HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT      #5066

PERIOD COVERED: 5am April 1 - 5am April 2, 2010 (DOY 091/09:00z-092/09:00z)

OBSERVATIONS SCHEDULED

ACS/WFC 11679

Probing The Globular Cluster / Low Mass X-ray Binary Connection in

Early-type Galaxies At Low X-ray Luminosities

Combined high-resolution images from Hubble and Chandra (CXO) have

revolutionized our understanding of extragalactic low-mass X-ray

binaries (LMXBs) and globular clusters (GCs), yet their connection in

early-type galaxies has remained unstudied at the luminosities of the

Galactic LMXBs in GCs. NGC 3379 and NGC 4278 are be the first

prototypical elliptical galaxies with complete, deep CXO observations

enabling the study of LMXBs at lower luminosities. We propose completing

mosaic ACS observations of both galaxies (5 fields per galaxy) that will

provide the most comprehensive view into the connection between GCs and

LMXBs in early-type galaxies. We will detect ~860 and ~270 GCs in all of

NGC 4278 and NGC 3379, respectively. These two galaxies will have among

the greatest number of detected GC-LMXBs to date (~130 & 50) and will

include the faintest GC-LMXBs in a normal early-type galaxy. We will

measure the fraction of GCs which contain LMXBs, as a function of X-ray

luminosity, galactocentric distance, color, and GC half-light radius.

Using the radial profiles of optical light, GCs, and LMXBs, we will

determine the percentage of field LMXBs which may have originated in

GCs. We will use the measured GC properties over the entire extent of

both galaxies to constrain theories of GC formation and evolution. This

is a resubmission of an approved Cycle 15 program (10835) which was only

partially completed.

COS/FUV 11897

FUV Spectroscopic Sensitivity Monitoring

The purpose of this proposal is to monitor sensitivity in each FUV

grating mode to detect any changes due to contamination or other causes.

COS/FUV/STIS/CCD/MA1 11592

Testing the Origin(s) of the Highly Ionized High-Velocity Clouds: A

Survey of Galactic Halo Stars at z>3 kpc

Cosmological simulation predicts that highly ionized gas plays an

important role in the formation and evolution of galaxies and their

interplay with the intergalactic medium. The NASA HST and FUSE missions

have revealed high-velocity CIV and OVI absorption along extragalactic

sightlines through the Galactic halo. These highly ionized high-velocity

clouds (HVCs) could cover 85% of the sky and have a detection rate

higher than the HI HVCs. Two competing, equally exciting, theories may

explain the origin of these highly ionized HVCs: 1) the "Galactic"

theory, where the HVCs are the result of feedback processes and trace

the disk-halo mass exchange, perhaps including the accretion of matter

condensing from an extended corona; 2) the "Local Group" theory, where

they are part of the local warm-hot intergalactic medium, representing

some of the missing baryonic matter of the Universe. Only direct

distance determinations can discriminate between these models. Our group

has found that some of these highly ionized HVCs have a Galactic origin,

based on STIS observations of one star at z<5.3 kpc. We propose an HST

FUV spectral survey to search for and characterize the high velocity NV,

CIV, and SiIV interstellar absorption toward 24 stars at much larger

distances than any previous searches (4<d<21 kpc, 3<|z|<13 kpc). COS

will provide atomic to highly ionized species (e.g.,OI, CII, CIV, SiIV)

that can be observed at sufficient resolution (R~22, 000) to not only

detect these highly ionized HVCs but also to model their properties and

understand their physics and origins. This survey is only possible

because of the high sensitivity of COS in the FUV spectral range.

