HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT      # 4548

PERIOD COVERED: UT February 14, 2008 (DOY 045)

OBSERVATIONS SCHEDULED

ACS/SBC 10862

Comprehensive Auroral Imaging of Jupiter and Saturn during the

International Heliophysical Year

A comprehensive set of observations of the auroral emissions from

Jupiter and Saturn is proposed for the International Heliophysical Year

in 2007, a unique period of especially concentrated measurements of

space physics phenomena throughout the solar system. We propose to

determine the physical relationship of the various auroral processes at

Jupiter and Saturn with conditions in the solar wind at each planet.

This can be accomplished with campaigns of observations, with a sampling

interval not to exceed one day, covering at least one solar rotation.

The solar wind plasma density approaching Jupiter will be measured by

the New Horizons spacecraft, and a separate campaign near opposition in

May 2007 will determine the effect of large-scale variations in the

interplanetary magnetic field {IMF} on the Jovian aurora by

extrapolation from near-Earth solar wind measurements. A similar Saturn

campaign near opposition in Jan. 2007 will combine extrapolated solar

wind data with measurements from a wide range of locations within the

Saturn magnetosphere by Cassini. In the course of making these

observations, it will be possible to fully map the auroral footprints of

Io and the other satellites to determine both the local magnetic field

geometry and the controlling factors in the electromagnetic interaction

of each satellite with the corotating magnetic field and plasma density.

Also in the course of making these observations, the auroral emission

properties will be compared with the properties of the near-IR

ionospheric emissions {from ground-based observations} and non thermal

radio emissions, from ground-based observations for Jupiter's decametric

radiation and Cassini plasma wave measurements of the Saturn Kilometric

Radiation {SKR}.

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.

NIC3 11236

Did Rare, Large Escape-Fraction Galaxies Reionize the Universe?

Lyman continuum photons produced in massive starbursts may have played a

dominant role in the reionization of the Universe. Starbursts are

important contributors to the ionizing metagalactic background at lower

redshifts as well. However, their contribution to the background depends

upon the fraction of ionizing radiation that escapes from the intrinsic

opacity of galaxies below the Lyman limit. Current surveys suggest that

the escape fraction is close to zero in most galaxies, even among young

starbursts, but is large in 15-25% of them. Non-uniform escape fractions

are expected as a result of violent events creating clear paths in small

parts of galaxies. The number of galaxies observed with high escape

fraction will result from the combination of the intrinsic number with

clear lines of sight and their orientation with respect to the observer.

We propose to measure the fraction of escaping Lyman continuum radiation

in a large sample (47) of z~0.7 starbursts in the COSMOS field. These

compact UV-luminous galaxies are good analogs to high redshift LBGs.

Using the SBC/PR130L we can quickly (1-4 orbits) detect relative escape

fractions (f_LC/f_1500) of 25% or more. This will be the first

measurement of the escape fraction in sources between z=1 and the local

universe. We expect ~10 detections. Stacking will set limits of <4% on

the relative escape fraction in the rest. We will correlate the LC

detections with the properties of the galaxies. By targeting z~0.7 in

COSMOS, we will have tremendous ancillary information on those sources.

A non-detection in all sources would be significant (99% confidence).

This would imply that QSOs provide the overwhelming majority of ionizing

radiation at z<1, requiring substantial evolution in the processes within

Lyman break galaxies which allow large escape fractions at high

redshift.

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 11291

Following Eta Carinae's Change of State

Eta Carinae is now known to be undergoing some unusually rapid changes

on a timescale of several years. They are probably essential for

modeling the star's long-term recovery from its Giant Eruption 160 years

ago -- the prototype "supernova impostor" event. Since high spatial

resolution is needed to isolate the central star, and the present state

will probably not recur in the future, it is important to obtain HST

data during the next two years. We propose a cost- effective set of ACS

observations with three goals: {1} to obtain a continuing record of the

star's rapid UV and visual brightening; {2} to lengthen the temporal

baseline of ACS images enough to settle an important question concerning

ejecta ages; and {3} to extend the record of morphological changes in

the inner ejecta past the midpoint of eta Car's 5.5-year cycle.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)

HSTARS:

11190 - REacq(2,1,2) failed to RGA Hold (Gyro Control)

           REacq(2,1,2) scheduled at 046/02:00:24 - 02:08:29 failed to RGA Hold due

           to (QF2STOPF) stop flag indication on FGS2. Pre-acq OBADs had (RSS)

           values of 858.68 and 9.83 arcseconds. Post-acq OBAD/MAP was not

           scheduled. Received ACS 779 Status Buffer Messages ("Fold Mechanism Move

           was Blocked") following the failure of the REacq.

COMPLETED OPS REQUEST:

18207-0 - 32Kbps Memory Dump @ 045/1419z

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL   

FGS GSacq               08                  08             

FGS REacq               07                  06    

OBAD with Maneuver 30                  30               

SIGNIFICANT EVENTS:

Flash Report : 32Kbps Memory Dump

Ops Request #18207 was successfully executed to collect 32Kbps memory

dump and verified that White Sands can handle the "J" (32Kbps memory

dump) format correctly.