Status Report

NASA Hubble Space Telescope Daily Report #4910

By SpaceRef Editor
August 25, 2009
Filed under , ,


PERIOD COVERED: 5am August 14 – 5am August 17, 2009 (DOY 226/09:00z-229/09:00z)


WFC3/UV 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/UV 11907

UVIS Cycle 17 Contamination Monitor

The UV throughput of WFC3 during Cycle 17 is monitored via weekly standard star observations in a subset of key filters covering 200-600nm and F606W, F814W as controls on the red end. The data will provide a measure of throughput levels as a function of time and wavelength, allowing for detection of the presence of possible contaminants.

WFC3/UV 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 (11909), will be used to generate the necessary superbias and superdark reference files for the calibration pipeline (CDBS).

COS/NUV 11896

NUV Spectroscopic Sensitivity Monitoring

Purpose is to monitor sensitivity of each NUV grating mode to detect any change due to contamination or other causes.

STIS/CCD 11846

CCD Bias Monitor-Part 1

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 11844

CCD Dark Monitor Part 1

Monitor the darks for the STIS CCD.

FGS 11789

An Astrometric Calibration of Population II Distance Indicators

In 2002 HST produced a highly precise parallax for RR Lyrae. That measurement resulted in an absolute magnitude, M(V)= 0.61+/-0.11, a useful result, judged by the over ten refereed citations each year since. It is, however, unsatisfactory to have the direct, parallax-based, distance scale of Population II variables based on a single star. We propose, therefore, to obtain the parallaxes of four additional RR Lyrae stars and two Population II Cepheids, or W Vir stars. The Population II Cepheids lie with the RR Lyrae stars on a common K-band Period-Luminosity relation. Using these parallaxes to inform that relationship, we anticipate a zero-point error of 0.04 magnitude. This result should greatly strengthen confidence in the Population II distance scale and increase our understanding of RR Lyrae star and Pop II Cepheid astrophysics.

FGS 11788

The Architecture of Exoplanetary Systems

Are all planetary systems coplanar? Concordance cosmogony makes that prediction. It is, however, a prediction of extrasolar planetary system architecture as yet untested by direct observation for main sequence stars other than the Sun. To provide such a test, we propose to carry out FGS astrometric studies on four stars hosting seven companions. Our understanding of the planet formation process will grow as we match not only system architecture, but formed planet mass and true distance from the primary with host star characteristics for a wide variety of host stars and exoplanet masses.

We propose that a series of FGS astrometric observations with demonstrated 1 millisecond of arc per-observation precision can establish the degree of coplanarity and component true masses for four extrasolar systems: HD 202206 (brown dwarf+planet); HD 128311 (planet+planet), HD 160691 = mu Arae (planet+planet), and HD 222404AB = gamma Cephei (planet+star). In each case the companion is identified as such by assuming that the minimum mass is the actual mass. For the last target, a known stellar binary system, the companion orbit is stable only if coplanar with the AB binary orbit.

ACS/WFC3 11695

Searching for the Bottom of the Initial Mass Function

The measurement of the minimum mass of the IMF would provide a fundamental test of theories of star and planet formation. In a Cycle 13 program, we used ACS and ground-based near-IR imaging and spectroscopy to measure the IMF down to a completeness limit of 10 M_Jup (i~24) in a 800″x1000″ area in the southern subcluster of the Chamaeleon I star-forming region (2 Myr, 160 pc). There is no sign of a low-mass cutoff in this IMF measurement. To provide a better constraint on the minimum mass of the IMF, we propose to obtain ACS images of this field again and use the two ACS epochs to identify substellar cluster members down to the detection limit of the data (i~27) via their proper motions. In this way, we will improve the completeness limit of our IMF measurement to 3 M_Jup. In addition, to improve the number statistics of our measurement of the substellar IMF in Chamaeleon I, we propose to double the number of objects in the IMF sample by performing ACS imaging of a second field toward the northern subcluster.


EG And: Providing the Missing Link Required for Modelling Red Giant Mass-loss

For the majority of red giant stars the basic mass-loss processes at work are unknown. Indeed, for stars of spectral types between K0 III and M5-M6 III, much remains unknown about the regions above the visible photosphere and the transportation of the processed material outwards to the ISM. Eclipsing symbiotic binary systems, consisting of an evolved giant in orbit with a white dwarf, provide an opportunity to take advantage of the finite size of the hot component to probe different levels of the chromosphere and wind acceleration region in absorption. This provides spatially resolved thermal, ionisation and dynamic information on the wind which can then be compared against predictions of hydrodynamical stellar atmosphere codes. The symbiotic binary EG And can be considered as a rosetta stone for understanding the winds of these objects. The system is ideal on a number of counts for utilising the ultraviolet eclipse of the white dwarf (WD) component to probe, layer-by-layer, the thermal and dynamic conditions at the very base of the wind and chromosphere of the RG. This information is vital for constraining, testing and calibrating the new generation of cool giant wind+chromosphere models and is not possible to obtain for isolated RGs. This team has studied the UV eclipses of this system in depth and detail, however in order to definitively constrain the wind acceleration profile and identify the location of the temperature rise just above the photosphere we require 4 STIS E140M observations of EG And at specific orbital phases. We are also requesting a E230M observation of an isolated spectral standard, corresponding to the RG in the binary, which will help place the EG And results into the context of the general RG population from analysis of the MgII wind diagnostic lines.

