Status Report

NASA Hubble Space Telescope Daily Report # 4456

By SpaceRef Editor
September 27, 2007
Filed under , ,
NASA Hubble Space Telescope Daily Report  # 4456

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.


– Continuing to collect World Class Science

PERIOD COVERED: UT September 26, 2007 (DOY 269)


NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration – CR Persistence Part 6

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=3Ddate/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 i mages. Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors.

NIC3 11082

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

(uses ACS/SBC and WFPC2)

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 undersampled, 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.

NIC3 11107

Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation in the Early Universe

We have used the ultraviolet all-sky imaging survey currently being conducted by the Galaxy Evolution Explorer {GALEX} to identify for the first time a rare population of low- redshift starbursts with properties remarkably similar to high-redshift Lyman Break Galaxies {LBGs}. These “compact UV luminous galaxies” {UVLGs} resemble LBGs in terms of size, SFR, surface brightness, mass, metallicity, kinematics, dust, and color. The UVLG sample offers the unique opportunity of investigating some very important properties of LBGs that have remained virtually inaccessible at high redshift: their morphology and the mechanism that drives their star formation. Therefore, in Cycle 15 we have imaged 7 UVLGs using ACS in order to 1} characterize their morphology and look for signs of interactions and mergers, and 2} probe their star formation histories over a variety of timescales. The images show a striking trend of small-scale mergers turning large amounts of gas into vigorous starbursts {a process referred to as dissipational or “wet” merging}. Here, we propose to complete our sample of 31 LBG analogs using the ACS/SBC F150LP {FUV} and WFPC2 F606W {R} filters in order to create a statistical sample to study the mechanism that triggers star formation in UVLGs and its implications for the nature of LBGs. Specifically, we will 1} study the trend between galaxy merging and SFR in UVLGs, 2} artificially redshift the FUV images to z=3D1-4 and compare morphologies with those in similarly sized samples of LBGs at the same rest-frame wavelengths in e.g. GOODS, UDF, and COSMOS, 3} determine the presence and morphology of significant stellar mass in “pre-burst” stars, and 4} study their immediate environment. Together with our Spitzer {IRAC+MIPS}, GALEX, SDSS and radio data, the HST observations will form a unique union of data that may for the first time shed light on how the earliest major episodes of star formation in high redshift galaxies came about. This proposal was adapted from an ACS HRC+WFC proposal to meet the new Cycle 16 observing constraints, and can be carried out using the ACS/SBC and WFPC2 without compromising our original science goals.

WEPC2 11196

An Ultraviolet Survey of Luminous Infrared Galaxies in the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared selected galaxies exceeds that of optically selected galaxies. These Luminous Infrared Galaxies {LIRGs} are primarily interacting or merging disk galaxies undergoing starbursts and creating/fueling central AGN. We propose far {ACS/SBC/F140LP} and near {WFPC2/PC/F218W} UV imaging of a sample of 27 galaxies drawn from the complete IRAS Revised Bright Galaxy Sample {RBGS} LIRGs sample and known, from our Cycle 14 B and I-band ACS imaging observations, to have significant numbers of bright {23 < B < 21 mag} star clusters in the central 30 arcsec. The HST UV data will be combined with previously obtained HST, Spitzer, and GALEX images to {i} calculate the ages of the clusters as function of merger stage, {ii} measure the amount of UV light in massive star clusters relative to diffuse regions of star formation, {iii} assess the feasibility of using the UV slope to predict the far- IR luminosity {and thus the star formation rate} both among and within IR-luminous galaxies, and {iv} provide a much needed catalog of rest-frame UV morphologies for comparison with rest-frame UV images of high-z LIRGs and Lyman Break Galaxies. These observations will achieve the resolution required to perform both detailed photometry of compact structures and spatial correlations between UV and redder wavelengths for a physical interpretation our IRX-Beta results. The HST UV data, combined with the HST ACS, Spitzer, Chandra, and GALEX observations of this sample, will result in the most comprehensive study of luminous starburst galaxies to date.

WFPC2 11105

The LBV progenitor of SN 2005gl – a new key to massive star evolution puzzles

The currently accepted theory regarding the last stages of massive star evolution maintains that the evolution of the envelope is coupled to that of the stellar core. For this reason, very massive stars are expected to shed their outer hydrogen envelopes before they develop large iron cores, and ultimately, explode as core-collapse supernovae {SNe}. It is therefore a strict prediction of current models that massive stars {certainly those above ~40 solar mass} will explode as hydrogen-poor SNe, i.e., of Types Ib and Ic. In particular, the class of luminous blue variables {LBVs} such as eta-Carina, which are known to be very massive {up to 100 solar masses and above} are expected to lose their entire hydrogen envelopes prior to their ultimate explosions as SNe. However, using pre-explosion HST/WFPC2 imaging of the location of the recent hydrogen-rich type IIn SN 2005gl, we have identified {Gal-Yam et al. 2007} its putative progenitor as a very luminous point source {with absolute V magnitude of -10.2}. If this is a single star, it must be an LBV from luminosity considerations {no other stars are as luminous}. If our progenitor identification is correct, at least in some cases, massive stars explode before losing most of their hydrogen envelope, indicating the core and envelope are decoupled, and requiring revision of stellar evolution theory. Here, we propose a single-orbit HST observation of the location of SN 2005gl designed to test whether the point source we identified as its LBV progenitor has indeed disappeared {as expected from a single star} or remained unchanged {as expected, e.g., if it is a compact star cluster}. These data are the last observational ingredient required to firmly establish {or refute} the explosion of an LBV as a type IIn SN, with fundamental implications for the theory of massive star evolution. Since the new data will be compared to pre-explosion WFPC2 images, this program is perfectly suited to be carried out with the WFPC2 camera.

WFPC2/NIC2 11193

A comprehensive study of the low-mass stellar population in the Galactic starburst region NGC 3603

NGC 3603, located in the Carina spiral arm, is one of the most luminous giant HII regions in the Milky Way, and as such it is often referred to as a prime template for extragalactic starbursts. While previous studies were focusing on the high and intermediate mass stellar content of the central starburst cluster, which powers the HII region, the effects of the starburst environment with its large number of ionizing O stars on the emerging low- mass population are unknown. As the most nearby, most easily accessible starburst, NGC 3603 provides the best testbed to study the long-lived, low-mass stars originating from a starburst environment. Taking advantage of the large field of view and high sensitivity of WFPC2, we want to survey the stellar population in an area of 10pc x 10pc {6′ x 6′} down to a mass limit of 0.2 to 0.5 Mo. This will enable us to derive the total cluster mass, look for spatial variations in the initial mass function, determine the age of the dispersed low-mass population in the HII region and search for evidence of sequential star formation. Ultimately, we aim at reconstructing the low-mass stellar initial mass function of the starburst epoch in NGC 3603, which in turn will advance our understanding of extragalactic starburst phenomena and the emerging low-mass stars as observed in ancient populations. The observations of NGC 3603 are part of our larger effort to study intense star-forming regions in the Milky Way, LMC and SMC.


Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)

HSTARS: (None)



                      SCHEDULED      SUCCESSFUL
FGS GSacq               06                 06
FGS REacq               08                 08
OBAD with Maneuver      28                 28


SpaceRef staff editor.