We are carrying out a comprehensive multi-wavelength study of dwarfs galaxies in the Local Volume... more We are carrying out a comprehensive multi-wavelength study of dwarfs galaxies in the Local Volume (< 5 Mpc), many of which were discovered only recently. In addition to ground-based observations for the determination of global integrated properties, of structural parameters, and of the H I content we are using a 200-orbit HST snapshot survey to measure distances to the dwarf
There are over 250 active spacecraft in the geosynchronous Earth orbit (GEO) regime, with another... more There are over 250 active spacecraft in the geosynchronous Earth orbit (GEO) regime, with another 500 inactive or debris pieces in the public catalog. Their orbits are primarily perturbed by gravitational effects from the Earth, Moon, and Sun, with inclination increasing from zero degrees to 15 degrees and back to zero over a 54 year period. We will review the dynamics of objects at GEO, and then show results from an optical survey for faint GEO debris with the University of Michigan's Curtis-Schmidt telescope at Cerro Tololo. Recently the CTIO 0.9-m was used to follow-up debris discoveries made with the Schmidt, and determine orbits and colors. Faint GEO debris has a very different angular rate and orbital distribution than bright debris. The consensus is that these objects have high area-to-mass (A/M) and their orbits are significantly perturbed by solar radiation. This is a classic problem of applied astronomy: using modern methods of imaging and astrometry to measure the di...
Monthly Notices of the Royal Astronomical Society, 2001
We present HST/WFPC2 observations of UGC 4483, an irregular galaxy in the M81/NGC 2403 complex. S... more We present HST/WFPC2 observations of UGC 4483, an irregular galaxy in the M81/NGC 2403 complex. Stellar photometry was carried out with HSTphot, and is complete to V~=26.0 and I~=24.7. We measure the red giant branch tip at I=23.56+/-0.10, and calculate a distance modulus of mu0=27.53+/-0.12 (corresponding to a distance of 3.2+/-0.2Mpc), placing UGC 4483 within the NGC 2403 subgroup. We were able to measure properties of a previously known young star cluster in UGC 4483, finding integrated magnitudes of V=18.66+/-0.21 and I=18.54+/-0.10 for the stellar contribution (integrated light minus Halpha and [Oiii] contribution), corresponding to an age of ~10-15Myr and an initial mass of ~104Msolar. This is consistent with the properties of the cluster's brightest stars, which were resolved in the data for the first time. Finally, a numerical analysis of the galaxy's stellar content yields a roughly constant star formation rate of 1.3×10-3Msolaryr-1 and mean metallicity of [Fe/H]=-1.3dex from 15Gyr ago to the present.
... DEPENDENCE OF KINEMATICS ON ABUNDANCE JOHN E. NORRIS AND KC FREEMAN Mount ... 1290 Sauverny, ... more ... DEPENDENCE OF KINEMATICS ON ABUNDANCE JOHN E. NORRIS AND KC FREEMAN Mount ... 1290 Sauverny, Switzerland; michel.mayor@obs.unige.ch AND PATRICk SEITZER Department ... observed strong s-process element enhancement) intermediate-to low-mass ones ...
We are carrying out a comprehensive multi-wavelength study of dwarfs galaxies in the Local Volume... more We are carrying out a comprehensive multi-wavelength study of dwarfs galaxies in the Local Volume (&amp;lt; 5 Mpc), many of which were discovered only recently. In addition to ground-based observations for the determination of global integrated properties, of structural parameters, and of the H I content we are using a 200-orbit HST snapshot survey to measure distances to the dwarf
We are carrying out a comprehensive multi-wavelength study of dwarfs galaxies in the Local Volume... more We are carrying out a comprehensive multi-wavelength study of dwarfs galaxies in the Local Volume (< 5 Mpc), many of which were discovered only recently. In addition to ground-based observations for the determination of global integrated properties, of structural parameters, and of the H I content we are using a 200-orbit HST snapshot survey to measure distances to the dwarf
There are over 250 active spacecraft in the geosynchronous Earth orbit (GEO) regime, with another... more There are over 250 active spacecraft in the geosynchronous Earth orbit (GEO) regime, with another 500 inactive or debris pieces in the public catalog. Their orbits are primarily perturbed by gravitational effects from the Earth, Moon, and Sun, with inclination increasing from zero degrees to 15 degrees and back to zero over a 54 year period. We will review the dynamics of objects at GEO, and then show results from an optical survey for faint GEO debris with the University of Michigan's Curtis-Schmidt telescope at Cerro Tololo. Recently the CTIO 0.9-m was used to follow-up debris discoveries made with the Schmidt, and determine orbits and colors. Faint GEO debris has a very different angular rate and orbital distribution than bright debris. The consensus is that these objects have high area-to-mass (A/M) and their orbits are significantly perturbed by solar radiation. This is a classic problem of applied astronomy: using modern methods of imaging and astrometry to measure the di...
Monthly Notices of the Royal Astronomical Society, 2001
We present HST/WFPC2 observations of UGC 4483, an irregular galaxy in the M81/NGC 2403 complex. S... more We present HST/WFPC2 observations of UGC 4483, an irregular galaxy in the M81/NGC 2403 complex. Stellar photometry was carried out with HSTphot, and is complete to V~=26.0 and I~=24.7. We measure the red giant branch tip at I=23.56+/-0.10, and calculate a distance modulus of mu0=27.53+/-0.12 (corresponding to a distance of 3.2+/-0.2Mpc), placing UGC 4483 within the NGC 2403 subgroup. We were able to measure properties of a previously known young star cluster in UGC 4483, finding integrated magnitudes of V=18.66+/-0.21 and I=18.54+/-0.10 for the stellar contribution (integrated light minus Halpha and [Oiii] contribution), corresponding to an age of ~10-15Myr and an initial mass of ~104Msolar. This is consistent with the properties of the cluster's brightest stars, which were resolved in the data for the first time. Finally, a numerical analysis of the galaxy's stellar content yields a roughly constant star formation rate of 1.3×10-3Msolaryr-1 and mean metallicity of [Fe/H]=-1.3dex from 15Gyr ago to the present.
... DEPENDENCE OF KINEMATICS ON ABUNDANCE JOHN E. NORRIS AND KC FREEMAN Mount ... 1290 Sauverny, ... more ... DEPENDENCE OF KINEMATICS ON ABUNDANCE JOHN E. NORRIS AND KC FREEMAN Mount ... 1290 Sauverny, Switzerland; michel.mayor@obs.unige.ch AND PATRICk SEITZER Department ... observed strong s-process element enhancement) intermediate-to low-mass ones ...
We are carrying out a comprehensive multi-wavelength study of dwarfs galaxies in the Local Volume... more We are carrying out a comprehensive multi-wavelength study of dwarfs galaxies in the Local Volume (&amp;lt; 5 Mpc), many of which were discovered only recently. In addition to ground-based observations for the determination of global integrated properties, of structural parameters, and of the H I content we are using a 200-orbit HST snapshot survey to measure distances to the dwarf
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