ACS/WFC3 11669

The Origins of Short Gamma-Ray Bursts

During the past decade extraordinary progress has been made in determining the origin of long- duration gamma-ray bursts. It has been conclusively shown that these objects derive from the deaths of massive stars. Nonetheless, the origin of their observational cousins, short-duration gamma-ray bursts (SGRBs) remains a mystery. While SGRBs are widely thought to result from the inspiral of compact binaries, this is a conjecture. SGRBs have been found in elliptical galaxies, Abell Clusters, star-forming dwarfs and even an edge-on spiral. Whether they primarily result from an old population, a young population, or rapid evolution of binaries in globular clusters remains open.

Here we propose to employ two related sets of observations which may dramatically advance our understanding of short bursts. The first is a variant of a technique that we pioneered and used to great effect in elucidating the origins of long-duration bursts. We will examine a statistical sample of hosts and measure the degree to which SGRB locations trace the red or blue light of their hosts, and thus old or young stellar populations. This will allow us to study the demographics of the SGRB population in a manner largely free of the distance dependent selection effects which have so far bedeviled this field. In the second line of attack we will use two targets of opportunity to obtain extremely precise positions of up to two nearby bursts — one on a star-forming galaxy and the other on a elliptical. Observation of the star-formation galaxy could link at least some bursts directly to a young population; however, a discovery in later images of a globular cluster at the site of the explosion in an elliptical would provide revolutionary evidence that SGRBs are formed from compact binaries.

WFC3/IR/ACS 11647

A Deep Exploration of Classes of Long Period Variable Stars in M31

We propose a thrifty but information-packed investigation with WFC3/IR F160W and F110W providing crucial information about Long Period Variables in M31, at a level of detail that has recently allowed the discovery of new variable star classes in the Magellanic Clouds, a very different stellar population. These observations are buttressed by an extensive map of the same fields with ACS and WFPC2 exposures in F555W and F814W, and a massive ground-based imaging patrol producing well-sampled light curves for more than 400, 000 variable stars. Our primary goal is to collect sufficient NIR data in order to analyze and classify the huge number of long-period variables in our catalog (see below) through Period-Luminosity (P/L) diagrams. We will produce accurate P/L diagrams for both the bulge and a progression of locations throughout the disk of M31. These diagrams will be similar in quality to those currently in the Magellanic Clouds, with their lower metallicity, radically different star formation history, and larger spread in distance to the variables. M31 offers an excellent chance to study more typical disk populations, in a manner which might be extended to more distant galaxies where such variables are still visible, probing a much more evenly spread progenitor age distribution than cepheids (and perhaps useful as a distance scale alternative or cross-check). Our data will also provide a massive and unique color-magnitude dataset; we expect that this study will produce several important results, among them a better understanding of P/L and P/L-color relations for pulsating variables which are essential to the extragalactic distance ladder. We will view these variables at a common distance over a range of metallicities (eliminating the distance-error vs. metallicity ambiguity between the LMC and SMC), allow further insight into possible faint-variable mass-loss for higher metallicities, and in general produce a sample more typical of giant disk galaxies predominant in many studies.

ACS 11603

A Comprehensive Study of Dust Formation in Type II Supernovae with HST, Spitzer, and Gemini

The recent discovery of three extremely bright Type II SNe, (2007it, 2007oc, 2007od) gives us a unique opportunity to combine observations with HST, Spitzer and Gemini to study the little understood dust formation process in Type II SNe. Priority 1 Spitzer Cycle 5 and band 1 Gemini 2008A time has already been approved for this project. Since late-time Type II SNe are faint and tend to be in crowded fields, we need the high sensitivity and high spatial resolution of ACS and NICMOS/NIC2 for these observations. This project is motivated by the recent detection of large amounts of dust in high redshift galaxies. The dust in these high-z galaxies must come from young, massive stars so Type II SNe could be potential sources. The mechanism and the efficiency of dust condensation in Type II SN ejecta are not well understood, largely due to the lack of observational data. We plan to produce a unique dataset, combining spectroscopy and imaging in the visible, near- and mid-IR covering the key phase, 400-700 days after maximum when dust is known to form in the SN ejecta. Therefore, we are proposing for coordinated HST/NOAO observations (HST ACS, NICMOS/NIC2 & Gemini/GMOS and TReCS) which will be combined with our Spitzer Cycle 5 data to study these new bright SNe. The results of this program will place strong constraints on the formation of dust seen in young high redshift (z>5) galaxies.

