Upper panel: total counts averaged over 5000 channels with a good sensitivity and outside of the source emission versus time in the 30 Dor leg for the pixel HFAV_PX00. The red and blue points indicate hot-load and cold-load measurements, respectively, and black points are the sky observations. Lower panel: sky count minus hot count divided by the gain, averaged over the same channels. See Guan et al. (2012) for the detailed formula. Black diamonds show the case without gain correction, green asterisks are after the gain correction within observations that share the same load measurement, red triangles represent the data after the final grain correction (see text).