NASA Hubble Space Telescope Daily Report #4119
HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science
DAILY REPORT # 4119
PERIOD COVERED: UT May 22, 2006 (DOY 142)
OBSERVATIONS SCHEDULED
ACS/HRC 10512
Search for Binaries Among Faint Jupiter Trojan Asteroids
We propose an ambitious SNAPSHOT program to survey faint Jupiter Trojan asteroids for binary companions. We target 150 objects, with the expectation of acquiring data on about 50%. These objects span Vmag = 17.5-19.5, a range inaccessible with ground-based adaptive optics. We now have a significant sample from our survey of brighter Trojans to suggest that the binary fraction is similar to that which we find among brighter main-belt asteroids, roughly 2%. However, our observations suggest a higher binary fraction for smaller main-belt asteroids, probably the result of a different formation mechanism {evident also from the physical characteristics of the binaries}. Because the collision environment among the Trojans is similar to that of the Main Belt, while the composition is likely to be very different, sampling the binary fraction among the fainter Trojans should help us understand the collisional and binary formation mechanisms at work in various populations, including the Kuiper Belt, and help us evaluate theories for the origin of the Trojans. Calibration of and constraints on models of binary production and collisional evolution can only be done using these large-scale, real-life physical systems that we are beginning now to find and utilize.
ACS/HRC 10525
Characterizing the Near-UV Environment of M Dwarfs: Implications for Extrasolar Planetary Searches and Astrobiology
We propose SNAP observations with the ACS HRC PR200L prism, designed to measure the near ultraviolet emission in a sample of 107 nearby M dwarfs. The sample spans the mass range from 0.1 – 0.6 solar masses {temperature range 2200K – 4000K} where the UV energy distributions vary widely between active and inactive stars. The strength and distribution of this UV emission can have critical consequences for the atmospheres of attendant planets. Our proposed observations will provide desperately needed constraints on models of the habitability zone and the atmospheres of possible terrestrial planets orbiting M dwarf hosts, and will be used to sharpen TPF target selection. In addition, the NUV data will be used in conjunction with existing optical, FUV and X-ray data to constrain a new generation of M dwarf atmospheric models, and to explore unanswered questions regarding the dynamo generation and magnetic heating in these low-mass stars.
ACS/HRC 10923
Measuring the size of the close-in transiting extrasolar planet HD 189733b
A new transiting exoplanet was found by our radial velocity search around the bright K dwarf HD 189733. With an apparent V magnitude of 7.67 and a distance of 19 pc, it is the closest star known with a transiting extrasolar planet. Moreover, the high radius ratio {Rpl/R ~ 0.17} makes it a uniquely favorable target for exoplanet studies. This planet is set to become the most observed hot Jupiter and a landmark in the understanding of hot Jupiter structure and formation. We propose a fundamental observations with the HST: to measure precisely the size of the transiting planet around HD189733 and the inclination angle of its orbit. The radius is an important characteristic of the planet in itself. A precise, model-independent radius determination is also a necessary prerequisite for further observations of the system with ground-based large telescopes and Spitzer {e.g. to detect reflected light and intrinsic infrared light from the planet, to measure the Rossiter-McLaughlin effect}. This observation requires a high-accuracy spectrophotometry light curve with ACS in the visible. Similar observations for the formerly closest transiting planet, HD 209458b, have revealed that the planet was much larger than accounted for by any model, and undergoing strong evaporation, two observations that have had a profound impact on our understanding of the structure of close-in exoplanets and the migration process.
ACS/HRC/WFC 10737
CCD Stability Monitor
This program will verify that the low frequency flat fielding, the photometry, and the geometric distortion are stable in time and across the field of view of the CCD detectors. A moderately crowded stellar field in the cluster 47 Tuc is observed every three months with the HRC {at the cluster core} and WFC {6′ West of the cluster core} using the full suite of broad and narrow band imaging filters. The positions and magnitudes of objects will be used to monitor local and large scale variations in the plate scale and the sensitivity of the detectors and to derive an independent measure of the detector CTE. An additional orbit is required to compare WFC observations taken at gain 1 with those taken at the new default gain 2.
