Status Report

NASA Hubble Space Telescope Daily Report #4913

By SpaceRef Editor
August 25, 2009
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HUBBLE SPACE TELESCOPE DAILY REPORT #4913

PERIOD COVERED: 5am August 19 – 5am August 20, 2009 (DOY 231/09:00z-232/09:00z)

OBSERVATIONS SCHEDULED

ACS/WFC3 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.

FGS 11874

Monitoring FGS2R2 S-Curves after SMOV4

This proposal satisfies the near-term requirement associated with SMOV4 activity OTA/FGS-10, as well as the long term Cycle 17 requirement to monitor the post-SM4 evolution of the FGS2R2 S-curves stability during its first year on orbit. The S-curves will be obtained from Trans mode observations of stars (point sources) at several locations in the FGS2R2 FOV in order to monitor both global and differential (i.e., field-dependent) changes. At each location, both F583W and PUPIL S-curves will be obtained. Stars in the M35 cluster will be used for this proposal since the field lies very near the ecliptic and can therefore be observed by HST at two Orients from August to May.

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.

STIS/CCD 11844

CCD Dark Monitor Part 1

Monitor the darks for the STIS CCD.

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 11852

STIS CCD Spectroscopic Flats C17

Obtain pixel-to-pixel lamp flat fields for the STIS CCD in spectroscopic mode.

STIS/CCD/MA1/MA2 11690

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.

WFC3 11428

D2 Calibration Lamp Test

This proposal verifies the health and performance of the calsystem deuterium lamp and assesses the status of the major UV filters by taking a full set of internal flatfields. A total of three nominal and one short exposure are obtained for each filter in order to establish an initial baseline of flatfield data as well as to confirm lamp repeatability and provide a contamination check. Additional iterations of D2 internal flatfields will be taken as part of WFC-19, UVIS Internal Flats (proposal 11432).

This proposal corresponds to SMOV ID WFC3-15. It should not be run until after the successful completion of WFC-06, the UVIS detector functional test (proposal 11419) and WFC-11, the initial UVIS alignment (proposal 11424).

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

WFC3/ACS/UVI 11360

Star Formation in Nearby Galaxies

Star formation is a fundamental astrophysical process; it controls phenomena ranging from the evolution of galaxies and nucleosynthesis to the origins of planetary systems and abodes for life. The WFC3, optimized at both UV and IR wavelengths and equipped with an extensive array of narrow-band filters, brings unique capabilities to this area of study. The WFC3 Scientific Oversight Committee (SOC) proposes an integrated program on star formation in the nearby universe which will fully exploit these new abilities. Our targets range from the well-resolved R136 in 30 Dor in the LMC (the nearest super star cluster) and M82 (the nearest starbursting galaxy) to about half a dozen other nearby galaxies that sample a wide range of star-formation rates and environments. Our program consists of broad band multiwavelength imaging over the entire range from the UV to the near-IR, aimed at studying the ages and metallicities of stellar populations, revealing young stars that are still hidden by dust at optical wavelengths, and showing the integrated properties of star clusters. Narrow-band imaging of the same environments will allow us to measure star-formation rates, gas pressure, chemical abundances, extinction, and shock morphologies. The primary scientific issues to be addressed are: (1) What triggers star formation? (2) How do the properties of star-forming regions vary among different types of galaxies and environments of different gas densities and compositions? (3) How do these different environments affect the history of star formation? (4) Is the stellar initial mass function universal or determined by local conditions?

WFC3/IR 11915

IR Internal Flat Fields

This program is the same as 11433 (SMOV) and depends on the completion of the IR initial alignment (program 11425). This version contains three instances of 37 internal orbits; to be scheduled early, middle, and near the end of Cycle 17, in order to use the entire 110-orbit allocation.

In this test, we will study the stability and structure of the IR channel flat field images through all filter elements in the WFC3-IR channel. Flats will be monitored, i.e. to capture any temporal trends in the flat fields, and delta flats produced. High signal observations will provide a map of the pixel-to-pixel flat field structure, as well as identify the positions of any dust particles.

WFC3/IR 11937

IR Grism Wavelength Calibration

This program will determine the wavelength calibration for the IR G102 and G141 grisms as a function of spatial position within the field of view. The planetary nebula Vy2-2 will be observed in a 9-point pattern in the IR field of view, which will provide FoV-dependent dispersion maps for the G102 and G141 grisms.

WFC3/UVI 11656

A Comprehensive Survey of Neptune’s Small Moons and Faint Rings

We will use a subarray of the WFC3/UVIS to study the inner rings, arcs and moons of Neptune with a sensitivity that exceeds that achieved by any previous observations, including Voyager 2 during its 1989 flyby. Our study will reveal any inner moons down to V magnitude 25, corresponding to a radius ~ 20 km (assuming 9% albedo), to address a peculiar, apparent truncation in the size distribution of inner moons and to look for the “shepherds” and source bodies for Neptune’s dusty rings. (For comparison, the radius of Neptune’s smallest known regular moon, Naiad, is ~ 33 km.) Monitoring of the arcs at fine resolution and sensitivity will reveal their ongoing evolution more clearly and will enable us to assess the role of Galatea, whose resonant perturbations are widely believed to confine the arcs. Our study will also reveal any broad, faint rings with optical depth ~ 10^-6, comparable to those now known to encircle all of the other giant planets.

WFC3/UVI 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).

WFC3/UVI 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.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11985 – GSAcq(1,2,1) scheduled at 231/08:19:50 – 08:27:01 had resulted in fine lock backup (2,0,2) using FGS-2 due to (QF1STOPF) stop flag indication on FGS-1.

Observations possibly affected, STIS 42 Proposal ID# 11567.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)


SCHEDULED SUCCESSFUL

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

SIGNIFICANT EVENTS: (None)

SpaceRef staff editor.