We present TESS photometry of the asynchronous polar BY Cam, which undergoes a beat cycle between the 199.384 min white dwarf (WD) spin period and the 201.244 min orbital period. This results in changes in the flow of matter onto the WD. The TESS light curve covers 92% of the beat cycle once and 71% of the beat cycle twice. The strongest photometric signal, at 197.560 min, is ascribed to a side-band period. During times of light-curve stability, the photometry modulates at the spin frequency, supporting our WD spin-period identification. Both one-pole and two-pole accretion configurations repeat from one beat cycle to the next with clear and repeatable beat-phase-dependent intensity variations. To explain these, we propose the operation of a magnetic valve at L1. The magnetic valve modulates the mass-transfer rate, as evidenced by a factor of 5 variation in orbital-averaged intensity, over the course of the beat cycle in a repeatable manner. The accretion stream threading distance from the WD is also modulated at the beat period, because of the variation of the WD magnetic field with respect to the stream and because of changes in the mass transfer rate due to the operation of the magnetic valve. Changes in the threading distance result in significant shifts in the position of accreting spots around the beat cycle. As a consequence, only the faintest photometric minima allow for an accurate ephemeris determination. Three regions on the WD appear to receive most of the accretion flow, suggestive of a complex WD magnetic field.

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We present a new multi-frequency catalog of polars and intermediate polars (IPs) called MCV-Catalog-1.0. The need for a new catalog of Magnetic Cataclysmic Variables (MCVs) is becoming increasingly important. The number of known and suspected cataclysmic variables (CVs) has doubled in just the last few years. It is expected to balloon by another factor of 10 in the next decade or so as several optical surveys, like LSST, take place. By establishing a catalog containing only magnetic CVs, i.e. MVCs, we have the freedom to tailor the catalog to a relatively homogeneous set of binaries. Along with cataloging the discovery of many new binaries, MCV-Catalog will keep track of poorly observed systems. Many of the most important astrophysical problems associated with accretion-binary astrophysics require the long-term study of a large sample of binaries. Multi-frequency and even multi-messenger observations are vital in developing our understanding of the interplay between gravity, angular momentum, magnetic fields, and fluid flow, characteristic of MCVs. Many studies focus on the hot new discoveries of albeit interesting binaries. By necessity, priorities are made and many binaries remain known but poorly studied. For this reason we find that MCV-catalog is a useful observing tool, and as a starting point for multi-frequency studies of MCVs. We anticipate that the MCV-catalog, established maintained by Picture Rocks Observatory, will be a 'living' catalog, beginning with all confirmed MCVs by January, 2020. New binaries will be added as they are reported and new data will be periodically added as they become available. Here we present a brief summary of the MCV-Catalog contents.