Status Report

NASA Hubble Space Telescope Daily Report # 3835

By SpaceRef Editor
April 11, 2005
Filed under , ,

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT        # 3835



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.


The White Dwarf Cooling Age and Dynamical History of the Metal-Poor
Globular Cluster NGC 6397

We propose to determine the white dwarf cooling age in the nearest
metal-poor {[Fe/H]=- 2} globular cluster, NGC 6397. This globular
cluster provides the best opportunity to test the white dwarf cooling
age in such a metal-poor system and at the same time provide a
comparison with the more metal-rich cluster {M4} which we recently
successfully observed with HST. Any {or even no} age difference
between these clusters will be important in understanding the
age-metallicity relation for these systems which reflects the star
formation history in the early Galaxy. The absolute age is an
important cosmological constraint. We expect to be able to detect age
DIFFERENCES between these clusters at the 0.5 Gyr level and absolute
ages should be accurate to 1.0 Gyr. In addition, and in contrast with
M4, NGC 6397 is highly dynamically evolved, has a collapsed core, and
the distribution of its white dwarfs throughout the cluster have
almost certainly been modified by dynamical processes. We are using
N-body simulations specifically developed for this cluster to
understand these modifications and to include their effects in our
measurement of the white dwarf luminosity function and cooling age.
Among the dynamical questions we expect to answer with this proposal
are: 1} what was the primordial binary frequency in NGC 6397? 2} can
we explain the high central concentration with a population of massive
white dwarfs and/or neutron stars? 3} do we see sufficient central
binaries to reverse the core collapse of the cluster?


ACS CCDs daily monitor – Cycle 13 – Part 2

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.

ACS/WFC/NIC/NIC3/W 10246 FPC2 The HST survey of the Orion Nebula

We propose a Treasury Program of 104 HST orbits to perform the
definitive study of the Orion Nebula Cluster, the Rosetta stone of
star formation. We will cover with unprecedented sensitivity {23-25
mag}, dynamic range {~12 mag}, spatial resolution {50mas}, and
simultaneous spectral coverage {5 bands} a ~450 square arcmin field
centered on the Trapezium stars. This represents a tremendous gain
over the shallow WFC1 study made in 1991 with the aberrated HST on an
area ~15 times smaller. We maximize the HST observing efficiency using
ACS/WFC and WFPC2 in parallel with two opposite roll angles, to cover
the same total field. We will assemble the richest, most accurate and
unbiased HR diagram for pre-main-sequence objects ever made. Combined
with the optical spectroscopy already available for ~1000 sources and
new deep near-IR imaging and spectroscopy {that we propose as Joint
HST-NOAO observations}, we will be able to attack and possibly solve
the most compelling questions on stellar evolution: the calibration of
pre-main-sequence evolutionary tracks, mass segration and the
variation of the initial mass function in different environments, the
evolution of mass accretion rates vs. age and environment, disk
dissipation in environments dominated by hard vs. soft-UV radiation,
stellar multiplicity vs. disk fraction. In addition, we expect to
discover and classify an unknown, but substantial, population of
pre-Main Sequence binaries, low mass stars and brown dwarfs down to
~10 MJup. This is also the best possible way to discover dark
silhouette disks in the outskirts of the Orion Nebula and study their
evolutionary status through multicolor imaging. This program is timely
and extremely well leveraged to other programs targeting Orion: the
ACS H-alpha survey of the Orion Nebula, the recently completed 850ks
ultradeep Chandra survey, the large GTO programs to be performed with
SIRTF, plus the availability of 2MASS and various deep JHK surveys of
the core recently done with 8m class telescopes.

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.

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.

WFPC2 10170

Atmospheric Variability on Uranus and Neptune

We propose Snapshot observations of Uranus and Neptune to monitor
changes in their atmospheres on time scales of weeks, months, and
years. Uranus is rapidly approaching equinox in 2007, with another 4
degrees of latitude becoming visible every year. Recent HST
observations during this epoch {including 6818: Hammel, Lockwood, and
Rages; 7885: Hammel, Karkoschka, and Marley; 8680: Hammel, Rages,
Lockwood, and Marley; and 8634: Rages, Hammel, Lockwood, Marley, and
McKay} have revealed strongly wavelength-dependent latitudinal
structure and the presence of numerous visible-wavelength cloud
features in the northern hemisphere. Long-term ground-based
observations {Lockwood and Thompson 1999} show seasonal brightness
changes whose origins are not well understood. Recent near-IR images
of Neptune obtained using adaptive optics on the Keck Telescope
together with images from our Cycle 9 Snapshot program {8634} show a
general increase in activity at south temperate latitudes as well as
the possible development of another Great Dark Spot. Further Snapshot
observations of these two dynamic planets will elucidate the nature of
long-term changes in their zonal atmospheric bands and clarify the
processes of formation, evolution, and dissipation of discrete albedo

FGS 10106

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.


