Searching for sub-kilometer TNOs using Pan-STARRS video mode lightcurves: Preliminary study and evaluation using engineering data
We present a pre-survey study of using Pan-STARRS high sampling rate video mode guide star images to search for TNOs. With suitable selection of the guide stars within the Pan-STARRS 7 deg^{2} field of view, the lightcurves of these guide stars can also be used to search for occultations by TNOs. The best target stars for this purpose are stars with high signal-to-noise ratio (SNR) and small angular size.In order to do this, we compiled a catalog using the SNR calculated from stars with m_V <13 mag in the Tycho2 catalog then cross matched these stars with the 2MASS catalog and estimated their angular sizes from (V-K) color. We also outlined a new detection method based on matched filter that is optimized to search for diffraction patterns in the lightcurves due to occultation by sub-kilometer TNOs. A detection threshold is set to compromise between real detections and false positives. Depending on the theoretical size distribution model used, we expect to find up to a hundred events during the three-year life time of the Pan-STARRS-1 project. We have tested the detection algorithm and the pipeline on a set of engineering data (taken at 10Hz in stead of 30Hz). No events were found within the engineering data, which is consistent with the small size of the data set and the theoretical models. Meanwhile, with a total of ~ 22 star-hours video mode data (|\beta| < 10^{\circ}), we are able to set an upper limit of N(>0.5 km) ~ 2.47x10^10 deg^-2 at 95% confidence limit.