WISRD Research & Engineering Journal

Detecting Occultations of Trans-Neptunian Objects (TNO’s) with Light Curve Graphs 1 R. Allenstein, J.A. Wise

1. Introduction Creating light curve graphs requires specific programming that is hard to find in most software. The RECON lab uses a QHYCCD174 m-gps camera that records its data in “.fits ” files which are also incompatible with some software. This leaves a very small amount of software that have the capability and are compatible with the system WISRD uses. The raw data is sent to the Southwest Research Institute, (SWRI) to analyze, but WISRD is responsible for pre-screening the data to see if we’ve captured the occultation. We use PyMovie version 3.3.1 and Pyote version 4.2.1 to do this.

Figure 1. Example of an occultation of the Jupiter Trojan Patroclus captured by WISRD on May 9, 2021, made using SAOimageDS9. RECON is a collection of telescopes along a longitudinal line in the western United States from the Mexican border north into Canada. Telescopes are spaced about every 200 - 250 miles apart. These telescopes are outfitted to detect and record occultations of Trans-Neptunian Objects (TNOs) under a grant from the National Science Foundation (NSF). The orbits of these small TNO objects (as small as 100 - 200 km in diameter are often not well known so that the location for observing the occultation might be anywhere along a 2000-mile longitudinal line. For a RECON event only 3 or 4 of all the telescopes may observe the actual occultation. The data from all the telescopes is put into a computer program that computes possible shapes for the object based on data. Multiple events for the same object further constrain the shape. TNOs are Kuiper Belt objects whose orbit around the Sun is sometimes within the orbit of Neptune and at other times outside the orbit of Neptune (Pluto is the most famous TNO). These objects have had few if any interactions with other Solar System bodies and are thus the oldest, pristine remnants of the earliest epoch of our Solar System. The data WISRD and the RECON network provide helps constrain the object’s orbit, its size and in some instances its shape. With an accurate size, the amount of reflected light can be used to determine the albedo of the object and

1 Sponsored by the Wildwood Institute for STEM Research and Development (WISRD) and the Southwest Research Institute (SWRI) with funding from the National Science Foundation.

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