Status Report

NASA Hubble Space Telescope Daily Report # 3801

By SpaceRef Editor
February 22, 2005
Filed under , ,
NASA Hubble Space Telescope Daily Report # 3801

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT        # 3801



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.

ACS/HRC 10377

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 coronagraphic
monitoring is required to assess the changing position of the spots.


ACS CCDs daily monitor- cycle 13 – part 1

This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in ACS CCD detectors. The files, biases and dark will be used to
create reference files for science calibration. This programme will be
for the entire lifetime of ACS.


Accurately Mapping M31’s Microlensing Population

We propose to augment an existing microlensing survey of M31 with
source identifications provided by a modest amount of ACS {and WFPC2
parallel} observations to yield an accurate measurement of the masses
responsible for microlensing in M31, and presumably much of its dark
matter. The main benefit of these data is the determination of the
physical {or “Einstein”} timescale of each microlensing event, rather
than an effective {“FWHM”} timescale, allowing masses to be determined
more than twice as accurately as without HST data. The Einstein
timescale is the ratio of the lensing cross-sectional radius and
relative velocities. Velocities are known from kinematics, and the
cross-section is directly proportional to the {unknown} lensing mass.
We cannot easily measure these quantities without knowing the
amplification, hence the baseline magnitude, which requires the
resolution of HST to find the source star. This makes a crucial
difference because M31 lens mass determinations can be more accurate
than those towards the Magellanic Clouds through our Galaxy’s halo
{for the same number of microlensing events} due to the better
constrained geometry in the M31 microlensing situation. Furthermore,
our larger survey, just completed, should yield at least 100 M31
microlensing events, more than any Magellanic survey. A small amount
of ACS+WFPC2 imaging will deliver the potential of this large database
{about 350 nights}. For the whole survey {and a delta-function mass
distribution} the mass error should approach only about 15%, or about
6% error in slope for a power-law distribution. These results will
better allow us to pinpoint the lens halo fraction, and the shape of
the halo lens spatial distribution, and allow
generalization/comparison of the nature of halo dark matter in spiral
galaxies. In addition, we will be able to establish the baseline
magnitude for about 50, 000 variable stars, as well as measure an
unprecedentedly detailed color-magnitude diagram and luminosity
function over much of M31.

ACS/WFC 10237

Low-Ionization BALs: Evolution or Orientation?

We propose to test the hypothesis that Low-Ionization Broad Absorption
Line Quasars {LoBALs} represent a special stage of quasar evolution:
young quasars in systems with strong interaction and star-formation.
We will carry out high resolution imaging using ACS/WFC and NICMOS to
measure the properties of the host galaxies of four LoBAL quasars at z
= 0.9 – 2.0 that show strong overlapping FeII absorption troughs. The
ACS imaging will be carried out in the passband with the strongest BAL
absorption, acting as a natural coronagraph. This results in a
reduction of quasar light by a factor of 15 – 26 in these passbands,
providing arguably the best view of the host galaxies of luminous,
high-redshift quasars. This method allows efficient detection and
detailed modeling of the host galaxy morphology in the rest-frame
ultraviolet, which is most sensitive to star formation and galaxy
interaction. We will also use NICMOS imaging to measure the rest-
frame light from the host galaxy to probe the old stellar populations
where the host galaxy is likely to be brighter. It has been suggested
that LoBALs might not be explained simply as an orientation effect but
rather as an early phase of quasar evolution. Such a phase is
typically associated with large amounts of dust and gas, and young
galaxies with strong star formation. With HST observations, we will
study the color and morphology of the FeLoBAL quasar host galaxies,
and measure the age of their dominant stellar populations. We will
also measure the density of close companions, and, in particular, look
for signs of ongoing or recent mergers. These measurements will be
compared to those of control samples of normal quasars at similar
redshift. If LoBALs are indeed young systems, then their host galaxies
are expected to show stronger interactions and merger activity,
younger stellar ages, and regions with strong star formation. If the
LoBAL host galaxies show no significant difference from those of
normal quasars, it will support the view that LoBAL quasars are not a
distinct population and that all quasars have BAL outflows along some
lines of sight.

ACS/WFC 10210

Groups of Dwarf Galaxies: Pools of Mostly Dark Matter?

