HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT       # 4562

PERIOD COVERED: UT March 06, 2008 (DOY 066)

OBSERVATIONS SCHEDULED

ACS/SBC 11050

ACS UV contamination monitor

The observations consist of imaging and spectroscopy with SBC of the

cluster NGC 6681 in order to monitor the temporal evolution of the UV

sensitivity of the SBC.

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 i

mages. Each observation will need its own CRMAP, as different SAA

passages leave different imprints on the NICMOS detectors.

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.

WEPC2 11196

An Ultraviolet Survey 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 starbursts and creating/fueling central AGN. We

propose far {ACS/SBC/F140LP} and near {WFPC2/PC/F218W} UV imaging of a

sample of 27 galaxies drawn from the complete IRAS Revised Bright Galaxy

Sample {RBGS} LIRGs sample and known, from our Cycle 14 B and I-band ACS

imaging observations, to have significant numbers of bright {23 < B < 21

mag} star clusters in the central 30 arcsec. The HST UV data will be

combined with previously obtained HST, Spitzer, and GALEX images to {i}

calculate the ages of the clusters as function of merger stage, {ii}

measure the amount of UV light in massive star clusters relative to

diffuse regions of star formation, {iii} assess the feasibility of using

the UV slope to predict the far-IR luminosity {and thus the star

formation rate} both among and within IR-luminous galaxies, and {iv}

provide a much needed catalog of rest- frame UV morphologies for

comparison with rest-frame UV images of high-z LIRGs and Lyman Break

Galaxies. These observations will achieve the resolution required to

perform both detailed photometry of compact structures and spatial

correlations between UV and redder wavelengths for a physical

interpretation our IRX-Beta results. The HST UV data, combined with the

HST ACS, Spitzer, Chandra, and GALEX observations of this sample, will

result in the most comprehensive study of luminous starburst galaxies to

date.

WFPC2 11103

A Snapshot Survey of The Most Massive Clusters of Galaxies

We propose the continuation of our highly successful SNAPshot survey of

a sample of 125 very X-ray luminous clusters in the redshift range

0.3-0.7. As demonstrated by the 25 snapshots obtained so far in Cycle14

and Cycle15 these systems frequently exhibit strong gravitational

lensing as well as spectacular examples of violent galaxy interactions.

The proposed observations will provide important constraints on the

cluster mass distributions, the physical nature of galaxy-galaxy and

galaxy-gas interactions in cluster cores, and a set of optically bright,

lensed galaxies for further 8-10m spectroscopy. All of our primary

science goals require only the detection and characterization of

high-surface-brightness features and are thus achievable even at the

reduced sensitivity of WFPC2. Because of their high redshift and thus

compact angular scale our target clusters are less adversely affected by

the smaller field of view of WFPC2 than more nearby systems.

Acknowledging the broad community interest in this sample we waive our

data rights for these observations. Due to a clerical error at STScI our

approved Cycle15 SNAP program was barred from execution for 3 months and

only 6 observations have been performed to date - reinstating this SNAP

at Cycle16 priority is of paramount importance to reach meaningful

statistics.

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 11233

Multiple Generations of Stars in Massive Galactic Globular Clusters

This is a follow-up to recent HST imaging of NGC 2808, which discovered

that its main sequence is triple, with three well-separated parallel

branches {Fig.~1}. Along with the double MS of Omega Centauri, this

challenges the long-held paradigm that globular clusters are simple,

single stellar populations. The cause of this main sequence multiplicity

in both clusters is likely to be differences in helium abundance, which

could play a fundamental role in the understanding of stellar

populations. We propose to image seven more of the most massive globular

clusters, to examine their main sequences for indications of splitting.

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                08                08                 

FGS REacq                06                06                 

OBAD with Maneuver  28                28                

SIGNIFICANT EVENTS: (None)