Status Report

NASA Hubble Space Telescope Daily Report # 3448

By SpaceRef Editor
September 17, 2003
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ACS 9655

ACS Post-SMOV UV Contamination Monitor

A standard star field {NGC6681} is observed about once a month through
all the ACS broad band UV filters. NGC6681 hosts several UV spectro –
photometric standard stars for which accurate spectra have been {and
will continue to be} measured with STIS. The target cannot be observed
for three months from mid November through to mid February, so the
standard star GRW+70 will be observed twice in its stead. This program
continues the UV sensitivity monitoring campaign {ACS SMOV proposal
9010} of the HRC and SBC after the end of the SMOV period. An SBC dark
current measurement is taken as the last exposure of each SBC

ACS 9658

ACS Earth Flats

This program will obtain sequences of flat field images by observing
the bright Earth. Several UV filters from the interim calibration
program {9564} require additional exposures to obtain the required
illumination. A few UV filters from this program will be repeated to
monitor for changes in the flat fields and to verify the interim
results. Since no streaks are observed in the UV, the wavelength
coverage is extended to longer wavelengths in order to explore the
severity of streaks in the flats from clouds in the FOV. We have added
exposures for the HRC in the visible filters to verify the results
derived from the L-flat campaign and to explore the severity of
streaks. We have also added exposures on WFC using the minimum
exposure time and using filters which will not saturate the brightest
WFC pixel by more than 10 times the full well.

ACS 9675

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 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

ACS/HRC 9853

A Search for Young Binary Brown Dwarfs: Constraining Formation
Scenarios and Masses Through Multiplicity

We propose to use the Advanced Camera for Surveys / High Resolution
Camera to conduct a direct imaging multiplicity survey of 34 young
brown dwarfs in the nearest regions of recent star formation, the T
association Taurus-Auriga and the OB association Upper Scorpius. The
determined multiplicity fraction, the separation distribution, and the
mass ratio distribution will offer stringent observational constraints
on proposed brown dwarf formation scenarios. Moreover, the small
semi-major axes of known field and open cluster brown dwarf binaries
suggest the exciting possibility of our identifying several very close
binaries {< 15 AU}. Continued monitoring of these systems would yield,
on a decade timescale, the first dynamical mass estimates of T Tauri
brown dwarfs. With masses intermediate between those of stars and
planets, brown dwarfs offer our best hope of relating the reasonably
well understood processes of star formation to the less well
understood processes of planet formation.

ACS/WFC 10056

Extreme Red Stars

ACS provides unprecedented sensitivity in the far red, this coupled
with recent astronomical pushes to ever cooler objects {e.g. new
classifications for L and T stellar dwarfs, and extremely high
redshift galaxies} increases the need for extending the photometric
calibration to include such objects. We propose observations of 2
stellar objects for which STIS spectra will exist, as well as NICMOS
grism. The two targets include a late M dwarf and a T dwarf. The M
dwarf provides a temporal check with WFC and new constraint for the
HRC. The T dwarf provides new results for the WFC.

ACS/WFC 9892

H-alpha Snapshots of Nearby Galaxies observed in F300W: Quantifying
Star Formation in a Dusty Universe

Previous studies of nearby galaxies show large discrepancies between
different star formation {SF} indicators on large {>100 pc, or even
global} scales: the strikingly complex interplay of young stars, dust
and ionized gas are the primary cause of this variance. The few
galaxies in the HST Archive with both WFPC2 H-alpha and mid-UV {F255W
or F300W} imaging show this complex geometry extending down to <10 pc
scales. We propose a SNAPshot survey in the ACS/WFC H-alpha filter of
48 galaxies of all Hubble types, that are nearby but beyond the Local
Group, and that were previously imaged with WFPC2 in the mid-UV and in
F814W. We aim to provide a benchmark for understanding the SF
processes in both normal and star-bursting galaxies, at spatial
resolutions unattainable from the ground for a large and varied galaxy
sample. These data can be applied to a wide range of astrophysical
problems and will, therefore, be made public immediately. Our science
goals are to: {1} spatially resolve the dust clouds and filaments
which strongly affect mid-UV and H-alpha derived SF rates, {2} test
how the large-scale correlation between H-alpha and mid-UV flux breaks
down on pc scales, and {3} model the propagation of star formation by
comparing the SF over time scales of ~100 Myr {via mid-UV} and ~5 Myr
{via H-alpha}. This will {4} significantly improve our insight into,
and calibration of SF in UV-bright galaxies at high z, and into the
cosmic SF history.