Within 5 Mpc, there are 6 groups with well-known luminous galaxies but
there also appears to be a comparable number of groups containing only
dwarfs. If these dwarf entities are truly bound then M/L values are an
order of magnitude higher than values found for groups with luminous
spiral galaxies. There are theoretical reasons to anticipate that low
mass halos may frequently be mostly dark. The dynamical influence of
low mass halos is negligible in familiar groups with luminous members.
By contrast, a study of the dynamics of `groups of dwarfs’ may provide
direct evidence of the existence of dark matter potential wells with
few baryons. The goal of the present study is to gather detailed
information on the 3-D distribution of dwarf galaxies suspected to lie
within 7 groups of dwarfs within 5 Mpc. Distances with 7% relative
accuracy can be measured with the Tip of the Giant Branch method with
ACS and integrations within 1 orbit per target.

ACS/HRC 10198

Probing the Dynamics of the Galactic Bar through the Kinematics of
Microlensed Stars

The observed optical depths to microlensing of stars in the Galactic
bulge are difficult to reconcile with our present understanding of
Galactic dynamics. The main source of uncertainty in those comparisons
is now shifting from microlensing measurements to the dynamical models
of the Galactic bar. We propose to constrain the Galactic bar models
with proper motion observations of Bulge stars that underwent
microlensing by determining both the kinematic identity of the
microlensed sources and the importance of streaming motions. The
lensed stars are typically farther than randomly selected stars.
Therefore, our proper motion determinations for 36 targeted MACHO
events will provide valuable constraints on the dynamics of bulge
stars as a function of distance. The first epoch data for our proposed
events is already available in the HST archive so the project can be
completed within a single HST cycle. The exceptional spatial
resolution of HST is essential for completion of the project.
Constraints on the total mass in the bulge will ultimately lead to the
determination of the amount of dark matter in inner Galaxy.


The Star Formation History and Metallicity Evolution of M33: A
Comprehensive Study of Disk Evolution

We will obtain deep, panchromatic imaging photometry of stellar
populations in four fields ranging from 0.5 to 4 scale lengths across
the disk of the Local Group spiral M33. The observations are designed
to detect the oldest main-sequence turnoffs in three outer disk
fields, and to reach the crowding limit in the innermost field. We
will combine the photometry data with information we already have
in-hand on abundances from stars and H II regions in M33 to derive the
star formation history and metallicity evolution of the M33 disk. The
information from our four fields will allow us to obtain {1} the ages
of the oldest disk stars and the radial variation of their ages; {2}
the radial variation of the star formation history and its nature
{e.g., constant, declining, or bursting}; and {3} the metallicity
distribution in each field and the time evolution of the metallicity
gradient. Our team, an experienced mix of photometrists,
spectroscopists, and galaxy evolution theorists, will use the results
from this program to construct a comprehensive chemo- dynamical model
for the M33 disk. This detailed study of M33 will be a key in
developing an understanding of the formation and evolution of disks
that can be applied to studies of disks at both low and high redshift,
and will also yield a wealth of information on stellar populations,
chemical evolution, and star clusters that will be of great value to
future investigators.

ACS/WFC/NIC2 10189

PANS-Probing Acceleration Now with Supernovae

Type Ia supernovae {SNe Ia} provide the most direct evidence for an
accelerating Universe, a result widely attributed to dark energy.
Using HST in Cycle 11 we extended the Hubble diagram with 6 of the 7
highest-redshift SNe Ia known, all at z>1.25, providing conclusive
evidence of an earlier epoch of cosmic deceleration. The full sample
of 16 new SNe Ia match the cosmic concordance model and are
inconsistent with a simple model of evolution or dust as alternatives
to dark energy. Understanding dark energy may be the biggest current
challenge to cosmology and particle physics. To understand the nature
of dark energy, we seek to measure its two most fundamental
properties: its evolution {i.e., dw/dz}, and its recent equation of
state {i.e., w{z=0}}. SNe Ia at z>1, beyond the reach of the ground
but squarely within the reach of HST with ACS, are crucial to break
the degeneracy in the measurements of these two basic aspects of dark
energy. The SNe Ia we have discovered and measured with HST in Cycle
11, now double the precision of our knowledge of both properties. Here
we propose to quadruple the sample of SNe Ia at z>1 in the next two
cycles, complementing on-going surveys from the ground at z<1, and again doubling the precision of dark energy constraints. Should the current best fit model prove to be the correct one, the precision expected from the current proposal will suffice to rule out a cosmological constant at the 99% confidence level. Whatever the result, these objects will provide the basis with which to extend our empirical knowledge of this newly discovered and dominant component of the Universe, and will remain one of the most significant legacies of HST. In addition, our survey and follow-up data will greatly enhance the value of the archival data within the target Treasury fields for galaxy studies.

