Status Report

NASA Hubble Space Telescope Daily Report #4170

By SpaceRef Editor
August 4, 2006
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NASA Hubble Space Telescope Daily Report #4170
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HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT # 4170

PERIOD COVERED: UT August 3, 2006 (DOY 215)

OBSERVATIONS SCHEDULED

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/WFC 10911

Calibration of ACS F814W Surface Brightness Fluctuations

The surface brightness fluctuations {SBF} method has emerged as the primary distance indicator for mapping local large-scale structures {Virgo, Fornax}, as well as the velocity field out to nearly 15,000 km/s {z < 0.05}. This is because other precision distance indicators either lack the requisite depth {Cepheids, TRGB} or are too rare for adequate sampling {supernovae}, while more traditional methods {Tully-Fisher, fundamental plane} lack the necessary precision. The SBF method is now being used with great success in several major ACS Wide Field Camera programs. However, whereas the band of choice for the nearby structure studies has been F850LP, for the distant large-scale flow studies it is F814W because of its much greater throughput. As a result, the current calibration for the more distant studies is inadequate. We propose to establish the first systematic calibration of the SBF method in the important F814W ACS WFC bandpass. We will do this by measuring SBF in an optimized sample of galaxies in the nearby compact Fornax cluster. Given the large amount of effort and HST time being dedicated to F814W SBF measurements, it is imperative that we correct this outstanding calibration problem while time remains. For an extremely modest expenditure of orbits, we will remove a significant systematic error and vastly improve the overall accuracy of the ongoing ACS F814W SBF work. These data will also greatly enhance the legacy value of the HST archive for future SBF studies.

FGS 10898

The orbit of the most massive known astrometric binary

We have recently used FGS and HRC observations to {a} resolve HD 93129A into two components with very similar optical/UV colors and a magnitude difference of 0.9 and to {b} detect their relative orbital motion over a span of 8 years. HD 93129Aa is the prototype O2 If* star, with an evolutionary mass near 100 M_Sun, while Ab is likely to be a very early O main-sequence star with a similar or only slightly smaller mass. Our HST astrometric measurements yield a total mass above 100 M_Sun, thus confirming the extremely high mass of the binary, and indicate that the system appears to be approaching periastron. We request new FGS and HRC observations to {a} calculate the mass ratio of the system by measuring the orbit of each of the components with respect to the nearby stars, {b} obtain the periastron epoch, and {c} start measuring the orbit in order to produce an estimate of the total mass. These measurements are crucial to shed light on the value of the stellar upper mass limit.

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.

NIC3 10538

Near-IR Spectrophotometry of 2MASSWJ 1207334-393254B – An Extra-Solar Planetary Mass Companion

We propose to obtain “short” wavelength near-IR diagnostic and characterizing spectra of the very high probability candidate extra-solar giant planet {EGP} companion to 2MASSWJ 1207334-393254 {2M1207}, a young brown dwarf and TW Hydrae Association member. Recent NICMOS camera 1 multi-band photometric imaging of the companion candidate, 0.77″ {54 AU projected} from 2M1207 – initially detected at longer wavelengths with VLT/NACO – implicate an object of several Jupiter masses based on cooling models of EGPs and the likely age of 2M1207 {~ 8 Myr}. Physical companionship of the EGP candidate with 2M1207 has been established at the 99.1% level of confidence via second- epoch NICMOS astrometric observations. Diagnostic spectra in the 0.8 to 1.9 micron region {unobtainable from the ground and overlapping the NICMOS imaging observations} will {a} critically inform on the physical nature of the EGP, {b} provide currently non-existing information to test/constrain theoretical models of EGP properties and evolution, and {c} unequivocally confirm the imaging of a bone fide EGP. Background light from 2M1207 would normally swamp the EGP spectrum with direct spectral imaging. To obviate this, we propose PSF-subtracted grism spectra of the EGP using 2M1207 as its own spectral template via two-orientation high-contrast image subtraction. The temporal stability of the HST+NICMOS PSF enables self-subtractions of targets at different field orientations resulting in contrast enhancements of 5 to 6 stellar magnitudes in the circumstellar background at ~ 0.8″ at these wavelengths. With the grism field oriented to place the EGP “above” and “below” 2M1207 {at two observational epochs} two independent spectra of the EGP will emerge from a difference image. This prototypical spectrum will serve to test and improve upon current models of young EGPs which predict flux suppression by molecular absorption in their atmospheres.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST:

17865-0 – Battery 1 Capacity Test Script & 5 Battery Pressure Limit COP (thru step 39) @ 215/1843z

COMPLETED OPS NOTES: (None)

                           SCHEDULED      SUCCESSFUL 
FGS 
GSacq                 13                    13 
FGS REacq                  01                    01 
OBAD with Maneuver    28                     28 

SIGNIFICANT EVENTS:

Battery 1 Capacity Test Flash Report

The Battery 1 discharge terminated at 2006/215 11:45 GMT (7:45 am local) and the battery was placed back on-line in hardware at 12:18 GMT (8:18 am local). The recovery period began at approximately 12:28 GMT (8:28 am local) with the batteries charging at the K1L4 equivalent. The ROC Trickle Charge Elapse Timer limit was restored to a nominal 4 orbits at 18:45 GMT (2:45 pm local) and the ROC safemode test was re-enabled at 18:47 GMT (2:47 pm local). (Continued)

Battery temperatures continue to cycle below 2.0 deg C. Battery 1 is still scheduled to be placed back on-line in FSW on 216/1655 GMT (08/04 at 12:55 pm).

SpaceRef staff editor.