NASA Hubble Space Telescope Daily Report #3934

Status Report From: Space Telescope Science Institute
Posted: Wednesday, August 31, 2005


HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science


PERIOD COVERED: UT August 29, 2005 (DOY 241)


ACS/HRC 10377

ACS Earth Flats

High signal sky flats will be obtained by observing the bright Earth with the HRC and WFC. These observations will be used to verify the accuracy of the flats currently used by the pipeline and will provide a comparison with flats derived via other techniques: L-flats from stellar observations, sky flats from stacked GO observations, and internal flats using the calibration lamps. Weekly coronagraphic monitoring is required to assess the changing position of the spots.

ACS/HRC 10458

ACS and WFPC2 TGSMOV Two-Gyro PSF, Pointing, and Dither Test

Goals: PSF, PSF repeatability, pointing and stability within orbit and between orbits. Also test results for different targets. {F2G requirements 1a, 1c, 2 ,

ACS/HRC 10460

ACS Two-Gyro mode coronography test

This test of the coronagraphic procedure will be run soon after entering the two gyro mode. It duplicates observations that have been taken in normal 3-gyro mode in proposals 9667 or 9668 and is simalar to the 2-Gyro test of Feb 2005. One orbit is used to measure the light which gets around the coronagraph in four filters. The second orbit is a test of the repeatibility and the third orbit replicates the others but at a different roll angle to permit a more detailed analysis of the coronagraphic performance. We include two pairs of HRC earth flats, immediately following the coronagraphic observations, taken with the coronagraph in place to measure the exact position of the spot.


ACS CCDs daily monitor - Cycle 13 - Part 2

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 program will be for the entire lifetime of ACS.


Kuiper Belt Binaries: Probes of Early Solar System Evolution

Binaries in the Kuiper Belt are a scientific windfall: in them we have relatively fragile test particles which can be used as tracers of the early dynamical evolution of the outer Solar System. We propose a Snapshot program using the ACS/HRC that has a potential discovery efficiency an order of magnitude higher than the HST observations that have already discovered the majority of known transneptunian binaries. By more than doubling the number of observed objects in dynamically hot and cold subpopulations we will be able to answer, with statistical significance, the question of whether these groups differ in the abundance of binaries as a result of their particular dynamical paths into the Kuiper Belt. Today's Kuiper Belt bears the imprints of the final stages of giant-planet building and migration; binaries may offer some of the best preserved evidence of that long-ago era.


Probing Evolution And Reionization Spectroscopically {PEARS}

While imaging with HST has gone deep enough to probe the highest redshifts, e.g. the GOODS survey and the Ultra Deep Field, spectroscopic identifications have not kept up. We propose an ACS grism survey to get slitless spectra of all sources in a wide survey region {8 ACS fields} up to z =27.0 magnitude, and an ultradeep field in the HUDF reaching sources up to z =28 magnitude. The PEARS survey will: {1} Find and spectrocopically confirm all galaxies between z=4-7. {2} Probe the reionization epoch by robustly determining the luminosity function of galaxies and low luminosity AGNs at z = 4 - 6. With known redshifts, we can get a local measure of star formation and ionization rate in case reionization is inhomogeneous. {3} Study galaxy formation and evolution by finding galaxies in a contiguous redshift range between 4 < z < 7, and black hole evolution through a census of low-luminosity AGNs. {4} Get a robust census of galaxies with old stellar populations at 1 < z < 2.5, invaluable for checking consistency with heirarchical models of galaxy formation. Fitting these galaxies' spectra will yield age and metallicity estimates. {5} Study star-formation and galaxy assembly at its peak at 1< z < 2 by identifying emission lines in star-forming galaxies, old populations showing the 4000A break, and any combination of the two. {6} Constrain faint white dwarfs in the Galactic halo and thus measure their contribution to the dark matter halo. {7} Derive spectro-photometric redshifts by using the grism spectra along with broadband data. This will be the deepest unbiased spectroscopy yet, and will enhance the value of the multiwavelength data in UDF and the GOODS fields to the astronomical community. To this end we will deliver reduced spectra to the HST archives.

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.

NIC2 10464

NICMOS 2-gyro Coronagraphic Performance Assessment

Coronagraphic acquisition should not be affected by transitioning from 3-gyro to 2-gyro mode guiding. However, coronagraphic performance is dependent upon positioning of a target within the coronagraphic hole and the ability to obtain a second observation with a roll of the telescope within the same visibility period. Observations of a bright target are needed to verify and confirm the coronagraphic performance, the ability to suppress the diffractive energy background and the stability to image coronagraphically occulted targets at two field orientations {rolls}.


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

HSTARS: (None)



                              SCHEDULED     SUCCESSFUL
FGS Gsacq                   11                     11
FGS Reacq                   03                     03
OBAD with Maneuver     26                     26


Flash Report for TGS Transition" - (ldunham, 241/12:30) -- All commanding for the transition to Two Gyro Science mode was successful. Operations requests 17528, 17530, and 17522 were executed beginning at 241/00:02. Commanding included modifying control law gains for T2G, loading FSW support files for TGS, modifying +D SPA commanding in new TGS safemode macros, transitioning to TGS mode, and performing a full RAM dump. Transition to TGS mode took place at 241/0217. The first FGS guide acquisition at 0812 was successful, as have all subsequent acquisitions. No HSTARs have been generated. From integrated gyro data processed, M2G (MSS/2 Gyro mode) attitude errors were maintained within 3 degrees. The largest correction of 3 OBAD (FHST On Board Attitude Determination) pairs was 0.82 degrees. The largest correction for the second OBAD of each pair was 11 arcseconds. Jitter in F2G (FGS/2 Gyro mode) was measured at approximately 3 milliarcseconds. All three acquisitions performed have been successful with no LOL.

// end //

More status reports and news releases or top stories.

Please follow SpaceRef on Twitter and Like us on Facebook.