NASA Hubble Space Telescope Daily Report # 3410
HUBBLE SPACE TELESCOPE
DAILY REPORT # 3410
PERIOD COVERED: DOY 203
OBSERVATIONS SCHEDULED
ACS/HRC 9361
Searching for Primeval Galaxies: the promising case of SBS 1415+437
Do primeval galaxies exist in the local Universe? The best candidates are
extremely metal-poor {Z < 1/20 Zo} blue compact dwarf {BCD} galaxies whose
photometric and chemical properties are consistent with a stellar population
younger than 100 Myr. SBS 1415+437 {Z = 1/21 Zo} is the closest candidate:
its
proximity {d = 11.4 Mpc}, detailed spectroscopic knowledge of its HII
regions
and low metal content, used to infer the primordial He^4 abundance, make it
the
best target for this investigation. We propose to take deep exposures of SBS
1415+437 with the ACS in the F814W and F606W filters. This instrument has
resolution and magnitude limits allowing us to reach and resolve with the
required accuracy individual stars 1 mag below the tip of the red giant
branch
{RGBT}. If present, these stars will provide a clear sign of an old stellar
population {with ages > 1 Gyr} and an independent distance indicator. If
absent,
this will unambiguously show that the system has started to form stars only
recently and can be considered the first robust case of local primeval
galaxy.
We propose to take exposures in the F658N {HAlpha Lambda6563} and FR505N
{HBeta
Lambda4861} filters to study the morphology of the ionized gas through
HAlpha
emission and map the dust content with the HAlpha/HBeta ratio in order to
solve
the age-dust degeneracy of the photometry by constraining reddening effects.
HST 9382
A Large Targeted Survey for z < 1.6 Damped Lyman Alpha Lines in SDSS QSO
MgII-FeII Systems.
We have searched the first public release of SDSS QSO spectra for low-z
{z<1.65}
metal absorption lines and found over 200 large rest equivalent width
MgII-FeII
systems. Previously, we empirically showed that such systems are good
tracers of
large neutral gas columns, with ~50% being classical damped Lyman alpha
{DLA}
systems {N_HI>=2*10^20 cm^-2}. Here we propose to follow up a well-defined
subset of 79 of them to search for DLAs with 0.47<z<1.60. Only QSOs brighter
than g’=19 were selected. The QSO emission and DLA absorption redshifts were
constrained to virtually eliminate data loss due to intervening Lyman limit
absorption. Consequently, we expect to discover ~40 new DLAs, which is a
three-fold increase in this redshift interval. This will significantly
improve
our earlier low-z DLA statistical results on their incidence, cosmological
mass
density, and N_HI distribution. The results will also allow us to better
quantify the empirical DLA — metal-line correlation. With this improved
understanding, the need for follow-up UV spectroscopy will lessen and, with
the
release of the final database of SDSS QSO spectra {an ~25-fold increase},
the
number of low-z DLAs could be increased arbitrarily. Thus, the power of the
large and statistically-sound SDSS database in combination with a proven
technique for finding low-z DLAs will, over the next few years, essentially
solve the problem of making an accurate determination of the cosmic
evolution of
the neutral gas component down to z~0.4.
ACS 9482
ACS Pure Parallel Lyman-Alpha Emission Survey {APPLES}
Ly-alpha line emission is an efficient tool for identifying young galaxies
at
high redshift, because it is strong in galaxies with young stars and little
or
no dust — properties expected in galaxies undergoing their first burst of
star- formation. Slitless spectroscopy with the ACS Wide-Field Camera and
G800L
grism allows an unmatched search efficiency for such objects over the
uninterrupted range 4 <~ z <~ 7. We propose the ACS Pure Parallel Ly-alpha
Emission Survey {“APPLES”}, to exploit this unique HST capability and so
obtain the largest and most uniform sample of high redshift Ly-alpha
emitters
yet. Parallel observations will allow this survey to be conducted with
minimal
impact on HST resources, and we will place reduced images and extracted
spectra
in the public domain within three months of observation. We aim to find ~
1000
Ly-alpha emitters, 5 times the biggest current sample of Ly-alpha emitters.
This
unprecedented sample will provide robust statistics on the populations and
evolution of Ly-alpha emitters between redshifts 4–7; a robust measurement
of
the reionization redshift completely independent of the Gunn-Peterson
trough;
spatial clustering information for Ly-alpha emitters which would let us
probe
their bias function and hence halo mass as a function of redshift; many
galaxies
at redshift exceeding 6; and lower redshift serendipitous discoveries.
STIS/CCD/MA2 9491
The Oxygen Abundance in the Metal-Poor Halo Star HD 140283 from UV-OH lines
Oxygen is critical in numerous astrophysical contexts, including the
derivation
of globular cluster ages and the early history of the Galaxy’s chemistry.
However, its abundance, particularly in metal-poor stars, remains
controversial,
with optical, IR and UV abundance indicators in dwarfs and giants yielding
different abundance patterns; a flat O/Fe ratio with Fe/H is suggested by
OI and
IR-OH lines, while a monotonically increasing O/Fe trend with decreasing
Fe/H is
measured from OI and UV-OH lines with a factor of 10 difference at Fe/H=-3.
We
propose an in-depth study of the UV- OH lines in the halo subgiant HD 140283
with R=110, 000 and S/N=200 spectra and state-of-the-art 3-D model
atmospheres.
Understanding UV-OH lines is particularly important because these provide
the
sole means of measuring the oxygen abundance in the most metal-poor stars
and
therefore in the early Galaxy. STIS will for the first time provide several
dozen unblended UV-OH lines. Predictions about the variation of line
strength
with excitation potential and the asymmetries of the OH line profiles will
be
tested and used to refine the cool outer layers of the 3-D models where the
OH
lines are formed. The end result will be an accurate oxygen abundance, a
thorough understanding of OH line formation, and a good characterization of
the
atmosphere of a metal-poor star.
