC resolution reveals many isolated stars in to the
very center of each cluster that remained blended or unresolved in previous
WFPC2 data. Given a two year baseline, we are confident that we can achieve
the proper motion precision required to place strict limits on the presence
of an IMBH. Therefore, we request the second-epoch, follow-up observations
to GO-10401 in order to measure the proper motions of stars in our target
clusters. These velocity measurements will allow us to: {i} place
constraints on the mass of a central black hole in each cluster; {ii} derive
the internal velocity dispersion as a function of cluster radius; {iii}
verify or reject previous reports of cluster rotation; and {iv} directly
measure velocity anisotropy as a function of radius. If no second epoch data
are obtained then the observing time already invested in the first epoch
will have been wasted.

WFPC2 10829

Secular Evolution at the End of the Hubble Sequence

The bulgeless disk galaxies at the end of the Hubble Sequence evolve at a
glacial pace relative to their more violent, earlier-type cousins. The
causes of their internal, or secular evolution are important because secular
evolution represents the future fate of all galaxies in our accelerating
Universe and is a key ingredient to understanding galaxy evolution in
lower-density environments at present. The rate of secular evolution is
largely determined by the stability of the cold ISM against collapse, star
formation, and the buildup of a central bulge. Key diagnostics of the ISM's
stability are the presence of compact molecular clouds and narrow dust
lanes. Surprisingly, edge-on, pure disk galaxies with circular velocities
below 120 km/s do not appear to contain such dust lanes. We propose to
obtain ACS/WFC F606W images of a well-selected sample of extremely late-type
disk galaxies to measure the characteristic scale size of the cold ISM and
determine if they possess the unstable, cold ISM necessary to drive secular
evolution. Our sample has been carefully constructed to include disk
galaxies above and below the critical circular velocity of 120 km/s where
the dust properties of edge-on disks change so remarkably. We will then use
surface brightness profiles to search for nuclear star clusters and
pseudobulges, which are early indicators that secular evolution is at work,
as well as measure the pitch angle of the dust lanes as a function of radius
to estimate the central mass concentrations.

WFPC2 10818

Very Young Globular Clusters in M31 ?

We propose to use HST's unique high spatial resolution imaging capabilities
to conclusively confirm or refute the presence of alleged very young
globular clusters in M31. Such young globular clusters with ages 3 Gyr are
not present in our galaxy, and, if real, would lead to a striking difference
in the age distribution of the GCs between M31 and the Millky Way. If the
apparent presence of very young globular clusters in M31 is confirmed
through our proposed ACS imaging {now WFPC2 imaging} with HST, this would
suggest major differences in the history of assembly of the two galaxies,
with probable substantial late accretion into M31 which did not occur in our
own galaxy.

NIC2 10802

SHOES-Supernovae, HO, for the Equation of State of Dark energy

The present uncertainty in the value of the Hubble constant {resulting in an
uncertainty in Omega_M} and the paucity of Type Ia supernovae at redshifts
exceeding 1 are now the leading obstacles to determining the nature of dark
energy. We propose a single, integrated set of observations for Cycle 15
that will provide a 40% improvement in constraints on dark energy. This
program will observe known Cepheids in six reliable hosts of Type Ia
supernovae with NICMOS, reducing the uncertainty in H_0 by a factor of two
because of the smaller dispersion along the instability strip, the
diminished extinction, and the weaker metallicity dependence in the
infrared. In parallel with ACS, at the same time the NICMOS observations are
underway, we will discover and follow a sample of Type Ia supernovae at z
1. Together, these measurements, along with prior constraints from WMAP,
will provide a great improvement in HST's ability to distinguish between a
static, cosmological constant and dynamical dark energy. The Hubble Space
Telescope is the only instrument in the world that can make these IR
measurements of Cepheids beyond the Local Group, and it is the only
telescope in the world that can be used to find and follow supernovae at z
1. Our program exploits both of these unique capabilities of HST to learn
more about one of the greatest mysteries in science.

WFPC2 10800

Kuiper Belt Binaries: Probes of Early Solar System Evolution

Binaries in the Kuiper Belt are a scientific windfall: in them we have
relatively fragile test particles which can be used as tracers of the early
dynamical evolution of the outer Solar System. We propose to continue a
Snapshot program using the ACS/HRC that has a demonstrated discovery
potential an order of magnitude higher than the HST observations that have
already discovered the majority of known transneptunian binaries. With this
continuation we seek to reach the original goals of this project: to
accumulate a sufficiently large sample in each of the distinct populations
collected in the Kuiper Belt to be able to measure, with statistical
significance, how the fraction of binaries varies as a function of their
particular dynamical paths into the Kuiper Belt. Today's Kuiper Belt bears
the imprints of the final stages of giant-planet building and migration;
binaries may offer some of the best preserved evidence of that long-ago era.

NIC3 10792

Quasars at Redshift z=6 and Early Star Formation History

We propose to observe four high-redshift quasars {z=6} in the NIR in order
to estimate relative Fe/Mg abundances and the central black hole mass. The
results of this study will critically constrain models of joint quasar and
galaxy formation, early star formation, and the growth of supermassive black
holes. Different time scales and yields for alpha-elements {like O or Mg}
and for iron result into an iron enrichment delay of ~0.3 to 0.6 Gyr. Hence,
despite the well-known complexity of the FeII emission line spectrum, the
ratio iron/alpha - element is a potentially useful cosmological clock. The
central black hole mass will be estimated based on a recently revised back
hole mass - luminosity relationship. The time delay of the iron enrichment
and the time required to form a supermassive black hole {logM8 Msol, tau
~0.5Gyr} as evidenced by quasar activity will be used to date the beginning
of the first intense star formation, marking the formation of the first
massive galaxies that host luminous quasars, and to constrain the epoch when
supermassive black holes start to grow by accretion.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10863 - GSAcq(1,2,1) failed due to Scan Step Limit Exceeded

At AOS 166/18:48:35 GSAcq (1,2,1) scheduled from 166/18:03:57-18:11:18
failed to RGA Hold (Gyro Control) due to Scan Step Limit Exceeded on FGS 1.
OBAD #1: V1 527.16, V2 -696.45, V3 25.60, RSS 873.84
OBAD #2: unavailable due to LOS
OBAD MAP: V1 1.15, V2 7.36, V3 0.79, RSS 7.49

10864 - GSacq(1,3,1) not attempted, open loop timer expired

GSacq(1,3,1) at 167/12:31:55 was not attempted due to open loop timer
expiration.

OBAD prior to GSAcq showed RSS error of 12.24 arcseconds, OBAD map after
GSACQ showed RSS error of 2226.42 arcseconds.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 20 18
FGS REacq 20 20
OBAD with Maneuver 80 80

SIGNIFICANT EVENTS: (None)
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