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Daily Report #5015



 
 
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Old January 20th 10, 05:54 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #5015

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5015

PERIOD COVERED: 5am January 19 - 5am January 20, 2010 (DOY 019/10:00z-
020/10:00z)

OBSERVATIONS SCHEDULED

S/C 12046

COS FUV DCE Memory Dump

Whenever the FUV detector high voltage is on, count rate and current
draw information is collected, monitored, and saved to DCE memory.
Every 10 msec the detector samples the currents from the HV power
supplies (HVIA, HVIB) and the AUX power supply (AUXI). The last 1000
samples are saved in memory, along with a histogram of the number of
occurrences of each current value.

In the case of a HV transient (known as a "crackle" on FUSE), where
one of these currents exceeds a preset threshold for a persistence
time, the HV will shut down, and the DCE memory will be dumped and
examined as part of the recovery procedure. However, if the current
exceeds the threshold for less than the persistence time (a
"mini-crackle" in FUSE parlance), there is no way to know without
dumping DCE memory. By dumping and examining the histograms regularly,
we will be able to monitor any changes in the rate of "mini-crackles"
and thus learn something about the state of the detector.

STIS/CCD 11606

Dynamical Hypermassive Black Hole Masses

We will use STIS spectra to derive the masses of 5 hypermassive black
holes (HMBHs). From the observed scaling relations defined by less
massive spheroids, these objects are expected to reside at the nuclei
of host galaxies with stellar velocity dispersions greater than 320
km/s. These 5 targets have confirmed regular gas distributions on the
scales of the black hole sphere of influence. It is essential that the
sphere of influence is resolved for accurate determinations of black
hole mass (0.1"). These scales cannot be effectively observed from the
ground. Only two HMBHs have had their masses modeled so far; it is
impossible to draw any general conclusions about the connections
between HMBH mass and their massive host galaxies. With these 5
targets we will determine whether these HMBHs deviate from the scaling
relations defined by less massive spheroids. A larger sample will
allow us to firmly anchor the high mass end of the correlation between
black hole mass and stellar velocity dispersion, and other scaling
relations. Therefore we are also conducting a SNAPshot program with
which we expect to detect a further 24 HMBH candidates for STIS
observation in future cycles. At the completion of this project we
will have populated the high mass end of the scaling relations with
the sample sizes enjoyed by less massive spheroids.

STIS/CCD 11844

CCD Dark Monitor Part 1

The purpose of this proposal is to monitor the darks for the STIS CCD.

STIS/CCD 11846

CCD Bias Monitor-Part 1

The purpose of this proposal is to monitor the bias in the 1x1, 1x2,
2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up
high-S/N superbiases and track the evolution of hot columns.

STIS/CCD/MA1 11737

The Distance Dependence of the Interstellar N/O Abundance Ratio: A
Gould Belt Influence?

The degree of elemental abundance homogeneity in the interstellar
medium is a function of the enrichment and mixing processes that
govern galactic chemical evolution. Observations of young stars and
the interstellar gas within ~500 pc of the Sun have revealed a local
ISM that is so well- mixed it is having an impact on ideas regarding
the formation of extrasolar planets. However, the situation just
beyond the local ISM is not so clear. Sensitive UV absorption line
measurements have recently revealed a pattern of inhomogeneities in
the interstellar O, N, and Kr gas-phase abundances at distances of
~500 pc and beyond that appear nucleosynthetic in origin rather than
due to dust depletion. In particular, based on a sample of 13
sightlines, Knauth et al. (2006) have found that the nearby stars (d
500 pc) exhibit a mean interstellar N/O abundance ratio that is
significantly higher (0.18 dex) than that toward the more distant
stars. Interestingly, all of their sightlines lie in the sky vicinity
of the Gould Belt of OB associations, molecular clouds, and diffuse
gas encircling the Sun at a distance of ~400 pc. Is it possible that
mixing processes have not yet smoothed out the recent ISM enrichment
by massive stars in the young Belt region? By measuring the
interstellar N/O ratios in a strategic new sample of sightlines with
STIS, we propose to test the apparent N/O homogeneity inside the Gould
Belt and determine if the apparent decline in the N/O ratio with
distance is robust and associated with the Belt region.

