Daily Report #4914

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT****** #4914

PERIOD COVERED: 5am August 20 - 5am August 21, 2009 (DOY
232/09:00z-233/09:00z)

OBSERVATIONS SCHEDULED

ACS/WFC3 11465

ACS CCD Monitoring and Calibration for WFC3

This program is a smaller version of our routine CCD monitoring
program, designed to run throughout SMOV, after which our regular
Cycle 17 CAL proposal will begin. This program obtains the bias and
dark frames needed to generate reference files for calibrating science
data, and allows us to monitor detector noise and the growth of hot
pixels.

ACS/WFC3 11695

Searching for the Bottom of the Initial Mass Function

The measurement of the minimum mass of the IMF would provide a
fundamental test of theories of star and planet formation. In a Cycle
13 program, we used ACS and ground- based near-IR imaging and
spectroscopy to measure the IMF down to a completeness limit of 10
M_Jup (i~24) in a 800"x1000" area in the southern subcluster of the
Chamaeleon I star-forming region (2 Myr, 160 pc). There is no sign of
a low-mass cutoff in this IMF measurement. To provide a better
constraint on the minimum mass of the IMF, we propose to obtain ACS
images of this field again and use the two ACS epochs to identify
substellar cluster members down to the detection limit of the data
(i~27) via their proper motions. In this way, we will improve the
completeness limit of our IMF measurement to 3 M_Jup. In addition, to
improve the number statistics of our measurement of the substellar IMF
in Chamaeleon I, we propose to double the number of objects in the IMF
sample by performing ACS imaging of a second field toward the northern
subcluster.

ACS/WFC3 11887

CCD Stability Monitor

This program will verify that the low frequency flat fielding, the
photometry, and the geometric distortion are stable in time and across
the field of view of the CCD arrays. A moderately crowded stellar
field in the cluster 47 Tuc is observed with the ACS (at the cluster
core) and WFC3 (6 arcmin West of the cluster core) using the full
suite of broad and narrow band imaging filters. The positions and
magnitudes of objects will be used to monitor local and large scale
variations in the plate scale and the sensitivity of the detectors and
to derive an independent measure of the detector CTE. The UV
sensitivity for the SBC and ACS will be addressed in the UV
contamination monitor program (11886, PI=Smith).

One additional orbit will be obtained at the beginning of the cycle
will allow a verification of the CCD gain ratios for WFC3 using gain
2.0, 1.4, 1.0, 0.5 and for ACS using gain 4.0 and 2.0. In addition,
one subarray exposure with the WFC3 will allow a verification that
photometry obtained in full-frame and in sub-array modes are
repeatable to better than 1%. This test is important for the ACS
Photometric Cross- Calibration program (11889, PI=Bohlin) which uses
sub-array exposures.

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 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.

NIC2/WFC3/ACS/IR 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. {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}.

STIS/CCD 11567

Boron Abundances in Rapidly Rotating Early-B Stars

Models of rotation in early-B stars predict that rotationally driven
mixing should deplete surface boron abundances during the
main-sequence lifetime of many stars. However, recent work has shown
that many boron depleted stars are intrinsically slow rotators for
which models predict no depletion should have occurred, while
observations of nitrogen in some more rapidly rotating stars show less
mixing than the models predict. Boron can provide unique information
on the earliest stages of mixing in B stars, but previous surveys have
been biased towards narrow-lined stars because of the difficulty in
measuring boron abundances in rapidly rotating stars.The two targets
observed as part of our Cycle 13 SNAP program 10175, just before STIS
failed, demonstrate that it is possible to make useful boron abundance
measurements for early-B stars with Vsin(i) above 100 km/s. We propose
to extend that survey to a large enough sample of stars to allow
statistically significant tests of models of rotational mixing in
early-B stars.

STIS/CCD 11844

CCD Dark Monitor Part 1

Monitor the darks for the STIS CCD.

STIS/CCD 11846

CCD Bias Monitor-Part 1

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 11852

STIS CCD Spectroscopic Flats C17

Obtain pixel-to-pixel lamp flat fields for the STIS CCD in
spectroscopic mode.

