Daily Report #4582

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4582

PERIOD COVERED: UT April 03, 2008 (DOY 094)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

A new proceedure proposed to alleviate the CR-persistence problem of NICMOS.
Dark frames will be obtained immediately upon exiting the SAA contour 23,
and everytime 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.

NIC2 11219

Active Galactic Nuclei in nearby galaxies: a new view of the origin of the
radio-loud radio-quiet dichotomy?

Using archival HST and Chandra observations of 34 nearby early-type galaxies
{drawn from a complete radio selected sample} we have found evidence that
the radio-loud/radio-quiet dichotomy is directly connected to the structure
of the inner regions of their host galaxies in the following sense: [1]
Radio-loud AGN are associated with galaxies with shallow cores in their
light profiles [2] Radio-quiet AGN are only hosted by galaxies with steep
cusps. Since the brightness profile is determined by the galaxy's evolution,
through its merger history, our results suggest that the same process sets
the AGN flavour. This provides us with a novel tool to explore the
co-evolution of galaxies and supermassive black holes, and it opens a new
path to understand the origin of the radio-loud/radio-quiet AGN dichotomy.
Currently our analysis is statistically incomplete as the brightness profile
is not available for 82 of the 116 targets. Most galaxies were not observed
with HST, while in some cases the study is obstructed by the presence of
dust features. We here propose to perform an infrared NICMOS snapshot survey
of these 82 galaxies. This will enable us to i} test the reality of the
dichotomic behaviour in a substantially larger sample; ii} extend the
comparison between radio-loud and radio-quiet AGN to a larger range of
luminosities.

NIC3 11120

A Paschen-Alpha Study of Massive Stars and the ISM in the Galactic Center

The Galactic center (GC) is a unique site for a detailed study of a
multitude of complex astrophysical phenomena, which may be common to nuclear
regions of many galaxies. Observable at resolutions unapproachable in other
galaxies, the GC provides an unparalleled opportunity to improve our
understanding of the interrelationships of massive stars, young stellar
clusters, warm and hot ionized gases, molecular clouds, large scale magnetic
fields, and black holes. We propose the first large-scale hydrogen Paschen
alpha line survey of the GC using NICMOS on the Hubble Space Telescope. This
survey will lead to a high resolution and high sensitivity map of the
Paschen alpha line emission in addition to a map of foreground extinction,
made by comparing Paschen alpha to radio emission. This survey of the inner
75 pc of the Galaxy will provide an unprecedented and complete search for
sites of massive star formation. In particular, we will be able to (1)
uncover the distribution of young massive stars in this region, (2) locate
the surfaces of adjacent molecular clouds, (3) determine important physical
parameters of the ionized gas, (4) identify compact and ultra-compact HII
regions throughout the GC. When combined with existing Chandra and Spitzer
surveys as well as a wealth of other multi-wavelength observations, the
results will allow us to address such questions as where and how massive
stars form, how stellar clusters are disrupted, how massive stars shape and
heat the surrounding medium, and how various phases of this medium are
interspersed.

WFPC2 11029

WFPC2 CYCLE 15 Intflat Linearity Check and Filter Rotation Anomaly Monitor

Intflat observations will be taken to provide a linearity check: the
linearity test consists of a series of intflats in F555W, in each gain and
each shutter. A combination of intflats, visflats, and earthflats will be
used to check the repeatability of filter wheel motions. {Intflat sequences
tied to decons, visits 1-18 in prop 10363, have been moved to the cycle 15
decon proposal xxxx for easier scheduling.} Note: long-exposure WFPC2
intflats must be scheduled during ACS anneals to prevent stray light from
the WFPC2 lamps from contaminating long ACS external exposures.

