NASA Hubble Space Telescope Daily Report # 3431

Status Report From: Space Telescope Science Institute
Posted: Thursday, August 21, 2003





ACS 9658

ACS Earth Flats

This program will obtain sequences of flat field images by observing the bright Earth. Several UV filters from the interim calibration program {9564} require additional exposures to obtain the required illumination. A few UV filters from this program will be repeated to monitor for changes in the flat fields and to verify the interim results. Since no streaks are observed in the UV, the wavelength coverage is extended to longer wavelengths in order to explore the severity of streaks in the flats from clouds in the FOV. We have added exposures for the HRC in the visible filters to verify the results derived from the L-flat campaign and to explore the severity of streaks. We have also added exposures on WFC using the minimum exposure time and using filters which will not saturate the brightest WFC pixel by more than 10 times the full well.

ACS 9675

CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. This programme will be executed once a day for the entire lifetime of ACS.

ACS 9984

Cosmic Shear With ACS Pure Parallels

Small distortions in the shapes of background galaxies by foreground mass provide a powerful method of directly measuring the amount and distribution of dark matter. Several groups have recently detected this weak lensing by large-scale structure, also called cosmic shear. The high resolution and sensitivity of HST/ACS provide a unique opportunity to measure cosmic shear accurately on small scales. Using 260 parallel orbits in Sloan textiti {F775W} we will measure for the first time: beginlistosetlength sep0cm setlengthemsep0cm setlength opsep0cm em the cosmic shear variance on scales <0.7 arcmin, em the skewness of the shear distribution, and em the magnification effect. endlist Our measurements will determine the amplitude of the mass power spectrum sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20, and the mass density Omega_m with s/n=4. They will be done at small angular scales where non-linear effects dominate the power spectrum, providing a test of the gravitational instability paradigm for structure formation. Measurements on these scales are not possible from the ground, because of the systematic effects induced by PSF smearing from seeing. Having many independent lines of sight reduces the uncertainty due to cosmic variance, making parallel observations ideal.

ACS/HRC 9747

An Imaging Survey of the Statistical Frequency of Binaries Among Exceptionally-Young Dynamical Families in the Main Asteroid Belt

We propose an ambitious SNAPSHOT program to determine the frequency of binaries among two very young asteroid families in the Main Belt, with potentially profound implications. These families {of C- and S-type} have recently been discovered {Nesvorny et al. 2002, Nature 417, 720}, through dynamical modeling, to have been formed at 5.8 MY and 8.3 MY ago in catastrophic impact events. This is the first time such precise and young ages have been assigned to a family. Main-belt binaries are almost certainly produced by collisions, and we would expect a young family to have a significantly higher frequency of binaries than the background, because they may not yet have been destroyed by impact or longer-term gravitational instabilities. In fact, one of the prime observables from such an event should be the propensity for satellites. This is the best way that new numerical models for binary production by collisions {motivated largely by our ground-based discoveries of satellites among larger asteroids}, can be validated and calibrated. HST is the only facility that can be used to search for binaries among such faint objects {V>17.5}. We will also measure two control clusters, one being an "old" family, and the other a collection of background asteroids that do not have a family association, and further compare with our determined value for the frequency of large main-belt binaries {2%}. We request visits to 180 targets, using ACS/HRC.

ACS/HRC 9853

A Search for Young Binary Brown Dwarfs: Constraining Formation Scenarios and Masses Through Multiplicity

We propose to use the Advanced Camera for Surveys / High Resolution Camera to conduct a direct imaging multiplicity survey of 34 young brown dwarfs in the nearest regions of recent star formation, the T association Taurus-Auriga and the OB association Upper Scorpius. The determined multiplicity fraction, the separation distribution, and the mass ratio distribution will offer stringent observational constraints on proposed brown dwarf formation scenarios. Moreover, the small semi-major axes of known field and open cluster brown dwarf binaries suggest the exciting possibility of our identifying several very close binaries {< 15 AU}. Continued monitoring of these systems would yield, on a decade timescale, the first dynamical mass estimates of T Tauri brown dwarfs. With masses intermediate between those of stars and planets, brown dwarfs offer our best hope of relating the reasonably well understood processes of star formation to the less well understood processes of planet formation.

ACS/HRC 9990

Investigating the multiplicity of the L dwarf LHS 102B

Cycle 11 NICMOS images of LHS 102B {Program 9485} suggest that the L dwarf is a close visual binary separated by about 88 milliarcsec, which corresponds to an apparent physical separation of 0.85 AU. We will image this L dwarf with the HRC approximately one year after the NICMOS observations to confirm this probable binarity and to investigate the nature of another faint object located within 2 arcsec of LHS 102B.

