Status Report

NASA Hubble Space Telescope Daily Report #4268

By SpaceRef Editor
December 27, 2006
Filed under , ,
NASA Hubble Space Telescope Daily Report #4268


– Continuing to collect World Class Science

PERIOD COVERED: UT December 27, 2006 (DOY 361)


ACS/HRC 11041

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. For cycle 15 the program will cover 18 months 12.1.06->05.31.08 and it has been divied into three different proposal each covering six months. The three proposals are 11041-11042-11043.

ACS/HRC 11054

Photometric and Spectrophotometric Absolute Calibration

Verify repeatability of the ACS instrumentation on a single bright star to ?0.2%. Determine any shift in the filter bandpasses since the preflight lab measurements. Determine the relative magnitude of the 3 primary WD calibrators to 0.1%. Refine the sensitivity calibration of the CCD prism and grisms at field center and determine the repeatability accuracy of this calibration. Determine the level of variability of the three HST red standard stars VB-8 {M7}, 2M0038+18 {L3.5} and 2M0559-14 {T5} and also measure their short wavelength {<7000A} fluxes. Measure the WFC red leak by adding one orbit for WFC observation of the sdF8 SDSS standard BD+17d4708 in order to look for continuity vs. SED from O,F,M,L,T.

ACS/WFC 10587

Measuring the Mass Dependence of Early-Type Galaxy Structure

We propose two-color ACS-WFC Snapshot observations of a sample of 118 candidate early- type gravitational lens galaxies. Our lens-candidate sample is selected to yield {in combination with earlier results} an approximately uniform final distribution of 40 early-type strong lenses across a wide range of masses, with velocity dispersions {a dynamical proxy for mass} ranging from 125 to 300 km/s. The proposed program will deliver the first significant sample of low-mass gravitational lenses. All of our candidates have known lens and source redshifts from Sloan Digital Sky Survey data, and all are bright enough to permit detailed photometric and stellar- dynamical observation. We will constrain the luminous and dark-matter mass profiles of confirmed lenses using lensed-image geometry and lens-galaxy structural/photometric measurements from HST imaging in combination with dynamical measurements from spatially resolved ground-based follow-up spectroscopy. Hence we will determine, in unprecedented detail, the dependence of early-type galaxy mass structure and mass-to-light ratio upon galaxy mass. These results will allow us to directly test theoretical predictions for halo concentration and star-formation efficiency as a function of mass and for the existence of a cuspy inner dark- matter component, and will illuminate the structural explanation behind the fundamental plane of early-type galaxies. The lens-candidate selection and confirmation strategy that we propose has been proven successful for high-mass galaxies by our Cycle 13 Snapshot program {10174}. The program that we propose here will produce a complementary and unprecedented lens sample spanning a wide range of lens-galaxy masses.

NIC1 11063

NICMOS Focus Monitoring

This program is a version of the standard focus sweep used since cycle 7. It has been modified to go deeper and uses more narrow filters for improved focus determination. For Cycle14 a new source has been added in order to accomodate 2-gyro mode: the open cluster NGC1850. The old target, the open cluster NGC3603, will be used whenever available and the new target used to fill the periods when NGC3603 is not visible. Steps: a} Use refined target field positions as determined from cycle 7 calibrations b} Use MULTIACCUM sequences of sufficient dynamic range to account for defocus c} Do a 17-point focus sweep, +/- 8mm about the PAM mechanical zeropoint for each cameras 1 and 2, in 1.0mm steps. d} Use PAM X/Y tilt and OTA offset slew compensations refined from previous focus monitoring/optical alignment activities

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.

NIC2 10847

Coronagraphic Polarimetry of HST-Resolved Debris Disks

We propose to take full advantage of the recently commissioned coronagraphic polarimetry modes of ACS and NICMOS to obtain imaging polarimetry of circumstellar debris disks that were imaged previously by the HST coronagraphs, but without the polarizers. It is well established that stars form in gas-rich protostellar disks, and that the planets of our solar system formed from a circum-solar disk. However, the connection between the circumstellar disks that we observe around other stars and the processes of planet formation is still very uncertain. Mid-IR spectral studies have suggested that disk grains are growing in the environments of young stellar objects during the putative planet-formation epoch. Furthermore, structures revealed in well resolved images of circumstellar disks suggest gravitational influences on the disks from co-orbital bodies of planetary mass. Unfortunately, existing imaging data provides only rudimentary information abou the disk grains and their environments. Our proposed observations, which can be obtained only with HST, will enable us to quantitatively determine the sizes of the grains and optical depths as functions of their location within the disks {i.e., detailed tomography}. Armed with these well-determine physical and geometrical systemic parameters, we will develop a set of self-consistent models of disk structures to investigate possible interactions between unseen planets and the disks from which they formed. Our results will also calibrate models of the thermal emission from these disks, that will in turn enable us to infer the properties of other debris disks that cannot be spatially resolved with current or planned instruments and telescopes.

