Daily Report #4559

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4559

PERIOD COVERED: UT March 3, 2008 (DOY 063)

OBSERVATIONS SCHEDULED

ACS/SBC 11230

HST FUV Observations of Brightest Cluster Galaxies: The Role of Star
Formation in Cooling Flows and BCG Evolution

The intracluster medium (ICM) now appears to be a very dynamic place where
heating and cooling processes vie for dominance and an uneasy equilibrium is
maintained. Since these same processes may operate during the process of
galaxy formation, the centers of clusters of galaxies provide low redshift
laboratories for studying the critical processes involved in galaxy
formation and black hole growth. At the present time, the main questions are
(1) How much gas is cooling out of the ICM? (2) How much star formation is
ongoing? (3) What is the impact of the gas and star formation on the central
BCG? In order to measure the current star formation in BCGs we have
undertaken a program of Spitzer IRAC and MIPS observations. We are in
process of obtaining observations of a sample of Brightest Cluster Galaxies
in 70 clusters selected from the ROSAT all sky survey. In about 25% of the
sources observed so far, we detect a mid-IR excess which we attribute to
dust heated by star formation. We propose to obtain ACS/SBC observations of
the Lyman Alpha emission line and the adjacent FUV continuum in 7 BCGs which
are in cooling core clusters of galaxies and have a large mid-IR excess. We
also propose WFPC2 F606W observations of the two clusters without high
resolution imaging to allow us to image the dust on the same scale as the
Far UV continuum. The FUV will allow us to confirm the presense of ongoing
starformation in these BCGs and will allow us to rule out an AGN as the
dominant contributer to the mid-IR. The morphology and spatial extent of the
young stars and the heated dust and CO will constrain the spatial scale over
which star formation occurs and thus where the cooling gas is deposited. The
combination of our FUV and IR observations will allow us to estimate the
star formation rates which must balance the rate at which cold gas is
deposited in the BCG. Our proposed FUV observations will produce unique
information about the cooling gas, the true mass accretion rates, and the
star formation rates in BCGs and its effect on the galaxy.

WFPC2 11024

WFPC2 CYCLE 15 INTERNAL MONITOR

This calibration proposal is the Cycle 15 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A variety of
internal exposures are obtained in order to provide a monitor of the
integrity of the CCD camera electronics in both bays {both gain 7 and gain
15 -- to test stability of gains and bias levels}, a test for quantum
efficiency in the CCDs, and a monitor for possible buildup of contaminants
on the CCD windows. These also provide raw data for generating annual
super-bias reference files for the calibration pipeline.

FGS 11295

Trigonometric Calibration of the Distance Scale for Classical Novae

The distance scale for classical novae is important for understanding the
stellar physics of their thermonuclear runaways, their contribution to
Galactic nucleosynthesis, and their use as extragalactic standard candles.
Although it is known that there is a relationship between their absolute
magnitudes at maximum light and their subsequent rates of decline--the
well-known maximum-magnitude rate-of-decline {MMRD} relation--it is
difficult to set the zero-point for the MMRD because of the very uncertain
distances of Galactic novae. We propose to measure precise trigonometric
parallaxes for the quiescent remnants of the four nearest classical novae.
We will use the Fine Guidance Sensors, which are proven to be capable of
measuring parallaxes with errors of ~0.2 mas, well below what is possible
from the ground.

NIC1/NIC2/NIC3 11330

NICMOS Cycle 16 Extended Dark

This takes a series of Darks in parallel to other instruments.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

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.

