Date: February 26th 2010

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  • Daily Report #5039 - 1 messages, 1 author http://groups google com/group/sci astro hubble/t/6038794a743da65f?hl=en
  • Daily Report #5040 - 1 messages, 1 author http://groups google com/group/sci astro hubble/t/b2fe605ea06d27ee?hl=en

============================================================================== TOPIC: Daily Report #5039

http://groups google com/group/sci astro hubble/t/6038794a743da65f?hl=en

== 1 of 1 == Date: Wed, Feb 24 2010 7:56 am From: "Cooper, Joe"

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5039

PERIOD COVERED: 5am February 23 - 5am February 24, 2010 (DOY 054/10:00z-055/10:00z)

OBSERVATIONS SCHEDULED

COS/NUV/FUV 11522

COS-GTO: Star Formation/Lyman-Alpha

A sample of 20 star-forming galaxies will be observed with COS G130M The galaxies were selected from the Kitt Peak International Spectroscopic Survey (KISSR) data release and cover a broad range of luminosity, oxygen abundance, and reddening The goal of the program is to characterize the Lyman-alpha properties and establish correlations with fundamental galaxy properties Each galaxy will be observed for one orbit

COS/NUV/FUV 11698

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

COS/NUV/FUV 11718

The Stellar Halos of Dwarf Galaxies

The metal-poor stellar halo is the oldest extended structure in the Galaxy Such halos are thought to form through hierarchical merging, and contain stars pulled from accreted subhalos The diffuse stellar halo therefore stores information about the prop reties of the accreted galaxies (i e , their orbits, stellar masses, and metallicities) It is therefore unsurprising that stellar halos have become a popular probe of the early epoch of galaxy formation

Almost all current work on stellar halos has focused on massive galaxies, however We propose to extend the work on stellar halos to much lower mass scales, by studying the halos of faint dwarf galaxies By taking halo studies into the dwarf galaxy regime, we can probe exceptionally small mass scales for the accreted halos At these mass scales the effects of reionization and supernova feedback have the largest impact on the galaxy population Stellar halos of dwarf galaxies are therefore a sensitive probe of the key processes needed to resolve the lack of substructure observed at low masses

We are requesting two far-field ACS pointings for the three closest isolated nearby dwarf irregular galaxies whose inner halos have already been mapped with the ACS Nearby Galaxy Survey Treasury These outer fields will allow us to trace the halo out to roughly half the virial radius, further than any previous study We will use the resulting distribution of halo stars (1) to unambiguously measure the structure of the stellar halo, with minimal contamination from the main galaxy; (2) to constrain the flattening of the stellar halo; (3) to measure the metallicity of halo stars as a function of radius; (4) to correlate any changes in halo profile with changes in metallicity The resulting data will constrain models of halo accretion and the epoch of reionization

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 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/CCD 11849

STIS CCD Hot Pixel Annealing

This purpose of this activity is to repair radiation induced hot pixel damage to the STIS CCD by warming the CCD to the ambient instrument temperature and annealing radiation-damaged pixels

Radiation damage creates hot pixels in the STIS CCD Detector Many of these hot pixels can be repaired by warming the CCD from its normal operating temperature near -83 deg C to the ambient instrument temperature (~ +5 deg C) for several hours The number of hot pixels repaired is a function of annealing temperature The effectiveness of the CCD hot pixel annealing process is assessed by measuring the dark current behavior before and after annealing and by searching for any window contamination effects

WFC3/ACS/UVIS 11684

The First Proper Motion Measurement for M31: Dynamics and Mass of the Local Group

We will perform observations to determine the proper motion of the Andromeda galaxy M31, which has been sought for almost a century without success While challenging, this measurement has now become possible due to the availability of existing deep ACS/WFC images of several M31 fields The requested second epoch images will yield the average shift of the M31 stars with respect to compact galaxies in the background Our observing strategy uses six different fields (three primary and three coordinated parallel) with two different instruments (ACS and WFC3) to provide a maximum handle on possible systematic effects The expected result will be sufficiently accurate to: (a) discriminate between different histories for the dynamics of the Local Group; (b) constrain the mass distribution of the Local Group; (c) determine the details of the expected future merger between M31 and the Milky Way; (d) infer the past interaction history between M31 and M33; (e) constrain the internal proper motion kinematics of the M31 spheroid, outer disk, and tidal stream; and (f) obtain a pilot estimate of the M31 distance through the method of rotational parallax

WFC3/IR 11591

Are Low-Luminosity Galaxies Responsible for Cosmic Reionization?