STIS/MA1/MA2 11857

STIS Cycle 17 MAMA Dark Monitor

This proposal monitors the behavior of the dark current in each of the
MAMA detectors.

The basic monitor takes two 1380s ACCUM darks each week with each
detector. However, starting Oct 5, pairs are only included for weeks
that the LRP has external MAMA observations planned. The weekly pairs
of exposures for each detector are linked so that they are taken at
opposite ends of the same SAA free interval. This pairing of exposures
will make it easier to separate long and short term temporal
variability from temperature dependent changes.

For both detectors, additional blocks of exposures are taken once
every six months. These are groups of five 1314s FUV-MAMA Time-Tag
darks or five 3x315s NUV ACCUM darks distributed over a single
SAA-free interval. This will give more information on the brightness
of the FUV MAMA dark current as a function of the amount of time that
the HV has been on, and for the NUV MAMA will give a better measure of
the short term temperature dependence.

WFC3/ACS/IR 11677

Is 47 Tuc Young? Measuring its White Dwarf Cooling Age and Completing
a Hubble Legacy

With this proposal we will firmly establish the age of 47 Tuc from its
cooling white dwarfs. 47 Tuc is the nearest and least reddened of the
metal-rich disk globular clusters. It is also the template used for
studying the giant branches of nearby resolved galaxies. In addition,
the age sensitive magnitude spread between the main sequence turnoff
and horizontal branch is identical for 47 Tuc, two bulge globular
clusters and the bulge field population. A precise relative age
constraint for 47 Tuc, compared to the halo clusters M4 and NGC 6397,
both of which we recently dated via white dwarf cooling, would
therefore constrain when the bulge formed relative to the old halo
globular clusters. Of particular interest is that with the higher
quality ACS data on NGC 6397, we are now capable with the technique of
white dwarf cooling of determining ages to an accuracy of +/-0.4 Gyrs
at the 95% confidence level. Ages derived from the cluster turnoff are
not currently capable of reaching this precision. The important role
that 47 Tuc plays in galaxy formation studies, and as the metal-rich
template for the globular clusters, makes the case for a white dwarf
cooling age for this metal-rich cluster compelling.

Several recent analyses have suggested that 47 Tuc is more than 2 Gyrs
younger than the Galactic halo. Others have suggested an age similar
to that of the most metal poor globular clusters. The current
situation is clearly uncertain and obviously a new approach to age
dating this important cluster is required.

With the observations of 47 Tuc, this project will complete a legacy
for HST. It will be the third globular cluster observed for white
dwarf cooling; the three covering almost the full metallicity range of
the cluster system. Unless JWST has its proposed bluer filters (700
and 900 nm) this science will not be possible perhaps for decades
until a large optical telescope is again in space. Ages for globular
clusters from the main sequence turnoff are less precise than those
from white dwarf cooling making the science with the current proposal
truly urgent.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more
reliably removed from science data using darks taken with the same
exposure sequences as the science data, than with a single dark
current image scaled by desired exposure time. Therefore, dark current
images must be collected using all sample sequences that will be used
in science observations. These observations will be used to monitor
changes in the dark current of the WFC3-IR channel on a day- to-day
basis, and to build calibration dark current ramps for each of the
sample sequences to be used by Gos in Cycle 17. For each sample
sequence/array size combination, a median ramp will be created and
delivered to the calibration database system (CDBS).