COS/NUV 11561

An Intensive COS Spectroscopic Study of the Planetary Debris Disks

Around two Warm White Dwarfs

It is very likely that the gas giants in our Solar system will survive

the evolution of the Sun into a white dwarf, and the same is thought to

be generally true for Jovian planets around solar-like stars if their

initial orbits are wider than ~3AU. Despite this prediction, no

unambiguous detection of a planet around a white dwarf has been

announced so far. However, over the past few years, about a dozen white

dwarfs have been identified which host metal-rich debris disks that are

thought to stem from the tidal disruption of asteroids. In most cases

the debris disks are observed in the form of an infrared flux excess,

and offer relatively little diagnostic potential for the study of their

structure. We have discovered three warm (T~20000K) white dwarfs with

metal-rich debris disks in a gaseous phase which display strong

double-peaked CaII emission lines in the I-band and weak Fe 5169A

emission. The line profiles can be modeled in terms of Keplerian disks

with an extension of ~1Rsun around the white dwarfs. Photospheric MgII

4481A absorption demonstrates that the white dwarfs are accreting from

the debris disks. Besides these spectral features, the optical

wavelength range is devoid of other useful metal transitions. Here, we

propose an intensive spectroscopic ultraviolet study of these systems,

which will provide (a) ~1000 photospheric absorption lines of 15

chemical elements, allowing an accurate abundance study of the material

accreted from the debris disks, and (b) ~2 dozen additional emission

lines of Mg, Cr, Ti, and Fe that will provide detailed insight into the

dynamical, thermal, and density structure of these exo-planetary debris

disks.

COS/NUV 11894

NUV Detector Dark Monitor

The purpose of this proposal is to 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.

FGS 11704

The Ages of Globular Clusters and the Population II Distance Scale

Globular clusters are the oldest objects in the universe whose age can

be accurately determined. The dominant error in globular cluster age

determinations is the uncertain Population II distance scale. We propose

to use FGS 1R to obtain parallaxes with an accuracy of 0.2

milliarcsecond for 9 main sequence stars with [Fe/H] < -1.5. This will

determine the absolute magnitude of these stars with accuracies of 0.04

to 0.06mag. This data will be used to determine the distance to 24

metal-poor globular clusters using main sequence fitting. These

distances (with errors of 0.05 mag) will be used to determine the ages

of globular clusters using the luminosity of the subgiant branch as an

age indicator. This will yield absolute ages with an accuracy of 5%,

about a factor of two improvement over current estimates. Coupled with

existing parallaxes for more metal-rich stars, we will be able to

accurately determine the age for globular clusters over a wide range of

metallicities in order to study the early formation history of the Milky

Way and provide an independent estimate of the age of the universe.

The Hipparcos database contains only 1 star with [Fe/H] < -1.4 and an

absolute magnitude error less than 0.18 mag which is suitable for use in

main sequence fitting. Previous attempts at main sequence fitting to

metal-poor globular clusters have had to rely on theoretical

calibrations of the color of the main sequence. Our HST parallax program

will remove this source of possible systematic error and yield distances

to metal-poor globular clusters which are significantly more accurate

than possible with the current parallax data. The HST parallax data will

have errors which are 10 times smaller than the current parallax data.

Using the HST parallaxes, we will obtain main sequence fitting distances

to 11 globular clusters which contain over 500 RR Lyrae stars. This will

allow us to calibrate the absolute magnitude of RR Lyrae stars, a

commonly used Population II distance indicator.

STIS/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CC 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/MA1/MA2 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 1314s FUV-MAMA Time-Tag darks or

five 3x315s 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.

WFC3/IR 11696

Infrared Survey of Star Formation Across Cosmic Time

We propose to use the unique power of WFC3 slitless spectroscopy to

measure the evolution of cosmic star formation from the end of the

reionization epoch at z>6 to the close of the galaxy- building era at

z~0.3.Pure parallel observations with the grisms have proven to be

efficient for identifying line emission from galaxies across a broad

range of redshifts. The G102 grism on WFC3 was designed to extend this

capability to search for Ly-alpha emission from the first galaxies.

Using up to 250 orbits of pure parallel WFC3 spectroscopy, we will

observe about 40 deep (4-5 orbit) fields with the combination of G102

and G141, and about 20 shallow (2-3 orbit) fields with G141 alone.