ACS/WFC 9991

The Orbit of a Newly Discovered Transneptunian Binary

We have recently discovered a binary companion to the transneptunian object {TNO} 1999 RZ253. We are requesting rapid followup observations during cycle 12 to make observations sufficient for a preliminary characterization of the orbital period, semimajor axis, eccentricity, and inclination. In particular, it is urgent to determine if this object is a candidate for observable mutual events in the near future, a possibility that would greatly add to its scientific interest. The study of TNBs is in a stage of explosive growth, fueled in large part by the capabilities of HST that we seek to exploit.


The local Hubble flow and the density field within 6 Mpc

Great progress has been made recently in accurate distance measurements of nearby galaxies beyond the Local Group based on the luminosity of the tip of the red giant branch {TRGB}. Over the last three years, snapshot surveys with HST have provided us with the TRGB distances for more than a hundred nearby galaxies obtained with an accuracy of about 10%. The local velocity field within 5 Mpc exhibits a significant anisotropy which disagrees with a spherical Virgo-centric flow. The local Hubble flow is very cold, with 1-D rms deviations of ~30 km/s. Cosmological simulations with Cold Dark Matter can only realize such low dispersions with a combination of a low mean density of matter and a substantial component with negative pressure. There may be a constraint on the equation of state w=-p/rho. Our observations will concentrate on 116 galaxies whose expected distances lie within 4 - 6 Mpc, allowing us to trace a Dark Matter distribution in the Local Volume with twice the information currently available. The program is a good one for SNAP mode because the order and rate that the observations are made are not very important, as long as there is good completion over several years.

FGS 9881

Dynamical Masses and Radii of Four White Dwarf Stars

The cool white dwarf stars WD1639+153 and WD1818+126 were recently resolved by HST FGS1r to be double degenerate binary systems with projected separations of 112 mas and 174 mas respectively. At a distance of less than 50 pc they may both have periods shorter than about 20 years, making them ideal candidates for follow up studies for dynamical mass determinations. This will increase the number of white dwarfs with dynamical mass measurements from the current 4 up to 8. Continued observations of these white dwarfs along with nearby field stars with the FGS will accurately determine the orbital elements and parallax of each system. The mass and radius of all four white dwarfs can be determined to an unprecedented 1%, making it possible to test and calibrate the theoretical white dwarf mass radius relation at the cool end of the cooling curve for the DA and DC subclasses. Since the components of the binary are coeval, once the mass and radius, and hence the cooling age of each star is known, it will be possible to estimate the relation between the initial mass and final mass for all four white dwarfs. We are requesting a total of 4 HST orbits per year for the next three cycles to initiate the process that will result in a determination of the mass and radius of the four white dwarfs.

FGS 9969

FGS Astrometry of the Extrasolar Planet of Epsilon Eridani

We propose observations with HST/FGS in Position Mode to determine the astrometric elements {perturbation orbit semimajor axis and inclination} of the candidate extra-solar planet around the K2 V star Epsilon Eridani that has been detected by Doppler spectroscopy. These observations will also permit us to determine the actual mass of the planet by providing the sin{i} factor which can not be determined with the radial velocity method. High precision radial velocity {RV} measurements spanning the years 1980.8--2000.0 for the nearby {3.22 pc} star Epsilon Eri show convincing variations with a period of ~ 7 yrs. These data represent a combination of six independent data sets taken with four different telescopes. A least squares orbital solution using robust estimation yields orbital parameters of period, P = 6.9 yrs, velocity K- amplitude = 19 m/s, eccentricity e = 0.6, projected companion mass M_B sin{i} = 0.83 M_Jupiter. An estimate of the inclination yields a perturbation semi-major axis, Alpha = 0arcs0022, easily within the reach of HST/FGS astrometry.

NIC1/NIC2 10063

NICMOS Focus and PAM Grid Tilt Tests

The purpose of this proposal is to determine if the focus has changed during the safing of NICMOS during the recent shutdown of the NCS, as well as to determine if the tilt of the PAM needs to be corrected. The program consists of: Visit 01: Focus sweep using NIC2 Visit 02: Focus sweep using NIC1 Visit 03: Uplink of PAM settings {on hold pending evaluation of visit 1 and 2} Visit 04: Focus sweep using NIC3 {on hold pending evaluation of visit 1 and 2} Visit 05: PAM X/Y grid tilt for NIC1 {on hold pending evaluation of visit 1 and 2} Visit 06: PAM X/Y grid tilt for NIC2 {on hold pending evaluation of visit 1 and 2} Visit 07: Uplink of PAM X/Y parameters {on hold pending execution of visit 5 and 6} After the focus sweeps with NIC1 and NIC2, the focus parameters will be evaluated together with a rough estimate of the coma. The results of this evaluation may lead to a decision to perform a focus sweep with NIC3 and/or a measurement of the PAM tilt grid. No measurement of the PAM tilt grid are planned for NIC3. The focus sweeps are based on the normal focus monitoring proposal 9637. The tilt grid measurements are based proposal 8977 {NIC1} and 9645 {NIC2}.

