Status Report

NASA Hubble Space Telescope Daily Report #5022

By SpaceRef Editor
February 2, 2010
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Continuing to Collect World Class Science

PERIOD COVERED: 5am January 28 – 5am January 29, 2010 (DOY 028/10:00z-029/10:00z)


COS/FUV 11897

FUV Spectroscopic Sensitivity Monitoring

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

STIS/CC/MA 11608

How Far Does H2 Go: Constraining FUV Variability in the Gaseous Inner Holes of Protoplanetary Disks

By studying the innermost, planet-forming regions of circumstellar disks around low-mass pre-main sequence stars we can refine theories of planet formation and develop timescales for the evolution of disks and their planets. Spitzer infrared observations of T Tauri stars have given us an unprecedented look at dust evolution in young objects, particularly the transitional disks. However, despite this ground breaking progress in studying the dust in young disks, the relationship between the dust and gas properties in the inner disk remains essentially unknown. Using STIS on HST, we propose to quantify the variability of H2 emission originating within the inner holes of transitional disks and explore its implications on dust distribution and planet formation.

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/CCD/MA2 11568

A SNAPSHOT Survey of the Local Interstellar Medium: New NUV Observations of Stars with Archived FUV Observations

We propose to obtain high-resolution STIS E230H SNAP observations of MgII and FeII interstellar absorption lines toward stars within 100 parsecs that already have moderate or high-resolution far-UV (FUV), 900-1700 A, observations available in the MAST Archive. Fundamental properties, such as temperature, turbulence, ionization, abundances, and depletions of gas in the local interstellar medium (LISM) can be measured by coupling such observations. Due to the wide spectral range of STIS, observations to study nearby stars also contain important data about the LISM embedded within their spectra. However, unlocking this information from the intrinsically broad and often saturated FUV absorption lines of low-mass ions, (DI, CII, NI, OI), requires first understanding the kinematic structure of the gas along the line of sight. This can be achieved with high resolution spectra of high-mass ions, (FeII, MgII), which have narrow absorption lines, and can resolve each individual velocity component (interstellar cloud). By obtaining short (~10 minute) E230H observations of FeII and MgII, for stars that already have moderate or high- resolution FUV spectra, we can increase the sample of LISM measurements, and thereby expand our knowledge of the physical properties of the gas in our galactic neighborhood. STIS is the only instrument capable of obtaining the required high resolution data now or in the foreseeable future.

WFC3/ACS/IR 11677

Is 47 Tuc Young? Measuring its White Dwarf Cooling Age and Completing a Hubble Legacy

With this proposal we will firmly establish the age of 47 Tuc from its cooling white dwarfs. 47 Tuc is the nearest and least reddened of the metal-rich disk globular clusters. It is also the template used for studying the giant branches of nearby resolved galaxies. In addition, the age sensitive magnitude spread between the main sequence turnoff and horizontal branch is identical for 47 Tuc, two bulge globular clusters and the bulge field population. A precise relative age constraint for 47 Tuc, compared to the halo clusters M4 and NGC 6397, both of which we recently dated via white dwarf cooling, would therefore constrain when the bulge formed relative to the old halo globular clusters. Of particular interest is that with the higher quality ACS data on NGC 6397, we are now capable with the technique of white dwarf cooling of determining ages to an accuracy of +/-0.4 Gyrs at the 95% confidence level. Ages derived from the cluster turnoff are not currently capable of reaching this precision. The important role that 47 Tuc plays in galaxy formation studies, and as the metal-rich template for the globular clusters, makes the case for a white dwarf cooling age for this metal-rich cluster compelling.

Several recent analyses have suggested that 47 Tuc is more than 2 Gyrs younger than the Galactic halo. Others have suggested an age similar to that of the most metal poor globular clusters. The current situation is clearly uncertain and obviously a new approach to age dating this important cluster is required.

With the observations of 47 Tuc, this project will complete a legacy for HST. It will be the third globular cluster observed for white dwarf cooling; the three covering almost the full metallicity range of the cluster system. Unless JWST has its proposed bluer filters (700 and 900 nm) this science will not be possible perhaps for decades until a large optical telescope is again in space. Ages for globular clusters from the main sequence turnoff are less precise than those from white dwarf cooling making the science with the current proposal truly urgent.

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 11640

Lyman Alpha Imaging of Two Quasar Host Galaxies at z>6

We propose to image the Lyman Alpha emission line in two of the highest redshift quasar host galaxies (redshifts z=6.31 and 6.42) to map the amount and extent of star formation in the hosts and in their immediate environment. These observations are now possible for the first time, as UVIS on WFC3 (coincidentally) provides narrow-band filters at the right wavelengths. Circumstantial evidence (based on NIR, radio/millimeter and molecular gas measurements) suggests that these quasar hosts are undergoing intense ~1000 Msun/yr bursts of star formation over scales of ~5kpc (0.6″). Our program will provide (continuum-subtracted) images of the Lyman Alpha emission in the host which will in turn directly constrain the extent and magnitude of star formation in the host. In the case of the host galaxy of J1148+5251 (z=6.42) the Lyman Alpha emission will be compared to resolved imaging of the molecular gas phase (CO and [CII]) which in turn will yield critical constraints on the structure of the host galaxy and the conditions of the interstellar medium. The observations should also be sensitive enough to reveal potential companion galaxies (if the quasars are residing in major overdensities at these redshifts) and infall signatures in the immediate vicinity of the quasar. The narrow-band filters of UVIS/WFC3 provide the unique opportunity to study host/bulge formation at the end of cosmic reionization (less than 1Gyr after the Big Bang).

WFC3/UVIS 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.

WFC3/UVIS 11577

Opening New Windows on the Antennae with WFC3

We propose to use WFC3 to provide key observations of young star clusters in “The Antennae” (NGC4038/39). Of prime importance is the WFC3’s ability to push the limiting UV magnitude FIVE mag deeper than our previous WFPC2 observations. This corresponds to pushing the limiting cluster mass from ~10**5 to ~10**3 solar masses for cluster ages ~10**8 yrs. In addition, the much wider field of view of the WFC3 IR channel will allow us to map out both colliding disks rather than just the Overlap Region between them. This will be especially important for finding the youngest clusters that are still embedded in their placental cocoons. The extensive set of narrow-band filters will provide an effective means for determining the properties of shocks, which are believed to be a primary triggering mechanism for star formation. We will also use ACS in parallel with WFC3 to observe portions of both the northern and southern tails at no additional orbital cost. Finally, one additional primary WFC3 orbit will be used to supplement existing HST observations of the star-forming “dwarf” galaxy at the end of the southern tail. Hence, when completed we will have full UBVI + H_alpha coverage (or more for the main galaxy) of four different environments in the Antennae. In conjunction with the extensive multi- wavelength database we have collected (both HST and ground based) these observations will provide answers to fundamental questions such as: How do these clusters form and evolve? How is star formation triggered? How do star clusters affect the local and global ISM, and the evolution of the galaxy as a whole? The Antennae galaxies are the nearest example of a major disk–disk merger, and hence may represent our best chance for understanding how mergers form tremendous numbers of clusters and stars, both in the local universe and during galaxy assembly at high redshift.

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 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)


18808-0 – Null genslews for proposal 12053 – Slots 2 and 3 @ 028/1836z


FGS GSAcq 9 9
FGS REAcq 7 7
OBAD with Maneuver 6 6


SpaceRef staff editor.