Status Report

NASA Hubble Space Telescope Daily Report # 3589

By SpaceRef Editor
April 12, 2004
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NASA Hubble Space Telescope Daily Report # 3589

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science




FGS 9888

Trigonometric Calibration of the Period- Luminosity Relations for
Fundamental and First-Overtone Galactic Cepheids

Cepheids are the primary distance indicators for the extragalactic
distance scale and the Hubble constant. The Hubble Constant Key
Project set the zero-point for their Cepheid distance scale by
adopting a distance to the LMC, averaged over a variety of techniques.
However, different methods give an LMC distance modulus ranging from
18.1 to 18.8, and the uncertainty in the Cepheid zero-point is now the
largest contributor to the error budget for H_0. Moreover, the low
metallicity of the LMC raises additional concerns, since the PL
relation probably depends on metallicity. The zero-point can be
determined from Hipparcos parallaxes of Galactic Cepheids out to
several hundred parsecs, but with a typical parallax error of 0.5-1
mas, the Hipparcos error bars are uncomfortably large for this
demanding application. By contrast, HST’s FGS1R interferometer can
achieve astrometric accuracy of 0.2 mas. We propose to use FGS1R to
determine trigonometric parallaxes for a sample of 9 nearby Cepheids,
including both fundamental {F} and first-overtone {FO} pulsators. We
show that the improvement in the PL relations for F and FO Cepheids
will be dramatic. We will determine the PL slopes from our nearby
solar- metallicity sample alone, without recourse to nearby galaxies
and the issue of [Fe/H] dependence. The zero-point will be determined
robustly to about 0.05 mag, based on accurate, purely geometrical
measurements. All of this can be achieved in the next few years with
HST, without having to wait for the technically demanding and risky
SIM and GAIA missions well into the next decade.


Boron in F Stars in the Hyades – Insights into the Li-Be Dip

Dramatic deficiencies of Li in the mid-F stars of the Hyades were
discovered by Boesgaard and Tripicco in 1986. Using ultraviolet,
high-resolution spectra from the Keck 10-m telescope, Boesgaard and
King have just discovered the corresponding deficiencies in Be in the
same narrow temperature region in the Hyades. We propose a precision
investigation into the B abundance in the Hyades F stars to ascertain
if there is a B dip. Boron can only be observed with HST and we plan
to use the resonance line of B I at 2497A. Each of these three light
elements is destroyed inside stars, but each has a different threshold
temperature: 2.5 x 10^6, 3.5 x 10^6, and 5 x 10^6 K for Li, Be, and B
respectively. Consequently, these elements survive to increasingly
greater depths in a star and their surface abundances act as a report
on the depth and thoroughness of mixing in the star. The mixing
mechanism in F stars is slow mixing, but not straight convective
mixing. These observations will help determine the nature of the
mixing mechanism{s}, and the connection to stellar rotation. The
abundance of *all three* light elements in a cluster ofknown age and
metallicity provides the necessary information to discern the internal
stellar processes. This mixing must be occurring in other stars of
this mass range {~10-25% more massive than the sun} and can best be
studied in a cluster of stars of common origin and known
characteristics. The Hyades cluster at 7 x 10^8 yr is close enough to
contain stars bright enough for this investigation.

FGS 9879

An Astrometric Calibration of the Cepheid Period-Luminosity Relation

We propose to measure the parallaxes of 10 Galactic Cepheid variables.
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.