NIC3/NIC2/NIC3 10064

Mini-SMOV NICMOS dark current, shading profile, and read noise program

The purpose of this proposal is to study the dark current, read noise, and shading profile for all three NICMOS detectors after the NICMOS starts operating due to safing. This proposal is a version of the NICMOS monitoring program.


NICMOS Post-SAA calibration - CR Persistence Part 2

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.

STIS 9606

CCD Dark Monitor-Part 2

Monitor the darks for the STIS CCD.

STIS 9608

CCD Bias Monitor - Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns.

STIS 9786

The Next Generation Spectral Library

We propose to continue the Cycle 10 snapshot program to produce a Next Generation Spectral Library of 600 stars for use in modeling the integrated light of galaxies and clusters. This program is using the low dispersion UV and optical gratings of STIS. The library will be roughly equally divided among four metallicities, very low {[Fe/H] lt -1.5}, low {[Fe/H] -1.5 to -0.5}, near-solar {[Fe/H] -0.3 to 0.1}, and super-solar {[Fe/H] gt 0.2}, well-sampling the entire HR-diagram in each bin. Such a library will surpass all extant compilations and have lasting archival value, well into the Next Generation Space Telescope era. Because of the universal utility and community-broad nature of this venture, we waive the entire proprietary period.

STIS/CCD 10000

STIS Pure Parallel Imaging Program: Cycle 12

This is the default archival pure parallel program for STIS during cycle 12.


UV Spectroscopic Observations of Luminous Narrow-line Seyfert 1 Galaxies

Narrow-line Seyfert 1 galaxies {NLS1s} have remarkably different properties than Active Galactic Nuclei with broad optical lines. The most promising explanation for this behavior is that NLS1s have a higher accretion rate relative to Eddington {L/M} than do broad-line Seyferts. Despite uniformity in optical line properties, detailed analysis reveals a divergence of the UV emission line properties that can be traced differences in the shape of the continuum. A link with similarly divergent X-ray properties suggests that there may be variations in L/M even among NLS1s. To test this scenario, we propose UV spectroscopic of two X-ray extreme NLS1s. These observations offer the opportunity to advance our understanding in the scatter in the relationship between line width and black hole mass, to understand physics of gas in AGN optical and UV emission-line regions, and to understand recently-discovered peculiar line-less high-z quasars that may be the early universe counterpart of luminous NLS1s.

WFPC2 9595


This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels.

WFPC2 9709

POMS Test Proposal: WFII parallel archive proposal

This is the generic target version of the WFPC2 Archival Pure Parallel program. The program will be used to take parallel images of random areas of the sky, following the recommendations of the 2002 Parallels Working Group.


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

HSTAR 9118: GS Re-acquisition (2,1,1) @ 227/20:53:03Z required two attempts to achieve FLDV on FGS 1. OTA SE, in review of TC error log from PTAS run of SA223N SMS, found FGS 1 took two attempts before achieving FLDV for this re-acquisition. The first attempt resulted in FGS 1 SSLEX. Under investigation.

COMPLETED OPS REQs: 17031-0 Adjust NCS PID Control Setpoints @ 232/20:08z


                           SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq               09                        09
FGS REacq               02                        02
FHST Update             32                        32


Successfully adjusted NCS PID control setpoints @ 232/20:08Z to change the detector temperature. The Prime (dewar, NOT active), and the Alternate (weighted average neon, ACTIVE) control points were set to 77.25 K and 72.45 K, respectively (OR 17031). The Compressor speed under PID control dropped just noticeably in speed to affect the commanded increase in control point temperature. MNCOINTRL successfully achieved 72.45 K at 232/20:17Z and system operation appears to be continuing nominally.

Completed CCS Release 5.0.3 Events Analyzer Comparison Test on Day 230 and 231 using CCS "D" and "B" Strings. The first part of the test ingesting real-time data was mostly successful, except for several data drops on the "D" String while a science data playback was being transmitted from the HST through the CCS and HSTPS systems using Packet Filter 1. The second part of the test using the PSSs as data sources was also mostly successful. There were several command data drops from both the "B" and "D" Strings using Packet Filter 15. This happened when sending FIVEBLCKs and NSSC-1 FSW loads. Lastly, the new "Key Monitor" was tried out on "D" String Test mode. Issue 19 was added to the CCS 5.0.3 Test Matrix to have CCS Development/Response Team copy the canned request job to the Test side of "D" String.

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