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Daily Rpt #4975



 
 
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Old November 19th 09, 06:03 PM posted to sci.astro.hubble
Bassford, Lynn[_2_]
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Default Daily Rpt #4975

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #4975

PERIOD COVERED: 5am November 18 - 5am November 19, 2009 (DOY 322/10:00z-323/10:00z)

OBSERVATIONS SCHEDULED

ACS/WFC 11879

CCD Daily Monitor (Part 1)

This program comprises basic tests for measuring the read noise and
dark current of the ACS WFC and for tracking the growth of hot pixels.
The recorded frames are used to create bias and dark reference images
for science data reduction and calibration. This program will be
executed four days per week (Mon, Wed, Fri, Sun) for the duration of
Cycle 17. To facilitate scheduling, this program is split into three
proposals. This proposal covers 352 orbits (22 weeks) from 31 August
2009 to 31 January 2010.

FGS 11704

The Ages of Globular Clusters and the Population II Distance Scale

Globular clusters are the oldest objects in the universe whose age can
be accurately determined. The dominant error in globular cluster age
determinations is the uncertain Population II distance scale. We
propose to use FGS 1R to obtain parallaxes with an accuracy of 0.2
milliarcsecond for 9 main sequence stars with [Fe/H] -1.5. This will
determine the absolute magnitude of these stars with accuracies of
0.04 to 0.06mag. This data will be used to determine the distance to
24 metal-poor globular clusters using main sequence fitting. These
distances (with errors of 0.05 mag) will be used to determine the ages
of globular clusters using the luminosity of the subgiant branch as an
age indicator. This will yield absolute ages with an accuracy of 5%,
about a factor of two improvement over current estimates. Coupled with
existing parallaxes for more metal-rich stars, we will be able to
accurately determine the age for globular clusters over a wide range
of metallicities in order to study the early formation history of the
Milky Way and provide an independent estimate of the age of the
universe.

The Hipparcos database contains only 1 star with [Fe/H] -1.4 and an
absolute magnitude error less than 0.18 mag which is suitable for use
in main sequence fitting. Previous attempts at main sequence fitting
to metal-poor globular clusters have had to rely on theoretical
calibrations of the color of the main sequence. Our HST parallax
program will remove this source of possible systematic error and yield
distances to metal-poor globular clusters which are significantly more
accurate than possible with the current parallax data. The HST
parallax data will have errors which are 10 times smaller than the
current parallax data. Using the HST parallaxes, we will obtain main
sequence fitting distances to 11 globular clusters which contain over
500 RR Lyrae stars. This will allow us to calibrate the absolute
magnitude of RR Lyrae stars, a commonly used Population II distance
indicator.

FGS 11873

FGS1r S-Curve Response and the PMT Dead Time Correction

This proposal observes two stars of very similar spectral type, one
with V=7.65 and one with V=1.99. By comparison of the observed
photometry, the deadtime constant of each of FGS1r's 4 PMTs will be
determined. This knowledge will be necessary for the analysis of
bright (V 9) binary star observations using the F583W filter, and V4
for the F5ND attenuator.

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.

WFC3/ACS/IR/WFC 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at
0.3z2.7 Using HST and Spitzer

We aim to determine physical properties of IR luminous galaxies at
0.3z2.7 by requesting coordinated HST/NIC2 and MIPS 70um
observations of a unique, 24um flux-limited sample with complete
Spitzer mid-IR spectroscopy. The 150 sources investigated in this
program have S(24um) 0.8mJy and their mid-IR spectra have already
provided the majority targets with spectroscopic redshifts
(0.3z2.7). The proposed 150~orbits of NIC2 and 66~hours of MIPS 70um
will provide the physical measurements of the light distribution at
the rest-frame ~8000A and better estimates of the bolometric
luminosity. Combining these parameters together with the rich suite of
spectral diagnostics from the mid-IR spectra, we will (1) measure how
common mergers are among LIRGs and ULIRGs at 0.3z2.7, and establish
if major mergers are the drivers of z1 ULIRGs, as in the local
Universe, (2) study the co-evolution of star formation and blackhole
accretion by investigating the relations between the fraction of
starburst/AGN measured from mid-IR spectra vs. HST morphologies,
L(bol) and z, and (3) obtain the current best estimates of the far-IR
emission, thus L(bol) for this sample, and establish if the relative
contribution of mid-to-far IR dust emission is correlated with
morphology (resolved vs. unresolved).

