... REFERENCES Frecker, JE, Gehrels, T., McMillan, RS, Merline, WJ, Perry, ML, Scotti, JV, and Sm... more ... REFERENCES Frecker, JE, Gehrels, T., McMillan, RS, Merline, WJ, Perry, ML, Scotti, JV, and Smith, PH (1984). In Proceedingsofthe Workshop on Improvements in Photometry, NASA CP-2350, edited by WJ Borucki and A. Young, (NASA, Washington, DC), pp. ...
Astrometry and photometry of asteroids and comets by Spacewatch have expanded in their rate, tele... more Astrometry and photometry of asteroids and comets by Spacewatch have expanded in their rate, telescopes used, and priorities since the summary in 2006 by McMillan et al. (2007 IAU Symp. 236, 329-340). Targeted recoveries of objects discovered by the Wide-field Infrared Survey Explorer (WISE) have been added to those on the JPL and NEODyS impact risk pages, the Minor Planet Center (MPC)'s Confirmation Page, PHAs, comets, and other NEOs. Automation of the dome of our 1.8-m telescope and other enhancements to software and hardware have aided this expansion. About 3000 tracklets of NEOs are accepted by the MPC from Spacewatch each year. Recoveries of WISE-discovered objects consolidate orbits and prevent objects from being lost. V or R-band photometry is essential to determine the albedo at the wavelength of the peak of incident solar flux, which reckons in modeling thermal properties from the WISE measurements of infrared (IR) flux. We specialize in the fainter objects and have rep...
Target-of-Opportunity (ToO) time is requested to recover and do astrometry and photometry on shor... more Target-of-Opportunity (ToO) time is requested to recover and do astrometry and photometry on short notice of carefully selected asteroids, comets, and suspected comets freshly discovered by WISE. The WISE all-sky thermal infrared survey is uncovering darker albedos and more extreme orbital inclinations of solar system objects than expected. More of the rare and newly discovered category of main belt comets
We have enhanced Spacewatch's (McMillan et al. 2007 IAU Symp. 236) astrometry and photometry ... more We have enhanced Spacewatch's (McMillan et al. 2007 IAU Symp. 236) astrometry and photometry of Near-Earth Objects (NEOs). We specialize in follow-up of the Congressionally-mandated "large" NEOs (absolute mag H≤22) as they recede from Earth after discovery and become fainter, as well as NEOs on impact risk pages, Potentially Hazardous Asteroids, and NEOs observed by WISE (Mainzer et al. 2012 ApJ 752, id 110). Spacewatch was the pre-eminent follower-up of NEOs discovered by WISE within 2 weeks of their discovery. We have observed at elongations as small as 46°. Follow-up on longer orbital arcs improves understanding of the statistics of the orbits and absolute magnitudes of the population as well as the recoverability of individual objects. The new CCD which we began operating on our 1.8-m telescope on 2011 Oct 16 makes 23rd mag asteroids more frequently accessible. Faster readout and smaller pixels yield 67% more observations of NEOs per year and astrometric residuals ...
We have conducted a large-area search for the brightest members of the trans-Neptunian and Centau... more We have conducted a large-area search for the brightest members of the trans-Neptunian and Centaur/scattered-disk asteroid populations by reprocessing archival scans from the Spacewatch 0.9 m telescope at Kitt Peak. Our survey encompasses 331 scans taken from 1995 September to 1999 September and has a raw sky coverage of 1483.8 deg2. We discovered Ðve trans-Neptunians and Ðve Centaur/ scattered-disk objects using an automated motion detection code. In addition, we serendipitously found four trans-Neptunians and two Centaur/scattered-disk objects that had been previously discovered. This survey is unique in that it involves a method that has a reasonable chance to reacquire its lost objects. In this paper we develop techniques to aid our understanding of our software efficiency and survey procedures. We use this understanding to "" convolve ÏÏ our raw sky coverage with our measured detection efficiency and a model of our scan coverage to estimate what fraction of survey areas can be considered "" new.ÏÏ Our large sky coverage extends the cumulative luminosity function of the trans-Neptunians into a region previously constrained only by upper limits, and it allows a power-law Ðt to be attempted to the Centaur cumulative luminosity function. In objects per square degree brighter than R \ 21.5, we Ðnd cumulative surface densities of Centaurs to be 0.017^0.011, of trans-Neptunians to be 0.040^0.018, and scattered-disk objects to be 0.007^0.004. We extrapolate these values to estimate the number of each class in the ecliptic brighter than R \ 21.5 : 100 Centaurs, 400 trans-Neptunians, and 70 scattereddisk objects. Orbit analysis by the Minor Planet Center suggests that three of our Ðve trans-Neptunians are resonators : 1998
Comet P/Shoemaker-Levy 9 (1993e) was observed by the Hubble Space Telescope (HST) on 1993 July 1,... more Comet P/Shoemaker-Levy 9 (1993e) was observed by the Hubble Space Telescope (HST) on 1993 July 1, approximately three months after its discovery and approximately one year before its predicted impact into the atmosphere of Jupiter. Approximately 20 individual nuclei were observed in images taken with the Planetary Camera (PC). Each nucleus is surrounded by a roughly spherical coma, which is
The found near-Earth asteroid are different objects with peculiar orbits. With the new technique ... more The found near-Earth asteroid are different objects with peculiar orbits. With the new technique of CCD scanning we entered the domain of the smallest, the fastest, and the closest near-Earth asteroids. The results are presented.