Probing IGM Phases, Metals, and the Cosmic Web with New SDSS QSOs

We propose STIS G140L SNAPSHOT observations of 100 new z < 1 QSOs from
the Sloan Digital Sky Survey for studies of the IGM. These targets
will be chosen to simultaneously maximize IGM pathlength and to form
closely spaced groups of 2-8 QSO sightlines within 1 h^-1 Mpc of a
foreground galaxy. These observations will, in the long term, provide
a rich database of target QSOs for detailed study by COS of the IGM
phases, metallicity, and relationship to the large scale structure. In
the near term, these observations will detect up to 10 Lyman alpha
clouds with N_HI > 10^14 and 3 clouds with N_HI > 10^15, per target.
Thus they will provide an immediate test of filamentary structure in
the "cosmic web" within 1 h^-1 Mpc of galaxies. We ask for 22 minute
exposures for each target with STIS/G140L to obtain S/N = 5-16 for
these V = 16 – 18 QSOs. These observations will be sensitive to Lyman
alpha equivalent widths ranging from 300 mA for the brighter sources
to 600 mA at the fainter end. These targets represent a Deltaz
pathlength of 17 {at 50% yield}, with Deltaz = 10 in the range where
Lya, Lyb, and O VI lie in the HST band. These observations will also
refine predictions of the FUV flux of QSOs based on the larger SDSS
sample and will estimate the degree to which such factors as intrinsic
and Galactic extinction, variability, and intervening absorption can
be controlled. If successful, this technique could make
UV-prequalification SNAPs of QSOs obsolete, at a significant savings
of HST time. Our observations lie at the median duration for SNAPs,
and in the range most likely to be executed. Our program accomplishes
both near- and long-term goals at a relatively low investment of time,
and thus is ideally suited for a SNAP proposal. To ensure maximum
scientific return for our own purposes and for additional science
{HVCs, Galactic halo} we waive the right to a proprietary data period.


The COSMOS 2-Degree ACS Survey

We will undertake a 2 square degree imaging survey {Cosmic Evolution
Survey — COSMOS} with ACS in the I {F814W} band of the VIMOS
equatorial field. This wide field survey is essential to understand
the interplay between Large Scale Structure {LSS} evolution and the
formation of galaxies, dark matter and AGNs and is the one region of
parameter space completely unexplored at present by HST. The
equatorial field was selected for its accessibility to all
ground-based telescopes and low IR background and because it will
eventually contain ~100, 000 galaxy spectra from the VLT-VIMOS
instrument. The imaging will detect over 2 million objects with I> 27
mag {AB, 10 sigma}, over 35, 000 Lyman Break Galaxies {LBGs} and
extremely red galaxies out to z ~ 5. COSMOS is the only HST project
specifically designed to probe the formation and evolution of
structures ranging from galaxies up to Coma-size clusters in the epoch
of peak galaxy, AGN, star and cluster formation {z ~0.5 to 3}. The
size of the largest structures necessitate the 2 degree field. Our
team is committed to the assembly of several public ancillary datasets
including the optical spectra, deep XMM and VLA imaging, ground-based
optical/IR imaging, UV imaging from GALEX and IR data from SIRTF.
Combining the full-spectrum multiwavelength imaging and spectroscopic
coverage with ACS sub-kpc resolution, COSMOS will be Hubble’s ultimate
legacy for understanding the evolution of both the visible and dark


Reverberation Mapping of the Least Luminous Seyfert 1 Galaxy NGC 4395

We propose to make a short UV and optical reverberation mapping
monitoring of NGC~4395, by far the least luminous Seyfert 1 galaxy
known {M_B~ -10}, where the Broad Line Region {BLR} is most likely
between a fraction of a light hour to a few light hours across. This
program will: 1. extend by a factor of ~100 the range of R_BLR probed
by RM, 2. allow to test models for AGN continuum emission and BLR
structure at very low L and M_BH. 3. provide significantly more
reliable estimates of its M_BH than currently available, 4. allow to
probe the M_BH-sigma_* relation in AGN at very low M_BH, which cannot
be probed by other methods. Existing archival FOS observations
indicate significant {up to 30-40%} line and continuum variations
within one orbit, suggesting that the proposed RM is likely to
succeed. The unusually small R_BLR in NGC 4395 implies that RM can be
performed here at only a fraction of the cost required in typical AGN.