ACS/HRC 10182

Towards a Comprehensive Understanding of Type Ia Supernovae: The
Necessity of UV Observations

Type Ia supernovae {SNe Ia} are very important to many diverse areas
of astrophysics, from the chemical evolution of galaxies to
observational cosmology which led to the discovery of dark energy and
the accelerating Universe. However, the utility of SNe Ia as
cosmological probes depends on the degree of our understanding of SN
Ia physics, and various systematic effects such as cosmic chemical
evolution. At present, the progenitors of SNe Ia and the exact
explosion mechanisms are still poorly understood, as are evolutionary
effects on SN Ia peak luminosities. Since early-time UV spectra and
light curves of nearby SNe Ia can directly address these questions, we
propose an approach consisting of two observational components: {1}
Detailed studies of two very bright, young, nearby SNe Ia with HST UV
spectroscopy at 13 epochs within the first 1.5 months after discovery;
and {2} studies of correlations with luminosity for five somewhat more
distant Hubble-flow SNe Ia, for which relative luminosities can be
determined with precision, using 8 epochs of HST UV spectroscopy
and/or broad-band imaging. The HST data, along with extensive
ground-based optical to near-IR observations, will be analyzed with
state-of-the-art models to probe SN Ia explosion physics and constrain
the nature of the progenitors. The results will form the basis for the
next phase of precision cosmology measurements using SNe Ia, allowing
us to more fully capitalize on the substantial past {and future}
investments of time made with HST in observations of high-redshift SNe

NIC2 10176

Coronagraphic Survey for Giant Planets Around Nearby Young Stars

A systematic imaging search for extra-solar Jovian planets is now
possible thanks to recent progress in identifying “young stars near
Earth”. For most of the proposed young {<~ 30 Myrs} and nearby {<~ 60 pc} targets, we can detect a few Jupiter-mass planets as close as a few tens of AUs from the primary stars. This represents the first time that potential analogs of our solar system - that is planetary systems with giant planets having semi-major axes comparable to those of the four giant planets of the Solar System - come within the grasp of existing instrumentation. Our proposed targets have not been observed for planets with the Hubble Space Telescope previously. Considering the very successful earlier NICMOS observations of low mass brown dwarfs and planetary disks among members of the TW Hydrae Association, a fair fraction of our targets should also turn out to posses low mass brown dwarfs, giant planets, or dusty planetary disks because our targets are similar to {or even better than} the TW Hydrae stars in terms of youth and proximity to Earth. Should HST time be awarded and planetary mass candidates be found, proper motion follow-up of candidate planets will be done with ground-based AOs.

NIC2 10173

Infrared Snapshots of 3CR Radio Galaxies

Radio galaxies are an important class of extragalactic objects: they
are one of the most energetic astrophysical phenomena and they provide
an exceptional probe of the evolving Universe, lying typically in high
density regions but well-represented across a wide redshift range. In
earlier Cycles we carried out extensive HST observations of the 3CR
sources in order to acquire a complete and quantitative inventory of
the structure, contents and evolution of these important objects.
Amongst the results, we discovered new optical jets, dust lanes,
face-on disks with optical jets, and revealed point-like nuclei whose
properties support FR-I/BL Lac unified schemes. Here, we propose to
obtain NICMOS infrared images of 3CR sources with z<0.3 as a major enhancement to an already superb dataset. We aim to deshroud dusty galaxies, study the underlying host galaxy free from the distorting effects of dust, locate hidden regions of star formation and establish the physical characteristics of the dust itself. We will measure frequency and spectral energy distributions of point-like nuclei, expected to be stronger and more prevalent in the IR, seek spectral turnovers in known synchrotron jets and find new jets. We will strongly test unified AGN schemes and merge these data with existing X-ray to radio observations. The resulting database will be an incredibly valuable resource to the astronomical community for years to come.

