HUBBLE SPACE TELESCOPE - Continuing To Collect World Class Science

DAILY REPORT #5088

PERIOD COVERED: 5am May 3, 2010 - 5am May 4, 2010 (DOY 123/09:00z-124/09:00z)

OBSERVATIONS SCHEDULED:

ACS/WFC 11995

CCD Daily Monitor (Part 2)

This program comprises basic tests for measuring the read noise and dark

current of the ACS WFC and for tracking the growth of hot pixels. The

recorded frames are used to create bias and dark reference images for

science data reduction and calibration. This program will be executed four

days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To

facilitate scheduling, this program is split into three proposals. This

proposal covers 320 orbits (20 weeks) from 1 February 2010 to 20 June

2010.

ACS/WFC/WFC3/UVI 11636

First Resolved Imaging of Escaping Lyman Continuum

The emission from star-forming galaxies appears to be responsible for

reionization of the universe at z > 6. However, the models that attempt to

describe the detailed impact of high-redshift galaxies on the surrounding

inter-galactic medium (IGM) are strongly dependent upon several uncertain

parameters. Perhaps the most uncertain is the fraction of HI-ionizing

photons produced by young stars that escape into the IGM. Most attempts to

measure this "escape fraction" have produced null results. Recently, a

small subset of z~3 Lyman Break Galaxies (LBGs) has been found exhibiting

large escape fractions. It remains unclear however, what differentiates

them from other LBGs. Several models attempt to explain how such a large

fraction of ionizing continuum can escape through the HI and dust in the

ISM (eg. "chimneys" created by SNe winds, globular cluster formation,

etc.), each producing unique signatures which can be observed with resolved

imaging of the escaping Lyman continuum. To date, there are only six LBGs

with individual detections of escaping Lyman continuum at any redshift. We

propose a single deep, high resolution WFC3/UVIS image of the ionizing

continuum (F336W) and the rest-frame UV/optical (F606W/F814W/F160W) of five

of these six LBGs with large escape fractions. These LBGs have a high

surface density and large escape fractions, and lie at the optimal redshift

for Lyman continuum imaging with UVIS filters, making our sample especially

suitable for follow-up. With these data we will discern the mechanisms

responsible for producing large escape fractions, and therefore gain

insight into the process of reionization.

COS/FUV/COS/NUV 11727

UV spectroscopy of Local Lyman Break Galaxy Analogs: New Clues to Galaxy

Formation in the Early Universe

Much of our information about galaxy evolution and the interaction between

galaxies and the IGM at high-z has been provided by the Lyman Break

Galaxies (LBGs). However, it is difficult to investigate these faint and

distant objects in detail. To address this, we have used the GALEX All-Sky

Imaging Survey and the SDSS to identify for the first time a rare

population of low-redshift galaxies with properties remarkably similar to

the high-redshift LBGs. These local "Lyman Break Analogs" (LBAs) resemble

LBGs in terms of morphology, size, UV luminosity, star formation rate, UV

surface brightness, stellar mass, velocity dispersion, metallicity, and

dust content. We are assembling a wide range of data on these objects with

the goal of using them as local laboratories for better understanding the

relevant astrophysical processes in LBGs. These data include HST imaging

(95 orbits in Cy15 and 16), Spitzer photometry and spectroscopy, Chandra

and XMM X-ray imaging and spectroscopy, and near-IR integral field

spectroscopy (VLT, Keck, and Gemini). In this proposal we are requesting

the most important missing puzzle piece: far-UV spectra with a

signal-to-noise and spectral resolution significantly better than available

for typical LBGs. We will use these spectra to study the LBA's galactic

winds, probe the processes that regulate the escape of Ly-a and Lyman

continuum radiation, determine chemical abundances for the stars and gas,

and constrain the form of the high-end of the Initial Mass Function. Adding

these new COS data will give us vital information about these extraordinary

sites of star formation in the local universe. In so-doing it will also

shed new light on the processes that led to the formation of stars, the

building of galaxies, and the enrichment and heating of the IGM in the

early universe.

