Status Report

NASA Hubble Space Telescope Status Update #4987

By SpaceRef Editor
December 10, 2009
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Continuing to Collect World Class Science

PERIOD COVERED: 5am December 7 – 5am December 8, 2009 (DOY 341/10:00z-342/10:00z)


ACS/WFC3 11879

CCD Daily Monitor (Part 1)

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 352 orbits (22 weeks) from 31 August 2009 to 31 January 2010.

NIC2/WFC3/IR 11548

Infrared Imaging of Protostars in the Orion A Cloud: The Role of Environment in Star Formation

We propose NICMOS and WFC3/IR observations of a sample of 252 protostars identified in the Orion A cloud with the Spitzer Space Telescope. These observations will image the scattered light escaping the protostellar envelopes, providing information on the shapes of outflow cavities, the inclinations of the protostars, and the overall morphologies of the envelopes. In addition, we ask for Spitzer time to obtain 55-95 micron spectra of 75 of the protostars. Combining these new data with existing 3.6 to 70 micron photometry and forthcoming 5-40 micron spectra measured with the Spitzer Space Telescope, we will determine the physical properties of the protostars such as envelope density, luminosity, infall rate, and outflow cavity opening angle. By examining how these properties vary with stellar density (i.e. clusters vs. groups vs. isolation) and the properties of the surrounding molecular cloud; we can directly measure how the surrounding environment influences protostellar evolution, and consequently, the formation of stars and planetary systems. Ultimately, this data will guide the development of a theory of protostellar evolution.

S/C 12046

COS FUV DCE Memory Dump

Whenever the FUV detector high voltage is on, count rate and current draw information is collected, monitored, and saved to DCE memory. Every 10 msec the detector samples the currents from the HV power supplies (HVIA, HVIB) and the AUX power supply (AUXI). The last 1000 samples are saved in memory, along with a histogram of the number of occurrences of each current value.

In the case of a HV transient (known as a “crackle” on FUSE), where one of these currents exceeds a preset threshold for a persistence time, the HV will shut down, and the DCE memory will be dumped and examined as part of the recovery procedure. However, if the current exceeds the threshold for less than the persistence time (a “mini-crackle” in FUSE parlance), there is no way to know without dumping DCE memory. By dumping and examining the histograms regularly, we will be able to monitor any changes in the rate of “mini-crackles” and thus learn something about the state of the detector.

STIS/CCD 11844

CCD Dark Monitor Part 1

The purpose of this proposal is to monitor the darks for the STIS CCD.

STIS/CCD 11846

CCD Bias Monitor-Part 1

The purpose of this proposal is to 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 11616

The Disks, Accretion, and Outflows (DAO) of T Tau Stars

Classical T Tauri stars undergo magnetospheric accretion, power outflows, and possess the physical and chemical conditions in their disks to give rise to planet formation. Existing high resolution FUV spectra verify that this spectral region offers unique diagnostics of these processes, which have the potential to significantly advance our understanding of the interaction of a star and its accretion disk. To date the limited results are intriguing, with dramatic differences in kinematic structure in lines ranging from C IV to H2 among the few stars that have been observed. We propose to use HST/COS to survey the disks, outflows, and accretion (the DAO) of 26 CTTS and 6 WTTS in the FUV at high spectral resolution. A survey of this size is essential to establish how properties of accretion shocks, winds and disk irradiation depend on disk accretion rate. Specifically, our goals are to (1) measure the radiation from and understand the physical properties of the gas very near the accretion shock as a function of accretion rate using emission line profiles of hot lines (C IV, Si IV, N V, and He II); (2) measure the opacity, velocity, and temperature at the base of the outflow to constrain outflow models using wind absorption features; and (3) characterize the radiation incident on disks and protoplanetary atmospheres using H2 line and continuum emission and reconstructed bright Ly-alpha line emission.


SAINTS – Supernova 1987A INTensive Survey

SAINTS is a program to observe SN 1987A, the brightest supernova since 1604, as it matures into the youngest supernova remnant at age 21. HST is the essential tool for resolving SN1987A’s many physical components. A violent encounter is underway between the fastest-moving debris and the circumstellar ring: shocks excite “hotspots.” Radio, optical, infrared and X-ray fluxes have been rising rapidly: we have organized Australia Telescope, HST, VLT, Spitzer, and Chandra observations to understand the several emission mechanisms at work. Photons from the shocked ring will excite previously invisible gas outside the ring, revealing the true extent of the mass loss that preceded the explosion of Sanduleak -69 202. This will help test ideas for the progenitor of SN 1987A. The inner debris, excited by radioactive isotopes from the explosion, is now resolved and seen to be aspherical, providing direct evidence on the shape of the explosion itself. Questions about SN 1987A remain unanswered. A rich and unbroken data set from SAINTS will help answer these central questions and will build an archive for the future to help answer questions we have not yet thought to ask.