ACS/WFC 9991

The Orbit of a Newly Discovered Transneptunian Binary

We have recently discovered a binary companion to the transneptunian
object {TNO} 1999 RZ253. We are requesting rapid follow up
observations during cycle 12 to make observations sufficient for a
preliminary characterization of the orbital period, semimajor axis,
eccentricity, and inclination. In particular, it is urgent to
determine if this object is a candidate for observable mutual events
in the near future, a possibility that would greatly add to its
scientific interest. The study of TNBs is in a stage of explosive
growth, fueled in large part by the capabilities of HST that we seek
to exploit.

FGS 9879

An Astrometric Calibration of the Cepheid Period-Luminosity Relation

We propose to measure the parallaxes of 10 Galactic Cepheid variables.
There is no other instrument on or off the earth that can consistently
deliver HST FGS level of precision for critical parallaxes. When these
parallaxes {with 1-sigma precisions of 10% or better} are added to our
recent HST FGS parallax determination of delta Cep {Benedict et al
2002}, we anticipate determining the Period-Luminosity relation zero
point with a 0.03 mag precision. In addition to permitting the test of
assumptions that enter into other Cepheid distance determination
techniques, this calibration will reintroduce Galactic Cepheids as a
fundamental step in the extragalactic distance scale ladder. A
Period-Luminosity relation derived from solar metallicity Cepheids can
be applied directly to extragalactic solar metallicity Cepheids,
removing the need to bridge with the Large Magellanic Cloud and its
associated metallicity complications.

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 9833

T Dwarf Companions: Searching for the Coldest Brown Dwarfs

Faint companions to known stars have historically led to the discovery
of new classes of stellar and substellar objects. Because these
discoveries are typically limited by the flux ratio of the components
in the system, the intrinsically faintest companions are most
effectively identified around the intrinsically faintest primaries. We
propose to use NICMOS to image a sample of 22 of the coolest known
{T-type} brown dwarfs in the Solar Neighborhood in order to search for
fainter and cooler brown dwarf companions. The high spatial resolution
of the NIC 1 detector enables us to distinguish binary systems with
apparent separations greater than 0"08, or physical separations
greater than 1.2 AU at the nominal distances of the objects in our
sample. Furthermore, the substantial sensitivity of NICMOS imaging
allows us to probe companion masses of 5-50 Jupiter masses and
companion effective temperatures of 250-1300 K in a maximally
efficient manner. Based on work to date, we expect that roughly 20% of
the objects in our sample will be binary, and that one or two of these
will likely harbor a significantly fainter secondary. Hence, we expect
to find a companion cooler than any currently known brown dwarf, a
potential prototype for the next spectral class. In addition, our
investigation will add substantially to the sample of known binary
brown dwarfs, allowing improved statistical analyses of the binary
fraction, separation distribution, and mass ratio distribution of
these systems, key quantities for probing brown dwarf formation. We
will also identify optimal substellar systems for astrometric mass
measurements, a critical check for theoretical models of brown dwarfs
and extrasolar planets.


Spectroscopy and Polarimetry of Mars at Closest Approach

We plan a coordinated program of spectroscopy, imaging, and
spectropolarimetry of Mars during the August 2003 opposition to study
the composition and physical state of surface materials and airborne
aerosols. The observations include {a} Moderate spectral resolution
290 to 570 nm STIS long-slit push-broom imaging spectroscopy of Mars,
to constrain the properties of airborne aerosol particles and to
search for and globally map iron-bearing minerals that are diagnostic
of specific past climatic conditions; {b} WFPC2 UV-VIS images designed
primarily to quantify the effects of ice and dust aerosols on our STIS
spectra; {c} NICMOS near-IR images to search for and globally map the
presence of hydrated surface minerals; and {d} ACS multispectral
polarizer images to provide critical phase function measurements
needed to constrain the physical properties of the Martian surface
layer. The observations are timed to take advantage of the closest
approach of Mars to Earth for the next several hundred years. Images
and spectra will be acquired at a spatial scale comparable to existing
spacecraft orbital spectroscopy data {~10 km/pixel} and in wavelength
regions not sampled by past or current Mars spacecraft
instrumentation. These observations also provide complementary
scientific and calibration measurements in support of current and
future NASA and ESA Mars exploration missions.

NIC2 9834

Finding Planets in the Stellar Graveyard: A Faint Companion Search of
White Dwarfs with NICMOS

We propose to do a deep search for substellar objects in orbit around
white dwarfs with the newly refurbished NICMOS camera as part of the
PI’s doctoral thesis work. Direct imaging of planets around main
sequence stars is difficult due to the large contrast ratio, a problem
which is much less severe for companions to white dwarfs. White dwarfs
are not usually considered in planet searches but recent theoretical
work and observations are motivating new searches for planetary
systems and dust disks around DAZ white dwarfs. We propose to conduct
the search with the NIC2 coronagraph to find resolved companions and
do photometry to search for unresolved companions through Near-IR
excesses. We estimate that the survey will be sensitive to brown
dwarfs, high mass jovian planets, and dust disks. By probing a wide
range of orbital separations and companion masses, this survey will
help to answer questions about the brown dwarf desert, common envelope
evolution, and planet formation. HST and NICMOS provide a unique
capability to do this search, as no ground based observatory with AO
can adequately search for faint companions as close and with such high


NICMOS Post-SAA calibration – CR Persistence Part 2

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 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.