COS/NUV 11894

NUV Detector Dark Monitor

Measure the NUV detector dark rate by taking long science exposures with no

light on the detector. The detector dark rate and spatial distribution of

counts will be compared to pre-launch and SMOV data in order to verify the

nominal operation of the detector. Variations of count rate as a function

of orbital position will be analyzed to find dependence of dark rate on

proximity to the SAA. Dependence of dark rate as function of time will also

be tracked.

S/C 12046

COS FUV DCE Memory Dump

Whenever the FUV detector high voltage is on, count rate and current draw

information is collected, monitored, and saved to DCE memory. Every 10 msec

the detector samples the currents from the HV power supplies (HVIA, HVIB)

and the AUX power supply (AUXI). The last 1000 samples are saved in memory,

along with a histogram of the number of occurrences of each current value.

In the case of a HV transient (known as a "crackle" on FUSE), where one of

these currents exceeds a preset threshold for a persistence time, the HV

will shut down, and the DCE memory will be dumped and examined as part of

the recovery procedure. However, if the current exceeds the threshold for

less than the persistence time (a "mini-crackle" in FUSE parlance), there

is no way to know without dumping DCE memory. By dumping and examining the

histograms regularly, we will be able to monitor any changes in the rate of

"mini-crackles" and thus learn something about the state of the detector.

S/C/STIS/MA1 11863

STIS MAMA Fold Distribution

The performance of MAMA microchannel plates can be monitored using a MAMA

fold analysis procedure. The fold analysis provides a measurement of the

distribution of charge cloud sizes incident upon the anode giving some

measure of changes in the pulse-height distribution of the MCP and,

therefore, MCP gain. This proposal executes the same steps as the STIS MAMA

Fold Analysis (10035) during Cycle 12.

S/C/WFC3/IR 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more

reliably removed from science data using darks taken with the same exposure

sequences as the science data, than with a single dark current image scaled

by desired exposure time. Therefore, dark current images must be collected

using all sample sequences that will be used in science observations. These

observations will be used to monitor changes in the dark current of the

WFC3-IR channel on a day-to-day basis, and to build calibration dark

current ramps for each of the sample sequences to be used by GOs in Cycle

17. For each sample sequence/array size combination, a median ramp will be

created and delivered to the calibration database system (CDBS).

STIS/CCD 11721

Verifying the Utility of Type Ia Supernovae as Cosmological Probes:

Evolution and Dispersion in the Ultraviolet Spectra

The study of distant type Ia supernova (SNe Ia) offers the most practical

and immediate discriminator between popular models of dark energy. Yet

fundamental questions remain over possible redshift-dependent trends in

their observed and intrinsic properties. High quality Keck spectroscopy of

a representative sample of 36 intermediate redshift SNe Ia has revealed a

surprising, and unexplained, diversity in their rest-frame UV fluxes. One

possible explanation is hitherto undiscovered variations in the progenitor

metallicity. Unfortunately, this result cannot be compared to local UV data

as only two representative SNe Ia have been studied near maximum light.

Taking advantage of two new `rolling searches' and the restoration of STIS,

we propose a non-disruptive TOO campaign to create an equivalent comparison

local sample. This will allow us to address possible evolution in the mean

UV spectrum and its diversity, an essential precursor to the study of SNe

beyond z~1.

STIS/CCD 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CCD 11847

CCD Bias Monitor-Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and

1x1 at gain = 4, to build up high-S/N superbiases and track the evolution

of hot columns.

STIS/CCD 11852

STIS CCD Spectroscopic Flats C17

Obtain pixel-to-pixel lamp flat fields for the STIS CCD in spectroscopic

mode.

STIS/MA1 11857

STIS Cycle 17 MAMA Dark Monitor

This proposal monitors the behavior of the dark current in each of the MAMA

detectors.

The basic monitor takes two 1380s ACCUM darks each week with each

detector. However, starting Oct 5, pairs are only included for weeks that

the LRP has external MAMA observations planned. The weekly pairs of

exposures for each detector are linked so that they are taken at opposite

ends of the same SAA free interval. This pairing of exposures will make it

easier to separate long and short term temporal variability from

temperature dependent changes.