Our primary science goals at the highest redshifts are: (1) Detect Lya

in ~100 galaxies with z>5.6 and measure the evolution of the Lya

luminosity function, independent of of cosmic variance; 2) Determine the

connection between emission line selected and continuum-break selected

galaxies at these high redshifts, and 3) Search for the proposed

signature of neutral hydrogen absorption at re-ionization. At

intermediate redshifts we will (4) Detect more than 1000 galaxies in

Halpha at 0.5<z<1.8 to measure the evolution of the extinction-corrected

star formation density across the peak epoch of star formation. This is

over an order-of-magnitude improvement in the current statistics, from

the NICMOS Parallel grism survey. (5) Trace ``cosmic downsizing" from

0.5<z<2.2; and (6) Estimate the evolution in reddening and metallicty in

star- forming galaxies and measure the evolution of the Seyfert

population. For hundreds of spectra we will be able to measure one or

even two line pair ratios -- in particular, the Balmer decrement and

[OII]/[OIII] are sensitive to gas reddening and metallicity. As a bonus,

the G102 grism offers the possibility of detecting Lya emission at

z=7-8.8.

To identify single-line Lya emitters, we will exploit the wide

0.8--1.9um wavelength coverage of the combined G102+G141 spectra. All

[OII] and [OIII] interlopers detected in G102 will be reliably separated

from true LAEs by the detection of at least one strong line in the G141

spectrum, without the need for any ancillary data. We waive all

proprietary rights to our data and will make high-level data products

available through the ST/ECF.

WFC3/IR/S/C 12097

Additional IR Subarray Dark Current Measurements (in support of GO

programs 11205, 11580)

This proposal will produce IR dark images necessary to calibrate GO

science observations (already taken, see proposals 11205 and 11580) that

use observing modes not supported by the existing IR dark current

monitor (proposal 11929). These modes are as follows: SQ256SUB/SPARS100,

SQ256SUB/SPARS200, SQ512SUB/SPARS10, SQ512SUB/SPARS100, and

SQ512SUB/SPARS200.

WFC3/UV/IR 11709

Stretching the Diversity of Cosmic Explosions: The Supernovae of

Gamma-ray Bursts

While the association between gamma-ray bursts (GRBs) and massive stars

is robust, there is a large diversity of properties among supernovae

(SNe) associated with GRBs. The converse is also true: Several recent

events show that there is a large brightness range among high energy

transients associated with SNe. As part of a comprehensive program, we

propose to use HST in order to search for and characterize the SNe

associated with GRB.

HST offers the means to cleanly separate the light curve of the GRB

afterglow from the supernova, and to remove the contamination from the

host galaxy, opening a clear path to the fundamental parameters of the

SN, and thence to the progenitor. From these observations, we will

determine the absolute magnitude at maximum, the shape of the spectral

energy distribution, and any change over time of the energy

distribution. We will also measure the rate of decay of the exponential

tail.

Merged with the ground-based data that we will obtain for each event, we

will be able to compare our data set to models and constrain the energy

of the explosion, the mass of the ejecta and the mass of Nickel

synthesized during the explosion. These results will shed light on the

apparent variety of supernovae associated with gamma-ray bursts and

X-ray flashes, and on the relation between these SNe and other, more

common, types of core-collapse explosions.

WFC3/UVIS 11594

A WFC3 Grism Survey for Lyman Limit Absorption at z=2

We propose to conduct a spectroscopic survey of Lyman limit absorbers at

redshifts 1.8 < z < 2.5, using WFC3 and the G280 grism. This proposal

intends to complete an approved Cycle 15 SNAP program (10878), which was

cut short due to the ACS failure. We have selected 64 quasars at 2.3 < z

< 2.6 from the Sloan Digital Sky Survey Spectroscopic Quasar Sample, for

which no BAL signature is found at the QSO redshift and no strong metal

absorption lines are present at z > 2.3 along the lines of sight. The

survey has three main observational goals. First, we will determine the

redshift frequency dn/dz of the LLS over the column density range 16.0 <

log(NHI) < 20.3 cm^-2. Second, we will measure the column density

frequency distribution f(N) for the partial Lyman limit systems (PLLS)

