NASA Hubble Space Telescope Daily Report # 4630

HUBBLE SPACE TELESCOPE DAILY REPORT # 4630

Continuing to collect World Class Science

PERIOD COVERED: 5am June 11 – 5am June 12, 2008 (DOY 163/0900z-164/0900z)

OBSERVATIONS SCHEDULED

ACS/SBC 11110

Searching for Lyman Alpha Emission from FUSE Lyman Continuum Candidates

We have recently been granted time on FUSE to characterize the escape fraction of hydrogen Lyman continuum (Lyc) photons from a morphologically diverse set of star forming galaxies. The FUSE program is designed to provide ~ 5 sigma detections of Lyc photons emitted from star forming galaxies with escape fractions ~5%. With this proposal we seek hydrogen Lyman alpha (Lya) observations of a representative subset of the FUSE program targets to constrain the observational relationship between Lyc, Lya, and hydrogen Balmer line emission in these systems. Such observations explore the detailed balance between the simple optically thin (Case A) and optically thick (Case B) limits in recombination theory. The ultimate goal of this program is to quantify the relationship between escaping Lya and Lyc emission and the first structures that form in the early universe.

WFPC2 10583

Resolving the LMC Microlensing Puzzle: Where Are the Lensing Objects?

We are requesting 32 HST orbits to help ascertain the nature of the population that gives rise to the observed set of microlensing events towards the LMC. The SuperMACHO project is an ongoing ground-based survey on the CTIO 4m that has demonstrated the ability to detect LMC microlensing events in real-time via frame subtraction. The improvement in angular resolution and photometric accuracy available from HST will allow us to 1} confirm that the detected flux excursions arise from LMC source stars rather than extended objects {such as for background supernovae or AGN}, and 2} obtain reliable baseline flux measurements for the objects in their unlensed state. The latter measurement is important to resolve degeneracies between the event timescale and baseline flux, which will yield a tighter constraint on the microlensing optical depth.

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=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.

NIC2/WFPC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3

We aim to determine physical properties of IR luminous galaxies at 0.3 0.8mJy and their mid-IR spectra have already provided the majority

targets with spectroscopic redshifts {0.31 ULIRGs, as in the local Universe. {2} study the co-evolution of star formation and blackhole accretion by investigating the relations between the fraction of starburst/AGN measured from mid-IR spectra vs. HST morphologies, L{bol} and z. {3} obtain the current best estimates of the far-IR emission, thus L{bol} for this sample, and establish if the relative contribution of mid-to-far IR dust emission is correlated with morphology {resolved vs. unresolved}.

WFPC2 11206

At the Cradle of the Milky Way: Formation of the Most Massive Field Disk Galaxies at z>1

We propose to obtain 2 orbit WFPC2 F814W images of a sample of the 15 most massive galaxies found at $1 < z < 1.3$. These were culled from over 20,000 Keck spectra collected as part of DEEP and are unique among high redshift massive galaxy samples in being kinematically selected. Through a recent HST NICMOS-2 imaging program {GO-10532}, we have confirmed that these galaxies have regular stellar disks, and their emission line kinematics are not due to gradients from merging components. These potentially very young galaxies are likely precursors to massive local disks, assuming no further merging. The proposed WFPC2 and existing NIC-2 data provide colors, stellar masses, and ages of bulge and disk subcomponents, to assess whether old stellar bulges and disks are in place at that time or still being built, and constrain their formation epochs. Finally, this sample will yield the first statistically significant results on the $z > 1$ evolution of the size-velocity-luminosity scaling relations, for massive galaxies at different wavelengths, and constrain whether this evolution reflects stellar mass growth, or passive evolution, of either bulge or disk components.

WFPC2 11311

The High-Amplification Microlensing Event OGLE-2007-BLG-224: a Substellar Lens in the Galactic Disk or a Low-Mass Stellar Lens in the Halo?

OGLE-2007-BLG-224/MOA-2007-BLG-163 is a remarkable microlensing event towards the Galactic bulge, which peaked on May 12, 2007. The light curve reached a peak magnification of ~3700, which is the highest magnification ever observed. The color and magnitude of the source indicate that it is a G-dwarf in the Galactic bulge, and source radius crossing time of t* = 8.2 minutes implies that the lens-source relative proper motion is 45 mas/yr. This indicates that the lens must either be a very nearby brown dwarf, or a halo star. The HST observations proposed here provide a very good chance to distinguish between these two possibilities and to determine the distance and mass of the lens. If it is a nearby brown dwarf, it is likely to be associated with a high-proper-motion star that is found close to the source. HST observations taken at two epochs will resolve out the geocentric and the heliocentric the proper-motions, thus providing unambiguous proof that it is a substellar lens. If the lens is a halo star, then it should be detectable as it separates from the source star over the next year. This would be the first definitive detection of a lens star in the Galactic halo and it would help to resolve the long running controversy over whether a significant fraction of the microlensing events seen towards the Magellanic Clouds are due to lens objects in the halo. Thus, it will either be the first clear proof of a substellar lens in the Galactic disk, or the first clear detection of a halo lens.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11340 – GSAcq(1,2,1) failed to RGA Hold

At acquisition of signal 164/02:16:00, GSAcq (1,2,1) scheduled from 164/02:08:02 – 02:15:38 had failed to RGA Hold. Received a QSTOPF flag on FGS 1. No 486 ESB messages received. OBAD #1 values: V1 705.62, V2 -373.10, V3 -342.08, RSS 868.40 arc seconds. OBAD #2 values: V1 0.10, V2 -2.40, V3 17.55, RSS 17.71. OBAD MAP not visible due to loss of signal.

Possible observations affected: WFPC Proposal # 11142, Observation #140 #143. NICMOS Proposal #11142, Observation #40-41.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                        SCHEDULED      SUCCESSFUL

FGS GSacq               09                  08
FGS REacq               02                  02
OBAD with Maneuver      22                  22

SIGNIFICANT EVENTS: (None)