Status Report

NASA Hubble Space Telescope Daily Report #5124

By SpaceRef Editor
June 25, 2010
Filed under , ,


Continuing to Collect World Class Science


PERIOD COVERED: 5am June 23 – 5am June 24, 2010 (DOY 174/09:00z-175/09:00z)


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

HSTARS: (None)



FGS GSAcq 6 6
FGS REAcq 9 9
OBAD with Maneuver 6 6



ACS/WFC 11655

Dynamics of the Galactic Bulge/bar

We request second-epoch ACS observations of four star fields in the Galactic bar. These will allow us to measure proper motions for tens of thousands of stars well below the turnoff, to construct a dynamical model for the bulge/bar (in combination with data already in hand from other HST fields, and from VLT spectroscopy), and hence to take a unique look at the internal dynamical structure of the central regions of our Galaxy. By relating the kinematics with stellar population we can elucidate the formation history of the bulge and bar, and their relation to the surrounding Galactic disk. This is a resubmission of an approved Cycle 15 proposal that was hit by the ACS malfunction.

ACS/WFC 11996

CCD Daily Monitor (Part 3)

This program comprises basic tests for measuring the read noise and dark current of the ACS WFC and for tracking the growth of hot pixels. The recorded frames are used to create bias and dark reference images for science data reduction and calibration. This program will be executed four days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To facilitate scheduling, this program is split into three proposals. This proposal covers 308 orbits (19.25 weeks) from 21 June 2010 to 1 November 2010.

COS/FUV 11541

COS-GTO: Cool, Warm, and Hot Gas in the Cosmic Web and in Galaxy Halos

COS G130M and G160M 20, 000 resolution observations will be obtained for 17 QSOs to study cool, warm and hot gas in the cosmic web and in galaxy halos. 5 QSOs with z from 0.177 to 0.574 and sum z = 1.68 will be observed with S/N = 40-50 per resolution element. 12 QSOs with z = 0.286 to 0.669 and sum z = 5.57 will be observed with S/N = 30-40. The observations will allow a wide range of IGM studies including determining the frequency of occurrence of the different types of absorption systems detected, along with studies of the physical conditions and elemental abundances in the different systems. Special emphasis will be given to a study of the properties of highly ionized IGM as traced by O VI, O V, O IV, N V, and C IV. The high S/N of the observations will allow a search for broad Lyman alpha absorption and weak metal line absorption that can be crucial for the evaluation of physical conditions and elemental abundances. Supporting ground based observations will allow studies of the association of the absorbers with galaxy structures along the 17 lines of sight. The overall goal of the program will be to obtain the information that will allow an assessment of the baryonic content of the IGM as revealed by UV and EUV absorption lines seen in the spectra of QSOs.


The Structure and Dynamics of Virgo’s Multi-Phase Intracluster Medium

The dynamical flows of the intracluster medium (ICM) are largely unknown. We propose to map the spatial and kinematic distribution of the warm ICM of the nearby Virgo cluster using the Cosmic Origins Spectrograph. 15 sightlines at a range of impact parameters within the virial radius of the cluster (0.2 – 1.7 Mpc) will be probed for Lyman-alpha absorption and the data compared to blind HI, dust and x-ray surveys to create a multi-phase map of the cluster’s ICM. Absorption line sightlines are commonly 40-100 kpc from a galaxy, allowing the flow of baryons between galaxies and the ICM to be assessed. The velocity distribution of the absorbers will be directly compared to simulations and used to constrain the turbulent motions of the ICM. This proposal will result in the first map of a cluster’s warm ICM and provide important tests for our theoretical understanding of cluster formation and the treatment of gas cooling in cosmological simulations.

STIS/CC 11693

Follow-up Observations of Debris Disks around Two Solar-Type Stars

Circumstellar debris disks offer direct views into the structure of extrasolar planetary systems. Their constituent dust, seen in scattered light and thermal emission, is created by the collisions of asteroidal and cometary parent bodies. The distribution of this dust provides information on the location of the parent bodies, and can be strongly affected by planetary perturbations. Dynamical signatures of planets can include asymmetries, warps, central clearings, and radial gaps in a disk, and thus are key features to search for in resolved images. Following up recent Spitzer measurements, we have now detected two new, nearby debris disks in scattered light. Our initial ACS F606W coronagraphic images show faint ringlike structures around the solar-type stars HD 10647 (F9V) and HD 207129 (G0V); both are also spatially resolved in Spitzer/MIPS 70 micron images. The HD 10647 disk, seen close to edge-on, represents the first disk ever imaged in scattered light around a star known to have a radial velocity planet. The inclined ring around HD 207129 is the faintest disk ever imaged in scattered light, and seems in the MIPS image to be asymmetric like the eccentric ring around Fomalhaut. We propose to obtain deep ACS coronagraphic images of these two disks. Our goals are to get definitive measurements of the dust spatial distributions (including disk asymmetries and sharpness of the ring edges), and measure the overall F606W-F814W color of each disk in order to constrain the dust properties. The results will be a definitive exploration of the Kuiper belts of two nearby, Sun-like stars. NOTE: HD 207129 was deleted from this program.