STIS/CCD 10000

STIS Pure Parallel Imaging Program: Cycle 12

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

STIS/MA1 9790

Separating Activity and Accretion in T Tauri Stars

Due to their unique evolutionary state, the naked {non-accreting} T
Tauri stars {NTTS} are the only real proxies for what the underlying
magnetically active star of a classical TTS {CTTS} system looks like.
Comparative analysis then allows us to separate stellar properties
from accretion properties in CTTS. In addition, the late-type NTTS are
excellent candidates for studying rotation-activity relationships in
fully convective stars and probing the properties of turbulent
dynamos. With the limited data currently available, NTTS appear to be
very magnetically active stars with higher than expected H-alpha/X-ray
flux ratios but lower transition region fluxes relative to other
active stars. However, the data are very incomplete. We will use
HST-STIS observations of transition region line fluxes on 11 fully
convective NTTS to establish the level and structure of dynamo
generated emission in these young stars. In principal, these far
ultraviolet emission lines are sensitive diagnostics of mass accretion
onto CTTS, since accretion shocks on the stellar surface should
produce substantial emission measure at 10^5 – 10^6 K. However, it is
imperative that we first understand the emissions from NTTS before we
can use these lines to study accretion onto CTTS.

WFPC2 10068

WFPC2 CYCLE 12 Standard Darks

This dark calibration program obtains dark frames every week in order
to provide data for the ongoing calibration of the CCD dark current
rate, and to monitor and characterize the evolution of hot pixels.
Over an extended period these data will also provide a monitor of
radiation damage to the CCDs.

WFPC2 9595


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

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.


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

HSTAR 9147: FHST Full Maneuver Updates (U1,3FM) failed @
259/02:16:57Z and 259/02:19:42Z with Error Box results showing "1
FAILED" for mnemonics QEBSTFG0 and QEBSTFG1 and "1 & 2 FAILED" for
QEBSTFG2. GS Acquisition @ 259/02:31:11Z failed due to SRLE. Under

HSTAR 9149: GS Acquisition (2,1,2) @ 259/02:23:11Z failed to Gyro
hold due to SRLE on FGS 2. GS Re-acquisition @ 259/03:20Z also
failed. FHST Map @ 259/02:30:43Z showed vehicle axis errors of 46.310,
-78.194, and 58.524. GS Re-acquisition @ 259/04:55:00Z failed. An
ARU/PRT was uplinked and GS Re-acquisition @ 259/06:31:22Z was
successful. Under investigation.

17040-0 R/T Map @259/0520z
17041-0 ARU/PRT @259/0550z

1155-0 Change Limits for MAMA2 Threshold Voltage (closed) @258/1343z

                          SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq              11                       10             
FGS REacq              5                          3              
& 0454z (HSTAR#9149)
FHST Update            28                        26            


Primary GS Acquisition failed @ 259/02:23:11Z, see HSTAR 9147 and
9149. FHST Full Maneuver Updates (U1,3FM) @ 259/02:16:57Z and
259/02:19:42Z failed with Error Box results showing "1 FAILED" for
mnemonics QEBSTFG0 and QEBSTFG1 and 1 & 3 Fail for QEBSTFG2.
Subsequent GS Acquisition @ 239/02:23Z failed due to SRLE. FHST Map @
259/02:30Z showed attitude errors of 46.310, -78.194, and 58.524 (V1,
V2, and V3 respectively). FOT attempted ARU/PRT generation based on
Map scheduled @ 259/03:32Z, but had insufficient time to process. A
FAD and ARU/PRT generation was performed @ 259/05:15Z and uplinked @
259/05:49:10Z. Resulting attitude allowed for a successful GS
Re-acquisition @ 259/06:31Z and science activities were resumed.

Battery 1 Capacity Test scheduled 259/11:24Z (OR 17035-1 with attached
script. There are three opportunities to connect SA Section 1 to Diode
Bus B: 259/11:33Z, 13:09Z, and 15:01Z. These three opportunities
ensure no large trickle discharge in the orbit prior to start of
capacity test. Estimate reconfiguration to FSW 6-Battery system @

SpaceRef staff editor.