STIS/CCD 11567

Boron Abundances in Rapidly Rotating Early-B Stars

Models of rotation in early-B stars predict that rotationally driven mixing should deplete surface boron abundances during the main-sequence lifetime of many stars. However, recent work has shown that many boron depleted stars are intrinsically slow rotators for which models predict no depletion should have occurred, while observations of nitrogen in some more rapidly rotating stars show less mixing than the models predict. Boron can provide unique information on the earliest stages of mixing in B stars, but previous surveys have been biased towards narrow-lined stars because of the difficulty in measuring boron abundances in rapidly rotating stars. The two targets observed as part of our Cycle 13 SNAP program 10175, just before STIS failed, demonstrate that it is possible to make useful boron abundance measurements for early-B stars with Vsin(i) above 100 km/s. We propose to extend that survey to a large enough sample of stars to allow statistically significant tests of models of rotational mixing in early-B stars.

WFC3/UVI 11565

A Search for Astrometric Companions to Very Low-Mass, Population II Stars

We propose to carry out a SNAPshot search for astrometric companions in a subsample of very low-mass, halo subdwarfs identified within 120 parsecs of the Sun. These ultra-cool M subdwarfs are local representatives of the lowest-mass H-burning objects from the Galactic Population II. The expected 3-4 astrometric doubles that will be discovered will be invaluable in that they will be the first systems from which gravitational masses of metal-poor stars at the bottom of the main sequence can be directly measured.

COS/FUV 11492

FUV Sensitivity

This activity confirms COS sensitivity versus wavelength over the entire observable spectrum for all FUV gratings and central wavelength settings. Obtain quick look sensitivity visit early in SMOV. Later, after wavelength calibration is verified, perform a precise-centering acquisition and observe an appropriate HST flux standard star (chosen from the HST prime standard and FASTEX lists) with the PSA. (A limited BOA characterization is obtained in Visit 13 using primary standard GD153.) No off aperture- center observations are performed in this activity (see COS32, program 11490, for off- center characterizations). Spectra will be obtained to meet a Poisson S/N criterion of ~30 per sensitivity extraction bin or higher; substantially higher S/N characterization will be utilized in routine Cycle 17 calibration.

COS 11486

COS FUV Target Acquisition Algorithm Verification

Verify the ability of the COS FSW to place an isolated point source at the center of the aperture, both for the BOA and PSA, using dispersed light from the object using the FUV gratings. The various options for target centering should be exercised and shown to work properly. This test is for acquisitions in dispersed-light mode only. This program is modeled from SMOV activity summary COS28.

This program should be executed two or more weeks after visit 12 of 11469, and after the SIAF update, so that we have confirmed that NUV imaging acquisitions work properly with the BOA.

COS 11476

COS NUV External Spectroscopic Performance – Part 1

The goal of this project is to measure the spectral resolution of absorption lines for each of the four COS NUV gratings. We will acquire science data at the central wavelength of each grating through both PSA and BOA apertures. We will also evaluate the effect of small pointing errors on the spectral resolution by acquiring additional spectra at spatially offset positions. The targets chosen for these observations have sharp absorption lines and will be either unresolved or marginally resolved at the COS resolution.

Our observations with the PSA will target the subdwarf B star Feige 48 (PG 1144+651). These observations will implement the following procedure: First, a target acquisition is performed to place the target at the center of the aperture. For each NUV grating we obtain moderately high S/N (~ 40 per resel counting statistics) observations at one central wavelength setting with the PSA. Next we repeat the sequence of observations at each of four additional positions, offset 0.25 arcseconds from the aperture center to form a diamond pattern. All of these observations will be performed in TIME-TAG mode with FLASH=YES, but with two differences: First, the summed exposure time for all four offset positions is equal to the exposure time of the central position. Second, the central position utilizes a four-position FP-split pattern (FP-POS=AUTO) while the offset positions are each split into two sub-exposures, one with FP-POS=3 and one with FP-POS=1. For one grating (G185M) and central wavelength (1850 A) we obtain a TIME-TAG exposure with FLASH=NO to verify the auto-wavecal capability of the NUV channel.

The observations with the BOA will be performed on the bright O subdwarf BD+75D325, a bright (M_V = 9.6) HST calibration standard. Here we obtain a single TIME-TAG exposure for each of the four NUV gratings with the object centered in the BOA to evaluate the spectral resolution in this mode. We aim for S/N = 20 in these observations.