Our group has demonstrated that massive clusters, acting as powerful cosmic lenses, can constrain the abundance and properties of low-luminosity star-forming sources beyond z~6; such sources are thought to be responsible for ending cosmic reionization The large magnification possible in the critical regions of well-constrained clusters brings sources into view that lie at or beyond the limits of conventional exposures such as the UDF We have shown that the combination of HST and Spitzer is particularly effective in delivering the physical properties of these distant sources, constraining their mass, age and past star formation history Indirectly, we therefore gain a valuable glimpse to yet earlier epochs Recognizing the result (and limitations) of blank field surveys, we propose a systematic search through 10 lensing clusters with ACS/F814W and WFC3/[F110W+F160W] (in conjunction with existing deep IRAC data) Our goal is to measure with great accuracy the luminosity function at z~7 over a range of at least 3 magnitude, based on the identification of about 50 lensed galaxies at 6 5

WFC3/IR 11666

Chilly Pairs: A Search for the Latest-type Brown Dwarf Binaries and the Prototype Y Dwarf

We propose to use HST/NICMOS to image a sample of 27 of the nearest (< 20 pc) and lowest luminosity T-type brown dwarfs in order to identify and characterize new very low mass binary systems Only 3 late-type T dwarf binaries have been found to date, despite that fact that these systems are critical benchmarks for evolutionary and atmospheric models at the lowest masses They are also the most likely systems to harbor Y dwarf companions, an as yet unpopulated putative class of very cold (T < 600 K) brown dwarfs Our proposed program will more than double the number of T5-T9 dwarfs imaged at high resolution, with an anticipated yield of ~5 new binaries with initial characterization of component spectral types We will be able to probe separations sufficient to identify systems suitable for astrometric orbit and dynamical mass measurements We also expect one of our discoveries to contain the first Y-type brown dwarf Our proposed program complements and augments ongoing ground-based adaptive optics surveys and provides pathway science for JWST

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 11589

Hypervelocity Stars as Unique Probes of the Galactic Center and Outer Halo

We propose to obtain high-resolution images of 11 new hypervelocity stars in the Galactic halo in order to establish the first-epoch astrometric frame, as a part of a long-term program to measure precise proper motions in an absolute inertial frame The origin of these recently discovered stars with extremely large positive radial velocities, in excess of the escape speed from the Galaxy, is consistent only with being ejected from the deep potential well of the massive black hole at the Galactic center Reconstructing the full three-dimensional space motion of the hypervelocity stars, through astrometric proper motions, provides a unique opportunity to measure the shape and orientation of the triaxial dark matter halo The hypervelocity stars allow determination of the Galactic potential out to 120 kpc, independently of and at larger distances than is afforded by tidal streams of satellite galaxies such as the Sagittarius dSph galaxy Proper motions of the full set of hypervelocity stars will provide unique constraints on massive star formation in the environment of the Galactic center and on the history of stellar ejection by the supermassive black hole We request one orbit with WFC3 for each of the 11 hypervelocity stars to establish their current positions relative to background galaxies We request a repeated observation of these stars in Cycle 19, which will conclusively measure the astrometric proper motions

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)

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                  SCHEDULED SUCCESSFUL

FGS GSAcq 10 10 FGS REAcq 7 7 OBAD with Maneuver 7 7

SIGNIFICANT EVENTS: (None)

============================================================================== TOPIC: Daily Report #5040

http://groups google com/group/sci astro hubble/t/b2fe605ea06d27ee?hl=en

== 1 of 1 == Date: Thurs, Feb 25 2010 9:14 am From: "Cooper, Joe"

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5040

PERIOD COVERED: 5am February 24 - 5am February 25, 2010 (DOY 055/10:00z-056/10:00z)

OBSERVATIONS SCHEDULED

ACS/WFC 11995

CCD Daily Monitor (Part 2)

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 320 orbits (20 weeks) from 1 February 2010 to 20 June 2010

COS/NUV/FUV 11718

The Stellar Halos of Dwarf Galaxies

The metal-poor stellar halo is the oldest extended structure in the Galaxy Such halos are thought to form through hierarchical merging, and contain stars pulled from accreted subhalos The diffuse stellar halo therefore stores information about the prop reties of the accreted galaxies (i e , their orbits, stellar masses, and metallicities) It is therefore unsurprising that stellar halos have become a popular probe of the early epoch of galaxy formation

Almost all current work on stellar halos has focused on massive galaxies, however We propose to extend the work on stellar halos to much lower mass scales, by studying the halos of faint dwarf galaxies By taking halo studies into the dwarf galaxy regime, we can probe exceptionally small mass scales for the accreted halos At these mass scales the effects of reionization and supernova feedback have the largest impact on the galaxy population Stellar halos of dwarf galaxies are therefore a sensitive probe of the key processes needed to resolve the lack of substructure observed at low masses

