HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT      #4924

PERIOD COVERED: 5am September 3 - 5am September 4, 2009 (DOY 246/09:00z-247/09:00z)

OBSERVATIONS SCHEDULED

ACS/WFC3 11880

External CTE Monitor

This program will obtain a direct calibration of photometric losses due

to imperfect CTE by imaging stars in 47 Tuc.

COS/FUV 11482

FUV Detector Dark

Measure the FUV 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 data in order to

verify the nominal operation of the detector, and for use in the CalCOS

calibration pipeline. Variations of count rate as a function of orbital

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

to the SAA.

This is SMOV Activity COS-24.

STIS/CCD 11844

CCD Dark Monitor Part 1

Monitor the darks for the STIS CCD.

STIS/CCD 11846

CCD Bias Monitor-Part 1

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 11850

CCD Sparse Field CTE Internal

CTE measurements are made using the "internal sparse field test", along

the parallel axis. The "Pos=" optional parameter, introduced during

Cycle 11, is used to provide off- center MSM positionings of some slits.

All exposures are internals.

STIS20 11402

STIS-20 NUV MAMA Dark Monitor

The STIS NUV-MAMA dark current is dominated by a phosphorescent glow

from the detector window. Meta-stable states in this window are

populated by cosmic ray impacts, which, days later, can be thermally

excited to an unstable state from which they decay, emitting a UV

photon. The equilibrium population of these meta-stable states is larger

at lower temperatures; so warming up the detector from its cold safing

will lead to a large, but temporary, increase in the dark current.

To monitor the decay of this glow, and to determine the equilibrium dark

current for Cycle 17, four 1380s NUV-MAMA ACCUM mode darks should be

taken each week during the SMOV period. Once the observed dark current

has reached an approximate equilibrium with the mean detector

temperature, the frequency of this monitor can be reduced to one pair of

darks per week.

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.

WFC3/UVIS 11432

UVIS Internal Flats

This proposal will be used to assess the stability of the flat field

structure for the UVIS detector. Flat fields will be obtained for all

filters using the internal D2 and tungsten lamps.

This proposal corresponds to Activity Description ID WF19. It should

execute only after the following proposals have executed: WF08 - 11421

WF09 - 11422 WF11 - 11424 WF15 - 11428

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 (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 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.

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: (None)

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL

FGS GSAcq               6                     6             

FGS REAcq               9                     9                

OBAD with Maneuver 3                     3               

SIGNIFICANT EVENTS: (None)