HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5171

PERIOD COVERED: 5am August 30 - 5am August 31, 2010 (DOY 242/09:00z-243/09:00z)

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

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

HSTARS:

12367 - GSAcq(2,1,1) at 242/18:55:15z failed to gyro control due to search radius limit

           exceeded on FGS2.

           Observations affected WFC3 17-18 Proposal ID#11644

12369 - GSAcq(2,1,1) at 243/06:33:18z and REAcq(1,2,1) at 243/07:47:55z acquired Fine Lock

           Backup on FGS 1 Due to Search Radius Limit Exceeded on FGS 2.

           Observations possibly affected WFC3 32-25 Proposal ID#11840 and WFC3 36 Proposal ID#11929.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES:

2072-0 - Battery Pressure and FSW SOC Ground Limit Update

                       SCHEDULED      SUCCESSFUL

FGS GSAcq                8                   7

FGS REAcq                8                    8

OBAD with Maneuver  6                    6

SIGNIFICANT EVENTS:

Flash Report:

At approximately DOY 2010/242 16:52 GMT (12:52pm local), the EPS FSW SOC

parameters and Battery Pressure (PSI) safing test limits were modified

by 15 AH to accommodate the increase in battery capacity.

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.

COS/FUV 11895

FUV Detector Dark Monitor

Monitor the FUV detector dark rate by taking long science exposures

without illuminating 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.

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 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.

COS/NUV 11896

NUV Spectroscopic Sensitivity Monitoring

The purpose of this proposal is to monitor sensitivity of each NUV

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

COS/NUV/FUV 12034

COS-GTO: Brown Dwarf Activity Part 2

Based on the Findings in our Cycle 17 program, we will focus on M-stars

in Cycle 18.

S/C 11639

Catching Accreting WDs Moving into Their Instability Strip(s)

Our past HST studies of the temperatures of 9 accreting, pulsating white

dwarfs in cataclysmic variables show that 3 are in the normal

instability strip for single white dwarfs, but the other 6 are much

hotter (15, 000-16, 500K). This dual strip has been proposed to be due

to mass differences in the white dwarfs related to evolutionary history

and driven by the ionization of different elements in their respective

driving regions. In 2007, GW Lib (the brightest and best studied of the

6 hot accreting pulsators) and V455 And (the brightest and best studied

of the 3 cool accreting pulsators) underwent rare large amplitude dwarf

nova outbursts (known to heat the white dwarf) and their pulsations

disappeared. We propose COS observations to: a) take advantage of the

unprecedented opportunity to view the change in pulsation modes due to

cooling of the white dwarf envelope and b) determine the masses of the

white dwarfs to test the dual strip theory. In addition, a nova that had

its outburst 22 yrs ago has begun non-radial pulsations as it returns to

quiescence. We will use COS to determine its temperature in relation to

the instability strip for the pulsating white dwarfs in dwarf novae.

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 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 11853

Cycle 17 STIS CCD Imaging Flats

This program periodically monitors the STIS CCD imaging mode flat fields

by using the tungsten lamps.

STIS/CCD/FGS 11848

CCD Read Noise Monitor

This proposal measures the read noise of all the amplifiers (A, B, C, D)

on the STIS CCD using pairs of bias frames. Full-frame and binned

observations are made in both Gain 1 and Gain 4, with binning factors of

1x1, 1x2, 2x1, and 2x2. All exposures are internals. Pairs of visits are

scheduled monthly for the first four months and then bi-monthly after

that.

WFC3/ACS/IR 11840

Identifying the Host Galaxies for Optically Dark Gamma-Ray Bursts

We propose to use the high spatial resolution of Chandra to obtain

precise positions for a sample of Gamma-Ray Bursts (GRBs) with no

optical afterglows, where the optical light is suppressed relative to

the X-ray flux. These bursts are likely to be highly obscured and may

have different environments from the optically bright GRBs. Our Chandra

observations will (unlike Swift XRT positions) allow for the unique

identification of a host galaxy. To locate these host galaxies we will

follow up our Chandra positions with deep optical and IR observations

with HST. The ultimate aim is to understand any differences between the

host galaxies of optically dark and bright GRBs, and how these affect

the use of GRBs as tracers of starformation and galaxy evolution at high

redshift.