We are requesting two far-field ACS pointings for the three closest isolated nearby dwarf irregular galaxies whose inner halos have already been mapped with the ACS Nearby Galaxy Survey Treasury These outer fields will allow us to trace the halo out to roughly half the virial radius, further than any previous study We will use the resulting distribution of halo stars (1) to unambiguously measure the structure of the stellar halo, with minimal contamination from the main galaxy; (2) to constrain the flattening of the stellar halo; (3) to measure the metallicity of halo stars as a function of radius; (4) to correlate any changes in halo profile with changes in metallicity The resulting data will constrain models of halo accretion and the epoch of reionization

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 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/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/ACS/UVIS/IR 11570

Narrowing in on the Hubble Constant and Dark Energy

A measurement of the Hubble constant to a precision of a few percent would be a powerful aid to the investigation of the nature of dark energy and a potent "end-to end" test of the present cosmological model In Cycle 15 we constructed a new streamlined distance ladder utilizing high- quality type Ia supernova data and observations of Cepheids with HST in the near-IR to minimize the dominant sources of systematic uncertainty in past measurements of the Hubble constant and reduce its total uncertainty to a little under 5% Here we propose to exploit this new route to reduce the remaining uncertainty by more than 30%, translating into an equal reduction in the uncertainty of the equation of state of dark energy We propose three sets of observations to reach this goal: a mosaic of NGC 4258 with WFC3 in F160W to triple its sample of long period Cepheids, WFC3/F160W observations of the 6 ideal SN Ia hosts to triple their samples of Cepheids, and observations of NGC 5584 the host of a new SN Ia, SN 2007af, to discover and measure its Cepheids and begin expanding the small set of SN Ia luminosity calibrations These observations would provide the bulk of a coordinated program aimed at making the measurement of the Hubble constant one of the leading constraints on dark energy

WFC3/IR 11189

Probing the Early Universe with GRBs

Cosmology is beginning to constrain the nature of the earliest stars and galaxies to form in the Universe, but direct observation of galaxies at z>6 remains highly challenging due to their scarcity, intrinsically small size, and high luminosity distance GRB afterglows, thanks to their extreme luminosities, offer the possibility of circumventing these normal constraints by providing redshifts and spectral information which couldn't be obtained through direct observation of the host galaxies themselves In addition, the association of GRBs with massive stars means that they are an indicator of star formation, and that their hosts are likely responsible for a large proportion of the ionizing radiation during that era Our collaboration is conducting a campaign to rapidly identify and study candidate very high redshift bursts, bringing to bear a network of 2, 4 and 8m telescopes with near-IR instrumentation Swift has proven capable of detecting faint, distant GRBs, and reporting accurate positions for many bursts in near real-time Here we propose to continue our HST program of targeting GRBs at z~6 and above HST is crucial to this endeavor, allowing us (a) to characterize the basic properties, such as luminosity and color, and in some cases morphologies, of the hosts, which is essential to understanding these primordial galaxies and their relationship to other galaxy populations; and (b) to monitor the late time afterglows and hence compare them to lower-z bursts and test the use of GRBs as standard candles

WFC3/IR 11719

A Calibration Database for Stellar Models of Asymptotic Giant Branch Stars

Studies of galaxy formation and evolution rely increasingly on the interpretation and modeling of near-infrared observations At these wavelengths, the brightest stars are intermediate mass asymptotic giant branch (AGB) stars These stars can contribute nearly 50% of the integrated luminosity at near infrared and even optical wavelengths, particularly for the younger stellar populations characteristic of high-redshift galaxies (z>1) AGB stars are also significant sources of dust and heavy elements Accurate modeling of AGB stars is therefore of the utmost importance

The primary limitation facing current models is the lack of useful calibration data Current models are tuned to match the properties of the AGB population in the Magellanic Clouds, and thus have only been calibrated in a very narrow range of sub-solar metallicities Preliminary observations already suggest that the models are overestimating AGB lifetimes by factors of 2-3 at lower metallicities At higher (solar) metallicities, there are no appropriate observations for calibrating the models

We propose a WFC3/IR SNAP survey of nearby galaxies to create a large database of AGB populations spanning the full range of metallicities and star formation histories Because of their intrinsically red colors and dusty circumstellar envelopes, tracking the numbers and bolometric fluxes of AGB stars requires the NIR observations we propose here The resulting observations of nearby galaxies with deep ACS imaging offer the opportunity to obtain large (100-1000's) complete samples of AGB stars at a single distance, in systems with well-constrained star formation histories and metallicities

