Status Report

NASA Hubble Space Telescope Daily Report #4051

By SpaceRef Editor
February 20, 2006
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NASA Hubble Space Telescope Daily Report #4051
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HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT        #4051

PERIOD COVERED: UT February 15, 2006 (DOY 046)

OBSERVATIONS SCHEDULED

ACS/HRC 10774

Confirming the Discovery of Two New Satellites of Pluto

We detected two new objects ~2 arcsec from Pluto during our recent deep search for companions using the ACS / WFC mode {HST GO program 10427}. Either these objects are newly discovered satellites of Pluto, or they are previously undiscovered Plutino KBOs that happened to be located along the line-of-sight to Pluto. The ramifications are enormous for our understanding of the origin and evolution of the Pluto-Charon system, and for our understanding of KBO satellite formation in general, if these new objects are satellites of Pluto. Thus, we request two orbits of HST observing time as soon as possible, to confirm that these newly discovered objects are truly satellites of Pluto.

ACS/HRC/WFC 10729

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 10543

Microlensing in M87 and the Virgo Cluster

Resolving the nature of dark matter is an urgent problem. The results of the MACHO survey of the Milky Way dark halo toward the LMC indicate that a significant fraction of the halo consists of stellar mass objects. The VATT/Columbia survey of M31 finds a similar lens fraction in the M31 dark halo. We propose a series of observations with ACS that will provide the most thorough search for microlensing toward M87, the central elliptical galaxy of the Virgo cluster. This program is optimized for lenses in the mass range from 0.01 to 1.0 solar masses. By comparing with archival data, we can detect lenses as massive as 100 solar masses, such as the remnants of the first stars. These observations will have at least 15 times more sensitivity to microlensing than any previous survey, e.g. using WFPC2. This is due to the factor of 2 larger area, factor of more than 4 more sensitivity in the I-band, superior pixel scale and longer baseline of observations. Based on the halo microlensing results in the Milky Way and M31, we might expect that galaxy collisions and stripping would populate the overall cluster halo with a large number of stellar mass objects. This program would determine definitively if such objects compose the cluster dark matter at the level seen in the Milky Way. A negative result would indicate that such objects do not populate the intracluster medium, and may indicate that galaxy harassment is not as vigorous as expected. We can measure the level of events due to the M87 halo: this would be the best exploration to date of such a lens population in an elliptical galaxy. Star-star lensing should also be detectable. About 20 erupting classical novae will be seen, allowing to determine the definitive nova rate for this giant elliptical galaxy. We will determine if our recent HST detection of an M87 globular cluster nova was a fluke, or indicative of a 100x higher rate of incidence of cataclysmic variables and nova eruptions in globulars than previously believed. We will examine the populations of variable stars, and will be able to cleanly separate them from microlensing.

ACS/WFC 10577

Resolving the non-radiative shock in SN1006

An ACS image of the H alpha filament in the supernova remnant SN1006 will resolve the thickness of the H alpha emission zone. This will permit us to derive an accurate pre-shock density, which in turn can be used to model the time-dependent X-ray spectrum of the bright X- ray ridge with no free parameters, thus benchmarking these widely used models. We will also search for evidence of a shock precursor, and we will use the scale of ripples in the shock to estimate the level of density inhomogeneity in the pre-shock gas.

ACS/WFC 10615

Timing Studies of the X-ray Binary Populations in Globular Clusters

Close binaries are fundamental to the dynamical stability and evolution of globular clusters, but large populations have been extremely difficult to identify. Chandra X-ray images provide a revolutionary resource, revealing a few to dozens of low-luminosity X-ray sources in every cluster deeply examined; our own Chandra programs uniformly study these ubiquitous X-ray sources {close binaries and their progeny} in a dozen clusters. We have obtained multicolor, single-epoch, ACS images, from which to obtain initial optical counterparts, especially CVs {the dominant population in most clusters}, BY Dra’s, and qLMXBs. As HST capability for follow-on, confirming, spectra of our multicolor-selected counterparts is now severely curtailed, we propose an ACS time-series imaging program that will yield equivalent follow-on information for 5 of our clusters. The proposed ACS time-series data with 6 min resolution and 8 hr time-span, will: provide variability information to secure our suggested multicolor identifications; allow secure classifications of the various X-ray subpopulations {e.g., CVs vs. BY Dra’s}; yield quality lightcurves, whose shape will help test the notion that magnetic CVs are more common in globular clusters than the field; and, provide interesting contraints on the period distributions of cluster X-ray binaries.

ACS/WFC/NIC3/WFPC2 10530

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.

FGS 10614

Internal Structure and Figures of Binary Asteroids

The goal of this proposal is to obtain very important information on the internal structure of a number of asteroids, and insight on the gravitational reaccumulation-process after a catastrophic disruptive collision. High resolutions observations with the HST/FGS interferometer are proposed to obtain high precision data for the topographic shape and size of a number of selected asteroids. Here we focus on objects with satellites, hence with known masses, so that the bulk density and porosity will be derived in the most accurate manner. This will yield plausible estimates on the internal properties of the objects, test wether they are close or not to figures of equilibrium {in terms of shape and adimensional rotational frequency}, and provide estimates of their relative density. The HST/FGS in interferometric mode is an ideal facility to carry out this program.

NIC1/NIC2/NIC3 8792

NICMOS Post-SAA calibration – CR Persistence Part 3

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.

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.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

10133 – GSacq(1,2,2) failed due to search radius limit exceeded on FGS 1 @ 046/1756z

During LOS the GSacq(1,2,2) scheduled at 046/17:56:03 failed due to search radius limit exceeded on FGS 1. ESB a07 FGS Coarse Track failed – Timed out waiting for data valid was received. The OBAD before the GSacq showed errors of V1=-8.30, V2=-8.41, V3=-13.00, RSS= 17.57.

10134 – REacq(1,2,2) failed @ 046/1908z

Reacq(1,2,2) scheduled at 046/19:02:17 failed. ESB a0e (FGS Sequential Attitude update failed because error was too large to correct) was received. The OBAD before the Reacg showed errors of V1=5.27, V2=-2.44, V3=6.27, RSS= 8.55. The Map at 19:09:20 showed errors of V1=1.86, V2= -3.67, V3=8.09, RSS= 9.07.

10135 – Roll (V1) attitude error vector limit violation (QDVEFGS1) @ 046/2051z

During GSacq(1,2,2) of 046/20:51:37, the mnemonic (QDVEFGS1) V1 attitude error vector flagged out of limits high 299.361 arcseconds. Per ref (HSTARs 10133,10134) when the acquisition fails, we do not compute a V1 Bias, but we still save the guide star quaternion at the occultation. Correct value for the V1 Bias was restored during #44 CMD (FGS Sequential attitude update). The acquisition was successful

COMPLETED OPS REQUEST:

17645-0 – ESTR-2R Monthly Recondition @ 047/0604z

COMPLETED OPS NOTES: (None)

                        SCHEDULED      SUCCESSFUL      FAILURE TIMES 
 FGS GSacq              11                      10                046/1756z 
 (HSTAR 10133) 
 FGS REacq               04                      03               046/1908z 
 (HSTAR 10134) 
 OBAD with Maneuver  30                     30 

SIGNIFICANT EVENTS: (None)

SpaceRef staff editor.