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The Center of the Core-Cusp Globular Cluster M15: CFHT and HST Observations, ALLFRAME Reductions
Stetson, Peter B.
The central brightness cusps seen in some globular clusters are thought to be the relics of a gravothermal core collapse that occurred in the clusters' past. Recent observations show that the centers of such clusters are bluer than their outskirts, indicating that the stellar populations there are somehow different than those farther out, presumab…
Removing Cosmic-Ray Hits from Multi-Orbit HST Wide Field Camera Images
Windhorst, Rogier A.; Franklin, Barbara E.; Neuschaefer, Lyman W.
We present an optimized algorithm that removes cosmic rays ("CRs") from multi-orbit HST Wide Field/Planetary Camera ("WF/PC") images. It computes the image noise in every iteration from the WF/PC CCD equation. This includes all known sources of random and systematic calibration errors. We test this algorithm on WF/PC stacks of 2-12 orbits as a fun…
The HST Quasar Absorption Line Key Project VIII. CCD Imaging of Hubble Space Telescope Quasar Fields
Maoz, Dan; Schneider, Donald P.; Sargent, W. L. W. +4 more
We present an analysis of CCD images of more than 100 quasars; many of the objects have been or will be observed in the HST Key Project Quasar Absorption Line Survey. The data set consists of B, g, and i photometry of 117 quasars and deeper g (limiting magnitude of ~22) images of 101 quasar fields. Positions accurate to ~1", measured with the Spac…
Astrometry with Hubble Space Telescope Fine Guidance Sensor Number 3: Position Mode Stability and Precision
Benedict, G. F.; Franz, O. G.; Hemenway, P. D. +11 more
We report results from a test exploring the long- and short-term astrometric stability of Hubble Space Telescope Fine Guidance Sensor #3. A test field was observed 40 times over 522 days to determine the precision and accuracy of FGS astrometry and to measure the character and magnitude of possible secular scale changes. We examine the astrometric…
Correlated Optical and Radio Structure in the QSO 1302-102
Hutchings, J. B.; Morris, S. C.; Lister, M. L. +1 more
We present new optical imaging in two broad-band colors ofthe z=0.29 bright QSO 1302-102, obtained with the Wide Field Camera of the Hubble Space Telescope. We have performed deconvolution on the HST data, previously published CFHT HRCam data, and the combined data. The structure and brightness are measured of an extended knot 2.3 arcsec from the …
HST Imaging of the Large Magellanic Cloud: The Field Star Population near 30 Doradus
Forbes, Duncan A.; Elson, Rebecca A. W.; Gilmore, Gerard F.
We present deep color-magnitude diagrams for two fields in the Large Magellanic Cloud, located about 6 arcminutes from 30 Doradus. The data are from images taken with the Hubble Space Telescope's Wide Field Camera, as part of the Medium Deep Survey Key Project. We describe a procedure for measuring stellar magnitudes in relatively crowded HST imag…
Geometry of the Hubble Space Telescope Wide Field/Planetary Camera Field
Gould, Andrew; Yanny, Brian
We present a solution for the relative positions and orientations of the four CCD chips on the Hubble Space Telescope (HST) Planetary Camera (PC). An accurate solution is required when matching HST images with ground-based images or with one another. The solution is accurate to about 2/3 PC pixel or about 0.03", a 10-fold improvement over the best…
The Effect of Double Stars on the Guiding System of the Hubble Space Telescope
Hershey, John L.; Bely, Pierre Y.
The interferometric system used for guidance of HST is sensitive to close binaries. Before the launch of HST it was believed that up to 25% of all guide star pairs would lead to guidance failure due to duplicity. After more than 3 years of operation the actual failure rate ascribable to duplicity is estimated to be just below 1%. A computer simula…
The UV Polarization of X-Ray Binary Systems Observed with the Hubble Space Telescope
Wolinski, Karen
The High-Speed Photometer (HSP) was one of the four axial instruments on the Hubble Space Telescope (HST) from April, 1990 to December, 1993. We used this instrument to observe the X-ray binary systems HD 153919, Vela XR-1 and Cyg XR-1 both photometrically and polarimetrically in the UV. The photometric and polarimetric light curves of each target…