Status Report

NASA Hubble Space Telescope Daily Report #4793

By SpaceRef Editor
February 21, 2009
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Continuing to collect World Class Science

PERIOD COVERED: 5am February 17 – 5am February 18, 2009 (DOY 048/1000z-049/1000z)


ACS/SBC 11984

Observing Saturn’s High Latitude Polar Auroras

Planetary auroral emissions are critical indicators of how the magnetospheres of the planets work. Recently, a new component of Saturn’s auroral emissions, i.e. high latitude auroras inside the main auroral oval, have been observed by the Cassini spacecraft during otherwise quiet auroral conditions. Such high latitude auroras are of immense interest since they occur on magnetic flux tubes connected to a region that is key to the overall dynamics of the system, the magnetotail, and where if conventional theories regarding Saturn’s magnetosphere are correct there should not be any auroras. These faint auroral emissions have not been previously observed by the Hubble Space Telescope (HST). However, the unique oblique viewing geometry afforded during early 2009 due to Saturn’s orbital longitude will result in the apparent brightening of these polar emissions due to the limb-brightening effect, with the result that they may be observable by HST for the first ever time. In addition, at this time the Cassini spacecraft will be in a high latitude orbit, with a trajectory that will take it through these magnetic flux tubes, providing essential simultaneous in situ data. This is the last time Cassini will be in such an orbit during its mission as currently scheduled and HST is the only instrument capable of obtaining sustained long-term observations of Saturn’s auroras. These observations will address the following: Does Saturn exhibit high latitude UV auroras observable by HST? Where do these auroras occur, and at what altitude? How do these auroras behave over time? How variable are they? Are they periodic? How do they behave with respect to other auroral components? What processes drive these auroras?

Are these auroras generated by processes internal to the magnetosphere or are they driven by the solar wind? How do the infrared (IR) auroras relate to the ultraviolet (UV) auroras?

FGS 11706

The Parallax of the Planet Host Star XO-3

We will use HST+FGS to measure the parallax of the transiting planet host star XO-3. The resulting accurate distance measurement will provide the most accurate radius determination to date for this massive extrasolar planet (XO-3b), allowing us to critically test current giant extrasolar planet structure models. These observations will also constrain the amount of heating that may be produced inside XO-3b by tides raised on the planet as it moves through its 3.2 d eccentric (e ~ 0.22) orbit.

WFPC2 11796

WFPC2 Cycle 16 Decontaminations and Associated Observations

This proposal is for the WFPC2 decons. Also included are instrument monitors tied to decons: photometric stability check, focus monitor, pre- and post-decon internals (bias, intflats, kspots, & darks), UV throughput check, VISFLAT sweep, and internal UV flat check.

WFPC2 11944

Binaries at the Extremes of the H-R Diagram

We propose to use HST/Fine Guidance Sensor 1r to survey for binaries among some of the most massive, least massive, and oldest stars in our part of the Galaxy. FGS allows us to spatially resolve binary systems that are too faint to observe using ground-based, speckle or optical long baseline interferometry, and too close to resolve with AO. We propose a SNAP-style program of single orbit FGS TRANS mode observations of very massive stars in the cluster NGC 3603, luminous blue variables, nearby low mass main sequence stars, cool subdwarf stars, and white dwarfs. These observations will help us to (1) identify systems suitable for follow up studies for mass determination, (2) study the role of binaries in stellar birth and in advanced evolutionary states, (3) explore the fundamental properties of stars near the main sequence-brown dwarf boundary, (4) understand the role of binaries for X-ray bright systems, (5) find binaries among ancient and nearby subdwarf stars, and (6) help calibrate the white dwarf mass – radius relation.

WFPC2 11966

The Recent Star Formation History of SINGS Galaxies

The Spitzer Legacy project SINGS provided a unique view of the current state of star formation and dust in a sample of galaxies of all Hubble types. This multi-wavelength view allowed the team to create current star formation diagnostics that are independent of the dust content and increased our understanding of the dust in galaxies. Even so, using the SINGS data alone we can only make rough estimates of the recent star formation history of these galaxies. The lack of high resolution observations (especially U-band and H-alpha) means that it is impossible to estimate the ages of young clusters. In addition, the low resolution of the Spitzer and ground-based observations means that what appear to be individual Spitzer sources can actually be composed of many individual clusters with varying ages. We need to know the ages, star formation histories, and extinction of these individual clusters to understand how these clusters form and age and thus influence the evolution of the galaxy. In this proposal we address this missing area of SINGS by obtaining high-resolution WFPC2 UBVI & H-alpha observations to not only accurately locate and determine the ages of the young stellar clusters in the actively star forming SINGS galaxies but to also address a variety of other scientific issues. Over 500 HST orbits and 500 hours of Spitzter observing time have been dedicated to observations of the SINGS sample. But the HST observations have not been systematic. By adding a relatively small fraction of this time for these requested observations, we will greatly enhance the legacy value of the SINGS observations by creating a uniform high resolution multi-wavelength HST archive that matches the quality of the lower resolution SINGS archive.

WFPC2 11989

The Integral Sign Galaxy

We will observe the unusual warped disk galaxy known as the Integral Sign Galaxy, UGC 3697, with a small two-position WFPC2 mosaic. Observations will be obtained in three broad band filters and the resulting image will be released on the 19th anniversary of the launch of the Hubble Space Telescope on ~April 24, 2009. Multidrizzled mosaics will be made available through the archive.


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


11678 – GSAcq(1,3,3) Loss of Lock while HST guiding under two FGSs @ 048/1100z

Observations possibly affected: WFPC 53 & 54, Proposal ID# 11989

11679 – REAcq(1,3,3) fails to Gyro Control, V1 error was too large to correct @ 048/1404z

Observations affected: WFPC 57 & 58, Proposal ID# 11989.

11680 – REAcq(1,3,3) failed to RGA Hold due to Stop Flag on FGS-1 @ 048/1534z

Observations affected: WFPC 59 and 60, Proposal ID# 11989

11681 – REAcq (1,3,3) failed to RGA Hold due to QF1STOPF flag on FGS-1 @ 048/1848z

Observations affected: WFPC 63 & 64, Proposal ID# 11989.

11682 – REAcq(1,3,3) fails to Gyro Control, V1 error was too large to correct @ 048/2047z

Observations affected: WFPC 65 & 66, Proposal ID# 11989

11683 – REAcq (1,3,3) failed to RGA Hold due to QF1STOPF flag on FGS-1 @ 048/2306z

Observations affected: WFPC 67 & 68, Proposal ID# 11989



                        SCHEDULED      SUCCESSFUL      FAILURE TIMES

FGS GSacq               07                 07
FGS REacq               08                 03
OBAD with Maneuver      30                 30
LOSS of LOCK                                             048/1100z


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