... 46.08 Four Modes of CCD Operation T. Gehrels, JE Frecker, R.. S. McMillan, ML Perry, and JV S... more ... 46.08 Four Modes of CCD Operation T. Gehrels, JE Frecker, R.. S. McMillan, ML Perry, and JV Scotti (U. Arizona) The 91-cm Newtonian reflector of the Steward Observatory on Kitt Peak, the First Spacewatch Camera, is in computer controlled operation for CCD scanning during ...
With the NEOWISE portion of the Wide-field Infrared Survey Explorer (WISE) project, we have carri... more With the NEOWISE portion of the Wide-field Infrared Survey Explorer (WISE) project, we have carried out a highly uniform survey of the near-Earth object (NEO) population at thermal infrared wavelengths ranging from 3 to 22 µm, allowing us to refine estimates of their numbers, sizes, and albedos. The NEOWISE survey detected NEOs the same way whether they were previously known or not, subject to the availability of ground-based follow-up observations, resulting in the discovery of more than 130 new NEOs. The survey's uniform sensitivity, observing cadence, and image quality have permitted extrapolation of the 428 near-Earth asteroids (NEAs) detected by NEOWISE during the fully cryogenic portion of the WISE mission to the larger population. We find that there are 981±19 NEAs larger than 1 km and 20,500±3000 NEAs larger than 100 m. We show that the Spaceguard goal of detecting 90% of all 1 km NEAs has been met, and that the cumulative size distribution is best represented by a broken power law with a slope of 1.32±0.14 below 1.5 km. This power law slope produces ∼ 13, 200±1,900 NEAs with D >140 m. Although previous studies predict another break in the cumulative size distribution below D ∼50-100 m, resulting in an increase in the number of NEOs in this size range and smaller, we did not detect enough objects to comment on this increase. The overall number for the NEA population between 100-1000 m is lower than previous estimates. The numbers of near-Earth comets and potentially hazardous NEOs will be the subject of future work. Road,
We have completed a low-inclination ecliptic survey for distant and slow-moving bright objects in... more We have completed a low-inclination ecliptic survey for distant and slow-moving bright objects in the outer solar system. This survey used data taken over 34 months by the University of Arizona's Spacewatch Project based at Steward Observatory, Kitt Peak. Spacewatch revisits the same sky area every three to seven nights in order to track cohorts of main-belt asteroids. This survey used a multiple-night detection scheme to extend our rate sensitivity to as low as 0.012 arcsec hr À1. When combined with our plate scale and flux sensitivity (V % 21), this survey was sensitive to Mars-sized objects out to 300 AU and Jupiter-sized planets out to 1200 AU. The survey covered approximately 8000 deg 2 of raw sky, mostly within 10 of the ecliptic but away from the Galactic center. An automated motiondetection program was modified for this multinight search and processed approximately 2 terabytes of imagery into motion candidates. This survey discovered 2003 MW 12 , currently the tenth largest classical Kuiper Belt object. In addition, several known large Kuiper Belt objects and Centaurs were detected, and the detections were used with a model of our observational biases to make population estimates as a check on our survey efficiency. We found no large objects at low inclinations despite having sufficient sensitivity in both flux and rate to see them out as far as 1200 AU. For low inclinations, we can rule out more than one to two Pluto-sized objects out to 100 AU and one to two Mars-sized objects to 200 AU.
