Daily Report #4570

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4570

PERIOD COVERED: UT March 18, 2008 (DOY 078)

OBSERVATIONS SCHEDULED

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 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.

NIC3 11195

Morphologies of the Most Extreme High-Redshift Mid-IR-luminous Galaxies II:
The `Bump' Sources

The formative phase of some of the most massive galaxies may be extremely
luminous, characterized by intense star- and AGN-formation. Till now, few
such galaxies have been unambiguously identified at high redshift, and thus
far we have been restricted to studying the low-redshift ultraluminous
infrared galaxies as possible analogs. We have recently discovered a sample
of objects which may indeed represent this early phase in galaxy formation,
and are undertaking an extensive multiwavelength study of this population.
These objects are optically extremely faint {R26} but nevertheless bright
at mid-infrared wavelengths {F[24um] 0.5 mJy}. Mid-infrared spectroscopy
with Spitzer/IRS reveals that they have redshifts z~2, implying luminosities
~1E13 Lsun. Their mid-IR SEDs fall into two broad, perhaps overlapping,
categories. Sources with brighter F[24um] exhibit power-law SEDs and SiO
absorption features in their mid-IR spectra characteristic of AGN, whereas
those with fainter F[24um] show a "bump" characteristic of the redshifted
1.6um peak from a stellar population, and PAH emission characteristic of
starformation. We have begun obtaining HST images of the brighter sources in
Cycle 15 to obtain identifications and determine kpc-scale morphologies for
these galaxies. Here, we aim to target the second class {the "bump" sources}
with the goal of determining if these constitute morphologically different
objects, or simply a "low-AGN" state of the brighter class. The proposed
observations will help us determine whether these objects are merging
systems, massive obscured starbursts {with obscuration on kpc scales!} or
very reddened {locally obscured} AGN hosted by intrinsically low-luminosity
galaxies.

NIC3 11333

NICMOS non-linearity tests

This program incorporates a number of tests to analyze the count rate
dependent non-linearity seen in NICMOS spectro-photometric observations.

We will observe a field with stars of a range in luminosity in NGC3603 with
NICMOS in NIC1: F090M, F110W, F140W, F160W NIC2: F110W, F160W, F187W, F205W,
and F222M NIC3: F110W, F150W, F160W, F175W, and F222M. We will repeat the
observations with flatfield lamp on, creating artificially high count-rates,
allowing tests of NICMOS linearity as function of count rate. We first take
exposures with the lamp off, then exposures with the lamp on, and repeat at
the end with lamp off. Finally, we continue with taking darks during
occultation.

We will furthermore observe spectro-photometric standard P041C using the
G096, G141, and G206 grisms in NIC3, and repeat the lamp off/on/off test to
artificially create a high background.

WFPC2 11207

Star Formation in the Perseus Cluster Cooling Flow

We propose to obtain high resolution, UV/optical imaging of the "accretion
populations" in the massive cooling flow of the Perseus cluster of galaxies.
New GALEX observations show that the dominant galaxy in this nearby cluster,
NGC 1275, has an extended network of UV-bright populations apparently formed
recently from the intracluster gas. Cluster cooling flows are the most
prominent of the environments where we can readily observe the cycle of gas
accretion, star formation, and feedback from active nuclei that is thought
to play a central role in the formation and evolution of galaxies. Because
they can be readily age-dated, the accretion populations help to trace the
sequence of exchange of material between galaxies and the intracluster
medium. The ACS/SBC and WFPC2/PC cameras offer the highest spatial
resolution and best panchromatic performance available to map the spatial
and age distribution of the accretion populations and their relationship to
radio-emitting plasma and the hot intracluster gas.

WFPC2 11235

HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in
the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared
selected galaxies exceeds that of optically selected galaxies. These
`luminous infrared galaxies' {LIRGs} are primarily interacting or merging
disk galaxies undergoing enhanced star formation and Active Galactic Nuclei
{AGN} activity, possibly triggered as the objects transform into massive S0
and elliptical merger remnants. We propose NICMOS NIC2 imaging of the
nuclear regions of a complete sample of 88 L_IR 10^11.4 L_sun luminous
infrared galaxies in the IRAS Revised Bright Galaxy Sample {RBGS: i.e., 60
micron flux density 5.24 Jy}. This sample is ideal not only in its
completeness and sample size, but also in the proximity and brightness of
the galaxies. The superb sensitivity and resolution of NICMOS NIC2 on HST
enables a unique opportunity to study the detailed structure of the nuclear
regions, where dust obscuration may mask star clusters, AGN and additional
nuclei from optical view, with a resolution significantly higher than
possible with Spitzer IRAC. This survey thus provides a crucial component to
our study of the dynamics and evolution of IR galaxies presently underway
with Wide-Field, HST ACS/WFC and Spitzer IRAC observations of these 88
galaxies. Imaging will be done with the F160W filter {H-band} to examine as
a function of both luminosity and merger stage {i} the luminosity and
distribution of embedded star clusters, {ii} the presence of optically
obscured AGN and nuclei, {iii} the correlation between the distribution of
1.6 micron emission and the mid- IR emission as detected by Spitzer IRAC,
{iv} the evidence of bars or bridges that may funnel fuel into the nuclear
region, and {v} the ages of star clusters for which photometry is available
via ACS/WFC observations. The NICMOS data, combined with the HST ACS,
Spitzer, and GALEX observations of this sample, will result in the most
comprehensive study of merging and interacting galaxies to date.

WFPC2 11343

Identifying the host galaxies for optically dark gamma-ray bursts

We propose to use the high spatial resolution capabilities of Chandra to
obtain precise positions for a sample of Gamma-ray bursts (GRBs) with no
optical afterglows, where the optical light is supresssed relative to the
X-ray flux. These bursts are likely to be highly obscured and may have
different environments from the optically bright GRBs. Our Chandra
observations will (unlike Swift-XRT positions) allow for the unique
identification of a host galaxy. To locate these host galaxies we will
follow up our Chandra positions with deep optical and IR observations with
HST. The ultimate aim is to understand any differences between the host
galaxies of optically dark and bright GRBs, and how these affect the use of
GRBs as tracers of starformation and galaxy evolution at high redshift.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 10 10
FGS REacq 04 04
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS: (None)