HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT      #5023

PERIOD COVERED: 5am January 29 - 5am February 01, 2010 (DOY 029/10:00z-032/10:00z)

OBSERVATIONS SCHEDULED

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 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 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).

ACS/WFC3 11879

CCD Daily Monitor (Part 1)

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 352 orbits (22 weeks) from 31 August 2009 to 31 January

2010.

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.

STIS/CC 11854

CCD Full-Field Sensitivity Monitor C17

Measure a photometric standard star field in Omega Cen in 50CCD mode

every few months to monitor CCD sensitivity over the whole field of

view. Keep the spacecraft orientation within a suitable range (+/- 5

degrees) to keep the same stars in the same part of the CCD for every

measurement. This test will give a direct transformation of the 50CCD

magnitudes to the Johnson-Cousins system for red sources. These

transformations should be accurate to 1%. The stability of these

transformations will be measured to the sub-percent level. These

observations also provide a check of the astrometric and PSF stability

of the instrument over its full field of view.

STIS/CCD 11846

CCD Bias Monitor-Part 1

The purpose of this proposal is to 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 11844

CCD Dark Monitor Part 1

The purpose of this proposal is to monitor the darks for the STIS CCD.

ACS/SBC 11791

The Wavelength Dependence of Accretion Disk Structure

We can now routinely measure the size of quasar accretion disks using

gravitational microlensing of lensed quasars. The next step to testing

accretion disk models is to measure the size of accretion disks as a

function of wavelength, particularly at the UV and X-ray wavelengths

that should probe the inner, strong gravity regime. Here we focus on two

four- image quasar lenses that already have optical (R band) and X-ray

size measurements using microlensing. We will combine the HST

observations with ground-based monitoring to measure the disk size as a

function of wavelength from the near-IR to the UV. We require HST to

measure the image flux ratios in the ultraviolet continuum near the

Lyman limit of the quasars. The selected targets have estimated black

hole masses that differ by an order of magnitude, and we should find

wavelength scalings for the two systems that are very different because

the Blue/UV wavelengths should correspond to parts of the disk near the

inner edge for the high mass system but not in the low mass system. The

results will be modeled using a combination of simple thin disk models

and complete relativistic disk models. While requiring only 18 orbits,

success for one system requires observations in both Cycles 16 and 17.

WFC3/UVIS 11732

The Temperature Profiles of Quasar Accretion Disks

We can now routinely measure the size of quasar accretion disks using

gravitational microlensing of lensed quasars. At optical wavelengths we

observe a size and scaling with black hole mass roughly consistent with

thin disk theory but the sizes are larger than expected from the

observed optical fluxes. One solution would be to use a flatter

temperature profile, which we can study by measuring the wavelength

dependence of the disk size over the largest possible wavelength

baseline. Thus, to understand the size discrepancy and to probe closer

to the inner edge of the disk we need to extend our measurements to UV

wavelengths, and this can only be done with HST. For example, in the UV

we should see significant changes in the optical/UV size ratio with

black hole mass. We propose monitoring 5 lenses spanning a broad range

of black hole masses with well-sampled ground based light curves,

optical disk size measurements and known GALEX UV fluxes during Cycles

17 and 18 to expand from our current sample of two lenses. We would

obtain 5 observations of each target in each Cycle, similar to our

successful strategy for the first two targets.

WFC3/ACS/UVIS 11724

Direct Age Determination of the Local Group dE Galaxies NGC 147 and NGC

185

The origin of dwarf elliptical (dE) galaxies remains a mystery and the

dE galaxies of the Local Group provide the best opportunity to study

this galaxy class in detail. We propose to obtain ACS photometry of main

sequence turnoff stars in the M31 dE satellites NGC 147 and NGC 185.

Because these galaxies have little to no stars younger than 1 Gyr,

resolving the main sequence turnoff is required to directly quantify

their star formation histories. NGC 147 and NGC 185 are the only two dEs

for which a clean measurement is feasible with the HST. This proposal

was accepted in Cycle 15, but little data were taken before the failure

of ACS. The main sequence turnoffs of NGC 147 and NGC 185 are expected

to be at an apparent magnitude of V=29; we request F606W/F814W imaging

one half magnitude fainter than this limit (three magnitudes fainter

than the deepest previous dE observations). Quantifying the ratio of old

to intermediate-age stars will allow us to discriminate between

competing models of dE formation. On-going Keck/DEIMOS spectroscopy of

several hundred red giant stars in each of these two dE galaxies,

coupled with dynamical modeling and spectral synthesis, will complement

the ACS measurement by providing information on chemical abundance

patterns, dark matter content and internal dynamics. The proposed ACS

data will be the first to directly quantify the onset and duration of

star formation episodes in dE galaxies, and will thereby form the

cornerstone in what promises to be the most comprehensive study of this

class of galaxies.

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/ACS/UVIS/IR/STIS/C 11653 CD SAINTS - Supernova 1987A INTensive

Survey

SAINTS is a program to observe SN 1987A, the brightest supernova since

1604, as it matures into the youngest supernova remnant at age 21. HST

is the essential tool for resolving SN1987A's many physical components.

A violent encounter is underway between the fastest- moving debris and

the circumstellar ring: shocks excite "hotspots." Radio, optical,

infrared and X- ray fluxes have been rising rapidly: we have organized

Australia Telescope, HST, VLT, Spitzer, and Chandra observations to

understand the several emission mechanisms at work. Photons from the

shocked ring will excite previously invisible gas outside the ring,

revealing the true extent of the mass loss that preceded the explosion

of Sanduleak -69 202. This will help test ideas for the progenitor of SN

1987A. The inner debris, excited by radioactive isotopes from the

explosion, is now resolved and seen to be aspherical, providing direct

evidence on the shape of the explosion itself. Questions about SN 1987A

remain unanswered. A rich and unbroken data set from SAINTS will help

answer these central questions and will build an archive for the future

to help answer questions we have not yet thought to ask.