WFC3/IR 11208

The Co-Evolution of Spheroids and Black Holes in the Last Six Billion Years

The masses of giant black holes are correlated with the luminosities, masses, and velocity dispersions of the bulges of their host galaxies. This empirical correlation of phenomena on widely different scales (from pcs to kpcs) suggests that the formation and evolution of galaxies and central black holes are closely linked. In Cycle 13, we have started a campaign to map directly the co-evolution of spheroids and black-holes by measuring in observationally favorable redshift windows the empirical correlations connecting their properties. By focusing on Seyfert 1s, where the nucleus and the stars contribute comparable fractions of total light, black hole mass and bulge dispersion are obtained from Keck spectroscopy. HST is required for accurate measurement of the non- stellar AGN continuum, the morphology of the galaxy, and the structural parameters of the bulge. The results at z=0.36 indicate a surprisingly fast evolution of bulges in the past 4 Gyrs (significant at the 95%CL), in the sense that bulges were significantly smaller for a given black hole mass. Also, the large fraction of mergers and disturbed galaxies (4+2 out of 20) identifies gas-rich mergers as the mechanisms responsible for bulge- growth. Going to higher redshift – where evolutionary trends should be stronger – is needed to confirm these tantalizing results. We propose therefore to push our investigation to the next suitable redshift window z=0.57 (lookback-time 6 Gyrs). Fifteen objects are the minimum number required to map the evolution of the empirical correlations between bulge properties and black-hole mass, and to achieve a conclusive detection of evolution (>99%CL).

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 11583

The Star Formation Rate In Nearby Elliptical Galaxies

Small amounts of star formation in normal elliptical galaxies are suggested by several results: some surprisingly young ages from optical line-index dating; cooling X-ray gas; and mid-IR dust emission. Previously, it was difficult to detect low levels of star formation, but UV imaging with WFPC3 will permit us to conclusively identify individual O/B stars in nearby normal ellipticals by their UV colors and magnitudes. This technique is orders of magnitude more sensitive than previous methods, allowing detections of star formation to levels of 1E-4 Msolar/yr. Proof of concept is provided by a very long UV ACS observation of M87 that revealed many O/B stars. We propose observations of four normal ellipticals where recent star formation is likely. This will yield their star formation rates and the locations of such activity.

WFC3/UVIS 11716

In Search of the Lost Remnant of M31 RV: Shedding Light on the New Class of Luminous Red Transients

M31 RV is a luminous red variable star that appeared in the bulge of M31 in 1988. During its outburst, which lasted a few months, it was one of the brightest stars in the Local Group. Unlike a classical nova, it was extremely cool during the eruption, and it never became optically thin or exposed a hot, blue source. There has been renewed interest in M31 RV recently, because of its remarkable similarities to V838 Mon, a luminous Galactic variable star that underwent a similar rapid expansion to become a red supergiant, and which is currently illuminating a spectacular light echo, extensively observed by HST. The outburst mechanism for this new class of luminous transients remains unknown, and is one of the major current challenges to our understanding of stellar physics.

Bond and Siegel have examined WFPC2 frames of the site of M31 RV, obtained fortuitously in 1999 as parallel observations during spectroscopic studies of the nucleus of M31. The explosion site shows only a pure old population of red giants, with no obvious remnant of M31 RV. I propose now to obtain second-epoch images of the site, in the same filters, to determine whether there is an object in the field that has faded or varied, and if so what its brightness and color is. This information may provide new constraints on proposed outburst mechanisms, such as stellar mergers or collisions, and could lead to a spectroscopic observation in a future HST cycle.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K subarray biases are acquired at less frequent intervals throughout the cycle to support subarray science observations. The internals from this proposal, along with those from the anneal procedure (Proposal 11909), will be used to generate the necessary superbias and superdark reference files for the calibration pipeline (CDBS).

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the UVIS detector (both CCDs) at the level of ~1%, lasting hours to days. Initially found via an unexpected bowtie-shaped feature in flatfield ratios, subsequent lab tests on similar e2v devices have since shown that it is also present as simply an overall offset across the entire CCD, i.e., a QE offset without any discernable pattern. These lab tests have further revealed that overexposing the detector to count levels several times full well fills the traps and effectively neutralizes the bowtie. Each visit in this proposal acquires a set of three 3×3 binned internal flatfields: the first unsaturated image will be used to detect any bowtie, the second, highly exposed image will neutralize the bowtie if it is present, and the final image will allow for verification that the bowtie is gone.

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.


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


#12113 GSAcq(1,2,1) @341/11:21:25z and REAcq(1,2,1) @341/12:18:13z failed to RGA control with Search Radius Limit exceeded on FGS 2

Observations affected: WFC3 #17-18, Proposal #11653



FGS GSAcq 6 5
FGS REAcq 8 7
OBAD with Maneuver 6 6


SpaceRef staff editor.