Astrometric observations of comets and asteroids and subsequent orbital investigations

The 155-cm reflector of the Smithsonian Astrophysical Observatory was used for observations of comets and minor planets on 35 nights during October l986- April l987. The distrubution was fairly uniform November-February, but poor weather permitted only 21 observations during March. Table I lists the 423 measurements published (in the MPCs) since the last report, two of them actually made at the very beginning of May l987. Forty-six of the observations refer to comets, 193 to numbered minor planets (numbered, that is, by the end of the semester; only 11 of them refer to minor planets already numbered at the time of the last report), and the remainder to unnumbered minor planets

Astrometric Observations of Comets and Asteroids and Subsequent Orbital Investigations

An earlier series of photographic observations was made with the 1.5-m reflector from 1972 to 1989. The start of the series to which this report refers occurred shortly before the conversion from photographic to CCD operation in August 1989, at which point there was a dramatic increase in the productivity of the program. This is evident gives a month-by-month summary of the observations; the earlier data refer to the measurement or remeasurement of photographic plates previously taken with the same telescope. The total number of observations made was 24,423, of which 1338 were of comets. Of the 23,085 observations of asteroids, 21,529 referred to asteroids that were unnumbered when the observations were made. Since an important emphasis of the program was to improve knowledge of the orbits to the point where asteroids can be numbered, the fact that only 4262 of the observations refer to asteroids that are still unnumbered is a measure of the program's success, with 30-35 percent of all the new numberings being habitually made solely because of the recent data from the Oak Ridge program, which even at the time of McCrosky's retirement was still the fourth largest comet-asteroid astrometric program in the world

High-resolution spectra of the 6300-A region of Comet P/Halley

A series of high resolution spectra of the 6300-A region of Comet P/Halley were taken with the echelle/reticon system on the 61-in. telescope at the Harvard-Smithsonian Oak Ridge Observatory from 23 October 1985 through 5 January 1986. Relative contributions of various rotational lines within the (0,8,0) band of NH2 and of the cometary and airglow contributions of O(1D) were clearly spectrally separated. Measurements were taken both centered on the nucleus as well as offset by various displacements in different directions. A number of important implications have resulted from the analysis of these data. (1) The relative fluxes of different rotational members of the NH2 (0,8,0) band vary not only from day-to-day, as previously reported, but also with radial distance within the coma. Indications are that the vib-rotational structure of the band could be useful as a diagnostic for coma temperatures and/or outflow kinematics. (2) Deviations from circular symmetry were negligible for NH2 but detectable for O(1D), having only a small (0-10%) average sunward asymmetry. (3) The inner radial brightness distribution for O(1D) is consistent with its production from the photodissociation of its parent (H2O). (4) The inner radial brightness distributions for NH2 were reasonably consistent with previously published results found for Halley and other comets. (5) Some inconsistencies were found in the comparison of the cometary NH2 line wavelengths with the standard laboratory values.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29303/1/0000366.pd

A search for the Perseus flasher and the limits on optical burst rates

We conducted a study of the error box of the possible optical burster, reported by Katz et al. (1986). This “Perseus Flasher” was subsequently identified with satellite glints by Maley (1987), a conclusion with which we fully concur. Our study, completed before Maley’s report, involved a search for highly-variable objects on archival and newly-taken plates, with a total integration time of about 260 hours, a proper-motion survey of the area, deep optical imaging with a CCD, and a single-dish radio monitoring. We found no optical or radio bursts or any other unusual objects in this area. Our upper limit to the optical flash rate from the error box of the flash photographed by Katz et al. is at least 20 times lower than the flash rate reported by those authors. Similar negative results were achieved independently by other groups; like them, we conclude that the photographed flash was most likely caused by an Earth-orbiting artifact and that most of the remaining, visually-detected flashes were spurious. From our data, we derive limits on the optical flash rates from astrophysically-interesting sources