ACS/WFC 9788

A Narrow-band Snapshot Survey of Nearby Galaxies

We propose to use ACS/WFC to conduct the first comprehensive HST
narrow-band {H-alpha + [N II]} imaging survey of the central regions
of nearby bulge-dominated disk {S0 to Sbc} galaxies. This survey will
cover, at high angular resolution extending over a large field, an
unprecedented number of galaxies representing many different
environments. It will have important applications for many
astrophysical problems of current interest, and it will be an
invaluable addition to the HST legacy. The observations will be
conducted in snapshot mode, drawing targets from a complete sample of
145 galaxies selected from the Palomar spectroscopic survey of nearby
galaxies. Our group will use the data for two primary applications.
First, we will search for nuclear emission-line disks suitable for
future kinematic measurements with STIS, in order to better constrain
the recently discovered relations between black hole mass and bulge
properties. Preliminary imaging of the type proposed here must be
done, sooner or later, if we are to make progress in this exciting new
field. Second, we will investigate a number of issues related to
extragalactic star formation. Specifically, we will systematically
characterize the properties of H II regions and super star clusters on
all galactic scales, from circumnuclear regions to the large-scale

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.


Galaxy Evolution in Action : The Detailed Morphology of Post-Starburst

If galaxies evolve morphologically, then some should be in transition
between late and early types. One proposed evolutionary mechanism is a
galaxy-galaxy merger, but evolved merger products are difficult to
find. Fortunately, spectroscopic surveys have now uncovered large
numbers of E+A galaxies, a class of objects whose post-starburst
spectra, current lack of HI gas, and pressure-supported kinematics
suggest that they are the missing panel that connects the "Toomre
sequence" of merging spirals with normal ellipticals and S0s. Our
first HST observations of five of these galaxies are intriguing. We
find a considerable range of tidally disturbed morphologies, an "E+A"
fundamental plane, significant differences among the color gradients
within 1 kpc {~0.8”}, and populations of bright, blue globular
clusters. These initial results are difficult to interpret, however,
because they are drawn from a small sample of galaxies whose very blue
overall colors may have selected a particular evolutionary path of
E+As. Here we propose for ACS imaging of the remaining 15 E+As from
the Las Campanas Redshift Survey to probe the full range of E+A
properties. The proposed observations will allow us to 1} determine
what fraction of the interactions that lead to E+As destroy all
disk-like structures {and therefore necessarily lead to elliptical
formation}, 2} measure the inner color gradients and constrain the
spatial distribution of stars produced as gas sinks to the center
during a merger, and 3} determine whether these interactions produce
globular clusters in the required numbers to account for the increased
specific frequency of clusters in early-type galaxies.


The local Hubble flow and the density field within 6 Mpc

Great progress has been made recently in accurate distance
measurements of nearby galaxies beyond the Local Group based on the
luminosity of the tip of the red giant branch {TRGB}. Over the last
three years, snapshot surveys with HST have provided us with the TRGB
distances for more than a hundred nearby galaxies obtained with an
accuracy of about 10%. The local velocity field within 5 Mpc exhibits
a significant anisotropy which disagrees with a spherical
Virgo-centric flow. The local Hubble flow is very cold, with 1-D rms
deviations of ~30 km/s. Cosmological simulations with Cold Dark Matter
can only realize such low dispersions with a combination of a low mean
density of matter and a substantial component with negative pressure.
There may be a constraint on the equation of state w=-p/rho. Our
observations will concentrate on 116 galaxies whose expected distances
lie within 4 – 6 Mpc, allowing us to trace a Dark Matter distribution
in the Local Volume with twice the information currently available.
The program is a good one for SNAP mode because the order and rate
that the observations are made are not very important, as long as
there is good completion over several years.


ACS Imaging and STIS Spectroscopy of Binary Brown Dwarfs

We have compiled a sample of 9 spatially resolved binary brown dwarfs
{18 objects}, and now propose ACS imaging and STIS spectroscopic
follow-up observations. While theoretical models on the interplay of
chemical and physical processes governing brown dwarf atmospheres have
reached a high level of sophistication, interpretation of
observational data remains difficult. As brown dwarfs never stabilize
themselves on the hydrogen main sequence, there is always an ambiguity
between the temperature or luminosity of any brown dwarf and its mass
or age. The individual components of brown dwarf binaries, however,
are expected to be coeval and have the same underlying chemical
composition. This provides crucial constraints on any model, thus
greatly reducing the number of the free parameters. The aim is to
obtain photometric and spectroscopic data to probe the physical and
chemical properties of the brown dwarf atmospheres, as well as second
epoch astrometric data to characterize th e orbital motion. The study
will provide important feedback on theoretical model atmospheres and
evolutionary tracks for brown dwarfs. As such, it will be an important
step towards a better understanding of objects with spectral
properties intermediate between those of giant planets and late-type

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.

