SPACEWATCH® Milestones, 2012-2016
Status as of 2016 May 30:
In 2011 we installed a new CCD on our 1.8-meter telescope that allows us to observe 50% more objects per unit time with half the astrometric residual as before. The current annual average number of detections of NEOs by SPACEWATCH® is ~2,900, in which one "detection" consists usually of a complete "tracklet" of three measurements of position. (Statistics of our observations quoted here are from the MPC's "MPCAT-OBS" file of late April 2016.) That statistic does not include our many observations contributing to the vetting and removal of candidates posted on the MPC's Confirmation Page (NEOCP) that turn out not to be NEOs. SPACEWATCH® has observed three quarters of all known PHAs. SPACEWATCH® also follows up accessible NEOs listed by JPL or NEODyS with potential impact solutions, contributing to the removal of half of such objects that were retired from that list. Per year we observe about 35 radar targets, 50 NEOs that were measured by NEOWISE, and 100 potential rendezvous destinations. In the last 3 years we have observed half of all NEOs and PHAs observed by anyone in that time.
Observing with Larger non-SPACEWATCH® Telescopes: We used the 4-meter Mayall Telescope of the Kitt Peak National Observatory (KPNO), the 3.5-m WIYN telescope on Kitt Peak, the 4-m Blanco telescope of the Cerro Tololo Interamerican Observatory (CTIO) in Chile, and the 2.3-meter Bok Telescope of Steward Observatory on Kitt Peak to reach fainter targets. The Bok Telescope is equipped with the 90Prime
Camera (Williams et al. 2004; which we used until 2015 October) and the Mayall 4-m also has a mosaic of CCDs (Sawyer et al. 2010). SPACEWATCH® reported astrometry of many NEOs discovered or detected by WISE, including the notable Earth Trojan 2010 TK7 that we arranged to be observed with the Blanco 4-m telescope at CTIO. After a long search we found the faint almost-lost "Virtual Impactor" (VI) 2011 BY24 discovered by WISE.
Priority Targets for the Bok 2.3-meter Telescope: MPC's NEO Confirmation Page: Freshly discovered objects on the NEOCP,
especially those discovered by surveys such as Pan-STARRS that cannot do their own followup, are our first priority on each night of observing.
In 2015 October we began changing operation of the 0.9-m telescope from a prearranged survey pattern to targeting specific NEOs, and as of 2017 January, specific targeting is the only way we use the 0.9-m telescope. Most recently, we have implemented stacking of mosaic images with the 0.9-m telescope to reach fainter objects, as we have been doing for years with the 1.8-m telescope. At both telescopes we are now tuning our exposure times more carefully according to the seeing conditions to maintain sufficient precision of astrometry in degrading conditions. More accurate measurements of objects’ rates across the sky are now achieved by cycling repeatedly through a series of targets to spread the measurements of each object over longer time intervals.
2015 September 27: Our new ProLine® PL23042 CCD camera system from Finger Lakes Instruments saw first light on the Bok 2.3-meter telescope of Steward Observatory. Installation of the new camera and use of our own targeting software and data processing pipeline has resulted in an average increase of 50% in targeted objects per night and a 300% increase in the number of images taken per night, compared with our previous use of the institutional camera and software. In addition to increasing our observing efficiency at the 2.3-m telescope, the new camera and targeting software have normalized many aspects of our observing procedures, image analysis efforts, logging tasks and archiving procedures with those procedures at SPACEWATCH®'s 0.9-m and 1.8-m recovery operations.
In 2012 August to October, SPACEWATCH® obtained a lightcurve of the horseshoe-orbiting Aten asteroid (3753) Cruithne (Larsen et al. 2014) at the request of the NEOWISE team who had determined its diameter. Its rotation period was close to one day and its frequently low solar elongation made it available for only an hour or two each morning. So it took 10 weeks to accumulate an acceptable lightcurve, which telescope time would have been difficult to obtain through a competitive allocation process.
Larsen, J. A., et al. 2014. The Lightcurve of 3753 Cruithne. The Minor Planet Bulletin (ISSN 1052-8091). Bulletin of the Minor Planets Section of the Association of Lunar and Planetary Observers, Vol. 41, No. 2, pp. 68-69: 2014MPBu...41...68L .