... REFERENCES Frecker, JE, Gehrels, T., McMillan, RS, Merline, WJ, Perry, ML, Scotti, JV, and Sm... more ... REFERENCES Frecker, JE, Gehrels, T., McMillan, RS, Merline, WJ, Perry, ML, Scotti, JV, and Smith, PH (1984). In Proceedingsofthe Workshop on Improvements in Photometry, NASA CP-2350, edited by WJ Borucki and A. Young, (NASA, Washington, DC), pp. ...
Astrometry and photometry of asteroids and comets by Spacewatch have expanded in their rate, tele... more Astrometry and photometry of asteroids and comets by Spacewatch have expanded in their rate, telescopes used, and priorities since the summary in 2006 by McMillan et al. (2007 IAU Symp. 236, 329-340). Targeted recoveries of objects discovered by the Wide-field Infrared Survey Explorer (WISE) have been added to those on the JPL and NEODyS impact risk pages, the Minor Planet Center (MPC)'s Confirmation Page, PHAs, comets, and other NEOs. Automation of the dome of our 1.8-m telescope and other enhancements to software and hardware have aided this expansion. About 3000 tracklets of NEOs are accepted by the MPC from Spacewatch each year. Recoveries of WISE-discovered objects consolidate orbits and prevent objects from being lost. V or R-band photometry is essential to determine the albedo at the wavelength of the peak of incident solar flux, which reckons in modeling thermal properties from the WISE measurements of infrared (IR) flux. We specialize in the fainter objects and have rep...
Target-of-Opportunity (ToO) time is requested to recover and do astrometry and photometry on shor... more Target-of-Opportunity (ToO) time is requested to recover and do astrometry and photometry on short notice of carefully selected asteroids, comets, and suspected comets freshly discovered by WISE. The WISE all-sky thermal infrared survey is uncovering darker albedos and more extreme orbital inclinations of solar system objects than expected. More of the rare and newly discovered category of main belt comets
We have enhanced Spacewatch's (McMillan et al. 2007 IAU Symp. 236) astrometry and photometry ... more We have enhanced Spacewatch's (McMillan et al. 2007 IAU Symp. 236) astrometry and photometry of Near-Earth Objects (NEOs). We specialize in follow-up of the Congressionally-mandated "large" NEOs (absolute mag H≤22) as they recede from Earth after discovery and become fainter, as well as NEOs on impact risk pages, Potentially Hazardous Asteroids, and NEOs observed by WISE (Mainzer et al. 2012 ApJ 752, id 110). Spacewatch was the pre-eminent follower-up of NEOs discovered by WISE within 2 weeks of their discovery. We have observed at elongations as small as 46°. Follow-up on longer orbital arcs improves understanding of the statistics of the orbits and absolute magnitudes of the population as well as the recoverability of individual objects. The new CCD which we began operating on our 1.8-m telescope on 2011 Oct 16 makes 23rd mag asteroids more frequently accessible. Faster readout and smaller pixels yield 67% more observations of NEOs per year and astrometric residuals ...
We have conducted a large-area search for the brightest members of the trans-Neptunian and Centau... more We have conducted a large-area search for the brightest members of the trans-Neptunian and Centaur/scattered-disk asteroid populations by reprocessing archival scans from the Spacewatch 0.9 m telescope at Kitt Peak. Our survey encompasses 331 scans taken from 1995 September to 1999 September and has a raw sky coverage of 1483.8 deg2. We discovered Ðve trans-Neptunians and Ðve Centaur/ scattered-disk objects using an automated motion detection code. In addition, we serendipitously found four trans-Neptunians and two Centaur/scattered-disk objects that had been previously discovered. This survey is unique in that it involves a method that has a reasonable chance to reacquire its lost objects. In this paper we develop techniques to aid our understanding of our software efficiency and survey procedures. We use this understanding to "" convolve ÏÏ our raw sky coverage with our measured detection efficiency and a model of our scan coverage to estimate what fraction of survey areas can be considered "" new.ÏÏ Our large sky coverage extends the cumulative luminosity function of the trans-Neptunians into a region previously constrained only by upper limits, and it allows a power-law Ðt to be attempted to the Centaur cumulative luminosity function. In objects per square degree brighter than R \ 21.5, we Ðnd cumulative surface densities of Centaurs to be 0.017^0.011, of trans-Neptunians to be 0.040^0.018, and scattered-disk objects to be 0.007^0.004. We extrapolate these values to estimate the number of each class in the ecliptic brighter than R \ 21.5 : 100 Centaurs, 400 trans-Neptunians, and 70 scattereddisk objects. Orbit analysis by the Minor Planet Center suggests that three of our Ðve trans-Neptunians are resonators : 1998
Comet P/Shoemaker-Levy 9 (1993e) was observed by the Hubble Space Telescope (HST) on 1993 July 1,... more Comet P/Shoemaker-Levy 9 (1993e) was observed by the Hubble Space Telescope (HST) on 1993 July 1, approximately three months after its discovery and approximately one year before its predicted impact into the atmosphere of Jupiter. Approximately 20 individual nuclei were observed in images taken with the Planetary Camera (PC). Each nucleus is surrounded by a roughly spherical coma, which is
The found near-Earth asteroid are different objects with peculiar orbits. With the new technique ... more The found near-Earth asteroid are different objects with peculiar orbits. With the new technique of CCD scanning we entered the domain of the smallest, the fastest, and the closest near-Earth asteroids. The results are presented.