NIC2 10852

Coronagraphic Polarimetry with NICMOS: Dust grain evolution in T Tauri stars

The formation of planetary systems is intimately linked to the dust
population in circumstellar disks, thus understanding dust grain evolution
is essential to advancing our understanding of how planets form. By
combining {1} the coronagraphic polarimetry capabilities of NICMOS, {2}
powerful 3-D radiative transfer codes, and {3} observations of objects known
to span the Class II- III stellar evolutionary phases, we will gain crucial
insight into dust grain growth. By observing objects representative of a
known evolutionary sequence of YSOs, we will be able to investigate how the
dust population evolves in size and distribution during the crucial
transition from a star+disk system to a system containing planetesimals.
When combine with our previous study on dust grain evolution in the Class
I-II phase, the proposed study will help to establish the fundamental time
scales for the depletion of ISM-like grains: the first step in understanding
the transformation from small submicron sized dust grains, to large
millimeter sized grains, and untimely to planetary bodies.

NIC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3

We aim to determine physical properties of IR luminous galaxies at
0.3z2.7 by requesting coordinated HST/NIC2 and MIPS 70um observations
of a unique, 24um flux-limited sample with complete Spitzer mid-IR
spectroscopy. The 150 sources investigated in this program have S{24um}
0.8mJy and their mid-IR spectra have already provided the majority
targets with spectroscopic redshifts {0.3z2.7}. The proposed 150~orbits of
NIC2 and 66~hours of MIPS 70um will provide the physical measurements of the
light distribution at the rest-frame ~8000A and better estimates of the
bolometric luminosity. Combining these parameters together with the rich
suite of spectral diagnostics from the mid-IR spectra, we will {1} measure
how common mergers are among LIRGs and ULIRGs at 0.3z2.7, and establish if
major mergers are the drivers of z1 ULIRGs, as in the local Universe. {2}
study the co-evolution of star formation and blackhole accretion by
investigating the relations between the fraction of starburst/AGN measured
from mid-IR spectra vs. HST morphologies, L{bol} and z. {3} obtain the
current best estimates of the far-IR emission, thus L{bol} for this sample,
and establish if the relative contribution of mid-to-far IR dust emission is
correlated with morphology {resolved vs. unresolved}.

NIC2 11157

NICMOS Imaging Survey of Dusty Debris Around Nearby Stars Across the Stellar
Mass Spectrum

Association of planetary systems with dusty debris disks is now quite
secure, and advances in our understanding of planet formation and evolution
can be achieved by the identification and characterization of an ensemble of
debris disks orbiting a range of central stars with different masses and
ages. Imaging debris disks in starlight scattered by dust grains remains
technically challenging so that only about a dozen systems have thus far
been imaged. A further advance in this field needs an increased number of
imaged debris disks. However, the technical challenge of such observations,
even with the superb combination of HST and NICMOS, requires the best
targets. Recent HST imaging investigations of debris disks were
sample-limited not limited by the technology used. We performed a search for
debris disks from a IRAS/Hipparcos cross correlation which involved an
exhaustive background contamination check to weed out false excess stars.
Out of ~140 identified debris disks, we selected 22 best targets in terms of
dust optical depth and disk angular size. Our target sample represents the
best currently available target set in terms of both disk brightness and
resolvability. For example, our targets have higher dust optical depth, in
general, than newly identified Spitzer disks. Also, our targets cover a
wider range of central star ages and masses than previous debris disk
surveys. This will help us to investigate planetary system formation and
evolution across the stellar mass spectrum. The technical feasibility of
this program in two-gyro mode guiding has been proven with on-orbit
calibration and science observations during HST cycles 13, 14, and 15.

WFPC2 11070

WFPC2 CYCLE 15 Standard Darks - part II

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 11138

The Physics of the Jets of Powerful Radio Galaxies and Quasars

We propose to obtain HST polarimetry of the jets of the quasars 1150+497 and
PKS 1136-135. Our goal is to solve the riddle of their high-energy emission
mechanism, and tackle issues such as particle acceleration and jet dynamics.
Our targets are the optically brightest quasar jets, and they span the range
of luminosities and beaming parameters seen in these objects. Recent
observations with Spitzer, HST and Chandra have shed new light on the
spectral morphology of quasar jets, throwing wide open the question of the
nature of their optical and X-ray emission. Three mechanisms are possible,
including synchrotron emission as well as two Comptonization processes.
Polarimetry can uniquely determine which of these mechanisms operates in the
optical. We will compare the optical polarimetry to in- hand radio
polarimetry as well as in-hand and new Spitzer, HST and Chandra imaging to
gain new insights on the structure of these jets, as well as particle
acceleration mechanisms and jet dynamics.

