Status Report

NASA Hubble Space Telescope Daily Report #3929

By SpaceRef Editor
August 23, 2005
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HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT August 22, 2005 (DOY 234)


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 10547

A SNAP Program to Obtain Complete Wavelength Coverage of Interstellar Extinction

We propose a SNAP program to obtain ACS/HRC spectra in the near-UV {PR200L} and near-IR {G800L} for a set of main sequence B stars with available IUE UV spectrophotometry, optical photometry, and 2MASS IR photometry. Together with these existing data, the new observations will provide complete photometric and spectrophotometric coverage from 1150 to 11000 A and enable us to produce complete extinction curves from the far-UV to the near-IR, with well- determined values of R{V}. The proposed set of 50 program sight lines includes the full range of interstellar extinction curve types and a wide range of color excesses. The new data will allow us to examine variability in the near-UV through near-IR spectral regions, including the UV-optical “knee” and the “Very Broad Structure.” We will examine the response of these features to different interstellar environments and their relationship to other curve features. These are largely unexplored aspects of extinction curves which will provide additional constraints on the properties of interstellar grains. The curves will be derived using stellar atmosphere models to represent the intrinsic spectral energy distributions of the program stars, eliminating the need to observe unreddened “standard stars.” This approach virtually eliminates “mismatch error”, allowing us to derive extinction curves with much higher precision than previously possible. In addition, the new spectra will provide higher S/N data for the peak of the 2175 A bump than previously available.


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.

ACS/SBC 10502

ACS Imaging of the Uranus Aurora and Hydrogen Corona

ACS SBC UV observations of Uranus are proposed with dual purposes that can be achieved with a single set of observations. First, we propose to observe the very unusual auroral of Uranus for the first time since IUE and Voyager in the 1980’s. The Uranus aurora are centered on the magnetic poles, corresponding to the 60 deg. tilted magnetic moment, closer to the equator than the rotational poles. The brighter auroral emission appears around the weaker magnetic pole. The auroral emissions are highly variable, as recorded with IUE, and the rotational phase of Uranus is not known. The observations will therefore cover the extent of a Uranus rotation {17.29 hours}, and will be repeated one-half solar rotation later to allow for variations in the solar wind at Uranus. The high sensitivity of the ACS SBC at long wavelengths will increase the sensitivity to auroral H2 emissions, and observations in cycle 14 near solar minimum will limit the sky background and reflected solar emissions from the Uranus disc. Secondly, these images will measure the extended hydrogen corona of Uranus, first seen by the Voyager 2 UVS. We propose to model the distribution of the hydrogen corona to determine the source processes in the Uranus upper atmosphere, by comparison with model runs from an exospheric code.

ACS/WFC 10496

Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters

We propose a novel HST approach to obtain a dramatically more useful “dust free” Type Ia supernovae {SNe Ia} dataset than available with the previous GOODS searches. Moreover, this approach provides a strikingly more efficient search-and-follow-up that is primarily pre- scheduled. The resulting dark energy measurements do not share the major systematic uncertainty at these redshifts, that of the extinction correction with a prior. By targeting massive galaxy clusters at z > 1 we obtain a five-times higher efficiency in detection of Type Ia supernovae in ellipticals, providing a well-understood host galaxy environment. These same deep cluster images then also yield fundamental calibrations required for future weak lensing and Sunyaev-Zel’dovich measurements of dark energy, as well as an entire program of cluster studies. The data will make possible a factor of two improvement on supernova constraints on dark energy time variation, and much larger improvement in systematic uncertainty. They will provide both a cluster dataset and a SN Ia dataset that will be a longstanding scientific resource.


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 10610

Astrometric Masses of Extrasolar Planets and Brown Dwarfs

We propose observations with HST/FGS to estimate the astrometric elements {perturbation orbit semi-major axis and inclination} of extra-solar planets orbiting six stars. These companions were originally detected by radial velocity techniques. We have demonstrated that FGS astrometry of even a short segment of reflex motion, when combined with extensive radial velocity information, can yield useful inclination information {McArthur et al. 2004}, allowing us to determine companion masses. Extrasolar planet masses assist in two ongoing research frontiers. First, they provide useful boundary conditions for models of planetary formation and evolution of planetary systems. Second, knowing that a star in fact has a plantary mass companion, increases the value of that system to future extrasolar planet observation missions such as SIM PlanetQuest, TPF, and GAIA.

NIC1/NIC2 10410

Anisotropy and obscuration in the near-nuclear regions of powerful radio galaxies

Despite the success of the orientation-based unified schemes for powerful radio sources, we are still far from understanding the distribution of obscuring material in the near-nuclear regions of such sources, and how this distribution evolves with radio power. Following on from our highly successful Cycle 7 pilot observations of Cygnus A, we propose a near-IR polarimetric survey of a complete sample of powerful radio galaxies in order map the near-nuclear illumination cones, and investigate the distribution of obscuring material on a 0.1 to 1kpc scale. In particular, the observations will allow us to test the “receding torus model” which predicts that the opening angles of the illumination cones are smaller in low redshift/low power radio galaxies than in their high redshift/high power counterparts.We will also investigate whether AGN- and jet-driven outflows have a substantial effect on distribution of obscuring material by “hollowing out” the quasar illumination cones in the more powerful sources. Finally, by using our polarization maps to search for signs of intrinsic anisotropy in the near-IR continuum within the cones, we will investigate the geometry of the near-IR continuum emitting regions close to the quasar nuclei. These observations are not only crucial for our understanding of radio source unification, but also provide key information about the effects of AGN-induced outflows on the ISM of the host galaxies.

NIC1/NIC2/NIC3 10721

NICMOS dark current tests for newly implemented SPARS sequences

On June 12, 2005, 4 new NICMOS multiaccum sequences {SPARS4, SPARS16, SPARS32, SPARS128} were implemented. The purpose of this observation is to measure the dark currents for these new multiaccum sequences for all three 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.

WFPC2 10359

WFPC2 CYCLE 13 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.


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

HSTARS: (None)

COMPLETED OPS REQUEST: 17523-0 – Null genslews for proposal 10487 – slots 12 and 13 @ 234/18:10z


                          SCHEDULED     SUCCESSFUL
FGS Gsacq              09                      09
FGS Reacq               07                     07
FHST Update            18                     18


SpaceRef staff editor.