ACS/HRC 10148

The Masses of the Ultraluminous X-Ray Sources

Ultraluminous X-ray sources are non-nuclear sources in normal disk
galaxies that are second only to AGNs in point-source luminosity.
These enigmatic objects are either stellar mass black holes that are
super-Eddington emitters, or sub-Eddington emission from 1E3-1E4
Msolar black holes. We can distinguish between these models by a
direct determination of the mass of the primary, which requires
knowing the spectral type of the secondary, its period, and its
orbital velocity around the black hole. We propose to obtain UV
spectra to determine the spectral type of two ULX secondaries {optical
counterparts}, to infer the masses and radii of the secondaries and
their suitability for radial velocity studies. For another ULX
secondary, we already obtained a UV spectrum showing it to be a B0I
star, so we propose three additional observations, which will yield
the characteristic orbital velocity, help constrain the period, and
reveal if the primary is a 1E3-1E4 Msolar black hole, which would
produce velocities > 1000 km/sec.

NIC1 10143

Ultracool companions to the nearest L dwarfs

We propose to conduct the most sensitive survey to date for low mass
companions to nearby L dwarfs. We will use NICMOS to image targets
drawn from a volume-complete sample of 70 L dwarfs within 20 parsecs.
The combination of infrared imaging and proximity will allow us to
search for T dwarf companions at separations as small as 1.6 AU. This
is crucial, since no ultracool binaries are currently known with
separations exceeding 15 AU. Only 10 dwarfs in this sample have
previous HST observations primarily at optical wavelengths. With the
increased sensitivity of our survey, we will provide the most
stringent test to date of brown dwarf models which envisage formation
as ejected stellar embryos. In addition, our observations will be
capable of detecting binaries with mass ratios as low as 0.3, and will
therefore also test the apparent preference for equal-mass ultracool
binaries. Finally, our observations offer the best prospect to date of
detecting companions significantly cooler than the coolest t dwarf
currently known.


Searching for the Bottom of the Initial Mass Function

The minimum mass of the Initial Mass Function {IMF} should be a direct
reflection of the physical processes that dominate in the formation of
stars and brown dwarfs. To date, the IMF has been measured down to 10
M_Jup in a few young clusters; there is no sign of a low-mass cutoff
in the data for these clusters. We propose to obtain deep images in
the SDSS i and z filters {i=26, z=25} with the ACS/WFC on HST for a
800″x1000″ field in the Chamaeleon I star-forming region {2 Myr, 160
pc}. By combining these HST data {0.8, 0.9 um} with comparably deep
broad-band photometry from ground-based telescopes {1.2, 1.6, 2.2 um}
and SIRTF {3.6, 4.5, 5.8, 8.0 um}, we will measure the mass function
of brown dwarfs down to the mass of Jupiter and thus determine the
lowest mass at which objects can form in isolation in a typical star
forming cluster.

ACS/WFC 10135

Unveiling the Progenitors and Physics of Cosmic Explosions

GRBs and XRFs are clearly highly asymmetric explosions and require a
long-lived power source {central engine}. In contrast, nearby
core-collapse events are essentially spherical explosions. However,
the failure of spherical neutrino driven collapses has led to the idea
that asymmetric energy release is essential for the explosion. The
recent finding of a Type Ic SN in GRB 030329, the association of the
low energy event GRB 980425 with SN 1998bw, the theoretical
development discussed above and the rise of collapsar models make it
timely to consider whether all these explosions contain engines. Given
the uncertainties in theoretical modeling it is clear that
observations are needed to guide models. A priori there is little
reason to expect connection between the ultra- relativistic jet that
powers the GRB and the explosive nucleosynthesis of the ~0.5 solar
masses of Nickel-56 that powers the accompanying supernova. We propose
a comprehensive program of ACS photometric searches {and measurements}
for SNe associated with GRBs and XRFs. In concert, we will undertake
ground-based spectroscopy to determine velocity widths, and measure
engine parameters from pan- chromatic afterglow observations. Our goal
is to produce a comprehensive database of engine and SN physical
parameters against which theoretical modeling will be guided.

