Date: October 25th 2006

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4225

PERIOD COVERED: UT October 23, 2006 (DOY 296)

OBSERVATIONS SCHEDULED

ACS/HRC 10556

Neutral Gas at Redshift z=0 5

Damped Lyman-alpha systems {DLAs} are used to track the bulk of the neutral hydrogen gas in the Universe Prior to HST UV spectroscopy, they could only be studied from the ground at redshifts z>1 65 However, HST has now permitted us to discover 41 DLAs at z<1 65 in our previous surveys Followup studies of these systems are providing a wealth of information about the evolution of the neutral gas phase component of the Universe But one problem is that these 41 low-redshift systems are spread over a wide range of redshifts spanning nearly 70% of the age of the Universe Consequently, past surveys for low-redshift DLAs have not been able to offer very good precision in any small redshift regime Here we propose an ACS-HRC- PR200L spectroscopic survey in the redshift interval z=[0 37, 0 7] which we estimate will permit us to discover another 41 DLAs This will not only allow us to double the number of low-redshift DLAs, but it will also provide a relatively high-precision regime in the low-redshift Universe that can be used to anchor evolutionary studies Fortunately DLAs have high absorption equivalent width, so ACS-HRC-PR200L has high-enough resoultion to perform this proposed MgII-selected DLA survey

ACS/HRC 10607

Probing Circumstellar and Interstellar Dust with Scattered-Light Echoes

Scattered-light echoes are one of the most powerful and efficient probes of the structure and composition of dust in circumstellar and interstellar {ISM} environments Observations of light echoes provide exact three-dimensional positions of dust while constraining its density, grain- size and chemical make-up Furthermore, echoes can be used as distance indicators via polarization measurements We propose to take deep, high-resolution ACS/HRC images of five supernovae {SNe} Two of these, SNe 1991T and 1998bu, have known circumstellar echoes that have only recently become fully resolvable with HST, and therefore require new observations Only four echo-producing SNe are currently known, and in an attempt to increase this sample, we will also observe SNe 1999bw, 2002hh, and 2004dj All three SNe are strong candidates for producing echoes from circumstellar and ISM dust, but only at angular sizes that HST can resolve With these observations, we will use light echoes to their full advantage, to study {1} the mass-loss histories of Type II and Ia SN progenitors, {2} the contributions of these SNe and their progenitors to the dust content of their galaxies, {3} the structure of gas and stars in the ISM of external galaxies, and {4} we will independently measure the distance to the host galaxies, including a member of the Virgo cluster, and M96, a Type Ia cosmological distance- scale calibrator

ACS/HRC/WFC 10733

CCD Hot Pixel Annealing

Hot pixel annealing will continue to be performed once every 4 weeks The CCD TECs will be turned off and heaters will be activated to bring the detector temperatures to about +20C This state will be held for approximately 6 hours, after which the heaters are turned off, the TECs turned on, and the CCDs returned to normal operating condition To assess the effectiveness of the annealing, a bias and four dark images will be taken before and after the annealing procedure for both WFC and HRC The HRC darks are taken in parallel with the WFC darks The charge transfer efficiency {CTE} of the ACS CCD detectors declines as damage due to on-orbit radiation exposure accumulates This degradation has been closely monitored at regular intervals, because it is likely to determine the useful lifetime of the CCDs We combine the annealling activity with the charge transfer efficiency monitoring and also merge into the routine dark image collection To this end, the CTE monitoring exposures have been moved into this proposal All the data for this program is acquired using internal targets {lamps} only, so all of the exposures should be taken during Earth occultation time {but not during SAA passages} This program emulates the ACS pre-flight ground calibration and post-launch SMOV testing {program 8948}, so that results from each epoch can be directly compared Extended Pixel Edge Response {EPER} and First Pixel Response {FPR} data will be obtained over a range of signal levels for both the Wide Field Channel {WFC}, and the High Resolution Channel {HRC}

ACS/HRC/WFC 10758

ACS CCDs daily monitor

This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors The files, biases and dark will be used to create reference files for science calibration This programme will be for the entire lifetime of ACS Changes from cycle 13:- The default gain for WFC is 2 e-/DN As before bias frames will be collected for both gain 1 and gain 2 Dark frames are acquired using the default gain {2} This program cover the period May, 31 2006- Oct, 1-2006 The first half of the program has a different proposal number: 10729

ACS/WFC 10766

A Deep X-ray Survey of the Small Magellanic Cloud

We request deep observations of 2 representative fields in the Small Magellanic Cloud with Chandra and HST,with the primary goal of measuring the luminosity function and space density of X-ray binaries and other sources down to an unprecedented faint luminosity limit of 2x10E32 erg/s This will be the faintest XLF ever obtained for any galaxy, including our own HST photometry to 24th magnitude in V and I filters will identify the sources and provide Fx/Fopt, which will be vital in quantifying the LMXB population and in measuring the properties of the first coronally active stars ever detected in an external galaxy