... 46.08 Four Modes of CCD Operation T. Gehrels, JE Frecker, R.. S. McMillan, ML Perry, and JV S... more ... 46.08 Four Modes of CCD Operation T. Gehrels, JE Frecker, R.. S. McMillan, ML Perry, and JV Scotti (U. Arizona) The 91-cm Newtonian reflector of the Steward Observatory on Kitt Peak, the First Spacewatch Camera, is in computer controlled operation for CCD scanning during ...
With the NEOWISE portion of the Wide-field Infrared Survey Explorer (WISE) project, we have carri... more With the NEOWISE portion of the Wide-field Infrared Survey Explorer (WISE) project, we have carried out a highly uniform survey of the near-Earth object (NEO) population at thermal infrared wavelengths ranging from 3 to 22 µm, allowing us to refine estimates of their numbers, sizes, and albedos. The NEOWISE survey detected NEOs the same way whether they were previously known or not, subject to the availability of ground-based follow-up observations, resulting in the discovery of more than 130 new NEOs. The survey's uniform sensitivity, observing cadence, and image quality have permitted extrapolation of the 428 near-Earth asteroids (NEAs) detected by NEOWISE during the fully cryogenic portion of the WISE mission to the larger population. We find that there are 981±19 NEAs larger than 1 km and 20,500±3000 NEAs larger than 100 m. We show that the Spaceguard goal of detecting 90% of all 1 km NEAs has been met, and that the cumulative size distribution is best represented by a broken power law with a slope of 1.32±0.14 below 1.5 km. This power law slope produces ∼ 13, 200±1,900 NEAs with D >140 m. Although previous studies predict another break in the cumulative size distribution below D ∼50-100 m, resulting in an increase in the number of NEOs in this size range and smaller, we did not detect enough objects to comment on this increase. The overall number for the NEA population between 100-1000 m is lower than previous estimates. The numbers of near-Earth comets and potentially hazardous NEOs will be the subject of future work. Road,
We have completed a low-inclination ecliptic survey for distant and slow-moving bright objects in... more We have completed a low-inclination ecliptic survey for distant and slow-moving bright objects in the outer solar system. This survey used data taken over 34 months by the University of Arizona's Spacewatch Project based at Steward Observatory, Kitt Peak. Spacewatch revisits the same sky area every three to seven nights in order to track cohorts of main-belt asteroids. This survey used a multiple-night detection scheme to extend our rate sensitivity to as low as 0.012 arcsec hr À1. When combined with our plate scale and flux sensitivity (V % 21), this survey was sensitive to Mars-sized objects out to 300 AU and Jupiter-sized planets out to 1200 AU. The survey covered approximately 8000 deg 2 of raw sky, mostly within 10 of the ecliptic but away from the Galactic center. An automated motiondetection program was modified for this multinight search and processed approximately 2 terabytes of imagery into motion candidates. This survey discovered 2003 MW 12 , currently the tenth largest classical Kuiper Belt object. In addition, several known large Kuiper Belt objects and Centaurs were detected, and the detections were used with a model of our observational biases to make population estimates as a check on our survey efficiency. We found no large objects at low inclinations despite having sufficient sensitivity in both flux and rate to see them out as far as 1200 AU. For low inclinations, we can rule out more than one to two Pluto-sized objects out to 100 AU and one to two Mars-sized objects to 200 AU.
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Papers by James Scotti