WFPC2 11083

The Structure, Formation and Evolution of Galactic Cores and Nuclei

A surprising result has emerged from the ACS Virgo Cluster Survey {ACSVCS},
a program to obtain ACS/WFC gz imaging for a large, unbiased sample of 100
early-type galaxies in the Virgo Cluster. On subarcsecond scales {i.e.,
0.1"-1"}, the HST brightness profiles vary systematically from the
brightest giants {which have nearly constant surface brightness cores} to
the faintest dwarfs {which have compact stellar nuclei}. Remarkably, the
fraction of galaxy mass contributed by the nuclei in the faint galaxies is
identical to that contributed by supermassive black holes in the bright
galaxies {0.2%}. These findings strongly suggest that a single mechanism is
responsible for both types of Central Massive Object: most likely internally
or externally modulated gas inflows that feed central black holes or lead to
the formation of "nuclear star clusters". Understanding the history of gas
accretion, star formation and chemical enrichment on subarcsecond scales has
thus emerged as the single most pressing question in the study of nearby
galactic nuclei, either active or quiescent. We propose an ambitious HST
program {199 orbits} that constitutes the next, obvious step forward:
high-resolution, ultraviolet {WFPC2/F255W} and infrared {NIC1/F160W} imaging
for the complete ACSVCS sample. By capitalizing on HST's unique ability to
provide high-resolution images with a sharp and stable PSF at UV and IR
wavelengths, we will leverage the existing optical HST data to obtain the
most complete picture currently possible for the history of star formation
and chemical enrichment on these small scales. Equally important, this
program will lead to a significant improvement in the measured structural
parameters and density distributions for the stellar nuclei and the
underlying galaxies, and provide a sensitive measure of "frosting" by young
stars in the galaxy cores. By virtue of its superb image quality and stable
PSF, NICMOS is the sole instrument capable of the IR observations proposed
here. In the case of the WFPC2 observations, high-resolution UV imaging {
0.1"} is a capability unique to HST, yet one that could be lost at any time.

WFPC2 11121

Proper Motion of the Remarkable Irradiated Jet HH399 in the Trifid Nebula

The Trifid nebula has recently been of much interest because of its
identification with a large number of massive protostars, as well as young
stellar objects. HH 399 is one of the most spectacular Herbig-Haro flows
recognized to be irradiated by the UV flux of the massive O7.5 star in the
Trifid nebula. The irradiated jet, which is propagating in a fully ionized
medium, contains numerous knots along the jet and also shows evidence for a
number of isolated knots running immediately outside the jet. Two different
HST observations of the nebula, with different scientific goals, were
carried out in 1997 and 2002, having sensitivities that differed by a factor
of 10. We performed preliminary proper motion measurements of the jet based
on these observations and discovered a continuous velocity structure of the
bright knots of about 230 km/sec. Here we propose four WFPC2 orbits to
reobserve HH 399 in order to carry out accurate proper motion measurements
over the full extent of the jet, based on observations spanning more than 10
years and having equally deep sensitivity. The proposed observations are not
simply a repeat of previous measurements, as this will be the first highly
accurate proper motion measurement of an irradiated jet based on two
identical epochs of WFPC2 observations. The observations will improve the
accuracy of proper motion measurements for HH 399 by more than a factor of
five and will address important questions beyond our preliminary result.
Currently measured velocity differences between the jet features are barely
significant. The factor of 5 increase in accuracy will establish the
evidence for deceleration along the jet and the lateral motion of the jet.
In addition, these measurements will address the kinematics of individual
entrained and isolated blobs of the jet as it propagates into an HII region
associated with the nebula. This is the last opportunity to perform this
experiment before WFPC2 is removed from HST.

WFPC2 11128

Time Scales Of Bulge Formation In Nearby Galaxies

Traditionally, bulges are thought to fit well into galaxy formation models
of hierarchical merging. However, it is now becoming well established that
many bulges formed through internal, secular evolution of the disk rather
than through mergers. We call these objects pseudobulges. Much is still
unknown about pseudobulges, the most pressing questions being: How, exactly,
do they build up their mass? How long does it take? And, how many exist? We
are after an answer to these questions. If pseudobulges form and evolve over
longer periods than the time between mergers, then a significant population
of pseudobulges is hard to explain within current galaxy formation theories.
A pseudobulge indicates that a galaxy has most likely not undergone a major
merger since the formation of the disk. The ages of pseudobulges give us an
estimate for the time scale of this quiescent evolution. We propose to use
24 orbits of HST time to complete UBVIH imaging on a sample of 33 nearby
galaxies that we have observed with Spitzer in the mid-IR. These data will
be used to measure spatially resolved stellar population parameters {mean
stellar age, metallicity, and star formation history}; comparing ages to
star formation rates allows us to accurately constrain the time scale of
pseudobulge formation. Our sample of bulges includes both pseudo- and
classical bulges, and evenly samples barred and unbarred galaxies. Most of
our sample is imaged, 13 have complete UBVIH coverage; we merely ask to
complete missing observations so that we may construct a uniform sample for
studying bulge formation. We also wish to compare the stellar population
parameters to a variety of bulge and global galaxy properties including star
formation rates, dynamics, internal bulge morphology, structure from
bulge-disk decompositions, and gas content. Much of this data set is already
or is being assembled. This will allow us to derive methods of pseudobulge
identification that can be used to accurately count pseudobulges in large
surveys. Aside from our own science goals, we will present this broad set of
data to the community. Thus, we waive proprietary periods for all
observations.

