Spacewatch NEO Astrometry and Characterization

Spacewatch continues to perform full-time targeted astrometric follow-up of unnumbered Near-Earth Objects (NEOs), primarily asteroids (NEAs), with the 1.8m and 0.9m telescopes on Kitt Peak. As exclusive users of these telescopes, we observe NEOs 24 nights per lunation, weather permitting. During bright time, we use competitive time on the Steward Observatory Bok 2.3m telescope to reach fainter magnitude NEAs than smaller aperture telescopes can at that lunar phase. We are designing and constructing a new imaging camera to double the width of the field-of-view of our current Cassegrain camera on the Bok.

Rapid follow-up is necessary before newly discovered NEAs' sky uncertainties grow too large and apparent magnitudes grow too faint to detect. Our targeting priorities from highest to lowest are virtual impactors (VIs), MPC NEO Confirmation Page objects, Potentially Hazardous Asteroids (PHAs), objects that have been observed by NEOWISE, potential targets of planetary radar, potential spacecraft mission rendezvous targets, and candidates for the Yarkovsky Effect. Our two telescopes are usually operated in person by one observer but can be operated remotely. In addition to our classically scheduled time, we have Target-of-Opportunity time to observe high priority VIs, 24<V<25, with the LBT, MMT, Keck, SOAR, the Blanco 4m, and Gemini N & S.

Our yearly average of MPC-accepted NEO astrometry is 9550 lines of an average 1350 different NEOs, including 210 different PHAs, 110 potential radar targets, 90 NEOWISE and 220 NHATS targets, about 20 Yarkovsky Effect candidates, and about 250 NEAs that will be closer to Earth than 0.03au within 30 years. We observed 63% of VIs discovered in 2019.

We are part of a sky survey collaboration with the Catalina Sky Survey and the University of Minnesota's Minnesota Institute for Astrophysics using the Bok to discover faint NEOs.

We measure NEA lightcurves to determine rotation periods. We choose planetary defense targets and/or targets of scientific interest (VIs, potential targets for planetary radar, binary asteroid systems, and candidates for the Yarkovsky Effect).

We have reprocessed our data from 1983 through 2016 and are working on corresponding PDS4 XML labels. The finalized 0.9m mosaic survey data (2003 through 2016) will be submitted soon to the PDS Small Bodies Node. Future PDS submissions will include old drift scan data and newer 1.8m data.