WFC3/ACS/IR 11563

Galaxies at z~7-10 in the Reionization Epoch: Luminosity Functions to

<0.2L* from Deep IR Imaging of the HUDF and HUDF05 Fields

The first generations of galaxies were assembled around redshifts

z~7-10+, just 500-800 Myr after recombination, in the heart of the

reionization of the universe. We know very little about galaxies in this

period. Despite great effort with HST and other telescopes, less than

~15 galaxies have been reliably detected so far at z>7, contrasting with

the ~1000 galaxies detected to date at z~6, just 200-400 Myr later, near

the end of the reionization epoch. WFC3 IR can dramatically change this

situation, enabling derivation of the galaxy luminosity function and its

shape at z~7-8 to well below L*, measurement of the UV luminosity

density at z~7-8 and z~8-9, and estimates of the contribution of

galaxies to reionization at these epochs, as well as characterization of

their properties (sizes, structure, colors). A quantitative leap in our

understanding of early galaxies, and the timescales of their buildup,

requires a total sample of ~100 galaxies at z~7-8 to ~29 AB mag. We can

achieve this with 192 WFC3 IR orbits on three disjoint fields

(minimizing cosmic variance): the HUDF and the two nearby deep fields of

the HUDF05. Our program uses three WFC3 IR filters, and leverages over

600 orbits of existing ACS data, to identify, with low contamination, a

large sample of over 100 objects at z~7-8, a very useful sample of ~23

at z~8-9, and limits at z~10. By careful placement of the WFC3 IR and

parallel ACS pointings, we also enhance the optical ACS imaging on the

HUDF and a HUDF05 field. We stress (1) the need to go deep, which is

paramount to define L*, the shape, and the slope alpha of the luminosity

function (LF) at these high redshifts; and (2) the far superior

performance of our strategy, compared with the use of strong lensing

clusters, in detecting significant samples of faint z~7-8 galaxies to

derive their luminosity function and UV ionizing flux. Our recent z~7.4

NICMOS results show that wide-area IR surveys, even of GOODS-like depth,

simply do not reach faint enough at z~7-9 to meet the LF and UV flux

objectives. In the spirit of the HDF and the HUDF, we will waive any

proprietary period, and will also deliver the reduced data to STScI. The

proposed data will provide a Legacy resource of great value for a wide

range of archival science investigations of galaxies at redshifts z~2-

9. The data are likely to remain the deepest IR/optical images until

JWST is launched, and will provide sources for spectroscopic follow up

by JWST, ALMA and EVLA.

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/IR/S/C 12089

Persistence - Part 2

The IR detectors on WFC3, like other IR detectors, trap charge when

exposed to sources near or above the full well of the detector diodes.

This charge leaks out, producing detectable afterglow images for periods

which can last for several hours, depending on the amount of over

exposure. These visits, which consist of tungsten lamp exposures of

varying durations followed by darks, are intended to provide a better

calibration of persistence over the full area of the IR detector of

WFC3.

WFC3/UV 12091

WFC3/UVIS Fringe Calibration - Part 2

Fringing has been observed in flat fields of 12 narrowband filters (4

full-frame and 3 quad spectral elements) longer than 600 nm, with

peak-to-peak fringe amplitude variations ranging from 0.5% to 14.2%

(WFC3 ISR 2010-04). Two filters (F953N and F656N) will be tested in

program 11922, supporting 88 Cycle 17 GO exposures in these filters.

