Notice: Due to the conversion of some ACS WFC or HRC observations into

WFPC2, or NICMOS observations after the loss of ACS CCD science

capability in January, there may be an occasional discrepancy between a

proposal's listed (and correct) instrument usage and the abstract that

follows it.

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT       # 4435

PERIOD COVERED: UT August 27, 2007 (DOY 239)

OBSERVATIONS SCHEDULED

WFPC2 10599

Multi-color imaging of two 1 Gyr old debris disks within 20 pc of the

Sun: Astrophysical mirrors of our Kuiper Belt

We report the first scattered light detections of two debris disk around

an F star and a K star using optical coronagraphy and the Hubble Space

Telescope. With ages ~1 Gyr, these are the oldest debris disks thus far

seen in the optical. We propose deep, multi-roll angle coronagraphic

imaging with HST ACS and NICMOS to confirm and characterize the disks in

terms of structure and composition. The disks appear to have belt-like

morphology that is consistent with the existence of planetary companions

or other perturbing bodies. Since these disks are close to our Kuiper

Belt in an evolutionary context, detailed understanding of their mass,

structure and composition will provide a fresh perspective for inferring

the history and properties of our own trans-Neptunian region.

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 11018

Long Term Stability of FGS1r in Position Mode

It is known from our experience with FGS3, and later with FGS1r, that an

FGS on orbit experiences long term evolution, presumably due to

disorption of water from the instrument's graphite epoxy composites. This

manifests primarily as a change in the plate scale and secondarily as a

change in the geometric distortions. These effects are well modeled by

adjustments to the rhoA and kA parameters which are used to transform

the star selector servo angles into FGS {x, y} detector space

coordinates. By observing the relative positions of selected stars in a

standard cluster at a fixed telescope pointing and orientation, the

evolution of rhoA and kA can be monitored and calibrated to preserve the

astrometric performance of FGS1r.

FGS 11212

Filling the Period Gap for Massive Binaries

The current census of binaries among the massive O-type stars is

seriously incomplete for systems in the period range from years to

millennia because the radial velocity variations are too small and the

angular separations too close for easy detection. Here we propose to

discover binaries in this observational gap through a Faint Guidance

Sensor SNAP survey of relatively bright targets listed in the Galactic O

Star Catalog. Our primary goal is to determine the binary frequency

among those in the cluster/association, field, and runaway groups. The

results will help us assess the role of binaries in massive star

formation and in the processes that lead to the ejection of massive

stars from their natal clusters. The program will also lead to the

identification of new, close binaries that will be targets of long term

spectroscopic and high angular resolution observations to determine

their masses and distances. The results will also be important for the

interpretation of the spectra of suspected and newly identified binary

and multiple systems.

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 11023

WFPC2 CYCLE 15 Standard Darks - part 1

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 11030

WFPC2 WF4 Temperature Reduction #3

In the fall of 2005, a serious anomaly was found in images from the WF4

CCD in WFPC2. The WF4 CCD bias level appeared to have become unstable,

resulting in sporadic images with either low or zero bias level. The

severity and frequency of the problem was rapidly increasing, making it

possible that WF4 would soon become unusable if no work-around were

found. Examination of bias levels during periods with frequent WFPC2

images showed low and zero bias episodes every 4 to 6 hours. This

periodicity is driven by cycling of the WFPC2 Replacement Heater, with

the bias anomalies occurring at the temperature peaks. The other three

CCDs {PC1, WF2, and WF3} appear to be unaffected and continue to operate

properly. Lowering the Replacement Heater temperature set points by a

few degrees C effectively eliminates the WF4 anomaly. On 9 January 2006,

the upper set point of the WFPC2 Replacement Heater was reduced from

14.9C to 12.2C. On 20 February 2006, the upper set point was reduced

from 12.2C to 11.3C, and the lower set point was reduced from 10.9C to

10.0C. These changes restored the WF4 CCD bias level; however, the bias

level has begun to trend downwards again, mimicking its behavior in late

2004 and early 2005. A third temperature reduction is planned for March

2007. We will reduce the upper set point of the heater from 11.3C to

10.4C and the lower set point from 10.0C to 9.1C. The observations

described in this proposal will test the performance of WFPC2 before and

after this temperature reduction. Additional temperature reductions may

be needed in the future, depending on the performance of WF4. Orbits:

internal 26, external 1

WFPC2 11033

Full Moon Earth Flats Closeout

Flat field exposures will be obtained by observing the moonlit Earth

with the broadband WFPC2 filters F606W and F814W, which saturate in the

minimum exposure time on the sunlit Earth. These observations will be

used to improve the flats currently in the pipeline and are part of the

WFPC2 closeout operations. Because CTE effects are large for star flats

and small for full field illumination, Earth flats are the superior

technique.

