Revealing a New Black Widow Binary 4FGL J0336.0+7502

We report on a discovery of promising candidate as black widow millisecond pulsar binary, 4FGL J0336.0+7502, which shows many pulsar-like properties in the 4FGL-DR2 catalog. Within 95% error region LAT source, we identified an optical counterpart with clear periodicity at P(orb) = 3.718178(9) hours using Bohyunsan 1.8-m Telescope, Lulin One-meter Canada-France-Hawaii and Gemini-North. At position, X-ray source was marginally detected Swift/XRT archival data, detection confirmed by our Chandra/ACIS DDT observation. The spectrum can be described power-law model Gamma 1.6+/-0.7 F(0.3-7keV) 3.5e-14 erg/cm^2/s. photon index low X-ray-to-gamma-ray flux ratio (i.e., < 1%) are both consistent that known pulsars. There is also hint orbital modulation Chandra although significance very (1.3 sigma). If identity confirmed, it would fifth binary showed orbitally-modulated emission X-rays.