Status Report

NASA Hubble Space Telescope Daily Report #4932

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

PERIOD COVERED: 5am September 16 – 5am September 17, 2009 (DOY 259/09:00z-260/09:00z)


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 11997

FUV Internal/External Wavelength Scale Monitor

This program monitors the offsets between the wavelength scale set by the internal wavecal versus that defined by absorption lines in external targets. This is accomplished by observing two external targets in the SMC: SK191 with G130M and G160M and Cl* NGC 330 ROB B37 with G140L (SK191 is too bright to be observed with G140L). The cenwaves observed in this program are a subset of the ones used during Cycle 17. Observing all cenwaves would require a considerably larger number of orbits. Constraints on scheduling of each target are placed so that each target is observed once every ~2-3 months. Observing the two targets every month would also require a considerably larger number of orbits.

COS/NUV 11896

NUV Spectroscopic Sensitivity Monitoring

The purpose of this proposal is to monitor sensitivity of each NUV grating mode to detect any changes due to contamination or other causes.


Dynamics in the Atmosphere of the Evaporating Planet HD189733b

With HST/STIS, we detected and characterized the upper atmosphere of the extrasolar planet HD209458b, showing that the planet must be evaporating at a rate of ~10^10 g/s in a “blow-off” mechanism.

More recently, using ACS we concluded that HD189733b is also evaporating. However, because of the low resolution of the ACS prism spectroscopy, the escape rate and mechanism are still to be determined. This is one of the prime objectives of the present proposal.

COS observations of the absorption line profile with 15 km/s resolution will allow us to probe the dynamics of the escaping gas, and therefore to determine the escape rate. Simultaneous observations of the transit depth and spectral shape in several important lines (not only HI, but also OI, CII and possibly NI) will constrain the escape mechanism and allow us to distinguish between several scenarios. The results will enlighten the physical phenomenons at work in the exosphere of these extrasolar planets, and provide new constraints for the modeling of the evaporation of hot-Jupiters.

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.

WFC3/ACS/IR 11600

Star Formation, Extinction, and Metallicity at 0.7< z<1.5: H-Alpha Fluxes and Sizes from a Grism Survey of GOODS-N The global star formation rate (SFR) is ~10x higher at z=1 than today. This could be due to drastically elevated SFR in some fraction of galaxies, such as mergers with central bursts, or a higher SFR across the board. Either means that the conditions in z=1 star forming galaxies could be quite different from local objects. The next step beyond measuring the global SFR is to determine the dependence of SFR, obscuration, metallicity, and size of the star-forming region on galaxy mass and redshift. However, SFR indicators at z=1 typically apply local calibrations for UV, [O II] and far-IR, and do not agree with each other on a galaxy-by-galaxy basis. Extinction, metallicity, and dust properties cause uncontrolled offsets in SFR calibrations. The great missing link is Balmer H-alpha, the most sensitive probe of SFR. We propose a slitless WFC3/G141 IR grism survey of GOODS-N, at 2 orbits/pointing. It will detect Ha+[N II] emission from 0.7 < z < 1.5, to L(Ha) = 1.7 x 10^41 erg/sec at z=1, measuring H-alpha fluxes and sizes for > 600 galaxies, and a small number of higher-redshift emitters. This will produce: an emission-line redshift survey unbiased by magnitude and color selection; star formation rates as a function of galaxy properties, e.g. stellar mass and morphology/mergers measured by ACS; comparisons of SFRs from H-alpha to UV and far-IR indicators; calibrations of line ratios of H-alpha to important nebular lines such as [O II] and H-beta, measuring variations in metallicity and extinction and their effect on SFR estimates; and the first measurement of scale lengths of the H-alpha emitting, star-forming region in a large sample of z~1 sources.

WFC3/UVIS 11650

Mutual Orbits, Colors, Masses, and Bulk Densities of 3 Cold Classical Trans-Neptunian Binaries

Many Trans-Neptunian Objects (TNOs) have been found to be binary or multiple systems. As in other astrophysical settings, Trans-Neptunian Binaries (TNBs) offer uniquely valuable information. Their mutual orbits allow the direct determination of their system masses, perhaps the most fundamental physical quantity of any astronomical object. Their frequency of occurrence and dynamical characteristics provide clues to formation conditions and evolution scenarios affecting both the binaries and their single neighbors. Combining masses with sizes, bulk densities can be measured. Densities constrain bulk composition and internal structure, key clues to TNO origins and evolution over time. Several TNB bulk densities have been determined, hinting at interesting trends. But none of them belongs to the Cold Classical sub- population, the one group of TNOs with demonstrably distinct physical characteristics. Two top-priority Spitzer programs will soon observe and measure the sizes of 3 Cold Classical TNBs. This proposal seeks to determine the mutual orbits and thus masses of these systems, enabling computation of their densities.

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 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/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.


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

HSTARS: (None)



FGS GSAcq 9 9
FGS REAcq 8 8
OBAD with Maneuver 8 8


SpaceRef staff editor.