WFPC2 10132

UV Confirmation of New Quasar Sightlines Suitable for the Study of
Intergalactic Helium

The reionization of intergalactic helium is thought to have occurred
between redshifts of about 3 and 4. The study of HeII Lyman-alpha
absorption towards a half-dozen quasars at 2.7 < z < 3.5 demonstrates the great potential of such probes of the IGM, but the current critically-small sample limits confidence in resulting cosmological inferences. The requisite unobscured quasar sightlines to high-redshift are extremely rare, especially due to severe absorption in random intervening Lyman-limit systems, but SDSS provides hundreds of bright, new quasars at such redshifts potentially suitable for HeII studies. Our cycle 13 SNAP program proposes to verify the UV detectability of 40 new, bright, z>2.9 SDSS quasars, but with special
emphasis on extending helium studies to the highest redshift
sightlines. Our proposed approach has already proven successful, and
additional sightlines will enable follow-up spectal observations to
measure the spectrum and evolution of the ionizing background
radiation, the density of intergalactic baryons, and the epoch of
reionization of the IGM.

ACS/HRC 10094

Mid-Ultraviolet Spectral Templates for Old Stellar Systems

We propose a three-year program to provide both observational and
theoretical mid- ultraviolet {2300A — 3100A} spectral templates for
interpreting the age and metallicity of globular clusters and
elliptical galaxies from spectra of their integrated light. The mid-UV
is the region most directly influenced by stellar age, and is observed
directly in optical and infrared studies of high-redshift quiescent
systems. The reliability of age and metallicity determinations remains
questionable until non-solar metallicities and abundance ratios are
considered, and stars spanning the color-magnitude diagram are
included, as we propose here. With archival HST STIS spectra we have
improved the list of mid-UV atomic line parameters, then calculated
spectra from first principles which match observed spectra of standard
stars up to one- fourth solar metallicity. We will extend both
observations and calculations to stars of solar metallicity and
beyond, and to those in short-lived stages hotter than the
main-sequence turnoff, stars not currently well-represented in
empirical libraries. The necessary line-list improvements will come
from new high-resolution mid-UV spectra of nine field stars. A key
application of the results of this program will be to the old systems
now being discovered as `Extremely Red Objects’ at high redshifts.
Reliable age-dating of these places constraints on the epoch when
large structures first formed in the universe.


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

HSTAR 9711 : GSacq(2,1,1) to RGA hold during Two Gyro Testing @
052/0414z – GSacq(2,1,1) scheduled for 052/04:14:07 – 04:22:50 failed
to RGA hold due to Loss Of Lock after fine lock was acquired. This
occurred during the F2G on-Orbit testing.  The FHST OBAD (no maneuver)
scheduled for 05:09:13 showed errors of 0.1405, -0.1796, 0.2046 (deg).
With a RSS of 0.3063 deg. Observations affected: NIC 2 – 3, ACS 1 – 3.  
Under investigation.

HSTAR 9712 : FHST not in FFOV during TGS test @ 052/0200z-FHST 1 was
hung in search mode at start of On-Orbit test until FFOV was
commanded. FHST 3 exhibited same symptom at 52/02:00 until an ops
request was sent to command it to FFOV. FFOV needed to be commanded
upon FHST availability by FSW. Under investigation.

HSTAR 9713 : GSacq(2,3,3) resulted in Planned FLBU during F2G On-Orbit
Test @ 052/0641z – GSacq(2,3,3) scheduled for 052/06:41:20 – 06:50:14
resulted in a planned Fine Lock Backup on FGS #2 due to a Scan Step
Limit Exceeded on Fgs #3.  Possible observations affected: NIC 4.
Under investigation.


  • 17367-0 – FSW 2.7A EEPROM Installation @ 049/1908z
  • 17375-1 – Reduce FGS1 K16ACLIM prior to F2G OOT entry @ 049/2114z
  • 17371-0 – Two Gyro OOT-3 Initialization @ 052/0056z
  • 17373-1 – Table 213 Dump @ 052/0119z
  • 17376-0 – Setup FGS1 K16ACLIM in TMDIAG for F2G OOT @ 052/0221z
  • 17382 2 – OBAD Test @ 052/0530z
  • 17381-0 – Activate HN format @ 052/0652z
  • 17377-0 – Reset FGS1 K16ACLIM to 4,982 @ 052/0739z


                             SCHEDULED     SUCCESSFUL    FAILURE TIMES 
 Gsacq                 28                        27              052/0414z 
 (HSTAR 9711) 
 FGS Reacq                 15                        15 
 FHST Update               40                        40 


On DOY 2005.049, Ops Request 17375-1 was successfully executed to
lower the FGS1 K16ACLIM value from the nominal 12,335.625 a-s/s/cycle
to 4,982.625 a-s/s/cycle. Commanding was successfully completed and
verified by 049/21:15 GMT.

SpaceRef staff editor.