STIS/CCD 11606

Dynamical Hypermassive Black Hole Masses

We will use STIS spectra to derive the masses of 5 hypermassive black

holes (HMBHs). From the observed scaling relations defined by less

massive spheroids, these objects are expected to reside at the nuclei of

host galaxies with stellar velocity dispersions greater than 320 km/s.

These 5 targets have confirmed regular gas distributions on the scales

of the black hole sphere of influence. It is essential that the sphere

of influence is resolved for accurate determinations of black hole mass

(0.1"). These scales cannot be effectively observed from the ground.

Only two HMBHs have had their masses modeled so far; it is impossible to

draw any general conclusions about the connections between HMBH mass and

their massive host galaxies. With these 5 targets we will determine

whether these HMBHs deviate from the scaling relations defined by less

massive spheroids. A larger sample will allow us to firmly anchor the

high mass end of the correlation between black hole mass and stellar

velocity dispersion, and other scaling relations. Therefore we are also

conducting a SNAPshot program with which we expect to detect a further

24 HMBH candidates for STIS observation in future cycles. At the

completion of this project we will have populated the high mass end of

the scaling relations with the sample sizes enjoyed by less massive

spheroids.

ACS/WFC3 11599

Distances of Planetary Nebulae from SNAPshots of Resolved Companions

Reliable distances to individual planetary nebulae (PNe) in the Milky

Way are needed to advance our understanding of their spatial

distribution, birthrates, influence on galactic chemistry, and the

luminosities and evolutionary states of their central stars (CSPN). Few

PNe have good distances, however. One of the best ways to remedy this

problem is to find resolved physical companions to the CSPN and measure

their distances by photometric main-sequence fitting. We have previously

used HST to identify and measure probable companions to 10 CSPN, based

on angular separations and statistical arguments only. We now propose to

use HST to re-observe 48 PNe from that program for which additional

companions are possibly present. We then can use the added criterion of

common proper motion to confirm our original candidate companions and

identify new ones in cases that could not confidently be studied before.

We will image the region around each CSPN in the V and I bands, and in

some cases in the B band. Field stars that appear close to the CSPN by

chance will be revealed by their relative proper motion during the 13+

years since our original survey, leaving only genuine physical

companions in our improved and enlarged sample. This study will increase

the number of Galactic PNe with reliable distances by 50 percent and

improve the distances to PNe with previously known companions.

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/ACS/UVIS/IR 11570

Narrowing in on the Hubble Constant and Dark Energy

A measurement of the Hubble constant to a precision of a few percent

would be a powerful aid to the investigation of the nature of dark

energy and a potent "end-to end" test of the present cosmological model.

In Cycle 15 we constructed a new streamlined distance ladder utilizing

high- quality type Ia supernova data and observations of Cepheids with

HST in the near-IR to minimize the dominant sources of systematic

uncertainty in past measurements of the Hubble constant and reduce its

total uncertainty to a little under 5%. Here we propose to exploit this

new route to reduce the remaining uncertainty by more than 30%,

translating into an equal reduction in the uncertainty of the equation

of state of dark energy. We propose three sets of observations to reach

this goal: a mosaic of NGC 4258 with WFC3 in F160W to triple its sample

of long period Cepheids, WFC3/F160W observations of the 6 ideal SN Ia

hosts to triple their samples of Cepheids, and observations of NGC 5584

the host of a new SN Ia, SN 2007af, to discover and measure its Cepheids

and begin expanding the small set of SN Ia luminosity calibrations.

These observations would provide the bulk of a coordinated program aimed

at making the measurement of the Hubble constant one of the leading

constraints on dark energy.

STIS/CCD 11567

Boron Abundances in Rapidly Rotating Early-B Stars

Models of rotation in early-B stars predict that rotationally driven

mixing should deplete surface boron abundances during the main-sequence

lifetime of many stars. However, recent work has shown that many boron

depleted stars are intrinsically slow rotators for which models predict

no depletion should have occurred, while observations of nitrogen in

some more rapidly rotating stars show less mixing than the models

predict. Boron can provide unique information on the earliest stages of

mixing in B stars, but previous surveys have been biased towards narrow-

lined stars because of the difficulty in measuring boron abundances in

rapidly rotating stars. The two targets observed as part of our Cycle 13

SNAP program 10175, just before STIS failed, demonstrate that it is

possible to make useful boron abundance measurements for early-B stars

with Vsin(i) above 100 km/s. We propose to extend that survey to a large

enough sample of stars to allow statistically significant tests of

models of rotational mixing in early-B stars.

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 followup by

JWST, ALMA and EVLA.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

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

HSTARS:

12177 - The GSAcq(2,1,1) scheduled at 031/17:43:10z failed on its first

           attempt due to scan step limit exceeded on FGS 1 at 17:46:46z. The second

           attempt resulted in fine lock backup (2,0,2).

           Observations possibly affected: WFC3 165 - 166 Proposal #ID11905;

           ACS 140 Proposal #ID11599

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                       SCHEDULED  SUCCESSFUL

FGS GSAcq               24             24      

FGS REAcq               25             25      

OBAD with Maneuver 14             14      

SIGNIFICANT EVENTS: (None)