Status Report

NASA Hubble Space Telescope Daily Report #3989

By SpaceRef Editor
November 16, 2005
Filed under , ,
NASA Hubble Space Telescope Daily Report #3989

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT November 15, 2005 (DOY 319)


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/WFC 10496

Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters

We propose a novel HST approach to obtain a dramatically more useful “dust free” Type Ia supernovae {SNe Ia} dataset than available with the previous GOODS searches. Moreover, this approach provides a strikingly more efficient search-and-follow-up that is primarily pre- scheduled. The resulting dark energy measurements do not share the major systematic uncertainty at these redshifts, that of the extinction correction with a prior. By targeting massive galaxy clusters at z > 1 we obtain a five-times higher efficiency in detection of Type Ia supernovae in ellipticals, providing a well-understood host galaxy environment. These same deep cluster images then also yield fundamental calibrations required for future weak lensing and Sunyaev-Zel’dovich measurements of dark energy, as well as an entire program of cluster studies. The data will make possible a factor of two improvement on supernova constraints on dark energy time variation, and much larger improvement in systematic uncertainty. They will provide both a cluster dataset and a SN Ia dataset that will be a longstanding scientific resource.

ACS/WFC 10523

The Halo Shape and Metallicity of Massive Spiral Galaxies

We propose to resolve the stellar populations of the halos of seven nearby, massive disk galaxies using a SNAP survey with WFC/ACS. These observations will provide star counts and color-magnitude diagrams 2-3 magnitudes below the tip of the Red Giant Branch along the two principal axes and one intermediate axis of each galaxy. We will measure the metallicity distribution functions and stellar density profiles from star counts down to very low average surface brightnesses, equivalent to ~31 V-mag per square arcsec. This proposal will create a unique sampling of galaxy halo properties, as our targets cover a range in galaxy mass, luminosity, inclination, and morphology. As function of these galaxy properties this survey will provide:- the first systematic measurement of radial light profiles and axial ratios of the diffuse stellar halos and outer disks of spiral galaxies- a comprehensive analysis of halo metallicity distributions as function of galaxy type and position within the galaxy- an unprecedented study of the stellar metallicity and age distribution in the outer disk regions where the disk truncations occur- the first comparative study of globular clusters and their field stellar populations We will use these fossil records of the galaxy assembly process to test halo formation models within the hierarchical galaxy formation scheme.

ACS/WFC 10592

An ACS Survey of a Complete Sample 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 enhanced star formation and Active Galactic Nuclei {AGN} activity, possibly triggered as the objects transform into massive S0 and elliptical merger remnants. We propose ACS/WFC imaging of a complete sample of 88 L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised Bright Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}. This sample is ideal not only in its completeness and sample size, but also in the proximity and brightness of the galaxies. The superb sensitivity, resolution, and field of view of ACS/WFC on HST enables a unique opportunity to study the detailed structure of galaxies that sample all stages of the merger process. Imaging will be done with the F439W and F814W filters {B and I-band} to examine as a function of both luminosity and merger state {i} the evidence at optical wavelengths of star formation and AGN activity and the manner in which instabilities {bars and bridges} in the galaxies may funnel material to these active regions, {ii} the relationship between star formation and AGN activity, and {iii} the structural properties {AGN, bulge, and disk components} and fundamental parameters {effective radius and surface brightness} of LIRGs and their similarity with putative evolutionary byproducts {elliptical, S0 and classical AGN host galaxies}. This HST survey will also bridge the wavelength gap between a Spitzer imaging survey {covering seven bands in the 3.6-160 micron range} and a GALEX UV imaging survey of these galaxies, but will resolve complexes of star clusters and multiple nuclei at resolutions well beyond the capabilities of either Spitzer or GALEX. The combined datasets will result in the most comprehensive multiwavelength study of interacting and merging galaxies to date.