WFC3/ACS/UVIS/IR 11360

Star Formation in Nearby Galaxies

Star formation is a fundamental astrophysical process; it controls
phenomena ranging from the evolution of galaxies and nucleosynthesis
to the origins of planetary systems and abodes for life. The WFC3,
optimized at both UV and IR wavelengths and equipped with an extensive
array of narrow-band filters, brings unique capabilities to this area
of study. The WFC3 Scientific Oversight Committee (SOC) proposes an
integrated program on star formation in the nearby universe which will
fully exploit these new abilities. Our targets range from the
well-resolved R136 in 30 Dor in the LMC (the nearest super star
cluster) and M82 (the nearest starbursting galaxy) to about half a
dozen other nearby galaxies that sample a wide range of star-formation
rates and environments. Our program consists of broad band
multiwavelength imaging over the entire range from the UV to the
near-IR, aimed at studying the ages and metallicities of stellar
populations, revealing young stars that are still hidden by dust at
optical wavelengths, and showing the integrated properties of star
clusters. Narrow-band imaging of the same environments will allow us
to measure star-formation rates, gas pressure, chemical abundances,
extinction, and shock morphologies. The primary scientific issues to
be addressed a (1) What triggers star formation? (2) How do the
properties of star-forming regions vary among different types of
galaxies and environments of different gas densities and compositions?
(3) How do these different environments affect the history of star
formation? (4) Is the stellar initial mass function universal or
determined by local conditions?

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/UV 11697

Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies

Using the superior resolution of HST, we propose to continue our
proper motion survey of Galactic dwarf galaxies. The target galaxies
include one classical dwarf, Leo II, and six that were recently
identified in the Sloan Digital Sky Survey data: Bootes I, Canes
Venatici I, Canes Venatici II, Coma Berenices, Leo IV, and Ursa Major
II. We will observe a total of 16 fields, each centered on a
spectroscopically- confirmed QSO. Using QSOs as standards of rest in
measuring absolute proper motions has proven to be the most accurate
and most efficient method. HST is our only option to quickly determine
the space motions of the SDSS dwarfs because suitable ground-based
imaging is only a few years old and such data need several decades to
produce a proper motion. The two most distant galaxies in our sample
will require time baselines of four years to achieve our goal of a
30-50 km/s uncertainty in the tangential velocity; given this and the
finite lifetime of HST, it is imperative that first-epoch observations
be taken in this cycle. The SDSS dwarfs have dramatically lower
surface brightnesses and luminosities than the classical dwarfs.
Proper motions are crucial for determining orbits of the galaxies and
knowing the orbits will allow us to test theories for the formation
and evolution of these galaxies and, more generally, for the formation
of the Local Group.

WFC3/UV 11783

The Dynamical Mass of the Bright Cepheid Polaris

Cepheid variables are of central importance in Galactic and
extragalactic astronomy. They are the primary standard candles for
measuring extragalactic distances, and they provide critical tests of
stellar-evolution theory. Surprisingly, however, until now there was
not a single Cepheid with a purely dynamical measurement of its mass.

Polaris (alpha UMi) is the nearest and brightest of all Cepheids. It
offers the unique opportunity to measure the dynamical mass of a
Cepheid, because it is in a binary system for which a single-lined
spectroscopic orbit is already available. In Cycle 14, we resolved the
system in the UV using ACS/HRC, thus providing the first direct
detection of the companion, as well as a first approximation to the
dynamical mass. In the present proposal we request one HST orbit per
year for the next 3 Cycles, in order to refine the visual orbit.
Combined with the HST/FGS parallax (see below), this program will
provide an accurate mass for the Cepheid (the error should be about
0.5 Msun by Cycle 17), and the only one based purely on dynamical
information. Only HST's combination of high spatial resolution and UV
sensitivity can achieve this result.

The parallax is a key ingredient in the mass determination. In an
ongoing multi-year program (GO-9888, GO-10113, GO-10482), we are using
the FGS to improve significantly upon the Hipparcos parallax of
Polaris. The continued ACS/HRC imaging proposed here (updated to WFC3
following SM4) will thus provide extremely valuable astrophysical
information from a very modest additional investment of observing
time.

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 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the
UVIS detector (both CCDs) at the level of ~1%, lasting hours to days.
Initially found via an unexpected bowtie-shaped feature in flatfield
ratios, subsequent lab tests on similar e2v devices have since shown
that it is also present as simply an overall offset across the entire
CCD, i.e., a QE offset without any discernable pattern. These lab
tests have further revealed that overexposing the detector to count
levels several times full well fills the traps and effectively
neutralizes the bowtie. Each visit in this proposal acquires a set of
three 3x3 binned internal flatfields: the first unsaturated image will
be used to detect any bowtie, the second, highly exposed image will
neutralize the bowtie if it is present, and the final image will allow
for verification that the bowtie is gone.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

#12080 GSAcq(1,2,1) @322/16:53:47z and 5 associated REAcqs
(@322/18:25:52z, 322/20:13:00z, 322/21:37:41z, 322/23:13:35z,
323/00:53:03z) failed due to search radius limit exceeded on FGS1

Observations affected: WFC3 #97-112 Proposal #11360 and STIS #25
Proposal #11844

COMPLETED OPS REQUEST:

#18764-3 R/T OBAD for Known Star Issue @ 323/00:14z

COMPLETED OPS NOTES:

#1953-0 Possible GSAcq failures on DOY 322 and 323

SCHEDULED SUCCESSFUL
FGS GSAcq 6 5
FGS REAcq 10 5
OBAD with Maneuver 3 3

SIGNIFICANT EVENTS: (None)
[ Part 2, "image001.jpg" Image/JPEG 4.4KB. ]
[ Unable to print this part. ]

 




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