The Spacewatch Wide-Area Survey for Bright Centaurs and Trans-Neptunian Objects

Abstract

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 is in the 3 : 2, 1995 appears to be in the 5 : 3, and 1998 appears VG 44 SM 55 SN 165 to be in the 7 : 5 resonance.

Photometric Light Curve for the Kuiper Belt Object 2000 EB173 on 78 Nights

“…Only in the last two years have a number of studies searched wide areas (Ferrin et al 2001;Larsen et al 2001;Sheppard et al 2000;Jewitt, Luu, & Trujillo 1998). As part of the QUEST KBO Survey (66.8deg 2 to R = 20.1), we discovered the very bright KBO 2000 EB 173 (Ferrin et al 2001).…”

Efficient intra- and inter-night linking of asteroid detections using kd-trees

“…The intra-night linking efficiency has been measured by some of the major NEO surveys by attempting to identify known asteroids in their fields. The measured peak efficiency for asteroids well above the limiting magnitude varies from about 65% (Spacewatch; Jedicke & Herron (1997)), ∼ 70% (Catalina Sky Survey, observatory 703; Beshore personal communication), ∼ 90% (Catalina Sky Survey, observatory G96; Beshore personal communication), and about 90% for the latest and reprocessed Spacewatch data (Larsen et al 2001). In both these survey's the intra-night linkings proposed by their algorithms are checked by a human observer.…”

Evidence for an Extended Scattered Disk

“…The only other SDO with a perihelion above 40 AU is 1995 TL 8 ( Fig. 1), an object discovered by the Spacewatch program (Larsen et al 2001). …”