ACS/WFC/NIC3 10541

Probing the jet mattter content of quasar PKS 0637-752

The matter content {electron-proton vs electron-positron composition} of extragalactic jets remains unknown, despite over three decades of work. Here, we propose NICMOS/NIC3 and ACS observations of the Chandra-detected, one sided jet of the superluminal quasar PKS 0637- 752 to derive the jet matter content by measuring the component of the Cosmic Microwave Background {CMB} radiation that is bulk-Comptonized {BC} by the cold electrons in the relativistically flowing large scale jet. What makes this source particularly suited for this procedure, is the absence of significant non-thermal jet emission from the ‘bridge’, the region between the core and the first bright knot WK7.8, guaranteeing that most of the electrons in the bridge are cold, leaving the BC scattered CMB radiation as the only significant source of photons in this region. The proposed NICMOS and ACS observations of the knot WK7.8 will provide spectral information in the IR-UV regime, which, together with existing multiwavelength data, will be used to derive the jet Doppler factor and minimum power necessary to power the knot emission as a function of the jet matter content. These will in turn be used to deduce, or strongly constrain, the actual jet matter content through comparison with the proposed NICMOS observations of the BC ‘bridge’ emission.

FGS 10610

Astrometric Masses of Extrasolar Planets and Brown Dwarfs

We propose observations with HST/FGS to estimate the astrometric elements {perturbation orbit semi-major axis and inclination} of extra-solar planets orbiting six stars. These companions were originally detected by radial velocity techniques. We have demonstrated that FGS astrometry of even a short segment of reflex motion, when combined with extensive radial velocity information, can yield useful inclination information {McArthur et al. 2004}, allowing us to determine companion masses. Extrasolar planet masses assist in two ongoing research frontiers. First, they provide useful boundary conditions for models of planetary formation and evolution of planetary systems. Second, knowing that a star in fact has a plantary mass companion, increases the value of that system to future extrasolar planet observation missions such as SIM PlanetQuest, TPF, and GAIA.


NICMOS Post-SAA calibration – CR Persistence Part 1.

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.

S/C/NIC1 10724

NICMOS Focus Monitoring

The purpose of this proposal is to determine the best focus for all three NICMOS detectors. The program will be executed every ~6 weeks. Each execution will concern a single detector, except two occasions which will include NIC3. In total NIC1 and NIC2 will be monitored 4 times each during the current cycle, while NIC3 will only be monitored twice. The program starts with a focus sweep using only the NIC1 camera {visit 11}. The following observation is with the NIC2 camera {visit 12} after about 45 days. This pattern is repeated throughout the period except for Jan 1-8 and Jul 1-8 where also the NIC3 camera is used. In total this will result in 10 orbits. Notice that VISIT #1 #2 refers to visits for #1 sequential visit number for a given camera #2 camera in question visit 32 is therefore the third visit for camera 2. Some tweaking of dates and sources are necessary to ensure visibility under 2-gyro mode. These are the dates and targets for Cycel14: Visit 11: Oct 01-08 NIC1 NGC1850 Visit 12: Nov 15-22 NIC2 NGC3603 Visit 21: Jan 01-15 NIC1 NGC3603 Visit 13: Jan 01-15 NIC3 NGC3603 Visit 22: Feb 15-22 NIC2 NGC3603 Visit 31: Apr 01-15 NIC1 NGC1850 Visit 32: May 22-31 NIC2 NGC3603 Visit 41: Jun 15-22 NIC1 NGC1850 Visit 23: Jun 15-22 NIC3 NGC1850 Visit 42: Aug 07-22 NIC2 NGC3603

WFPC2 10601

The high proper motion of PSR B0540-69.3

We wish to pin down the proper motion of the Crab-like pulsar PSR B0540-69.3. HST/WFPC2 archival data have an epoch separation by 4 years which we have already used to obtain a very high transverse velocity, 1190 +/- 560 km/s. The indicated direction of the proper motion is consistent with it being along the southern jet of the pulsar wind nebula. The high velocity could be linked to the high asymmetry of the supernova ejecta, which suggests a highly asymmetric supernova explosion. We need a third epoch of HST imaging to test our present 2-sigma limit. With the suggested observation we will obtain a 1-sigma limit on the transverse motion better than 200 km/s. PSR B0540-69.3 could be the third young pulsar connected to a supernova remnant for which a proper motion is established. The other two are the Crab and Vela pulsars. Both these pulsars have their proper motions aligned with the jet axis of their pulsar wind nebulae. PSR B0540-69.3 could thus be the third object {of three} to reveal that it shares this property. This would provide vital information to supernova explosion and pulsar kick models. PSR B0540-69.3 would undoubtedly also be the most distant pulsar ever for which a proper motion is established.


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

HSTARS: (None)



                            SCHEDULED      SUCCESSFUL
FGS GSacq                 09                      09
FGS REacq                 02                      02
OBAD with Maneuver    22                      22


SpaceRef staff editor.