ACS/HRC/WFC 10758
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 10491
A Snapshot Survey of the most massive clusters of galaxies
We propose a snapshot survey of a sample of 124 high X-ray luminosity clusters in the redshift range 0.3-0.7. Similarly luminous clusters at these redshifts frequently exhibit strong gravitational lensing. The proposed observations will provide important constraints on the nature of the cluster mass distributions and a set of optically bright, lensed galaxies for further 8-10m spectroscopy. We acknowledge the broad community interest in this sample and waive our data rights for these observations.
ACS/WFC 10775
An ACS Survey of Galactic Globular Clusters
We propose to conduct an ACS/WFC imaging survey of Galactic globular clusters. We will construct the most extensive and deepest set of photometry and astrometry to-date for these systems reaching a main sequence mass of ~0.2 solar mass with S/N >= 10. We will combine these data with archival WFPC2 and STIS images to determine proper motions for the stars in our fields. The resultant cleaned cluster CMDs will allow us to study a variety of scientific questions. These include [but are not limited to] 1} the determination of cluster ages and distances 2} the construction of main sequence mass functions and the issue of mass segregation 3} the internal motions and dynamical evolution of globular clusters, and 4} absolute cluster motions, orbits, and the Milky Way gravitational potential. We anticipate that the unique resource provided by the proposed treasury archive will play a central role in the field of globular cluster studies for decades, with a stature comparable to that of the Hubble Deep Field for high redshift studies.
FGS 10611
Precise Distances to Nearby Planetary Nebulae
We propose to carry out astrometry with the FGS to obtain accurate and precise distances to four nearby planetary nebulae. In 1992, Cahn et al. noted that “The distances to Galactic planetary nebulae remain a serious, if not THE most serious, problem in the field, despite decades of study.” Twelve years later, the same statement still applies. Because the distances to planetary nebulae are so uncertain, our understanding of their masses, luminosities, scale height, birth rate, and evolutionary state is severely limited. To help remedy this problem, HST astrometry can guarantee parallaxes with half the error of any other available approach. These data, when combined with parallax measurements from the USNO, will improve distance measurements by more than a factor of two, producing more accurate distances with uncertainties that are of the order of ~6%. Lastly, most planetary nebula distance scales in the literature are statistical. They require several anchor points of known distance in order to calibrate their zero point. Our program will provide “gold standard” anchor points by the end of 2006, a decade before any anticipated results from future space astrometry missions.
NICMOS 8790
NICMOS Post-SAA calibration – CR Persistence Part 1.
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.
WFPC2 10628
Determining the Lifetime of Planetary Nebula Knots from Observations of the Core of the Helix Nebula.
Knots within the Planetary Nebulae {PN} are ubiquitous components and form at the interface of the expanding ionized zone and the surrounding dusty and molecule-rich neutral layers. About half of the total mass ejected by the precursor star becomes trappped in the Knots, which will join the Interstellar Medium {ISM} within a few tens of thousands of years. If they survive, they may be the source of the micro-structures that appear to be common in the ISM, a result that would be important in understanding the exchange of matter between stars and the ISM. We propose observations that will characterize the Knots over a wider ionization range and ages than has been done before, which should yield the best model for the Knots and therefore the best prediction of their fates. Knots are not seen within a well defined distance from the central star. We don’t know if this is because they are being destroyed by photoevaporation {since the inner Knots would be the youngest}, an important factor in our modeling. However, the inner core of the Helix Nebula has not been imaged in the HeII emission that dominates the region. We propose eight orbits of observations that will search the inner core of the Helix for undetected knots using the WFPC2 HeII F469N filter and the ACS-WFC F502N filter that isolates [OIII] emission. Our WFPC2 pointing will also allow imaging the best studied knot in HeII, giving us the best possible data for that Knot. These combined results will be modeled with the new Hydro- Cloudy code, allowing us to determine if they will survive the PN stage and become components of the ISM. At no additional cost of observing time we will be able to derive a calibration of the WFPC2 F469N filter, to make unprecedented quality parallel images in molecular hydrogen, and to extended the coverage of high resolution emission-line images of the Helix Nebula.
WFPC2 10748
WFPC2 CYCLE 14 Standard Darks
This dark calibration program obtains dark frames every week in order to provide data for the ongoing calibration of the CCD dark current rate, and to monitor and characterize the evolution of hot pixels. Over an extended period these data will also provide a monitor of radiation damage to the CCDs.
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: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSacq 09 09
FGS REacq 05 05
OBAD with Maneuver 28 28
SIGNIFICANT EVENTS: (None)
