Status Report

NASA Hubble Space Telescope Daily Report #4164

By SpaceRef Editor
July 27, 2006
Filed under , ,
NASA Hubble Space Telescope Daily Report #4164

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT July 26, 2006 (DOY 207)


ACS/HRC 10738

Earth Flats

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 in the pipeline and to monitor any changes. Weekly coronagraphic monitoring is required to assess the changing position of the spots.

ACS/HRC 10800

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 to continue a Snapshot program using the ACS/HRC that has a demonstrated discovery potential an order of magnitude higher than the HST observations that have already discovered the majority of known transneptunian binaries. With this continuation we seek to reach the original goals of this project: to accumulate a sufficiently large sample in each of the distinct populations collected in the Kuiper Belt to be able to measure, with statistical significance, how the fraction of binaries varies as a function 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.

ACS/HRC 10805

ACS Imaging of Uranus’ Atmosphere Near Equinox

Uranus’ 97-degree spin axis inclination results in the largest fractional seasonal variation of solar insolation in the solar system. Uranus is now close to its 7 December 2007 equinox, and we can now see most of the northern hemisphere, which was in darkness when Voyager provided our first detailed view of the planet in 1986. If Uranus’ seasonal response has the large phase shift expected from its long radiative time constant, it should now exhibit nearly maximal hemispheric contrast. Although the long time constant also suggests a small physical response, significant hemispheric asymmetries in cloud structure and dynamics are becoming apparent. We propose a detailed characterization of Uranus’ current response to this forcing with a 10-orbit program consisting of 4 orbits of WFC imaging with narrowband ramp filters and 6 orbits of HRC imaging using both broadband and narrowband filters. Nine narrow-band filters between 0.62 and 0.955 microns will provide vertical sensing depths scanning through the pressure range where the putative methane and deeper H2S clouds might plausibly exist and provide strong constraints on their optical properties and parent gas mixing ratios. The high resolution HRC images will characterize the dynamics of discrete features at the 15-30 hour time scale unavailable from the ground. Short wavelength HRC images will enable a characterization of the stratospheric haze. These observations have unique combinations of spectral range and resolution with needed temporal and spatial resolution not available from groundbased observations.


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 May, 31 2006- Oct, 1- 2006. The first half of the program has a different proposal number: 10729.

ACS/WFC 10846

The Halo Structure of RCS2-2327.4-0204

We propose ACS, NICMOS, and Chandra observations of the central region of the extraordinary and newly discovered galaxy cluster: RCS2-2327.4-0204 at z=0.700. This cluster shows 3 or more arcs in ground-based imaging, with an Einstein radius of 49″. Such a large Einstein radius {3-4 times larger than seen in most clusters} has been seen in precisely one other cluster in the universe – namely Abell 1689 at z=0.18. From our proposed data we expect to see ~70 lensed source images, from ~20 image families. We will use both strong and weak lensing constraints from these data to construct the central mass profile of the cluster, which, when combined with ground based data extending to a half degree FOV, will allow us to measure critically important dark matter halo parameters {such as concentration}. The target cluster is selected from a large ongoing survey with a well-defined search volume, which allows us to compare our results to expectations from simulations. We will also compare the lensing derived mass profiles to the x-ray equivalent measures; this will illuminate whether the dominant baryonic component is in equilibrium with the potential. The area of high magnification behind this cluster is an order of magnitude larger than typical lensing clusters observed previously by HST; this order of magnitude increase in area directly translates into a 10 times better chance for finding very high redshift galaxies. Many of the highest redshift galaxies found to date have been found behind massive lensing clusters observed by HST, and we expect to add to that sample dramatically.

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration – CR Persistence Part 5

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 10849

Imaging Scattered Light from Debris Disks Discovered by the Spitzer Space Telescope around 21 Sun-like Stars

We propose to use the high-contrast capability of the NICMOS coronagraph to image a sample of newly discovered circumstellar disks associated with Sun-like stars. These systems were identified by their strong thermal infrared {IR} emission with the Spitzer Space Telescope as part of the Spitzer Legacy Science program titled “The Formation and Evolution of Planetary Systems” {FEPS, P.I.: M.Meyer}. Modeling of the thermal excess emission from the spectral energy distributions alone cannot distinguish between narrowly confined high-opacity disks and broadly distributed, low-opacity disks. By resolving light scattered by the circumstellar material, our proposed NICMOS observations can break this degeneracy, thus revealing the conditions under which planet formation processes are occuring or have occured. For three of our IR-excess stars that have known radial-velocity planets, resolved imaging of the circumstellar debris disks may further offer an unprecedented view of planet-disk interactions in an extrasolar planetary system. Even non-detections of the light scattered by the circumstellar material will place strong constraints on the disk geometries, ruling out disk models with high optical depth. Unlike previous disk imaging programs, our program contains a well-defined sample of ~1 solar mass stars covering a range of ages from 3 Myr to 3 Gyr, thus allowing us to study the evolution of disks from primordial to debris for the first time. The results from our program will greatly improve our understanding of the architecture of debris disks around Sun-like stars, and will create a morphological context for the existence of our own solar system. This proposal is for a continuation of an approved Cycle 14 program {GO/10527, P.I.: D. Hines}.


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


#10376 GSAcq (2,1,1) failed due to Scan Step Limit Exceeded on FGS 2 @ 207/14:13:41z

Observations affected: ACS 90. Same guide star pair used in HSTAR 10372. OBAD #1: V1 -434.44, V2 3657.35, V3 52.30, RSS 3683.43. OBAD #2: V1 0.68, V2 -3.06, V3 0.31, RSS 3.15. OBAD MAP @ 207/14:43:41 indicated the following: V1 -781.82, V2 4505.00, V3 -128.39, RSS 4574.14

#10378 GSacq(2,11) failed to RGA control @ 207/18:21:17z

During LOS, GSAcq(2,11) failed due to stop flag QF2STOPF on FGS 2. OBAD2 showed errors of V1=0.15, V2=-6.58, V3=-6.28, RSS=9.10. Observation affected: ACS 94

#10379 GSacaq(2,1,1) failed due to scan step limit exceeded on FGS 2 @ 207/21:33:08z

This is the same guide star that failed in HSTARs 10372, 10376, and 10378. Observations affected: ACS 97

#10380 GSACQ(2,1,1) failed @ 208/00:43:29z

During LOS, FGS2 scan step flag QF2SSLEX and stop flag QF2STOPF were set. NICMOS 705 status buffer message (TDF down when a target acquisition SAM request is made) with parameter 0 and time 32142 occurred at 00:52:39. Further information will be available after next SSR engineering recorder dump. Observations affected: NICMOS 29 to 31.



                           SCHEDULED    SUCCESSFUL 
FGS GSacq                10            06                     
FGS REacq                03            01 
OBAD with Maneuver   26            26 


SpaceRef staff editor.