NASA Hubble Space Telescope Daily Status Report # 4407

Notice: Due to the conversion of some ACS WFC or HRC observations into WFPC2, or NICMOS observations after the loss of ACS CCD science capability in January, there may be an occasional discrepancy between a proposal’s listed (and correct) instrument usage and the abstract that follows it.

HUBBLE SPACE TELESCOPE DAILY REPORT # 4407

– Continuing to collect World Class Science

PERIOD COVERED: UT July 18, 2007 (DOY 199)

OBSERVATIONS SCHEDULED

ACS/SBC 10907

New Sightlines for the Study of Intergalactic Helium: A Dozen High-Confidence, UV-Bright Quasars from SDSS/GALEX

The reionization of intergalactic helium is thought to have occurred between redshifts of about 3 and 4. Detailed study of HeII Lyman-alpha absorption toward a handful quasars at 2.73.1 quasars potentially suitable for HeII studies. We have cross-correlated SDSS quasars with GALEX UV sources to obtain a dozen new, very high-confidence, candidate quasars/sightlines {z=3.1 to 4.1} potentially useful for detailed HeII studies even with current HST instruments. We propose brief, 2-orbit per target, reconnaissance spectral exposures with the ACS SBC prism to definitively verify UV flux down to the HeII break. Our combined SDSS/GALEX selection insures a very high- yield of confirmations, as the quasars are already known to be UV-bright from broadband GALEX images. The additional sightlines, extending to very high-redshift, will directly enable ensemble spectral stacks, as well as long exposure follow-up spectra, at high S/N with the ACS/SBC ultraviolet prisms {or perhaps STIS or COS later}, to confidently measure the spectrum and evolution of the ionizing background radiation, the evolution of HeII opacity, and the density of intergalactic baryons.

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration – CR Persistence Part 5

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.

NIC1/NIC3 10924

Constraints on the Assembly and Dynamical Masses of z~2 Galaxies

We propose deep NICMOS/NIC2 F160W imaging of seven star-forming galaxies at z~2. These galaxies comprise an entirely unique sample, with not only redshifts measured from optical and near-IR spectra, but also SINFONI/VLT near-IR integral field spectroscopic measurements providing kinematic maps of H-alpha emission out to radii of >=10 kpc. We aim to determine the dynamical masses and evolutionary states of these systems, as part of the larger goal of understanding how mass is assembled in distant galaxies. In order to interpret our novel H-alpha integral field maps in terms of mass, we require detailed knowledge of the structural parameters of our target objects at rest-frame optical wavelengths and on ~1 kpc scales. We want to establish if the mass is distributed in a disk, bulge, or merging sub-units, and if we can detect tidal features associated with a merger. F160W imaging with NICMOS/NIC2 provides the perfect combination of sensitivity and resolution to address these questions, and arrive at the fundamental quantity: the dynamical mass.

NIC2 10849

Imaging Scattered Light from Debris Disks Discovered by the Spitzer Space Telescope around 21 Sun-like Stars

We propose to use the high-contrast capability of the NICMOS coronagraph to image a sample of newly discovered circumstellar disks associated with Sun-like stars. These systems were identified by their strong thermal infrared {IR} emission with the Spitzer Space Telescope as part of the Spitzer Legacy Science program titled “The Formation and Evolution of Planetary Systems” {FEPS, P.I.: M.Meyer}. Modeling of the thermal excess emission from the spectral energy distributions alone cannot distinguish between narrowly confined high-opacity disks and broadly distributed, low-opacity disks. By resolving light scattered by the circumstellar material, our proposed NICMOS observations can break this degeneracy, thus revealing the conditions under which planet formation processes are occurring or have occurred. For three of our IR-excess stars that have known radial-velocity planets, resolved imaging of the circumstellar debris disks may further offer an unprecedented view of planet-disk interactions in an extrasolar planetary system. Even non-detections of the light scattered by the circumstellar material will place strong constraints on the disk geometries, ruling out disk models with high optical depth. Unlike previous disk imaging programs, our program contains a well-defined sample of ~1 solar mass stars covering a range of ages from 3 Myr to 3 Gyr, thus allowing us to study the evolution of disks from primordial to debris for the first time. The results from our program will greatly improve our understanding of the architecture of debris disks around Sun-like stars, and will create a morphological context for the existence of our own solar system. This proposal is for a continuation of an approved Cycle 14 program {GO/10527, P.I.: D. Hines}.

NIC3 11082

NICMOS Imaging of GOODS: Probing the Evolution of the Earliest Massive Galaxies, Galaxies Beyond Reionization, and the High Redshift Obscured Universe

Deep near-infrared imaging provides the only avenue towards understanding a host of astrophysical problems, including: finding galaxies and AGN at z > 7, the evolution of the most massive galaxies, the triggering of star formation in dusty galaxies, and revealing properties of obscured AGN. As such, we propose to observe 60 selected areas of the GOODS North and South fields with NICMOS Camera 3 in the F160W band pointed at known massive M > 10^11 M_0 galaxies at z > 2 discovered through deep Spitzer imaging. The depth we will reach {26.5 AB at 5 sigma} in H_160 allows us to study the internal properties of these galaxies, including their sizes and morphologies, and to understand how scaling relations such as the Kormendy relationship evolved. Although NIC3 is out of focus and under sampled, it is currently our best opportunity to study these galaxies, while also sampling enough area to perform a general NIR survey 1/3 the size of an ACS GOODS field. These data will be a significant resource, invaluable for many other science goals, including discovering high redshift galaxies at z > 7, the evolution of galaxies onto the Hubble sequence, as well as examining obscured AGN and dusty star formation at z > 1.5. The GOODS fields are the natural location for HST to perform a deep NICMOS imaging program, as extensive data from space and ground based observatories such as Chandra, GALEX, Spitzer, NOAO, Keck, Subaru, VLT, JCMT, and the VLA are currently available for these regions. Deep high-resolution near-infrared observations are the one missing ingredient to this survey, filling in an important gap to create the deepest, largest, and most uniform data set for studying the faint and distant universe. The importance of these images will increase with time as new facilities come on line, most notably WFC3 and ALMA, and for the planning of future JWST observations.

WFPC2 11022

WFPC2 Cycle 15 Decontaminations and Associated Observations

This proposal is for the WFPC2 decons. Also included are instrument monitors tied to decons: photometric stability check, focus monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, UV throughput check, VISFLAT sweep, and internal UV flat check.

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)

                                SCHEDULED SUCCESSFUL 

FGS GSacq                       05              05 
FGS REacq                       10              10 
OBAD with Maneuver              30              30 

COMPLETED OPS NOTES: (None)

SIGNIFICANT EVENTS: (None)