STIS/CCD 11858

CCD Spectroscopic Dispersion Solution

Constrain wavelength and spatial distortion maps using internal
wavecals obtained with all 6 gratings (G230LB, G230MB, G430L, G430M,
G750L, G750M) supported for use with the CCD. Data will be obtained
for the nearly identical set of 38 central wavelengths used in the
9617 and 10025 programs.

STIS/MA1/MA2 11859

MAMA Dispersion Solutions

Wavelength dispersion solutions will be determined on a yearly basis
as part of a long- term monitoring program. Deep engineering wavecals
for each MAMA grating will be obtained at common cenwaves.
Intermediate settings will also be taken to check the reliability of
derived dispersion solutions. Final selection was determined on basis
of past monitoring and C17 requirements. The internal wavelength
calibrations will be taken using the LINE line lamp. Extra-deep
wavecals are included for some echelle modes and first order modes to
ensure detection of weak lines.

STIS20 11402

STIS-20 NUV MAMA Dark Monitor

The STIS NUV-MAMA dark current is dominated by a phosphorescent glow
from the detector window. Meta-stable states in this window are
populated by cosmic ray impacts, which, days later, can be thermally
excited to an unstable state from which they decay, emitting a UV
photon. The equilibrium population of these meta-stable states is
larger at lower temperatures; so warming up the detector from its cold
safing will lead to a large, but temporary, increase in the dark
current.

To monitor the decay of this glow, and to determine the equilibrium
dark current for Cycle 17, four 1380s NUV-MAMA ACCUM mode darks should
be taken each week during the SMOV period. Once the observed dark
current has reached an approximate equilibrium with the mean detector
temperature, the frequency of this monitor can be reduced to one pair
of darks per week.

WFC3/IR 11915

IR Internal Flat Fields

This program is the same as 11433 (SMOV) and depends on the completion
of the IR initial alignment (program 11425). This version contains
three instances of 37 internal orbits; to be scheduled early, middle,
and near the end of Cycle 17, in order to use the entire 110-orbit
allocation.

In this test, we will study the stability and structure of the IR
channel flat field images through all filter elements in the WFC3-IR
channel. Flats will be monitored, i.e. to capture any temporal trends
in the flat fields, and delta flats produced. High signal observations
will provide a map of the pixel-to-pixel flat field structure, as well
as identify the positions of any dust particles.

WFC3/UVI 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 (11909),
will be used to generate the necessary superbias and superdark
reference files for the calibration pipeline (CDBS).

WFC3/UVI 11909

UVIS Hot Pixel Anneal

The on-orbit radiation environment of WFC3 will continually generate
new hot pixels. This proposal performs the procedure required for
repairing those hot pixels in the UVIS CCDs. During an anneal, the
two-stage thermo-electric cooler (TEC) is turned off and the
four-stage TEC is used as a heater to bring the UVIS CCDs up to ~20
deg. C. As a result of the CCD warmup, a majority of the hot pixels
will be fixed; previous instruments such as WFPC2 and ACS have seen
repair rates of about 80%. Internal UVIS exposures are taken before
and after each anneal, to allow an assessment of the procedure's
effectiveness in WFC3, provide a check of bias, global dark current,
and hot pixel levels, as well as support hysteresis (bowtie)
monitoring and CDBS reference file generation. One IR dark is taken
after each anneal, to provide a check of the IR detector.

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:

18683-5 - Install WFC3 CS FSW 4.00 and NSSC-I BQ 9.0.6 @ 232/1830z

COMPLETED OPS NOTES: (None)

*********************** SCHEDULED***** SUCCESSFUL

FGS GSAcq************** 12***************** 12
FGS REAcq************** 03***************** 03
OBAD with Maneuver **** 06***************** 06

SIGNIFICANT EVENTS:

Flash Report:

Wide Field Camera 3 CS Flight Software version 4.00 and NSSC-I Flight
Software version BQ 9.0.6 have been successfully loaded via Ops
Request 18683-5