Status Report

NASA Hubble Space Telescope Daily Report #4696

By SpaceRef Editor
September 16, 2008
Filed under , ,


Continuing to collect World Class Science

PERIOD COVERED: 5am September 15 – 5am September 16, 2008 (DOY 259/0900z-260/0900z)


ACS/SBC 11158

HST Imaging of UV Emission in Quiescent Early-type Galaxies

We have constructed a sample of early type galaxies at z~0.1 that have blue UV-optical colors, yet also show no signs of optical emission, or extended blue light. We have cross-correlated the SDSS catalog and the Galaxy Evolution Explorer Medium Imaging Survey to select a sample of galaxies where this UV emission is strongest. The origin of the UV rising flux in these galaxies continues to be debated, and the possibility that some fraction of these galaxies may be experiencing low levels of star formation cannot be excluded. There is also a possibility that low level AGN activity {as evidenced by a point source} is responsible We propose to image the UV emission using the HST/SBC and to explore the morphology of the UV emission relative to the optical light.


UV Imaging to Determine the Location of Residual Star Formation in Galaxies Recently Arrived on the Red Sequence

We have identified a sample of low-redshift {z = 0.04 – 0.10} galaxies that are candidates for recent arrival on the red sequence. They have red optical colors indicative of old stellar populations, but blue UV-optical colors that could indicate the presence of a small quantity of continuing or very recent star formation. However, their spectra lack the emission lines that characterize star-forming galaxies. We propose to use ACS/SBC to obtain high-resolution imaging of the UV flux in these galaxies, in order to determine the spatial distribution of the last episode of star formation. WFPC2 imaging will provide B, V, and I photometry to measure the main stellar light distribution of the galaxy for comparison with the UV imaging, as well as to measure color gradients and the distribution of interstellar dust. This detailed morphological information will allow us to investigate the hypothesis that these galaxies have recently stopped forming stars and to compare the observed distribution of the last star formation with predictions for several different mechanisms that may quench star formation in galaxies.

FGS 11212

Filling the Period Gap for Massive Binaries

The current census of binaries among the massive O-type stars is seriously incomplete for systems in the period range from years to millennia because the radial velocity variations are too small and the angular separations too close for easy detection. Here we propose to discover binaries in this observational gap through a Faint Guidance Sensor SNAP survey of relatively bright targets listed in the Galactic O Star Catalog. Our primary goal is to determine the binary frequency among those in the cluster/association, field, and runaway groups. The results will help us assess the role of binaries in massive star formation and in the processes that lead to the ejection of massive stars from their natal clusters. The program will also lead to the identification of new, close binaries that will be targets of long term spectroscopic and high angular resolution observations to determine their masses and distances. The results will also be important for the interpretation of the spectra of suspected and newly identified binary and multiple systems.

FGS 11213

Distances to Eclipsing M Dwarf Binaries

We propose HST FGS observations to measure accurate distances of 5 nearby M dwarf eclipsing binary systems, from which model-independent luminosities can be calculated. These objects have either poor or no existing parallax measurements. FGS parallax determinations for these systems, with their existing dynamic masses determined to better than 0.5%, would serve as model-independent anchor points for the low-mass end of the mass-luminosity diagram.


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


11493 – NCC safed during Restart

at 259/20:17:02z while executing Ops Request #18286-0 “NCS Restart and Cooldown” step #10, NCS PCE On to Circulator On, due to exceeding the maximum circulator speed limit. Status Buffer Message EXEC 908 P=200 T=8371 was received. Per SE request the 8051 memory was dumped.

11494 – NCC safed after restart

at 259/23:57:14z while executing Ops Request #18289-1. Status Buffer Message EXEC 908 P=200 T=48531 was received. The 8051 memory was dumped.


18286-0 NCS Restart and Cooldown (Execution Failed) @ 259/20:17z

18289-1 NCS Restart and Cooldown (Execution Failed) @ 259/23:57z


                        SCHEDULED      SUCCESSFUL

FGS GSacq               12                   12
FGS REacq               01                   01
OBAD with Maneuver      26                   26


NCS Restart operations unsuccessful

Upon execution of circulator start up commanding (Ops Request 18286), a NSCC-1 Status Buffer Message indicated that the circulator was shut down and the NCC was safed due to exceeding the maximum circulator speed limit of 1396 rps (Device Table 120). A memory dump is in progress.

Flash Report: DOY 259 – 2nd NCS Restart Attempt.

Following circulatorstart up via Ops Request 18289 and approximately 20 minutes of circulator runtime, a NSSC-1 Status Buffer Message indicated that the circulator was shut down and the NCC was safed due to exceeding the maximum circulator current limit of 150mA (Device Table 251). A memory dump of the start-up is in progress, history buffer of the safing event is not available.

The CPL start-up heater was commanded back on at 260/00:24:46

SpaceRef staff editor.