HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science



DAILY REPORT #5180



PERIOD COVERED: 5am September 13 - 5am September 14, 2010 (DOY 256/09:00z-257/09:00z)



FLIGHT OPERATIONS SUMMARY:



Significant Spacecraft Anomalies: (The following are preliminary reports

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



HSTARS:

12402 - COS 1021 STB Message received at 257/01:22z, following successful

GSAcq (2,1,1) at 257/01:15:46z, indicating take data flag was down when a target

acquisition macro was about to make a slew request.



Observations possibly affected: WFC3 20-21 Proposal ID#11905.





COMPLETED OPS REQUEST: (None)



COMPLETED OPS NOTES: (None)



SCHEDULED SUCCESSFUL

FGS GSAcq 7 7

FGS REAcq 9 9

OBAD with Maneuver 3 3



SIGNIFICANT EVENTS: None.





OBSERVATIONS SCHEDULED:



ACS/WFC 11996



CCD Daily Monitor (Part 3)



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 308 orbits (19.25 weeks) from 21 June 2010 to 1 November

2010.



ACS/WFC 12210



SLACS for the Masses: Extending Strong Lensing to Lower Masses and

Smaller Radii



Strong gravitational lensing provides the most accurate possible

measurement of mass in the central regions of early-type galaxies

(ETGs). We propose to continue the highly productive Sloan Lens ACS

(SLACS) Survey for strong gravitational lens galaxies by observing a

substantial fraction of 135 new ETG gravitational-lens candidates with

HST-ACS WFC F814W Snapshot imaging. The proposed target sample has been

selected from the seventh and final data release of the Sloan Digital

Sky Survey, and is designed to complement the distribution of previously

confirmed SLACS lenses in lens-galaxy mass and in the ratio of Einstein

radius to optical half-light radius. The observations we propose will

lead to a combined SLACS sample covering nearly two decades in mass,

with dense mapping of enclosed mass as a function of radius out to the

half-light radius and beyond. With this longer mass baseline, we will

extend our lensing and dynamical analysis of the mass structure and

scaling relations of ETGs to galaxies of significantly lower mass, and

directly test for a transition in structural and dark-matter content

trends at intermediate galaxy mass. The broader mass coverage will also

enable us to make a direct connection to the structure of well-studied

nearby ETGs as deduced from dynamical modeling of their line-of-sight

velocity distribution fields. Finally, the combined sample will allow a

more conclusive test of the current SLACS result that the intrinsic

scatter in ETG mass-density structure is not significantly correlated

with any other galaxy observables. The final SLACS sample at the

conclusion of this program will comprise approximately 130 lenses with

known foreground and background redshifts, and is likely to be the

largest confirmed sample of strong-lens galaxies for many years to come.



ACS/WFC 12292



SWELLS: Doubling the Number of Disk-dominated Edge-on Spiral Lens

Galaxies



The formation of realistic disk galaxies within the LCDM cosmology is

still largely an unsolved problem. Theory is now beginning to make

predictions for how dark matter halos respond to galaxy formation, and

for the properties of disk galaxies. Measuring the density profiles of

dark matter halos on galaxy scales is therefore a strong test for the

standard paradigm of galaxy formation, offering great potential for

discovery. However, the degeneracy between the stellar and dark matter

contributions to galaxy rotation curves remains a major obstacle. Strong

gravitational lensing, when combined with spatially resolved kinematics

and stellar population models, can solve this long-standing problem.

Unfortunately, this joint methodology could not be exploited until

recently due to the paucity of known edge-on spiral lenses. We have

developed and demonstrated an efficient technique to find exactly these

systems. During supplemental cycle-16 we discovered five new spiral lens

galaxies, suitable for rotation curve measurements. We propose

multi-color HST imaging of 16 candidates and 2 partially-imaged

confirmed systems, to measure a sample of eight new edge-on spiral

lenses. This program will at least double the number of known

disk-dominated systems. This is crucial for constraining the relative

contribution of the disk, bulge and dark halo to the total density

profile.



ACS/WFC3 11734



The Hosts of High Redshift Gamma-Ray Bursts



Gamma-ray bursts are the most luminous explosive events known, acting as

beacons to the high redshift universe. Long duration GRBs have their

origin in the collapse of massive stars and thus select star forming

galaxies across a wide range of redshift. Due to their bright afterglows

we can study the details of GRB host galaxies via absorption

spectroscopy, providing redshifts, column densities and metallicities

for galaxies far too faint to be accessible directly with current

technology. We have already obtained deep ground based observations for

many hosts and here propose ACS/WFC3 and WFC3 observations of the fields

of bursts at z>3 which are undetected in deep ground based images. These

observations will study the hosts in emission, providing luminosities

and morphologies and will enable the construction of a sample of high-z

galaxies with more detailed physical properties than has ever been

possible before.



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/MA 11668



Cosmo-chronometry and Elemental Abundance Distribution of the Ancient

Star HE1523-0901



We propose to obtain near-UV HST/STIS spectroscopy of the extremely

metal-poor, highly r-process-enhanced halo star HE 1523-0901, in order

to produce the most complete abundance distribution of the heaviest

stable elements, including platinum, osmium, and lead. These HST

abundance data will then be used to estimate the initial abundances of

the long-lived radioactive elements thorium and uranium, and by

comparison with their observed abundances, enable an accurate age

determination of this ancient star. The use of radioactive chronometers

in stars provides an independent lower limit on the age of the Galaxy,

which can be compared with alternative limits set by globular clusters

and by analysis from WMAP. Our proposed observations of HE1523-0901 will

also provide significant new information about the early chemical

history of the Galaxy, specifically, the nature of the first generations

of stars and the types of nucleosynthetic processes that occurred at the

onset of Galactic chemical evolution.



