NASA Hubble Space Telescope Daily Report # 4413
Notice: Due to the conversion of some ACS WFC or HRC observations into WFPC2, or NICMOS observations after the loss of ACS CCD science capability in January, there may be an occasional discrepancy between a proposal’s listed (and correct) instrument usage and the abstract that follows it.
HUBBLE SPACE TELESCOPE DAILY REPORT # 4413
– Continuing to collect World Class Science
PERIOD COVERED: UT July 26, 2007 (DOY 207)
OBSERVATIONS SCHEDULED
WFPC2 10583
Resolving the LMC Microlensing Puzzle: Where Are the Lensing Objects ? We are requesting 32 HST orbits to help ascertain the nature of the population that gives rise to the observed set of microlensing events towards the LMC. The SuperMACHO project is an ongoing ground-based survey on the CTIO 4m that has demonstrated the ability to detect LMC microlensing events in real-time via frame subtraction. The improvement in angular resolution and photometric accuracy available from HST will allow us to 1} confirm that the detected flux excursions arise from LMC source stars rather than extended objects {such as for background supernovae or AGN}, and 2} obtain reliable baseline flux measurements for the objects in their unlensed state. The latter measurement is important to resolve degeneracies between the event timescale and baseline flux, which will yield a tighter constraint on the microlensing optical depth. S/C 4974
TRTTEST
The Transient Response Test is for the periodic performance monitoring of the FGS 2R servo A mechanism.
WFPC2 10900
Optical polarimetry of PSR B0540-69 and its synchrotron nebula. Polarization measurements of pulsars and of their synchrotron nebulae are uniquely able to provide deep insights into the highly magnetized relativistic environment of young rotating neutron stars. Apart from the radio band, pulsar polarization is best measured in the optical, for the rare cases of detectable optical emission. One of the brightest pulsars together with Crab {PSR B0531+21} and Vela {PSR B0833-45}, for which optical polarization measurements support the newly developed two-pole caustic model {TPC}, is PSR B0540-69 in the Large Magellanic Clouds, often referred as the Crab Twin for their overall similarities in both age and energetics. Together with the Crab, PSR B0540-69 is also the only pulsar embedded in a synchrotron nebula visible at optical wavelengths. We plan to observe PSR B0540-69 and its compact nebula {4 arcsec diameter} with the Advanced Camera for Surveys {ACS} and the Wide Field Channel {WFC} detector using UV and visual polarization filters. Thanks to the superb angular resolution of ACS, these observations will allow us to spectacularly resolve the pulsar from its nebular background, providing the first firm measure of the pulsar polarization which will be crucial to assess, on a broader sample, the validity of the TPC model with respect to other pulsars magnetosphere models. These observations will also provide the first detailed polarization map of the nebula, including the jet and the torus seen in our previous WFPC2 images.
WFPC2 11079
Treasury Imaging of Star Forming Regions in the Local Group: Complementing the GALEX and NOAO Surveys
We propose to use WFPC2 to image the most interesting star-forming regions in the Local Group galaxies, to resolve their young stellar populations. We will use a set of filters including F170W, which is critical to detect and characterize the most massive stars, to whose hot temperatures colors at longer wavelengths are not sensitive. WFPC2’s field of view ideally matches the typical size of the star-forming regions, and its spatial resolution allows us to measure individual stars, given the proximity of these galaxies. The resulting H-R diagrams will enable studies of star- formation properties in these regions, which cover largely differing metallicities {a factor of 17, compared to the factor of 4 explored so far} and characteristics. The results will further our understanding of the star-formation process, of the interplay between massive stars and environment, the properties of dust, and will provide the key to interpret integrated measurements of star-formation indicators {UV, IR, Halpha} available for several hundreds more distant galaxies. Our recent deep surveys of these galaxies with GALEX {FUV, NUV} and ground-based imaging {UBVRI, Halpha, [OIII] and [SII]} provided the identification of the most relevant SF sites. In addition to our scientific analysis, we will provide catalogs of HST photometry in 6 bands, matched corollary ground-based data, and UV, Halpha and IR integrated measurements of the associations, for comparison of integrated star-formation indices to the resolved populations. We envisage an EPO component.
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:
#18116-0 TRT Test #15 @ 207/1625z
#18054-0 Preview KF Sun Vector Data via Telemetry Diags (Generic) @ 207/1626z
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FGS GSacq 9 9 FGS REacq 3 3 OBAD with Maneuver 28 28
SIGNIFICANT EVENTS:
The FGS-2R TRT test #15 was successfully completed today at 207/16:26z. Analysis and results will be presented at the next GSAWG meeting.