NIC2 10852

Coronagraphic Polarimetry with NICMOS: Dust grain evolution in T Tauri stars

The formation of planetary systems is intimately linked to the dust population in circumstellar disks, thus understanding dust grain evolution is essential to advancing our understanding of how planets form. By combining {1} the coronagraphic polarimetry capabilities of NICMOS, {2} powerful 3-D radiative transfer codes, and {3} observations of objects known to span the Class II-III stellar evolutionary phases, we will gain crucial insight into dust grain growth. By observing objects representative of a known evolutionary sequence of YSOs, we will be able to investigate how the dust population evolves in size and distribution during the crucial transition from a star+disk system to a system containing planetesimals. When combine with our previous study on dust grain evolution in the Class I-II phase, the proposed study will help to establish the fundamental time scales for the depletion of ISM-like grains: the first step in understanding the transformation from small submicron sized dust grains, to large millimeter sized grains, and untimely to planetary bodies.

WFPC2 10915

ACS Nearby Galaxy Survey

Existing HST observations of nearby galaxies comprise a sparse and highly non-uniform archive, making comprehensive comparative studies among galaxies essentially impossible. We propose to secure HST’s lasting impact on the study of nearby galaxies by undertaking a systematic, complete, and carefully crafted imaging survey of ALL galaxies in the Local Universe outside the Local Group. The resulting images will allow unprecedented measurements of: {1} the star formation history {SFH} of a >100 Mpc^3 volume of the Universe with a time resolution of Delta[log{t}]=0.25; {2} correlations between spatially resolved SFHs and environment; {3} the structure and properties of thick disks and stellar halos; and {4} the color distributions, sizes, and specific frequencies of globular and disk clusters as a function of galaxy mass and environment. To reach these goals, we will use a combination of wide-field tiling and pointed deep imaging to obtain uniform data on all 72 galaxies within a volume-limited sample extending to ~3.5 Mpc, with an extension to the M81 group. For each galaxy, the wide-field imaging will cover out to ~1.5 times the optical radius and will reach photometric depths of at least 2 magnitudes below the tip of the red giant branch throughout the limits of the survey volume. One additional deep pointing per galaxy will reach SNR~10 for red clump stars, sufficient to recover the ancient SFH from the color-magnitude diagram. This proposal will produce photometric information for ~100 million stars {comparable to the number in the SDSS survey} and uniform multi-color images of half a square degree of sky. The resulting archive will establish the fundamental optical database for nearby galaxies, in preparation for the shift of high-resolution imaging to the near-infrared.

WFPC2 10990

Dynamical Masses and Third Bodies in the Sirius System

Sirius B is the nearest and brightest of all white dwarfs {WDs}, but it is fiendishly difficult to observe from the ground because of the overwhelming brightness of Sirius A. We propose a continuation of our program of imaging observations of the Sirius system with WFPC2, which has been underway since 2001. The resulting astrometric data will not only greatly improve the precision of the binary orbit and the dynamical mass measurements for both the main-sequence and WD components, but will also test definitively for the claimed presence of a third body in this famous system, down to planetary masses. At present, there is a tantalizing suggestion in our data that there indeed may exist a substellar or planetary third body in the system. Our team has also obtained superb spectra of Sirius B using STIS, and we have achieved an excellent fit to the spectrum using model stellar atmospheres. However, the implied mass of the WD disagrees significantly with the dynamical mass implied by the existing visual-binary orbit {which still has to be based on a combination of low-accuracy ground-based astrometry plus the small number of existing HST astrometric observations}. This is another critical motivation for improving the astrometry.


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


10579 – OBAD Failed Identification (ESB 1902) At 361/13:48:02, OBAD1 using trackers FHST-1 and FHST-2 failed. One 486 ESB message 1902 (OBAD Failed Identification) was received. OBAD1 had (RSS) value of 33547.01 arcseconds. OBAD success flag (mnemonic GCHACL09) returned to the “no success” state (a value of 1). OBAD2 at 361/13:53:04 was successful with (RSS) value of 1366.47 arcseconds. The subsequent acquisition at 361/14:04:00 was successful.

10580 – GSACQ(2,1,1) failed GSACQ(2,1,1) at 362/22:37:47 failed to RGA control with QF2STOPF and QSTOP flags set. No other flags were seen. Vehicle was LOS at time of failure.



                         SCHEDULED      SUCCESSFUL
FGS GSacq               10                     09
FGS REacq               04                     04
OBAD with Maneuver  28                     27


SpaceRef staff editor.