Status Report

NASA Hubble Space Telescope Daily Status Report #4400

By SpaceRef Editor
July 10, 2007
Filed under , ,
NASA Hubble Space Telescope Daily Status Report #4400

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.


– Continuing to collect World Class Science

PERIOD COVERED: UT July 9, 2007 (DOY 190)


ACS/SBC 10872

Lyman Continuum Emission in Galaxies at z=3D1.2

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

escape fractions of a few percent, up to 10%, with very few detections

{as opposed to upper limits} having been reported. No detections have

been reported in the epochs between z=3D0.1 and z=3D2. We propose to = measure

the fraction of escaping Lyman continuum radiation from 15 luminous

z~1.2 galaxies in the GOODS fields. Using the tremendous sensitivity of

the ACS Solar-blind Channel, we will reach AB=3D30 mag., allowing us to

detect an escape fraction of 1%. We will correlate the amount of

escaping radiation with the photometric and morphological properties of

the galaxies. A non-detection in all sources would imply that QSOs

provide the overwhelming majority of ionizing radiation at z=3D1.3, and = it

would strongly indicate that the properties of galaxies at higher

redshift have to be significantly different for galaxies to dominate

reionization. The deep FUV images will also be useful for extending the

FUV study of other galaxies in the GOODS fields.

WFPC2 11024


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


ACS/SBC 10920

High-Resolution Imaging of Nearby Lyman Break Galaxy Analogs in the

GALEX All-Sky Survey

We have used the ultraviolet all-sky imaging survey currently being

conducted by the Galaxy Evolution Explorer {GALEX} to identify for the

first time a rare population of low-redshift starbursts with properties

remarkably similar to high-redshift Lyman Break Galaxies. These compact

UV luminous galaxies {UVLGs} resemble Lyman Break Galaxies in terms of

size, UV luminosity, star-formation rate, surface brightness, mass,

metallicity, kinematics, dust content, and color. They have

characteristic “ages” {stellar mass/SFR} of only a few hundred Myr.

This population of galaxies is thus worthy of study in its own right and

as a sample of local analogs of Lyman Break Galaxies. We propose to

image a sample of the 9 nearest and brightest compact UVLGs in the

near-ultraviolet, near-infrared, and H-alpha using ACS. With these

images we will 1} characterize their structure and morphology, 2} look

for signs of interactions and mergers, 3} investigate the distribution

and propagation of star formation over varying time scales, and 4}

quantify the stellar populations and star formation history, in order to

determine whether a previous generation of stars formed long before the

current burst. These data will perfectly complement our existing

Spitzer, GALEX, and SDSS data, and will provide important information on

star-formation in the present-day universe as well as shed light on the

earliest major episodes of star formation in high-redshift galaxies.


NICMOS Post-SAA calibration – CR Persistence Part 2

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=3Ddate/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.

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 11079

Treasury Imaging of Star Forming Regions in the Local Group:

Complementing the GALEX and NOAO Surveys

We propose to use WFPC2 to image the most interesting star-forming

regions in the Local Group galaxies, to resolve their young stellar

populations. We will use a set of filters including F170W, which is

critical to detect and characterize the most massive stars, to whose hot

temperatures colors at longer wavelengths are not sensitive. WFPC2’s

field of view ideally matches the typical size of the star-forming

regions, and its spatial resolution allows us to measure individual

stars, given the proximity of these galaxies. The resulting H-R diagrams

will enable studies of star- formation properties in these regions,

which cover largely differing metallicities {a factor of 17, compared to

the factor of 4 explored so far} and characteristics. The results will

further our understanding of the star-formation process, of the

interplay between massive stars and environment, the properties of dust,

and will provide the key to interpret integrated measurements of

star-formation indicators {UV, IR, Halpha} available for several

hundreds more distant galaxies. Our recent deep surveys of these

galaxies with GALEX {FUV, NUV} and ground-based imaging {UBVRI, Halpha,

[OIII] and [SII]} provided the identification of the most relevant SF

sites. In addition to our scientific analysis, we will provide catalogs

of HST photometry in 6 bands, matched corollary ground-based data, and

UV, Halpha and IR integrated measurements of the associations, for

comparison of integrated star-formation indices to the resolved

populations. We envisage an EPO component.

WFPC2 11113

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


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 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.

WFPC2 11229

SEEDS: The Search for Evolution of Emission from Dust in Supernovae with

HST and Spitzer

The role that massive stars play in the dust content of the Universe is

extremely uncertain. It has long been hypothesized that dust can

condense within the ejecta of supernovae {SNe}, however there is a

frustrating discrepancy between the amounts of dust found in the early

Universe, or predicted by nucleation theory, and inferred from SN

observations. Our SEEDS collaboration has been carefully revisiting the

observational case for dust formation by core- collapse SNe, in order to

quantify their role as dust contributors in the early Universe. As dust

condenses in expanding SN ejecta, it will increase in optical depth,

producing three simultaneously observable phenomena: {1} increasing

optical extinction; {2} infrared {IR} excesses; and {3} asymmetric

blue-shifted emission lines. Our SEEDS collaboration recently reported

all three phenomena occurring in SN2003gd, demonstrating the success of

our observing strategy, and permitting us to derive a dust mass of up to

0.02 solar masses created in the SN. To advance our understanding of the

origin and evolution of the interstellar dust in galaxies, we propose to

use HST’s WFPC2 and NICMOS instruments plus Spitzer’s photometric

instruments to monitor ten recent core-collapse SNe for dust formation

and, as a bonus, detect light echoes that can affect the dust mass

estimates. These space-borne observations will be supplemented by

ground-based spectroscopic monitoring of their optical emission line

profiles. These observations would continue our 2-year HST and Spitzer

monitoring of this phenomena in order to address two key questions: Do

all SNe produce dust? and How much dust do they produce? As all the SN

are within 15 Mpc, each SN stands an excellent chance of detection with

HST and Spitzer and of resolving potential light echoes.


Significant Spacecraft Anomalies: (The following are preliminary reports

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


#10884 GSAcq(2,1,2) failed to RGA Hold (Gyro Control).

Upon acquisition of signal (AOS) at 190/15:59:30, the GSAcq(2,1,2)

scheduled at 190/15:51:38 – 15:59:43 had failed to RGA Hold due to a

Search Radius Limit Exceeded Error on FGS-2. Pre-acquisition OBAD1 attitude

correction value not available due to LOS. OBAD2 had (RSS) value of 122.17

arcseconds. Post-acq OBAD/MAP (without maneuver) not scheduled.

                                 SCHEDULED SUCCESSFUL

FGS GSacq                         8            7
FGS REacq                         6            6
OBAD with Maneuver          28                28



SpaceRef staff editor.