WFPC2 11113

Binaries in the Kuiper Belt: Probes of Solar System Formation and

Evolution

The discovery of binaries in the Kuiper Belt and related small body

populations is powering a revolutionary step forward in the study of

this remote region. Three quarters of the known binaries in the Kuiper

Belt have been discovered with HST, most by our snapshot surveys. The

statistics derived from this work are beginning to yield surprising and

unexpected results. We have found a strong concentration of binaries

among low-inclination Classicals, a possible size cutoff to binaries

among the Centaurs, an apparent preference for nearly equal mass

binaries, and a strong increase in the number of binaries at small

separations. We propose to continue this successful program in Cycle 16;

we expect to discover at least 13 new binary systems, targeted to

subgroups where these discoveries can have the greatest impact.

WFPC2 11156

Monitoring Active Atmospheres on Uranus and Neptune

We propose Snapshot observations of Uranus and Neptune to monitor

changes in their atmospheres on time scales of weeks and months. Uranus

equinox is only months away, in December 2007. Hubble Space Telescope

observations during the past several years {Hammel et al. 2005, Icarus

175, 284 and references therein} have revealed strongly

wavelength-dependent latitudinal structure, the presence of numerous

visible-wavelength cloud features in the northern hemisphere, at least

one very long-lived discrete cloud in the southern hemisphere, and in

2006 the first dark spot ever seen on Uranus. Long-term ground-based

observations {Lockwood and Jerzekiewicz, 2006, Icarus 180, 442; Hammel

and Lockwood 2007, Icarus 186, 291} reveal seasonal brightness changes

whose origins are not well understood. Recent near-IR images of Neptune

obtained using adaptive optics on the Keck Telescope, together with HST

observations {Sromovsky et al. 2003, Icarus 163, 256 and references

therein} which include previous Snapshot programs {GO 8634, 10170,

10534} show a general increase in activity at south temperate latitudes

until 2004, when Neptune returned to a rather Voyager-like appearance.

Further Snapshot observations of these two dynamic planets will

elucidate the nature of long-term changes in their zonal atmospheric

bands and clarify the processes of formation, evolution, and dissipation

of discrete albedo features.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of

Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens a

window into dynamical conditions in the protoplanetary disk where they

formed as well as the history of subsequent events which sculpted the

outer Solar System and emplaced them onto their present day heliocentric

orbits. To date, at least 47 TNBs have been discovered, but only about a

dozen have had their mutual orbits and separate colors determined,

frustrating their use to investigate numerous important scientific

questions. The current shortage of data especially cripples scientific

investigations requiring statistical comparisons among the ensemble

characteristics. We propose to obtain sufficient astrometry and

photometry of 23 TNBs to compute their mutual orbits and system masses

and to determine separate primary and secondary colors, roughly tripling

the sample for which this information is known, as well as extending it

to include systems of two near-equal size bodies. To make the most

efficient possible use of HST, we will use a Monte Carlo technique to

optimally schedule our observations.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

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

HSTARS:

10961 - REacq(2,1,1) results in fine lock backup (2,0,2) using FGS-2

           The REacq(2,1,1) scheduled at 239/19:37:08 - 19:45:12 resulted in fine

           lock backup (2,0,2) using FGS-2 due to (QF1STOPF) stop flag indication

           on FGS-1. Pre-acquisition OBADs showed (RSS) attitude correction values

           of 868.94 and 7.06 arcseconds. Post-acquisition OBAD/MAP had (RSS) value

           of 15.80 arcseconds.

10962 - Coarse Mode Angle Check Failure

           At AOS (240/07:22:01) observed 486 ESB “A0C”, Coarse Mode Angle Check

           Failed. During the LOS from 240/05:23:04 – 07:22:01 there was a ReAcq @

           05:55:07 and after slewing to a new attitude a GSAcq @ 06:51:52. The #44

           command (-205.746) has not changed since the GSAcq @ 04:18:46. Currently

           awaiting an engineering dump for further analysis.

           At AOS OBAD #2: V1 -5.68, V2 -6.75, V3 -6.96, RSS 11.24

           At AOS (240/09:04:16) received 486 ESB “A0C”, Coarse Mode Angle Check

           Failed. REAcq occurred at 08:24:13 and the #44 command has not changed.

           No other flags were noted.

           OBAD #2 V1 -8.77, V2 -6.00, V3 -8.99, RSS 13.92

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                SCHEDULED      SUCCESSFUL 

FGS GSacq          08              08                       

FGS REacq          06              04 

OBAD with Maneuver 24              24              

SIGNIFICANT EVENTS: (None)