Status Report

NASA Hubble Space Telescope Daily Report #4930

By SpaceRef Editor
September 18, 2009
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Continuing to Collect World Class Science

PERIOD COVERED: 5am September 14 – 5am September 15, 2009 (DOY 257/09:00z-258/09:00z)


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.

COS/FUV 11482

FUV Detector Dark

The purpose of this proposal is to measure the FUV detector dark rate by taking long science exposures with no light on the detector. The detector dark rate and spatial distribution of counts will be compared to pre-launch data in order to verify the nominal operation of the detector, and for use in the CalCOS calibration pipeline. Variations of count rate as a function of orbital position will be analyzed to find dependence of dark rate on proximity to the SAA.

This is SMOV Activity COS-24.

COS/FUV 11490

COS FUV External Spectroscopic Performance – Part 2

The goal of this activity is to verify the spatial resolution of COS in the FUV and to characterize the interdependence of the spatial and spectral resolution of the instrument in that wavelength band. By stepping the source along the cross-dispersion direction out to the edge of the PSA, we will be able to quantify the variation of the spatial profile of the source with off-axis position, both by measuring the shape and width of the profile and by measuring the amount of flux transmitted through the aperture as the source is stepped past the edge of the aperture. Aside from measuring the spatial resolution of COS spectra, this study will be particularly useful for understanding the contamination of sources near the targeted object in crowded stellar fields.

This test is ideally performed with a spatially unresolved point source with an emission line spectrum. Our observations with the PSA will target the symbiotic star LIN 358 in the Large Magellanic Cloud. This star produces little or no continuum in the FUV, but exhibits line emission from He II (particularly strong), C IV, N IV and N V. The individual lines are unresolved in FOS spectra of this object, but the lines within the C IV and N V doublets are well resolved from one another. This indicates that the emission lines in the COS observations are likely to be narrow (<~ 60 km/s). 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 FUV grating we obtain moderately high S/N (~ 30 per resel counting statistics) observations at one central wavelength setting with the PSA. Next we repeat the sequence of observations at each of five additional positions, with offsets of 0.25, 0.5, 1.0, 1.5, and 1.75 arcseconds in the cross-dispersion (Y) direction from the center of the aperture. The procedure is then repeated for five more POSTARGs offset in the negative cross-dispersion direction (-Y). This results in a total of 11 exposures with the G130M and G140L gratings. For observations with the G160M grating we include an additional set of 5 POSTARGs each along the positive (+X) and negative (-X) dispersion directions. The goal of these observations is to test variations in the shape and width of the profile along the dispersion direction, and to compare the results with those from the cross-dispersion direction. All of these observations will be performed in Time-Tag mode with Flash=Yes for all three FUV gratings, but with FP-POS set to the default value of 3. The observations with the BOA will be performed on the Galactic symbiotic star AG Draconis (M_V = 9.8). This object is a bright recurrent nova (period ~ 15 yrs) and a source of strong ultraviolet line emission. Here we obtain a single Time-Tag exposure for each of the four FUV gratings with the object centered in the BOA to evaluate the spatial resolution in this mode. We aim for S/N = 20 for the brightest emission line in each observation. 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 32. Implementation Method: Stored Commanding Data Requirements: Approximately 420 MB Dependencies: Execute after verification based upon results of Activity COS 30 (Internal FUV Wavelength Calibration) (SMOV Proposal 11488) Applicable SMOV Requirements: L.; L.; L. COS/FUV 11494 COS FUV High S/N Verification Collect data for a single central wavelength for each FUV grating in Time-Tag mode, using multiple FP-POS positions, in order to verify that high signal-to-noise spectra can be obtained. All spectra will have enough counts to permit standard reduction techniques to be used to obtain spectra with a signal-to-noise ratio of more than 30. 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. 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/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/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 11998 Determining the Rotational Phase of Comet 9P/Tempel 1 in Support of the StardustNExT Mission A primary objective of the StardustNExT mission is to image the crater created by NASA’s Deep Impact (DI) mission. The 12-year ground- and space-based DI observing campaign provided an exceptional data set for investigating the rotation of comet 9P/Tempel 1. The just-completed analysis shows that the spin period increased in a stepwise manner through the perihelia in 2000 and 2005, due to an outgassing of water from a southern jet. Our water-sublimation jet torque model has been moderately successful in predicting the integrated change in the nucleus longitude at the 2005 perihelion and beyond, and has been used to predict the rotation state at the planned Stardust-NExT encounter just after perihelion on 02/14/2011. We propose a 19-orbit Hubble program to perform light curve observations of 9P/Tempel 1 that will allow us to determine the time-of-arrival adjustment of the Stardust-NExT spacecraft trajectory that is needed to ensure that the spacecraft arrives at encounter with the (as yet unseen) artificial DI crater at the sub-spacecraft point and fully illuminated by the sun. The trajectory correction maneuver is in Feb 2010, and we need to know the nucleus rotation phase to a precision of 1% and the period to 10 sec by Jan 2010. HST is the only facility capable of obtaining the high-quality data necessary to determine the shape and phase of the rotational light curve. When combined with ground-based data 2-3 months later, we will achieve the required precision. 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. 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: 18701-0 – Null genslew for proposal 11487 – slot 2 @ 257/16:58z COMPLETED OPS NOTES: (None)

FGS GSAcq 04 04
FGS REAcq 12 12
OBAD with Maneuver 04 04


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