opCAT: Nanosecond Optical Pulse Detector for Small Telescopes
Year: 2025
Type: article
Abstract: Project opCAT was inspired by the question posed at the last PSeti Conference: How can Pro/Am astronomers follow up on candidate transient sub-second optical pulses detected by wide field surveys such as the PanoSeti project? The opCAT 3×3 mm MPPC detector is similar to the multichannel MPPC arrays used in PanoSeti. opCAT uses a Hamamatsu MPPC module coupled to a beamsplitter, which is confocal with a small CMOS camera. When coupled to a telescope, the CMOS camera is used for focusing and targeting the star field of interest. Most parts of opCAT are commercially available and can be assembled at home. When coupled to a small 55 mm aperture refractor telescope, the field of view (FOV) of the opCAT MPPC detector is 51×51 arcminutes. With larger aperture telescopes such as a 279 mm aperture C11 SCT telescope, the FOV is 5×5 arcminutes. Within this FOV range, galaxies, bright stars, and star fields can be monitored. Images from the CMOS camera can be used to detect false positives from satellite trails and cloud interference, as well as taking photometry measurements of stars. With the wider FOV configurations, opCAT can be used in drift scan mode. Using two opCAT telescopes with overlapping FOVs allows for optical event verification and artifact rejection. The output from opCAT is coupled to a digital counter PC card with photon counts saved to a computer SSD every 100 microseconds. Initial feasibility was demonstrated from bench testing with a nanosecond pulsed laser, triggered at very low to high frequency repetitions. Observational use demonstrated sensitivity to periodic sub-millisecond optical pulses from LIDAR satellites. Data was collected from several galaxies and stars for analysis with custom software to detect periodic triplet pulses and FFT semi-periodic triple peak frequency events. opCAT offers the potential of doing optical SETI at home.
Author: Benni, Paul
Language: English
Subfield: Instrumentation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7117123540