Status Report

NASA Hubble Space Telescope Daily Report # 3485

By SpaceRef Editor
November 8, 2003
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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


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.

ACS/WFC 10046

CCD Hot Pixel Annealing

Hot pixel annealing will be performed once every 4 weeks. The CCD TECs
will be turned off and heaters will be activated to bring the detector
temperatures to about +20C. This state will be held for approximately
12 hours, after which the heaters are turned off, the TECs turned on,
and the CCDs returned to normal operating condition. To assess the
effectiveness of this procedure, a bias and two dark images will be
taken after the annealing procedure for both WFC and HRC. The HRC
darks are taken in parallel with the WFC darks.

ACS/WFC 9744

HST Imaging of Gravitational Lenses

Gravitational lenses offer unique opportunities to study cosmology,
dark matter, galactic structure, galaxy evolution and quasar host
galaxies. They are also the only sample of galaxies selected based on
their mass rather than their luminosity or surface brightness. While
gravitational lenses can be discovered with ground-based optical and
radio observations, converting them into astrophysical tools requires
HST. HST has demonstrated that it is the only telescope that can in
each case precisely locate the lens galaxy, measure its luminosity,
color and structure, and search for lensed images of the source host
galaxy given the typical image separations of ~1”. We will obtain
ACS/WFC V and I images and NICMOS H images of 21 new lenses never
observed by HST and NICMOS H images of 16 lenses never observed by HST
in the IR. As in previous cycles, we request that the data be made
public immediately.

NIC/NIC3 9865

The NICMOS Parallel Observing Program

We propose to continue managing the NICMOS pure parallel program.
Based on our experience, we are well prepared to make optimal use of
the parallel opportunities. The improved sensitivity and efficiency of
our observations will substantially increase the number of
line-emitting galaxies detected. As our previous work has
demonstrated, the most frequently detected line is Halpha at
0.7<z<1.9, which provides an excellent measure of current star
formation rate. We will also detect star-forming and active galaxies
in other redshift ranges using other emission lines. The grism
observations will produce by far the best available Halpha luminosity
functions over the crucial–but poorly observed–redshift range where
galaxies appear to have assembled most of their stellar mass. This key
process of galaxy evolution needs to be studied with IR data; we found
that observations at shorter wavelengths appear to have missed a large
fraction of the star-formation in galaxies, due to dust reddening. We
will also obtain deep F110W and F160W images, to examine the space
densities and morphologies of faint red galaxies. In addition to
carrying out the public parallels, we will make the fully reduced and
calibrated images and spectra available on-line, with some
ground-based data for the deepest parallel fields included.

NIC1 9737

A NICMOS direct imaging search for giant planets around the seven
single white dwarfs in the Hyades

We propose to use the NIC1 camera on HST to search for massive giant
planets around the known seven single white dwarfs in the nearby
Hyades cluster at sub-arcsec separations. At an age of 625 Myr, the
white dwarfs had protogenitor masses of about 3 solar masses, and
massive gaseous giant planets should have formed in the massive
circumstellar disks around these ex Herbig A0 stars, probably at
orbital separations similar or slightly larger than that of Jupiter {5
AU} in our own solar system. Such planets would have survived the
post-Main Sequence mass loss of the parent star, and would have
migrated outward adiabatically by a factor 4.5, equal to the ratio of
initial to final stellar mass {3Mo/0.66Mo}, due to conservation of
orbital angular momentum during the mass loss {AGB and PN} phase. Thus
the orbital separation NOW would be 4.5 x 5 AU = 22.5 AU, which at the
distance of the Hyades {45 pc} corresponds to 0.50 arcsec. Simulations
with TinyTim then show that giant planets at this separation with
masses in the range 6-12 Jupiter masses and apparent J and H
magnitudes in the range 20.5-23.3 mag {from Baraffe or Burrows models}
can be spatially resolved around the Hyades white dwarfs. Their J and
H brightnesses are known to be 15 +/- 0.5 mag, implying a median
star-planet brightness ratio of 1000:1 {7.5 mag}. This combination of
dynamic range and orbital separation is observable with NICMOS, by
subtracting images taken at two roll angles. Therefore, the proposed
near-IR diffraction-limited observations in the F110W and F160W
filters promise to resolve giant planets around low-mass stars for the
first time. If successful, the observations would also prove that
giant planets do form around early-type stars more massive than the

NIC1/NIC2/NIC3 8792

NICMOS Post-SAA calibration – CR Persistence Part 3

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.

STIS/CCD 10000

STIS Pure Parallel Imaging Program: Cycle 12

This is the default archival pure parallel program for STIS during
cycle 12.

STIS/CCD 10016

STIS CCD Performance Monitor

This activity measures the baseline performance and commandability of
the CCD subsystem. Only primary amplifier D is used. Bias and Flat
Field exposures are taken in order to measure bias level, read noise,
CTE, and gain. Numerous bias frames are taken to permit construction
of "superbias" frames in which the effects of read noise have been
rendered negligible. Full frame and binned observations are made, with
binning factors of 2 x 1, 1 x 2, 2 x 2, 4 x 1, and 4 x 2. Bias frames
are taken in subarray readouts to check the bias level for ACQ and
ACQ/PEAK observations. All exposures are internals.

