| 62 | 64 | Here is a image of part of the above r-band mosaic of four stacks, with sextractor detections in green. Interestingly, the skycells have gaps between them (I thought they would overlap slightly?), and one of the cells has many more detections. The reason for the latter is not clear. The pixel-pixel noise and background levels are indistinguishable from the other three - the only difference appears to be in the structure of the background (Jim's mottling effect). Note also the dark halos around bright objects where the background subtraction has been too aggressive. |