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

HSTAR #9764:  GSACQ(3,1,1) failed, search radius limit exceeded @
098/09:47:24z GSacq(3,1,1) at 098/09:42:46 failed to gyro control due
to Search Radius Limit Exceeded on FGS 3 at 09:47:24 and a second time
at 09:50:27.  Roll delay update at 08:45:49 had attitude errors of
5.176 on V1, 1.795 V2, 7.622 V3. Map at 09:51:00 had attitude errors
of 4.528, 10.110, -9.884. Observations Affected: ACS 23 to 28, NICMOS
73 to 75, WFPC 205 to 209. The Subsequent REacq(3,1,1) at 098/10:38:17
failed to RGA control. Under investigation.

HSTAR #9767: GSaq(1,3,1) failed, search radius limit exceeded @
098/23:58:31z GSacq(1,3,1) at 098/23:53:36z failed to gyro control due
to search radius limit exceed on FGS 1 at 23:58:31z. The REacq at
01:02:01z was successful. Observations Affected: WFPC 224 – 225, NIC
78. Under investigation.

HSTAR #9768: REACQ(1,3,1) requires 2 attempts to acquire Fine Lock
(FL) @ 100/ 01:04:04z.  REACQ(1,3,1) at 100/01:01:38z required two
attempts to enter FL, with Scan Step Limit exceeded at 01:04:04z.
Second attempt to acquire was successful.  Primary GSACQ had no
problems. Under investigation.

HSTAR #9769: NICMOS suspended, debug exception @ 100/23:3:56z. NICMOS
status buffer message 104, Parameter 2, Time 37290, was received at
acquisition of signal at 23:07:45.  Parameter 2 indicates a DEBUG
EXCEPTION occurred.  Under investigation.

HSTAR #9770: GSACQ(1,3,3) Fine Lock Backup @ 101/06:30:00z.
GSACQ(1,3,3)  occurred at 05:51:24z while vehicle was LOS. At AOS at
06:30z, vehicle was in Fine Lock on FGS 3 only, QF1STOPF and QSTOP
flags were set.  Additional information will be available after
Engineering Dump is merged.  Observations affected: WFPC 9 to 13, ACS
15 to 19, NICMOS 6.  Under investigation. Under investigation.

17416-2  Eclipse Management, GMT Day 098 @ 098/2355z
17417-1  NICMOS Memory Dump after Suspend @ 100/08:42:21z

0916-0  Tabulation of Slew Attitude Error (Miss-distance) @ 101/0035z
1327-0  Exec 272 while NICMOS is Suspended @ 101/0316z

                              SCHEDULED     SUCCESSFUL    FAILURE TIMES 
 Gsacq                  28                        26 
 098/09:47:24z, 098/23:58:31z 
 Reacq                  17                        16             098/10:38:17z 
 FHST Update                34                        34 


Eclipse Summary of SE Eclipse Flash Report (Fri, 08 Apr 2005) There
were five eclipse events occurring between GMT 98/18:05 to 98/22:39.
OPS Request 17416 was successfully executed in preparation for these
events by temporarily disabling the Rate of Charge and SA Cold
Protection safemode tests. The CSS timer was also modified to prevent
software logic from potentially detecting a false CSS failure due to
the eclipse. With trickle charge verified and a forward link available
following the fifth eclipse, resetting of the safemode tests and CSS
timer to their nominal state was completed at 23:55. Preliminary
results from limited real-time data appear to indicate that trickle
charge was still reached during all but the last eclipse. Near EON at
22:31, the fifth eclipse started as well as a 127.14 deg vehicle
maneuver which caused trickle charge not to be reached before start of
night as anticipated. Trickle charge was reached in the following
orbit day at about 23:50 and EPS is nominal.

NICMOS suspended at 100/23:03:46 due to an Intel Debug Exception (ESB
104, P=2). HSTAR 9769 was generated by the FOT. NICMOS memory was
successfully dumped via Ops Request 17417 at 101/08:42z and the files
transferred to the Payload FSW team for analysis. NICMOS recovery is
scheduled to begin at 101/12:50z via Ops Request 17418.

SpaceRef staff editor.