WFPC2 9595
WFPC2 CYCLE 11 SUPPLEMENTAL DARKS pt3/3
This dark calibration program obtains 3 dark frames every day to provide
data
for monitoring and characterizing the evolution of hot pixels.
STIS 9606
CCD Dark Monitor-Part 2
Monitor the darks for the STIS CCD.
STIS 9608
CCD Bias Monitor – Part 2
Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1, and
1×1
at gain = 4, to build up high-S/N superbiases and track the evolution of hot
columns.
STIS 9615
Cycle 11 MAMA Dark Monitor
This test performs the routine monitoring of the MAMA detector dark noise.
This
proposal will provide the primary means of checking on health of the MAMA
detectors systems through frequent monitoring of the background count rate.
The
purpose is to look for evidence of change in dark indicative of detector
problem
developing.
ACS 9674
CCD Daily Monitor
This program consists of basic tests to monitor, the read noise, the
development
of hot pixels and test for any source of noise in ACS CCD detectors. This
programme will be executed once a day for the entire lifetime of ACS.
STIS 9708
STIS Pure Parallel Imaging Program: Cycle 11
This is the default archival pure parallel program for STIS during cycle 11.
WFPC2 9709
POMS Test Proposal: WFII parallel archive proposal
This is the generic target version of the WFPC2 Archival Pure Parallel
program.
The program will be used to take parallel images of random areas of the sky,
following the recommendations of the 2002 Parallels Working Group.
WFPC2 9710
POMS Test Proposal: WFII backup parallel archive proposal
This is a POMS test proposal designed to simulate scientific plans.
STIS 9786
The Next Generation Spectral Library
We propose to continue the Cycle 10 snapshot program to produce a Next
Generation Spectral Library of 600 stars for use in modeling the integrated
light of galaxies and clusters. This program is using the low dispersion UV
and
optical gratings of STIS. The library will be roughly equally divided among
four
metallicities, very low {[Fe/H] lt -1.5}, low {[Fe/H] -1.5 to -0.5},
near-solar
{[Fe/H] -0.3 to 0.1}, and super-solar {[Fe/H] gt 0.2}, well-sampling the
entire
HR-diagram in each bin. Such a library will surpass all extant compilations
and
have lasting archival value, well into the Next Generation Space Telescope
era.
Because of the universal utility and community-broad nature of this venture,
we
waive the entire proprietary period.
ACS/WFC/HRC 9889
ACS Photometric Zero Point Verification
The uncertainties in the photometric zero points create a fundamental limit
to
the accuracy of photometry. The current state of the ACS calibration is
surprisingly poor, with zero point uncertainties of 0.03 magnitudes in the
Johnson filters. The reason for this is that ACS observations of excellent
ground-based standard fields, such as the omega Cen field used for WFPC2
calibrations, have not been obtained. Instead, the ACS photometric
calibrations
are based primarily on semi-emprical synthetic zero points and observations
of
fields too crowded for accurate ground-based photometry. I propose to remedy
this problem by obtaining ACS broadband images of the omega Cen standard
field
with both the WFC and HRC. This will permit the direct determination of the
ACS
transformations, and is expected to double the accuracy to which the ACS
zero
points are known. A second benefit is that it will facilitate the comparison
of
the WFPC2 and ACS photometric systems, which will be important as WFPC2 is
phased out and ACS becomes HST’s primary imager
ACS 9984
Cosmic Shear With ACS Pure Parallels
Small distortions in the shapes of background galaxies by foreground mass
provide a powerful method of directly measuring the amount and distribution
of
dark matter. Several groups have recently detected this weak lensing by
large-scale structure, also called cosmic shear. The high resolution and
sensitivity of HST/ACS provide a unique opportunity to measure cosmic shear
accurately on small scales. Using 260 parallel orbits in Sloan textiti
{F775W}
we will measure for the first time: beginlistosetlength sep0cm
setlengthemsep0cm
setlength opsep0cm em the cosmic shear variance on scales <0.7 arcmin, em
the
skewness of the shear distribution, and em the magnification effect.
endlist Our
measurements will determine the amplitude of the mass power spectrum
sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20, and the mass density
Omega_m with s/n=4. They will be done at small angular scales where
non-linear
effects dominate the power spectrum, providing a test of the gravitational
instability paradigm for structure formation. Measurements on these scales
are
not possible from the ground, because of the systematic effects induced by
PSF
smearing from seeing. Having many independent lines of sight reduces the
uncertainty due to cosmic variance, making parallel observations ideal.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of
potential non-nominal performance that will be investigated.)
HSTAR 9094: Upon AOS @ 203/10:44Z, HST was operating in FL backup on FGS 3
only.
Further information after engineering recorder
playback. Under
investigation.
COMPLETED OPS REQs: None
OPS NOTES EXECUTED: None
SCHEDULED SUCCESSFUL FAILURE TIMES
FGS GSacq 9 9
FGS REacq 7 7
FHST Update 15 15
LOSS of LOCK
SIGNIFICANT EVENTS:
Back-up Packet Filter 13 test scheduled 204/16:00Z – 20:00Z with GDOC,
SOC, HITT, CCS, Sys Admin using CCS "C" String with CCS Release 4.0.2,
PRD S07200, and Building 25 SOC CCSPSS with Release 3.2.8.2. The
purpose of this test is to verify the functionality of back-up Packet
Filter 13 for Service Mission operations.