over the column density range 16.0 < log(NHI) < 17.5 cm^-2. Third, we

will identify those sightlines which could provide a measurement of the

primordial D/H ratio. By carrying out this survey, we can also help

place meaningful constraints on two key quantities of cosmological

relevance. First, we will estimate the amount of metals in the LLS using

the f(N), and ground based observations of metal line transitions.

Second, by determining f(N) of the PLLS, we can constrain the amplitude

of the ionizing UV background at z~2 to a greater precision. This survey

is ideal for a snapshot observing program, because the on-object

integration times are all well below 30 minutes, and follow-up

observations from the ground require minimal telescope time due to the

QSO sample being bright.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set of

full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K

subarray biases are acquired at less frequent intervals throughout the

cycle to support subarray science observations. The internals from this

proposal, along with those from the anneal procedure (Proposal 11909),

will be used to generate the necessary superbias and superdark reference

files for the calibration pipeline (CDBS).

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the

UVIS detector (both CCDs) at the level of ~1%, lasting hours to days.

Initially found via an unexpected bowtie-shaped feature in flatfield

ratios, subsequent lab tests on similar e2v devices have since shown

that it is also present as simply an overall offset across the entire

CCD, i.e., a QE offset without any discernable pattern. These lab tests

have further revealed that overexposing the detector to count levels

several times full well fills the traps and effectively neutralizes the

bowtie. Each visit in this proposal acquires a set of three 3x3 binned

internal flatfields: the first unsaturated image will be used to detect

any bowtie, the second, highly exposed image will neutralize the bowtie

if it is present, and the final image will allow for verification that

the bowtie is gone.

WFC3/UVIS/IR 11909

UVIS Hot Pixel Anneal

The on-orbit radiation environment of WFC3 will continually generate new

hot pixels. This proposal performs the procedure required for repairing

those hot pixels in the UVIS CCDs. During an anneal, the two-stage

thermo-electric cooler (TEC) is turned off and the four-stage TEC is

used as a heater to bring the UVIS CCDs up to ~20 deg. C. As a result of

the CCD warm up, a majority of the hot pixels will be fixed; previous

instruments such as WFPC2 and ACS have seen repair rates of about 80%.

Internal UVIS exposures are taken before and after each anneal, to allow

an assessment of the procedure's effectiveness in WFC3, provide a check

of bias, global dark current, and hot pixel levels, as well as support

hysteresis (bowtie) monitoring and CDBS reference file generation. One

IR dark is taken after each anneal, to provide a check of the IR

detector.

WFC3/UV 12077

Monitoring the Aftermath of an Asteroid Impact Event

Our Director's Discretionary program (GO-12053) to image the newly

discovered object P/2010 A2 executed successfully on 2010 Jan 25 and 29

with spectacular results. Hubble has apparently borne witness to the

first detection of a collision in the asteroid belt. Hubble imaging with

the WFC3 has revealed an object unlike anything ever seen before and

with details impossible to detect with any other facility. We request 6

more orbits of Hubble time (1 orbit every 20 days over the next few

months, until the object enters Hubble's solar exclusion zone in

late-June 2010) to monitor the evolution of this remarkable object and

further clarify the nature of this event. These observations may usher

in a new era of searching for and characterizing collisional events

within the asteroid belt. 

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:

18837-0 - Null Genslew for proposal 12077 - slot 13 @ 091/1345z

COMPLETED OPS NOTES: (None)

                      SCHEDULED  SUCCESSFUL

FGS GSAcq              10             10       

FGS REAcq               5               5

OBAD with Maneuver 4               4

SIGNIFICANT EVENTS: (None)