Status Report

NASA Hubble Space Telescope Daily Report #3968

By SpaceRef Editor
October 18, 2005
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NASA Hubble Space Telescope Daily Report #3968

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT October 17, 2005 (DOY 290)


ACS/HRC 10557

Probing Asteroid Families for Evidence of Ultraviolet Space Weathering Effects

We propose six HST orbits to obtain UV reflectance spectra covering 200-460 nm of two Vesta asteroid family members, asteroid 832 Karin, and two Karin family members. These observations extend work done under a Cycle 13 AR grant, where we analyzed all of the existing IUE and HST S-class asteroids in the MAST database to investigate the effects of space weathering at UV wavelengths. Our hypothesis is that the manifestation of space weathering at UV wavelengths is a spectral bluing, in contrast with a spectral reddening at visible-NIR wavelengths, and that UV wavelengths can be more sensitive to relatively small amounts of weathering than longer wavelengths. The proposed observations will address two objectives: {1} Measure the UV-visible spectra of 832 Karin and two members of the young Karin family {absolute age of 5.8 My}, in order to determine whether intermediate space weathering is observable in objects likely pristine when they originated from the interior of Karin’s pa rent body. {2} Measure the UV-visible spectra of two members of the Vesta family to compare with our analysis of IUE Vesta spectra. These observations will probe Vesta’s interior, and test our hypothesis by contrasting the apparent amount of alteration on the surfaces of Vestoids with excavated material on Vesta.


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 Oct, 2 2005- May, 29-2006. The second half of the program has a different proposal number: 10758.

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 10576

An ACS Imaging Survey of the Galaxies Hosting Strong Mg II Absorption

Strong MgII absorbers {with rest-frame absorption equivalent width W_MgII > 0.3 A} at redshift z < 1 are known to arise in extended gaseous halos around luminous galaxies. Detailed absorption line studies based on high-solution spectra of background quasars yield tight constraints on the metallicity, ionization state, and kinematics of the gaseous clouds. But whether they originate in gas accreted from surrounding satellite galaxies or outflows associated with active starburst in the host galaxies remains unclear. We have recently completed a search of the Sloan Digital Sky Survey data archive for strong MgII absorbers and identified over 1000 new systems that are previously unknown. A subset of these MgII absorbers with W_MgII > 1.8 A exhibit extreme kinematics with velocity widths {exceeding 200 km/s} in our follow-up echelle spectra. Their dynamics are consistent with various scenarios that include gas accretion {with speeds exceeding the virial velocity} and starburst outflows {possibly driven by recent merger events}. Independent of their exact nature, it is clear that strong MgII systems serve as signposts to galactic halos with extreme gas dynamics. Here we propose to conduct a snapshot survey of galaxies in the fields toward high-redshift quasars with known, strong MgII absorbers at 0.5 < z < 2. We plan to obtain high spatial-resolution ACS/WFC images of 60 fields to uncover galaxies fainter than L* at the redshifts of these absorbers and study their morphology. We will complement the HST observations with follow-up spectroscopic observations and IR images acquired at the Keck and Magellan Observatories to for redshift identifications and for measuring broad-band colors. We will investigate the correlation between absorption line kinematics and galaxy morphology. In particular, we will address whether on-going mergers is responsible for the extreme dynamics observed in MgII absorption based on their rest-frame ultraviolet morphology.

ACS/WFC 10579

ULX counterparts: the key to finding intermediate-mass black holes

The origin and formation mechanism for supermassive black holes {SMBHs} found in the centres of most, if not all, galaxies remains one of the outstanding questions in astrophysics. Most scenarios involve the presence of massive black holes in the early universe, formed by the collapse of primordial Population III stars. It is predicted that a relic of this population could still be present in galactic halos in the current epoch, possessing masses from a few hundred times solar mass upwards. However, to date no CONCLUSIVE evidence for such a class of “intermediate-mass” black holes has been found. The most likely current candidates are the ultraluminous X-ray sources {ULXs}, which show tantalising evidence for IMBHs {e.g. the extreme X-ray luminosities and low disk temperatures expected from accreting IMBHs}. We propose to address this issue by identifying optical counterparts for six of the nearest ULXs. We will use this programme as a pathfinder for future radial velocity measurements, which will allow the orbital parameters and hence the first undisputed mass constraints for these systems to be determined.

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 6.5< z <8.5 - using the Lyman break technique - and to place a first constrain on the luminosity function at z>6.5. 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.

WFPC2 10359

WFPC2 CYCLE 13 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.


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

HSTARS: 9980 – ACS 889, MIEUTIL_GETTIME_CMD_FAILED @ 291/04:53:54z At 291/04:53:54, ACS Status Buffer messages 889, parameter 2000, was received while ACS was in operate followed by multiples of ACS 889. ACS has continued to remain in operate mode and maintain its normal observation schedule while this is under investigation.



                   SCHEDULED   SUCCESSFUL
FGS Gsacq                11      11
FGS Reacq                04      04
OBAD with Maneuver   30      30


Lynn F. Bassford
CHAMP HST Missions Operations Manager
Lockheed Martin Technical Operations
GSFC PH#: 301-286-2876
STScI PH#: 410-338-4895 (shared)

SpaceRef staff editor.