The number of exposures in this program is somewhat larger than the number described in the Activity Summary, but is necessary to perform the intended tests of the COS spectral resolution.

This activity is SMOV program COS 16.


DATA REQUIREMENTS: Approximately 420 MB

DEPENDENCIES: Execute after verification based upon results of activity COS 15 (Internal NUV Wavelength Calibration)


COS 11472

COS NUV Dispersed-light Acquisition Algorithm Verification

Verify the ability of the COS FSW to place an isolated point source at the center of the aperture, both for the BOA and PSA, using dispersed light from the object using an NUV grating. The various options for target centering should be exercised and shown to work properly.

COS 11471

COS NUV Imaging Acquisition Algorithm Verification

Verify the ability of the COS FSW to place an isolated point source at the center of the aperture, both for the BOA and PSA, and for MIRRORA and MIRRORB. The various options for target centering should be exercised and shown to work properly. This test is for acquisitions in imaging mode only. Acquisitions using dispersed light are tested in separate SMOV activities.

ACS 11465

ACS CCD Monitoring and Calibration for WFC3

This program is a smaller version of our routine CCD monitoring program, designed to run throughout SMOV, after which our regular Cycle 17 CAL proposal will begin. This program obtains the bias and dark frames needed to generate reference files for calibrating science data, and allows us to monitor detector noise and the growth of hot pixels.

WFC3 11447

WFC3 IR Dark Current, Readnoise, and Background

This proposal obtains full-frame, four-amp readout images. Un-illuminated internals are taken at regularly spaced intervals throughout SMOV in order to assess and monitor readnoise and dark current (of both light-sensitive pixels and reference pixels), and bad (warm, hot, dead, variable) pixels. In addition, externals aimed at fields with sparse stellar density are taken to measure diffuse background light.

This program corresponds to WFC3-34.

WFC3 11446

WFC3 UVIS Dark Current, Readnoise, and CTE

This proposal obtains full-frame, four-amp readout bias and dark frames at regularly-spaced intervals throughout SMOV in order to assess and monitor dark current, bad (warm, hot, dead) pixels, and readnoise. In addition, a set of internals using the WFC3 calsystem are taken to provide a baseline CTE measurement. WFC3-33

STIS20 11402

STIS-20 NUV MAMA Dark Monitor

The STIS NUV-MAMA dark current is dominated by a phosphorescent glow from the detector window. Meta-stable states in this window are populated by cosmic ray impacts, which, days later, can be thermally excited to an unstable state from which they decay, emitting a UV photon. The equilibrium population of these meta-stable states is larger at lower temperatures; so warming up the detector from its cold safing will lead to a large, but temporary, increase in the dark current.

To monitor the decay of this glow, and to determine the equilibrium dark current for Cycle 17, four 1380s NUV-MAMA ACCUM mode darks should be taken each week during the SMOV period. Once the observed dark current has reached an approximate equilibrium with the mean detector temperature, the frequency of this monitor can be reduced to one pair of darks per week.

NIC2 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}.

NIC2/WFPC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3 0.8mJy and their mid-IR spectra have already provided the majority targets with spectroscopic redshifts {0.31 ULIRGs, as in the local Universe. {2} study the co-evolution of star formation and blackhole accretion by investigating the relations between the fraction of starburst/AGN measured from mid-IR spectra vs. HST morphologies, L{bol} and z. {3} obtain the current best estimates of the far-IR emission, thus L{bol} for this sample, and establish if the relative contribution of mid-to-far IR dust emission is correlated with morphology {resolved vs. unresolved}.


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


11979 – Loss of lock on FGS 1 occurred at 18:07:39 with recovery at 226/18:08:49. FGS 2 lost lock at 226/18:07:48 and recovered at 226/18:08:15.

Observations affected: COS 57 – 61, Proposal ID# 11472.

11982 – GSAcq(2,3,3)at 228/14:20:10 failed due to search radius limit exceeded(SRLEX) on FGS 2 and FGS 3.

Observations affected: ACS 59 – 62 Proposal ID# 11647, WFC3 109 Proposal ID# 11647.

11984 – GSAcq(2,1,1) scheduled at 229/05:23:31 – 05:31:02 failed to RGA Hold (gyro control) due to search radius limit exceeded on FGS-2.

Observations affected: WFC3 5,6 Proposal ID# 11905, STIS 1 Proposal ID# 11567.


18685-0 – Null genslews for proposal 11492 – slots 1 and 2 @ 226/16:30z



FGS GSAcq 21 19
FGS REAcq 21 21
OBAD with Maneuver 23 23
LOSS of LOCK 226/18:07:39z


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