WFPC2 11201

Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images

In Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in the
Magellanic Clouds centered on background quasars. We used these data to
determine the proper motions of the LMC and SMC to better than 5% and 15%
respectively. These are by far the best determinations of the proper motions
of these two galaxies. The results have a number of unexpected implications
for the Milky Way-LMC-SMC system. The implied three-dimensional velocities
are larger than previously believed, and are not much less than the escape
velocity in a standard 10^12 solar mass Milky Way dark halo. Orbit
calculations suggest the Clouds may not be bound to the Milky Way or may
just be on their first passage, both of which would be unexpected in view of
traditional interpretations of the Magellanic Stream. Alternatively, the
Milky Way dark halo may be a factor of two more massive than previously
believed, which would be surprising in view of other observational
constraints. Also, the relative velocity between the LMC and SMC is larger
than expected, leaving open the possibility that the Clouds may not be bound
to each other. To further verify and refine our results we now request an
epoch of WFPC2/PC data for the fields centered on 40 quasars that have at
least one epoch of ACS imaging. We request execution in snapshot mode, as in
our previous programs, to ensure the most efficient use of HST resources. A
third epoch of data of these fields will provide crucial information to
verify that there are no residual systematic effects in our previous
measurements. More importantly, it will increase the time baseline from 2 to
5 yrs and will increase the number of fields with at least two epochs of
data. This will reduce our uncertainties correspondingly, so that we can
better address whether the Clouds are indeed bound to each other and to the
Milky Way. It will also allow us to constrain the internal motions of
various populations within the Clouds, and will allow us to determine a
distance to the LMC using rotational parallax.

WFPC2 11297

Reducing Systematic Errors on the Hubble Constant: Metallicity Calibration
of the Cepheid PL Relation

Reducing the systematic errors on the Hubble constant is still of
significance and of immediate importance to modern cosmology. One of the
largest remaining uncertainties in the Cepheid-based distance scale (which
itself is at the foundation of the HST Key Project determination of H_o)
which can now be addressed directly by HST, is the effect of metallicity on
the Cepheid Period-Luminosity relation. Three chemically distinct regions in
M101 will be used to directly measure and thereby calibrate the change in
zero point of the Cepheid PL relation over a range of metallicities that run
from SMC-like, through Solar, to metallicities as high as the most
metal-enriched galaxies in the pure Hubble flow. ACS for the first time
offers the opportunity to make a precise calibration of this effect which
currently accounts for at least a third of the total systematic uncertainty
on Ho. The calibration will be made in the V and I bandpasses so as to be
immediately and directly applicable to the entire HST Cepheid-based distance
scale sample, and most especially to the highest-metallicity galaxies that
were hosts to the Type Ia supernovae, which were then used to extend the the
distance scale calibration out to cosmologically significant distances.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11205 - GSacq(1,2,1) failed, Search Radius Limit exceeded on FGS 1

Upon acquisition of signal at 18:06:12, vehicle was in gyro control with
FGS1 search radius limit and stop flags set. GSACQ(1,2,1) at 17:55:27 failed
to RGA control. One 486 status buffer "A05" message (FGS Coarse Track
failed- Search Radius Limit exceeded) was received. OBAD map after GSACQ had
RSS error of 53.33 arcseconds. NICMOS 705 status buffer message (TDF down
when a target acquisition SAM request is made) was posted at 18:05:08.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES:

1647-0 - Reset NICMOS Error Counter @ 063/20:04z

SCHEDULED SUCCESSFUL

FGS GSacq 09 08
FGS REacq 05 05
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS: (None)