STIS/CCD 10017

CCD Dark Monitor-Part 1

Monitor the darks for the STIS CCD.

STIS/CCD 10019

CCD Bias Monitor – Part 1

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/CCD/MA1 10081

Is the exoplanet HD209458b’s exosphere in a blowoff state ?

Using HST Lyman alpha observations, we have detected an extended tail
shaped upper atmosphere around the extra-solar planet HD209458b. The
Cycle 10 STIS G140M observations revealed an absorption of 15+/-4% of
the stellar Lyman alpha emission line during the planetary transit in
front of the star {Vidal-Madjar, et al. 2003}. This showed that HI
evaporation is taking place within a highly extended upper atmosphere.
Very recent studies on the evaporation mechanism are now indicating
that instead of “Jeans escape” a more probable mechanism is complete
atmospheric “blowoff” as suffered by the telluric planets in the
early solar system. This mecanism could be directly tested with HST by
searching for the escape of species slightly heavier than HI. It is
easy to show that neither oxygen nor carbon would be detected with HST
if only “Jeans escape” takes place while both species, under
“blowoff” conditions, should reach the Roche limit of the planet and
escape as hydrogen. If this is the case an absorption during transit
of about 15% should be observed for both. Twelve orbits with the STIS
G140L spectrograph will allow us to detect the presence of these
species during three transits with a better than 5% accuracy, needed
to detect an object of the size of the planetary Roche lobe.
Simultaneously these observations will confirm and give more precision
about the extention of the HI cometary like tail expected to occult
the star well after the end of the visible transit. This proposed
investigation is a unique opportunity to further study hot giant
planets upper atmospheres, reveal the precise evaporation mechanism
and give new constraints on the “hot Jupiters” lifetime. This could
explain the lack of planets discovered so far at less than 0.04~AU
from their star. We ask for HST observations under Director
Discretionnary time to have access to the coming transits observable
in the early fall of 2003.


Whirling Dervish Dynamos: Magnetic Activity in CV Secondaries

The mass-losing secondary stars of cataclysmic variables {CVs} are the
most rapidly rotating cool dwarfs observable. Other rapid rotators
show a maximal, "saturated" level of magnetic activity {e.g., X-ray
emission}, but there are hints from contact binaries and young
clusters that activity may be suppressed at the highest rotation
rates. CV secondaries are thus important probes of magnetic dynamos at
rotational extremes. Implications for CV evolution {e.g., the “period
gap", accretion variability} may also be profound. Unfortunately,
study of CV secondaries is hampered by pesky accretion-related
phenomena and reflection effects. As a result, little systematic work
has been done. To explore activity in these stars, we therefore
propose to study far-UV spectra of AM Her-type systems {which have no
accretion disks} in deep photometric minima in which accretion is shut
off. Magnetic-related emission from the secondary will be separated
{in velocity} from residual accretion emission by observations near
quadratures. Lower chromospheric irradiation due to the white dwarf
primary will be removed by modeling, yielding the true level of
magnetic activity on the secondary. We will compare the results to
other dMe stars and draw implications for magnetic dynamos and
activity at rotational extremes, and for CV evolution and behavior.

WFPC2 10069

WFPC2 CYCLE 12 Supplemental Darks, Part 1/3

This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot

WFPC2 10082

POMS Test Proposal: WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans

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 9729

Probing the nature of Type Ia SNe through HST astrometry

Type Ia supernovae are of key importance in cosmology. Empirical
relations allow their use as cosmological standard candles. The
generally accepted picture is that the exploding star is a C+O white
dwarf which accretes matter from a companion in a binary system.
However, the nature of the companion is still unknown. It could either
be another WD, or be a giant, subgiant, or main-sequence star.
Calculations have shown that it is possible to distinguish among those
possibilities by the effect that the supernova explosion has on the
companion star. We propose to identify the companion star of the two
historical well-known SNeIa through ACS imaging of the targets
complemented by WFPC2 observations. A radial-velocity study of the
stars in those two Galactic SNeIa has been done from ground-based
facilities. To obtain the full motion vector of those stars, we plan
to use ACS for high-resolution astrometry in two different epochs.
That should allow to detect motion imparted during the explosion in
the d ir ection perpendicular to the line of sight, down to a level of
a few milliarcsecs/yr.


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

HSTAR 9193: GS Acquisition (2,1,2) @ 310/20:33:10Z ended in FL backup
on FGS 2 due to SSLE on FGS 2 @ 310/20:36:07Z. GS Re-acquisition @
310/21:58:52Z also ended in FL backup. Under investigation.

HSTAR 9194: GS Acquisition (2,1,1) @ 310/22:35:59Z ended in FL backup
on FGS 2 due to SSLE on FGS 2 @ 310/22:35:59Z. GS Re-acquisition @
310/22:37:36Z also ended in FL backup.Under investigation.


1167-0 Lim Restore JERRCNT (Closed) @310/1205z

                            SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq                13                        13
FGS REacq                 6                          6
FHST Update               20                        20


SpaceRef staff editor.