The point source masks are maps, in FITS format, with the same footprint and World Coordinate System as the associated ACTPol 148 GHz map. The mask is unity everywhere except in circles of 10 arcminute diameter around sources detected in the data, where it is zero. These sources were detected in the combined 148 GHz data from the two seasons of ACTPol observation with a matched filter, which uses the ACTPol beam profile along with an estimation of the map noise. After filtering, sources detected with a signal to noise ratio > 5 and with a 148 GHz flux density >15 mJy were identified for masking. Due to edge effects, some spurious detections are masked in regions of low hits-per-pixel. Such edge regions are generally undesirable for analysis.
To use the mask, read in both the data and the mask and multiply the data, pixel-wise, by the mask.