S/C 10097

NICMOS Temperature Setpoint Darks

NICMOS darks at different temperatures are needed to calibrate the
software tool used to create synthetic darks. Synthetic darks are used
during calibration. The temperatures of the NICMOS detectors will be
adjusted by +0.5 to -1.0 K from the nominal operating temperature.
Darks in each camera will be obtained at each of the temperature
settings. At the end of the Proposal the NCS nominal setpoint
temperature for the NICMOS detectors will be increased by 0.07 K for
the cool season {routine seasonal adjustment}.

WFPC2 10070

WFPC2 CYCLE 12 Supplemental Darks Part 2/3

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

WFPC2 10067

WFPC2 Cycle 12 Decontaminations and Associated Observations

This proposal is for the monthly WFPC2 decons. Also included are
instrument monitors tied to decons: photometric stability check, focus
monitor, pre- and post-decon internals {bias, intflats, kspots, &
darks}, UV throughput check, VISFLAT sweep, and internal UV flat


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/HRC 10050

ACS Earth Flats

High signal sky flats will be obtained by observing the bright Earth
with the HRC and WFC. These observations will be used to verify the
accuracy of the flats currently used by the pipeline and will provide
a comparison with flats derived via other techniques: L-flats from
stellar observations, sky flats from stacked GO observations, and
internal flats using the calibration lamps. Weekly coronographic
monitoring is required to assess the changing position of the spots.


ACS internal CTE monitor

The charge transfer efficiency {CTE} of the ACS CCD detectors will
decline as damage due to on-orbit radiation exposure accumulates. This
degradation will be closely monitored at regular intervals, because it
is likely to determine the useful lifetime of the CCDs. All the data
for this program is acquired using internal targets {lamps} only, so
all of the exposures should be taken during Earth occultation time
{but not during SAA passages}. This program emulates the ACS
pre-flight ground calibration and post-launch SMOV testing {program
8948}, so that results from each epoch can be directly compared.
Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}
data will be obtained over a range of signal levels for both the Wide
Field Channel {WFC}, and the High Resolution Channel {HRC}.

STIS/CCD 10020

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/CCD 10018

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.


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

HSTAR 9371: Upon AOS @ 100/11:00:52Z, HST was operating in FL backup
on FGS 1 only. No FGS flags were set. Further information after
engineering recorder dump. Secondary FGS GS ID 0024400268 is the same
star as in previous HSTAR 9370, primary GS ID is different from
previous HSTAR. Under investigation.

HSTAR 9372: GS Acquisition (2,1,1) @ 101/03:12:07Z ended in FL backup
on FGS 2 due to SSLE on FGS 1 @ 101/03:15:09Z. GS Reacquisitions @
101/04:31:22Z and 06:07:20Z also ended in FL backup on FGS 2. Under

HSTAR 9373: CCS "G" String CCLIsp alarming due to process count of
zero @ 103/05:20Z. Steve Brandenburg advised this is a known problem
and requires a full string recycle. FOT recycled string, problem
cleared. Under investigation.



  • 0900-1 COMMAND PROBLEM @ 101/06:40:23z
  • 0900-1 COMMAND PROBLEM @ 102/17:02:23z
  • 0911-0 Limit Management During WFPC2 Decontamination (M001) @100/1941z
  • 0911-0 Limit Management During WFPC2 Decontamination (M001) @101/0738z
  • 1216-0 HST486 S/W Memory Dump (RAM) @ 102/2100z
  • 1217-0 HST486 S/W Memory Dump (EEPROM) @ 103/0200z

                           SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq               25                        25
FGS REacq               26                        26
FHST Update             43                        43


SpaceRef staff editor.