The Taiwanese-American Occultation Survey (TAOS) aims to detect serendipitous occultations of stars by small (∼1 km diameter) objects in the Kuiper Belt and beyond. Such events are very rare (< 10 −3 events per star per year) and short in duration (∼200 ms), so many stars must be monitored at a high readout cadence. TAOS monitors typically ∼500 stars simultaneously at a 5 Hz readout cadence with four telescopes located at Lulin Observatory in central Taiwan. In this paper, we report the results of the search for small Kuiper Belt Objects (KBOs) in seven years of data. No occultation events were found, resulting in a 95% c.l. upper limit on the slope of the faint end of the KBO size distribution of q = 3.34 to 3.82, depending on the surface density at the break in the size distribution at a diameter of about 90 km.

ABSTRACT. The Taiwanese-American Occultation Survey (TAOS) monitors fields of up to ∼1000 stars at 5 Hz simultaneously with four small telescopes to detect occultation events from small (∼1 km) Kuiper Belt Objects (KBOs). The survey presents a number of challenges, in particular the fact that the occultation events we are searching for are extremely rare and are typically manifested as slight flux drops for only one or two consecutive time series measurements. We have developed a statistical analysis technique to search the multi-telescope data set for simultaneous flux drops which provides a robust false-positive rejection and calculation of event significance. In this article, we describe in detail this statistical technique and its application to the TAOS data set.

We present the results of a search for occultation events by objects at distances between 100 and 1000 AU in lightcurves from the Taiwanese-American Occultation Survey (TAOS). We searched for consecutive, shallow flux reductions in the stellar lightcurves obtained by our survey between 7 February 2005 and 31 December 2006 with a total of ∼ 4.5 × 10 9 three-telescope simultaneous photometric measurements. No events were detected, allowing us to set upper limits on the number density as a function of size and distance of objects in Sedna-like orbits, using simple models.