For both detectors, additional blocks of exposures are taken once every

six months. These are groups of five 1314 s FUV-MAMA TIME-TAG darks or five

3x315 s NUV ACCUM darks distributed over a single SAA free interval. This

will give more information on the brightness of the FUV MAMA dark current

as a function of the amount of time that the HV has been on, and for the

NUV MAMA will give a better measure of the short term temperature

dependence.

STIS/MA1 11861

MAMA FUV Flats

This program will obtain FUV-MAMA observations of the STIS internal Krypton

lamp to construct an FUV flat applicable to all FUV modes.

WFC3/IR 11700

Bright Galaxies at z>7.5 with a WFC3 Pure Parallel Survey

The epoch of reionization represents a special moment in the history of the

Universe as it is during this era that the first galaxies and star clusters

are formed. Reionization also profoundly affects the environment where

subsequent generations of galaxies evolve. Our overarching goal is to test

the hypothesis that galaxies are responsible for reionizing neutral

hydrogen. To do so we propose to carry out a pure parallel WFC3 survey to

constrain the bright end of the redshift z>7.5 galaxy luminosity function

on a total area of 176 arcmin^2 of sky. Extrapolating the evolution of the

luminosity function from z~6, we expect to detect about 20 Lyman Break

Galaxies brighter than M_* at z~8 significantly improving the current

sample of only a few galaxies known at these redshifts. Finding

significantly fewer objects than predicted on the basis of extrapolation

from z=6 would set strong limits to the brightness of M_*, highlighting a

fast evolution of the luminosity function with the possible implication

that galaxies alone cannot reionize the Universe. Our observations will

find the best candidates for spectroscopic confirmation, that is bright

z>7.5 objects, which would be missed by small area deeper surveys. The

random pointing nature of the program is ideal to beat cosmic variance,

especially severe for luminous massive galaxies, which are strongly

clustered. In fact our survey geometry of 38 independent fields will

constrain the luminosity function like a contiguous single field survey

with two times more area at the same depth. Lyman Break Galaxies at z>7.5

down to m_AB=26.85 (5 sigma) in F125W will be selected as F098M dropouts,

using three to five orbits visits that include a total of four filters

(F606W, F098M, F125W, F160W) optimized to remove low-redshift interlopers

and cool stars. Our data will be highly complementary to a deep field

search for high-z galaxies aimed at probing the faint end of the luminosity

function, allowing us to disentangle the degeneracy between faint end slope

and M_* in a Schechter function fit of the luminosity function. We waive

proprietary rights for the data. In addition, we commit to release the

coordinates and properties of our z>7.5 candidates within one month from

the acquisition of each field.

WFC3/UVI 11595

Turning out the Light: A WFC3 Program to Image z>2 Damped Lyman Alpha

Systems

We propose to directly image the star-forming regions of z>2 damped Lya

systems (DLAs) using the WFC3/UVIS camera on the Hubble Space Telescope. In

contrast to all previous attempts to detect the galaxies giving rise to

high redshift DLAs, we will use a novel technique that completely removes

the glare of the background quasar. Specifically, we will target quasar

sightlines with multiple DLAs and use the higher redshift DLA as a

``blocking filter'' (via Lyman limit absorption) to eliminate all FUV

emission from the quasar. This will allow us to carry out a deep search for

FUV emission from the lower redshift DLA, shortward of the Lyman limit of

the higher redshift absorber. The unique filter set and high spatial

resolution afforded by WFC3/UVIS will then enable us to directly image the

lower redshift DLA and thus estimate its size, star-formation rate and

impact parameter from the QSO sightline. We propose to observe a sample of

20 sightlines, selected primarily from the SDSS database, requiring a total

of 40 HST orbits. The observations will allow us to determine the first FUV

luminosity function of high redshift DLA galaxies and to correlate the DLA

galaxy properties with the ISM characteristics inferred from standard

absorption-line analysis to significantly improve our understanding of the

general DLA population.

WFC3/UVI 11700