STIS/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CC 11847

CCD Bias Monitor-Part 2

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

STIS/CCD/MA1/MA2 11860

MAMA Spectroscopic Sensitivity and Focus Monitor

The purpose of this proposal is to monitor the sensitivity of each MAMA grating mode to detect any change due to contamination or other causes, and to also monitor the STIS focus in a spectroscopic and an imaging mode.

STIS/MA1/MA2 11857

STIS Cycle 17 MAMA Dark Monitor

This proposal monitors the behavior of the dark current in each of the MAMA detectors.

The basic monitor takes two 1380s ACCUM darks each week with each detector. However, starting Oct 5, pairs are only included for weeks that the LRP has external MAMA observations planned. The weekly pairs of exposures for each detector are linked so that they are taken at opposite ends of the same SAA free interval. This pairing of exposures will make it easier to separate long and short term temporal variability from temperature dependent changes.

For both detectors, additional blocks of exposures are taken once every six months. These are groups of five 1314s FUV-MAMA Time-Tag darks or five 3x315s NUV ACCUM darks distributed over a single SAA-free interval. This will give more information on the brightness of the FUV MAMA dark current as a function of the amount of time that the HV has been on, and for the NUV MAMA will give a better measure of the short term temperature dependence.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more reliably removed from science data using darks taken with the same exposure sequences as the science data, than with a single dark current image scaled by desired exposure time. Therefore, dark current images must be collected using all sample sequences that will be used in science observations. These observations will be used to monitor changes in the dark current of the WFC3-IR channel on a day-to-day basis, and to build calibration dark current ramps for each of the sample sequences to be used by Gos in Cycle 17. For each sample sequence/array size combination, a median ramp will be created and delivered to the calibration database system (CDBS).

WFC3/UVIS/IR 11644

A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into the Formation of the Outer Solar System

The eight planets overwhelmingly dominate the solar system by mass, but their small numbers, coupled with their stochastic pasts, make it impossible to construct a unique formation history from the dynamical or compositional characteristics of them alone. In contrast, the huge numbers of small bodies scattered throughout and even beyond the planets, while insignificant by mass, provide an almost unlimited number of probes of the statistical conditions, history, and interactions in the solar system. To date, attempts to understand the formation and evolution of the Kuiper Belt have largely been dynamical simulations where a hypothesized starting condition is evolved under the gravitational influence of the early giant planets and an attempt is made to reproduce the current observed populations. With little compositional information known for the real Kuiper Belt, the test particles in the simulation are free to have any formation location and history as long as they end at the correct point. Allowing compositional information to guide and constrain the formation, thermal, and collisional histories of these objects would add an entire new dimension to our understanding of the evolution of the outer solar system. While ground based compositional studies have hit their flux limits already with only a few objects sampled, we propose to exploit the new capabilities of WFC3 to perform the first ever large-scale dynamical-compositional study of Kuiper Belt Objects (KBOs) and their progeny to study the chemical, dynamical, and collisional history of the region of the giant planets. The sensitivity of the WFC3 observations will allow us to go up to two magnitudes deeper than our ground based studies, allowing us the capability of optimally selecting a target list for a large survey rather than simply taking the few objects that can be measured, as we have had to do to date. We have carefully constructed a sample of 120 objects which provides both overall breadth, for a general understanding of these objects, plus a large enough number of objects in the individual dynamical subclass to allow detailed comparison between and within these groups. These objects will likely define the core Kuiper Belt compositional sample for years to come. While we have many specific results anticipated to come from this survey, as with any project where the field is rich, our current knowledge level is low, and a new instrument suddenly appears which can exploit vastly larger segments of the population, the potential for discovery — both anticipated and not — is extraordinary.

WFC3/UVIS/IR 11909

UVIS Hot Pixel Anneal

The on-orbit radiation environment of WFC3 will continually generate new hot pixels. This proposal performs the procedure required for repairing those hot pixels in the UVIS CCDs. During an anneal, the two-stage thermo-electric cooler (TEC) is turned off and the four-stage TEC is used as a heater to bring the UVIS CCDs up to ~20 deg. C. As a result of the CCD warmup, a majority of the hot pixels will be fixed; previous instruments such as WFPC2 and ACS have seen repair rates of about 80%. Internal UVIS exposures are taken before and after each anneal, to allow an assessment of the procedure’s effectiveness in WFC3, provide a check of bias, global dark current, and hot pixel levels, as well as support hysteresis (bowtie) monitoring and CDBS reference file generation. One IR dark is taken after each anneal, to provide a check of the IR detector.

SpaceRef staff editor.