Publications by Robert S. McMillan and Spacewatch in 2007: Hajian, A. R., Behr, B. B., Cenko, A. T., Olling, R. P., Mozurkewich, D., Armstrong, J. T., Pohl, B., Petrossian, S., Knuth, K. H., Hindsley, R. B., Murison, M., Efroimsky, M., Dantowitz, R., Kozubal, M., Currie, D. G., Nordgren, T. E., Tycner, C., and McMillan, R. S. 2007. Initial Results from the USNO Dispersed Fourier Transform Spectrograph. ApJ, 661, 616-633. (Instrumentation) Larsen, J. A., Roe, E. S., Albert, C. E., Descour, A. S., McMillan, R. S., Gleason, A. E., Jedicke, R., Block, M., Bressi, T. H., Cochran, K. C., Gehrels, T., Montani, J. L., Perry, M. L., Read, M. T., Scotti, J. V., Tubbiolo, A. F. 2007. The Search for Distant Objects in the Solar System Using Spacewatch. AJ, 133: 1247-1270. (Solar System) McMillan, R. S. 2007. Spacewatch preparations for the era of deep all-sky surveys. In Near Earth Objects, our Celestial Neighbors: Opportunity and Risk, Proceedings if IAU Symposium 236. Edited by G.B. Valsecchi and D. Vokrouhlický. Cambridge: Cambridge University Press, 329-340. (Solar System) McMillan, R. S., Bressi, T. H., Descour, A. S., Gehrels, T., Jedicke, R., Larsen, J. A., Montani, J. L., Read, M. T., Scotti, J. V., and Tubbiolo, A. F. 2007. Observations of Asteroids and Comets in approximately 384 Minor Planet Electronic Circulars listed at http://spacewatch.lpl.arizona.edu/mnptcrc_chron.shtml#2007 . (Solar System) Scotti, J. V., and McNaught, R. H. 2007. Independent Recovery of Comet P/1998 S1=P/2007 J7. IAU Circ. 8853. (Solar System) Tubbiolo, A. F., Tichy, M., Ticha, J., and Buzzi, L. 2007. Discovery Observations of Comet C/2007 D2 (Spacewatch). IAU Circ. 8809. (Solar System)
Ongoing Research by Robert S. McMillan et al.: Observing: The Spacewatch Project detects Earth-approaching Asteroids (EAs) to fainter limiting magnitudes than most other groups. Spacewatch equipment nowadays is best suited to followup, recovery, and archival prediscovery observations of EAs. We continued to observe with our 0.9-meter and 1.8-meter telescopes to the magnitude limits of V=22 and 23, respectively. The mosaic of CCDs on the 0.9-m telescope covers in each lunation an average of 1400 square degrees along the ecliptic near the opposition point. Spacewatch followed and recovered known EAs that needed updated orbits and were too faint for other observatories. Priority is given to Potentially Hazardous Asteroids, potential impactors listed on the web, faint objects on the MPC's Confirmation Page, special requests from the Minor Planet Center and the JPL NEO Office, and targets of radar and spacecraft. During 2007, Spacewatch made ~1700 detections (≈5100 observations) of EAs, 47 of which were new Spacewatch discoveries. Spacewatch followup astrometry contributed to the removal of 86 Virtual Impactors from JPL’s impact risk page during 2007. Also during 2007, Spacewatch sent ~370,000 incidental detections of field asteroids to the MPC. (One "detection" by Spacewatch usually equals three observations of position.) (Solar System) Improvements in Observing: The accuracy of pointing the 1.8-meter telescope has been improved. An improvement to the flat-field correction of the CCD mosaic was also made in 2007, which greatly reduced the incidence of false detections of asteroids and thereby reduced the workload on the observers who have to reject them. A new version of our image detection program is under development. (Solar System) Collaboration: WISE spacecraft mission: The Wide-field Infrared Survey Explorer (WISE) mission is scheduled for launch in 2009 November. McMillan is a Co-Investigator and the leader of the Solar System Subgroup of the mission. Detection and reporting of moving objects (asteroids and comets) in time for ground-based followup is being considered for addition to the mission. Many stars that are variable in the IR will also be detected. (Solar System and Stellar/Galactic) Collaboration: Assistance to Pan STARRS: Listings of unmatched point sources detected in survey mode by the mosaic of CCDs on the Spacewatch 0.9-m telescope continued to be sent to the Pan-STARRS team responsible for developing the Pan-STARRS software to detect moving objects. These data continue to be very useful to them for practice and testing. (Solar System) The future of NASA’s Near-Earth Object (NEO) Observation program will necessarily see more attention to followup of the hazardous NEOs already discovered. It will also include extensions of the search to the remaining 10 percent of the NEOs >=1 km and to the more numerous smaller objects. Discoveries of EAs by Pan-STARRS and WISE will fully utilize the magnitude sensitivity of Spacewatch followup. (Solar System) Population Estimates: One major scientific objective is to assemble, debias, and analyze our detections of asteroids and redetermine the numbers and distributions of Earth Approachers (EAs), Main-Belt Asteroids, and other orbital types as functions of absolute magnitude H, semimajor axis a, eccentricity e, and inclination i. The Spacewatch Survey for Hazardous Asteroids has now been funded by NASA's NEO Observation Program through mid-2009, which will provide hundreds of thousands more incidental detections of asteroids beyond what have been analyzed in the literature to date. Systematic surveying with the Spacewatch mosaic of CCDs to the limiting V magnitude of 21.7 will have been conducted for a full six years with uniform procedures, yielding H, a, e, and i of ~100,000 main belt asteroids. Simulation software can then debias the distributions of asteroids' absolute magnitudes and orbital elements. The distributions will have higher resolution in semimajor axis than any previous large-scale debiasing of the main belt, and will add for the first time the debiased main belt distribution vs. eccentricity. For EAs, the absolute magnitude distribution will be extended to at least magnitude 26 and possibly 29, 6 mag fainter than has been determined reliably to date. (Solar System) The outer solar system continues to be explored for distant, large TNOs. Knowledge of the efficiency and biases of our search will allow quantitative upper limits on the presence of any such objects that remain undetected in the volume searched. Larsen et al. (2007) used the relative shallow limiting magnitude of 20.5 which, while competitive with other surveys, does not represent the faintest search that could be performed. The brighter magnitude limit was chosen to search for the most interesting objects with the smallest number of false positives. There are still data of interest in the survey down to the magnitude limit of at least 21.5 without coadding. By mid-2009, the Spacewatch search for large, distant TNOs will have covered up to 20,000 square degrees of the sky with a unique distance range of 1000 AU. This is relevant to hypotheses that large planetesimals might still exist at great distances from the Sun. (Solar System) McMillan is collaborating in a campaign to improve knowledge of the orbits and masses of stars in spectroscopic binary systems by means of accurate measurements of Doppler shift. Several successful observing runs with the Bok 2.3-meter telescope of Steward Observatory have yielded hundreds of radial velocity measurements. (Stellar/Galactic)