Here we propose to observe globular cluster Omega Centauri (NGC 5139) in

the other 10 filters affected by fringing, supporting 319 Cycle 17 GO

exposures in these filters. By measuring the relative changes in

brightness of stars at different positions on the detector, we will

determine the local variations induced by the fringing pattern.

The data will serve two purposes: characterize the effect of fringing on

photometry of on-orbit data, and verify models used to correct for

fringing effects. The models rely on Thermal Vacuum Test 3 (TV3) data

between 845-990 nm and NASA/GSFC Detector Characterization Laboratory

(DCL) test data from 700-1060 nm. Only the F953N filter in program 11922

overlaps with the test data wavelength range, making it difficult to

compare the efficacy of fringe models. This program will expand the

on-orbit fringing data so that we can compare models at 6 new

wavelengths within the ground test data wavelength range, as well as 4

new wavelengths not covered by the ground test data. Flight data in

these 4 filters can be corrected by extrapolating the model beyond the

wavelength range of the test data used to create the model.

WFC3/UVIS 11657

The Population of Compact Planetary Nebulae in the Galactic Disk

We propose to secure narrow- and broad-band images of compact planetary

nebulae (PNe) in the Galactic Disk to study the missing link of the

early phases of post-AGB evolution. Ejected AGB envelopes become PNe

when the gas is ionized. PNe expand, and, when large enough, can be

studied in detail from the ground. In the interim, only the HST

capabilities can resolve their size, morphology, and central stars. Our

proposed observations will be the basis for a systematic study of the

onset of morphology. Dust properties of the proposed targets will be

available through approved Spitzer/IRS spectra, and so will the

abundances of the alpha- elements. We will be able thus to explore the

interconnection of morphology, dust grains, stellar evolution, and

populations. The target selection is suitable to explore the nebular and

stellar properties across the galactic disk, and to set constraints on

the galactic evolutionary models through the analysis of metallicity and

population gradients.

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 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 its 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 11644

A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into

the Formation of the Outer Solar System

The eight planets overwhelmingly dominate the solar system by mass, but

their small numbers, coupled with their stochastic pasts, make it

impossible to construct a unique formation history from the dynamical or

compositional characteristics of them alone. In contrast, the huge

numbers of small bodies scattered throughout and even beyond the

planets, while insignificant by mass, provide an almost unlimited number

of probes of the statistical conditions, history, and interactions in

the solar system. To date, attempts to understand the formation and

evolution of the Kuiper Belt have largely been dynamical simulations

where a hypothesized starting condition is evolved under the

gravitational influence of the early giant planets and an attempt is

made to reproduce the current observed populations. With little

compositional information known for the real Kuiper Belt, the test

particles in the simulation are free to have any formation location and

history as long as they end at the correct point. Allowing compositional

information to guide and constrain the formation, thermal, and

collisional histories of these objects would add an entire new dimension

to our understanding of the evolution of the outer solar system. While

ground based compositional studies have hit their flux limits already

with only a few objects sampled, we propose to exploit the new

capabilities of WFC3 to perform the first ever large-scale

dynamical-compositional study of Kuiper Belt Objects (KBOs) and their

progeny to study the chemical, dynamical, and collisional history of the

region of the giant planets. The sensitivity of the WFC3 observations

will allow us to go up to two magnitudes deeper than our ground based

studies, allowing us the capability of optimally selecting a target list

for a large survey rather than simply taking the few objects that can be

measured, as we have had to do to date. We have carefully constructed a

sample of 120 objects which provides both overall breadth, for a general

understanding of these objects, plus a large enough number of objects in

the individual dynamical subclass to allow detailed comparison between

and within these groups. These objects will likely define the core

Kuiper Belt compositional sample for years to come. While we have many

specific results anticipated to come from this survey, as with any

project where the field is rich, our current knowledge level is low, and

a new instrument suddenly appears which can exploit vastly larger

segments of the population, the potential for discovery -- both

anticipated and not -- is extraordinary.