STIS/CCD/MA1 11737



The Distance Dependence of the Interstellar N/O Abundance Ratio: A Gould

Belt Influence?



The degree of elemental abundance homogeneity in the interstellar medium

is a function of the enrichment and mixing processes that govern

galactic chemical evolution. Observations of young stars and the

interstellar gas within ~500 pc of the Sun have revealed a local ISM

that is so well-mixed it is having an impact on ideas regarding the

formation of extrasolar planets. However, the situation just beyond the

local ISM is not so clear. Sensitive UV absorption line measurements

have recently revealed a pattern of inhomogeneities in the interstellar

O, N, and Kr gas-phase abundances at distances of ~500 pc and beyond

that appear nucleosynthetic in origin rather than due to dust depletion.

In particular, based on a sample of 13 sightlines, Knauth et al. (2006)

have found that the nearby stars (d < 500 pc) exhibit a mean

interstellar N/O abundance ratio that is significantly higher (0.18 dex)

than that toward the more distant stars. Interestingly, all of their

sightlines lie in the sky vicinity of the Gould Belt of OB associations,

molecular clouds, and diffuse gas encircling the Sun at a distance of

~400 pc. Is it possible that mixing processes have not yet smoothed out

the recent ISM enrichment by massive stars in the young Belt region? By

measuring the interstellar N/O ratios in a strategic new sample of

sightlines with STIS, we propose to test the apparent N/O homogeneity

inside the Gould Belt and determine if the apparent decline in the N/O

ratio with distance is robust and associated with the Belt region.



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 12265



Determining the Physical Nature of a Unique Giant Lya Emitter at z=6.595



We propose deep WFC3/IR imaging for a giant Lya emitter (LAE) with a

Keck spectroscopic redshift of z=6.595 discovered by extensive

narrow-band imaging with Subaru in the SXDS-UKIDSS/UDS field. This

remarkable object is unique in many respects including its large stellar

mass and luminous nebula which extends over 17 kpc; no equivalent source

has been found in other surveys. The nature of this rare object is

unclear. Fundamental to progress is determining the origin of star

formation in such an early massive object; if the age of the stellar

population is short we are likely witnessing a special moment in the

formation history of a massive galaxy. The heating source for the nebula

is also unclear; options include intense star formation, the infall of

cold gas onto a dark halo or shock heating from a merger. We will take

deep broad-band (F125W and F160W) images and an intermediate-band

(F098M) image which will be analyzed in conjunction with ultra-deep IRAC

3.6 and 4.5 micron data being taken by the Spitzer/SEDS project. These

data will enable us to constrain the star formation rate and stellar

age. Moreover, the UV continuum morphology and Lya-line distribution

will be investigated for evidence of a major merger, cold accretion, or

hot bubbles associated with outflows. We will address the physical

origin of the remarkable object observed at an epoch where massive

galaxies are thought to begin their assembly.



WFC3/IR/S/C 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).



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 11914



UVIS Earth Flats



This program is an experimental path finder for Cycle 18 calibration.

Visible-wavelength flat fields will be obtained by observing the dark

side of the Earth during periods of full moon illumination. The

observations will consist of full-frame streaked WFC3 UVIS imagery: per

22- min total exposure time in a single "dark-sky" orbit, we anticipate

collecting 7000 e/pix in F606W or 4500 e/pix in F814W. To achieve

Poisson S/N > 100 per pixel, we require at least 2 orbits of F606W and 3

orbits of F814W.



For UVIS narrowband filters, exposures of 1 sec typically do not

saturate on the sunlit Earth, so we will take sunlit Earth flats for

three of the more-commonly used narrowband filters in Cycle 17 plus the

also-popular long-wavelength quad filters, for which we get four filters

at once.



Why not use the Sunlit Earth for the wideband visible-light filters? It

is too bright in the visible for WFC3 UVIS minimum exposure time of 0.5

sec. Similarly, for NICMOS the sunlit-Earth is too bright which

saturates the detector too quickly and/or induces abnormal behaviors

such as super-shading (Gilmore 1998, NIC 098-011). In the narrowband

visible and broadband near- UV is not too bright (predictions in Cox et

al. 1987 "Standard Astronomical Sources for HST: 6. Spatially Flat

Fields." and observations in ACS Program 10050).



Other possibilities? Cox et al.'s Section II.D addresses many other

possible sources for flat fields, rejecting them for a variety of

reasons. A remaining possibility would be the totally eclipsed moon.

Such eclipses provide approximately 2 hours (1 HST orbit) of opportunity

per year, so they are too rare to be generically useful. An advantage of

the moon over the Earth is that the moon subtends less than 0.25 square

degree, whereas the Earth subtends a steradian or more, so scattered

light and light potentially leaking around the shutter presents

additional problems for the Earth. Also, we're unsure if HST can point

180 deg from the Sun.



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 warmup, 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.