WFPC2 11229

SEEDS: The Search for Evolution of Emission from Dust in Supernovae with HST
and Spitzer

The role that massive stars play in the dust content of the Universe is
extremely uncertain. It has long been hypothesized that dust can condense
within the ejecta of supernovae {SNe}, however there is a frustrating
discrepancy between the amounts of dust found in the early Universe, or
predicted by nucleation theory, and inferred from SN observations. Our SEEDS
collaboration has been carefully revisiting the observational case for dust
formation by core- collapse SNe, in order to quantify their role as dust
contributors in the early Universe. As dust condenses in expanding SN
ejecta, it will increase in optical depth, producing three simultaneously
observable phenomena: {1} increasing optical extinction; {2} infrared {IR}
excesses; and {3} asymmetric blue-shifted emission lines. Our SEEDS
collaboration recently reported all three phenomena occurring in SN2003gd,
demonstrating the success of our observing strategy, and permitting us to
derive a dust mass of up to 0.02 solar masses created in the SN. To advance
our understanding of the origin and evolution of the interstellar dust in
galaxies, we propose to use HST's WFPC2 and NICMOS instruments plus
Spitzer's photometric instruments to monitor ten recent core-collapse SNe
for dust formation and, as a bonus, detect light echoes that can affect the
dust mass estimates. These space-borne observations will be supplemented by
ground-based spectroscopic monitoring of their optical emission line
profiles. These observations would continue our 2-year HST and Spitzer
monitoring of this phenomena in order to address two key questions: Do all
SNe produce dust? and How much dust do they produce? As all the SN are
within 15 Mpc, each SN stands an excellent chance of detection with HST and
Spitzer and of resolving potential light echoes.

WFPC2 11326

Polarizers Closeout (Internal Observations)

Verify stability of polarization calibration.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11239 - GSacq(2,1,2) failed, Search Radius Limit exceeded on FGS 2

Upon acquisition of signal at 12:55:55, vehicle was in gyro control with
FGS2 search radius limit and stop flags set. GSACQ(2,1,2) at 12:11:54 failed
to RGA control. One 486 status buffer "A05" message (FGS Coarse Track
failed- Search Radius Limit exceeded) was received. OBAD at 11:59:49 prior
to GSACQ had RSS error correction of 15.40 arc seconds, OBAD map at 12:57:29
after GSACQ had RSS error of 2340.74 arcseconds.

OBAD at 11:51:59 prior to GSACQ had RSS error correction of 5217.70 arc
seconds.

11240 - GSacq(2,1,2) failed, Search Radius Limit exceeded on FGS 2

Upon acquisition of signal at 14:02:15, vehicle was in gyro control with
FGS2 search radius limit and stop flags set. GSACQ(2,1,2) at 13:47:16 failed
to RGA control. One 486 status buffer "A05" message (FGS Coarse Track
failed- Search Radius Limit exceeded) was received. OBAD at 13:35:37 prior
to GSACQ had RSS error correction of 11.12 arc seconds, OBAD map at 14:32:55
after GSACQ had RSS error of 1678.45 arcseconds.

11242 - GSAcq(2,1,2) failed

OTA SE review of PTAS processing revealed that GSAcq(2,1,2) at 086/23:42:09
failed to RGA Hold with a stop flag on FGS2.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 10 08
FGS REacq 03 03
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS: (None)