ACS/WFC 10816

The Formation History of Andromeda's Extended Metal-Poor Halo

We propose deep ACS imaging in the outer spheroid of the Andromeda galaxy, in order to measure the star formation history of its true halo For the past 20 years, nearly all studies of the Andromeda "halo" were focused on the spheroid within 30 kpc of the galaxy's center, a region now known to host significant substructure and populations with high metallicity and intermediate ages However, two groups have recently discovered an extended metal-poor halo beyond 30 kpc; this population is distinct in its surface-brightness profile, abundance distribution, and kinematics In earlier cycles, we obtained deep images of the inner spheroid {11 kpc on the minor axis}, outer disk {25 kpc on the major axis}, and giant tidal stream, yielding the complete star formation history in each field We now propose deep ACS imaging of 4 fields bracketing this 30 kpc transition point in the spheroid, so that the inner spheroid and the extended halo populations can be disentangled, enabling a reconstruction of the star formation history in the halo A wide age distribution in the halo, as found in the inner spheroid, would imply the halo was assembled through ongoing accretion of satellite galaxies, while a uniformly old population would be a strong indication that the halo was formed during the early rapid collapse of the Andromeda proto-galaxy

ACS/WFC 10895

Closure on the IRAS "Big Four": A High Contrast Study of Epsilon Eridani's Dust Belt in Scattered Light

The ACS / HRC coronagraph has now demonstrated an unmatched capability to detect dusty debris disks around bright, nearby stars Among the "Big Four" debris disks discovered with IRAS twenty years ago, only Epsilon Eridani {SpT=K2V, d=3 2 pc} has yet to be targeted with ACS Beta Pictoris, Fomalhaut and Vega have been imaged with the ACS coronagraph, with the recent detection of reflected light from Fomalhaut's dust belt {Kalas, Graham & Clampin 2005} The direct detection of dust scattered light around Fomalhaut shows disk structure and asymmetry that can be directly linked to dynamical models of planetary perturbation Here we propose to use the ACS HRC and WFC to detect Eps Eri's dust belt A new motivation to attempt this observations arises from recent 350 micron images that reveal two dust arcs ~60 AU to the southeast and northwest of the star Contrary to previous 850 and 450 micron maps, the northwest arc is brighter than the southeast arc, and the northwest region has not been targeted by previous STIS imaging at lower contrast The optical detection of dust features around Eps Eri would be significant because a high resolution optical image, together with Spitzer and sub-mm images, would help anchor dynamical models of Eps Eri's planetary system, in addition to providing direct visual indications of disk-planet interactions

ACS/WFC/NIC3 10632

Searching for galaxies at z>6 5 in the Hubble Ultra Deep Field

We propose to obtain deep ACS {F606W, F775W, F850LP} imaging in the area of the original Hubble Ultra Deep Field NICMOS parallel fields and - through simultaneous parallel observations - deep NICMOS {F110W, F160W} imaging of the ACS UDF area Matching the extreme imaging depth in the optical and near-IR bands will result in seven fields with sufficiently sensitive multiband data to detect the expected typical galaxies at z=7 and 8 Presently no such a field exist Our combined optical and near-IR ultradeep fields will be in three areas separated by about 20 comoving Mpc at z=7 This will allow us to give a first assessment of the degree of cosmic variance If reionization is a process extending over a large redshift interval and the luminosity function doesn't evolve strongly beyond z=6, these data will allow us to identify of the order of a dozen galaxies at 6 56 5 Conversely, finding fewer objects would be an indication that the bulk of reionization is done by galaxies at z=6 By spending 204 orbits of prime HST time we will capitalize on the investment of 544 prime orbits already made on the Hubble Ultra Deep Field {UDF} We have verified that the program as proposed is schedulable and that it will remain so even if forced to execute in the 2-gyro mode The data will be non-proprietary and the reduced images will be made public within 2 months from the completion of the observations

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

A new procedure proposed to alleviate the CR-persistence problem of NICMOS Dark frames will be obtained immediately upon exiting the SAA contour 23, and every time a NICMOS exposure is scheduled within 50 minutes of coming out of the SAA The darks will be obtained in parallel in all three NICMOS Cameras The POST-SAA darks will be non-standard reference files available to users with a USEAFTER date/time mark The keyword 'USEAFTER=date/time' will also be added to the header of each POST-SAA DARK frame The keyword must be populated with the time, in addition to the date, because HST crosses the SAA ~8 times per day so each POST-SAA DARK will need to have the appropriate time specified, for users to identify the ones they need Both the raw and processed images will be archived as POST-SAA DARKSs Generally we expect that all NICMOS science/calibration observations started within 50 minutes of leaving an SAA will need such maps to remove the CR persistence from the science images Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors

NIC3 10996

NICMOS J-band Imaging of Strongly Lensing Clusters

We propose to use deep imaging in the F110W {'J'} band over a large area to search for highly magnified galaxies around massive lensing clusters

WFPC2 10748

WFPC2 CYCLE 14 Standard Darks

This dark calibration program obtains dark frames every week in order to provide data for the ongoing calibration of the CCD dark current rate, and to monitor and characterize the evolution of hot pixels Over an extended period these data will also provide a monitor of radiation damage to the CCDs

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: 17943-0 - Genslew for proposal 10896 - slot 10 @ 296/1452z 17944-0 - Genslew for proposal 10896 - slot 11 @ 296/1453z

COMPLETED OPS NOTES: (None)

                     SCHEDULED      SUCCESSFUL

FGS GSacq 11 11 FGS REacq 04 04 OBAD with Maneuver 30 30

SIGNIFICANT EVENTS: (None)

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