WFC3/UVIS 11577

Opening New Windows on the Antennae with WFC3

We propose to use WFC3 to provide key observations of young star
clusters in "The Antennae" (NGC4038/39). Of prime importance is the
WFC3's ability to push the limiting UV magnitude FIVE mag deeper than
our previous WFPC2 observations. This corresponds to pushing the
limiting cluster mass from ~10**5 to ~10**3 solar masses for cluster
ages ~10**8 yrs. In addition, the much wider field of view of the WFC3
IR channel will allow us to map out both colliding disks rather than
just the Overlap Region between them. This will be especially
important for finding the youngest clusters that are still embedded in
their placental cocoons. The extensive set of narrow- band filters
will provide an effective means for determining the properties of
shocks, which are believed to be a primary triggering mechanism for
star formation. We will also use ACS in parallel with WFC3 to observe
portions of both the northern and southern tails at no additional
orbital cost. Finally, one additional primary WFC3 orbit will be used
to supplement exisiting HST observations of the star-forming "dwarf"
galaxy at the end of the southern tail. Hence, when completed we will
have full UBVI + H_alpha coverage (or more for the main galaxy) of
four different environments in the Antennae. In conjunction with the
extensive multi-wavelength database we have collected (both HST and
ground based) these observations will provide answers to fundamental
questions such as: How do these clusters form and evolve? How is star
formation triggered? How do star clusters affect the local and global
ISM, and the evolution of the galaxy as a whole? The Antennae galaxies
are the nearest example of a major disk--disk merger, and hence may
represent our best chance for understanding how mergers form
tremendous numbers of clusters and stars, both in the local universe
and during galaxy assembly at high redshift.

WFC3/UVIS 11657

The Population of Compact Planetary Nebulae in the Galactic Disk

We propose to secure narrow- and broad-band images of compact
planetary nebulae (PNe) in the Galactic Disk to study the missing link
of the early phases of post-AGB evolution. Ejected AGB envelopes
become PNe when the gas is ionized. PNe expand, and, when large
enough, can be studied in detail from the ground. In the interim, only
the HST capabilities can resolve their size, morphology, and central
stars. Our proposed observations will be the basis for a systematic
study of the onset of morphology. Dust properties of the proposed
targets will be available through approved Spitzer/IRS spectra, and so
will the abundances of the alpha-elements. We will be able thus to
explore the interconnection of morphology, dust grains, stellar
evolution, and populations. The target selection is suitable to
explore the nebular and stellar properties across the galactic disk,
and to set constraints on the galactic evolutionary models through the
analysis of metallicity and population gradients.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set
of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K
subarray biases are acquired at less frequent intervals throughout the
cycle to support subarray science observations. The internals from
this proposal, along with those from the anneal procedure (Proposal
11909), will be used to generate the necessary superbias and superdark
reference files for the calibration pipeline (CDBS).

WFC3/UVIS/IR 11644

A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into
the Formation of the Outer Solar System

The eight planets overwhelmingly dominate the solar system by mass,
but their small numbers, coupled with their stochastic pasts, make it
impossible to construct a unique formation history from the dynamical
or compositional characteristics of them alone. In contrast, the huge
numbers of small bodies scattered throughout and even beyond the
planets, while insignificant by mass, provide an almost unlimited
number of probes of the statistical conditions, history, and
interactions in the solar system. To date, attempts to understand the
formation and evolution of the Kuiper Belt have largely been dynamical
simulations where a hypothesized starting condition is evolved under
the gravitational influence of the early giant planets and an attempt
is made to reproduce the current observed populations. With little
compositional information known for the real Kuiper Belt, the test
particles in the simulation are free to have any formation location
and history as long as they end at the correct point. Allowing
compositional information to guide and constrain the formation,
thermal, and collisional histories of these objects would add an
entire new dimension to our understanding of the evolution of the
outer solar system. While ground based compositional studies have hit
their flux limits already with only a few objects sampled, we propose
to exploit the new capabilities of WFC3 to perform the first ever
large-scale dynamical-compositional study of Kuiper Belt Objects
(KBOs) and their progeny to study the chemical, dynamical, and
collisional history of the region of the giant planets. The
sensitivity of the WFC3 observations will allow us to go up to two
magnitudes deeper than our ground based studies, allowing us the
capability of optimally selecting a target list for a large survey
rather than simply taking the few objects that can be measured, as we
have had to do to date. We have carefully constructed a sample of 120
objects which provides both overall breadth, for a general
understanding of these objects, plus a large enough number of objects
in the individual dynamical subclass to allow detailed comparison
between and within these groups. These objects will likely define the
core Kuiper Belt compositional sample for years to come. While we have
many specific results anticipated to come from this survey, as with
any project where the field is rich, our current knowledge level is
low, and a new instrument suddenly appears which can exploit vastly
larger segments of the population, the potential for discovery -- both
anticipated and not -- is extraordinary.

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 6 6
FGS REAcq 9 9
OBAD with Maneuver 4 4

SIGNIFICANT EVENTS: (None)


 




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