A Systematic MillimeterTransient Seach Using ACT Data

Until now the millimeter transient sky has been largely unobserved. However, CMB surveys now have high enough resolution to study these events. The Atacama Cosmology Telescope (ACT) is a 6-meter telescope with arcminute-scale angular resolution that is primarily used to study the cosmic microwave background. The telescope covers roughly 40 percent of the sky with a weekly cadence and provides sufficient resolution to study millimeter waveband transient events. We conducted a systematic search of three years of ACT data using mean subtracted maps with CMB, asteroids, planets and bright sources removed. We begin searching for transients with a signal to noise cut of 5, taking the position to be the center of mass by flux. Next, we cut spurious sources close to the edges of the maps, clustered in large groupings, or along zero variance contours. Finally, we cross match each event across different frequencies and arrays. Any source which does not appear in at least two arrays is considered spurious. Once all the data cuts are complete we are left with 524 candidate events. There are 73 independent sources and the majority have several repeated events. We identify each candidate by cross matching with external catalogs and by studying their lightcurves.