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/UV 12019

After the Fall: Fading AGN in Post-starburst Galaxies

We propose joint Chandra and HST observations of an extraordinary sample of 12 massive post-starburst galaxies at z=0 4-0 8 that are in the short-lived evolution phase a few 100 Myr after the peak of merger-driven star formation and AGN activity We will use the data to measure X-ray luminosities, black hole masses, and accretion rates; and with the accurate "clocks" provided by post-starburst stellar populations, we will directly test theoretical models that predict a power-law decay in the AGN light curve We will also test whether star formation and black hole accretion shut down in lock-step, quantify whether the black holes transition to radiatively inefficient accretion states, and constrain the observational signatures of black hole mergers

WFC3/UVIS 11594

A WFC3 Grism Survey for Lyman Limit Absorption at z=2

We propose to conduct a spectroscopic survey of Lyman limit absorbers at redshifts 1 8 < z < 2 5, using WFC3 and the G280 grism This proposal intends to complete an approved Cycle 15 SNAP program (10878), which was cut short due to the ACS failure We have selected 64 quasars at 2 3 < z < 2 6 from the Sloan Digital Sky Survey Spectroscopic Quasar Sample, for which no BAL signature is found at the QSO redshift and no strong metal absorption lines are present at z

2 3 along the lines of sight The survey has three main observational goals First, we will determine the redshift frequency dn/dz of the LLS over the column density range 16 0 < log(NHI) < 20 3 cm^-2 Second, we will measure the column density frequency distribution f(N) for the partial Lyman limit systems (PLLS) over the column density range 16 0 < log(NHI) < 17 5 cm^-2 Third, we will identify those sightlines which could provide a measurement of the primordial D/H ratio By carrying out this survey, we can also help place meaningful constraints on two key quantities of cosmological relevance First, we will estimate the amount of metals in the LLS using the f(N), and ground based observations of metal line transitions Second, by determining f(N) of the PLLS, we can constrain the amplitude of the ionizing UV background at z~2 to a greater precision This survey is ideal for a snapshot observing program, because the on-object integration times are all well below 30 minutes, and follow-up observations from the ground require minimal telescope time due to the QSO sample being bright

WFC3/UVIS 11595

Turning Out the Light: A WFC3 Program to Image z>2 Damped Lyman Alpha Systems

We propose to directly image the star-forming regions of z>2 damped Lya systems (DLAs) using the WFC3/UVIS camera on the Hubble Space Telescope In contrast to all previous attempts to detect the galaxies giving rise to high redshift DLAs, we will use a novel technique that completely removes the glare of the background quasar Specifically, we will target quasar sightlines with multiple DLAs and use the higher redshift DLA as a ``blocking filter'' (via Lyman limit absorption) to eliminate all FUV emission from the quasar This will allow us to carry out a deep search for FUV emission from the lower redshift DLA, shortward of the Lyman limit of the higher redshift absorber The unique filter set and high spatial resolution afforded by WFC3/UVIS will then enable us to directly image the lower redshift DLA and thus estimate its size, star- formation rate and impact parameter from the QSO sightline We propose to observe a sample of 20 sightlines, selected primarily from the SDSS database, requiring a total of 40 HST orbits The observations will allow us to determine the first FUV luminosity function of high redshift DLA galaxies and to correlate the DLA galaxy properties with the ISM characteristics inferred from standard absorption-line analysis to significantly improve our understanding of the general DLA population

WFC3/UVIS 11786

HST Observations of Astrophysically Important Visual Binaries

This is a continuation of a project begun in Cycle 7 and continued up through Cycle 14 The program consists of annual FGS or WFPC2 observations of three visual binary stars that will yield fundamental astrophysical results, once their orbits and masses are determined In Cycle 17 we are changing WFPC2 to WFC3

Our targets are the following: (1) Procyon (P = 40 9 yr), for which our first WFPC2 images yielded an extremely accurate angular separation of the bright F star and its much fainter white- dwarf companion Combined with ground-based astrometry of the bright star, our observation significantly revised downward the derived masses, and brought Procyon A into much better agreement with theoretical evolutionary masses for the first time With the continued monitoring proposed here, we will obtain masses to an accuracy of better than 1%, providing a testbed for theories of both Sun-like stars and white dwarfs (2) G 107-70, a close double white dwarf (P = 18 5 yr) that promises to add two accurate masses to the tiny handful of white-dwarf masses that are directly known from dynamical measurements (3) Mu Cas (P = 20 8 yr), a famous nearby metal-deficient G dwarf for which accurate masses will lead to the stars' helium contents, with cosmological implications For all three stars, we will also be setting increasingly stringent limits on the presence of planetary-mass bodies in the systems

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 3x3 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

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                  SCHEDULED  SUCCESSFUL

FGS GSAcq 7 7 FGS REAcq 9 9 OBAD with Maneuver 4 4

SIGNIFICANT EVENTS: (None)

==============================================================================

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