| 3 | | Today's DRAVG noted that I had not shown an example that the false positive rate was resolved as a result of changing the V2/SOFTEN.VARIANCE changes. To correct this, I've run psphot on a sample of deep stacks that I constructed as part of the stack rejection improvements. The ipp-20130620 tag version of psphot was used, as it implements these changes. The image below illustrates the improvement. The top row shows the central portion |
| | 3 | Today's DRAVG noted that I had not shown an example that the false positive rate was resolved as a result of changing the V2/SOFTEN.VARIANCE changes. To correct this, I've run psphot on a sample of deep stacks that I constructed as part of the stack rejection improvements. The ipp-20130620 tag version of psphot was used, as it implements these changes. The image below illustrates the improvement. The top row shows the central portion (shown in the small cut-out in the center) of MD09/y/skycell.027 with the full set of inputs (left), and with just the 2009 inputs (right). In the full set of inputs, this region has a strong gradient in the number of inputs as the post-2009 data runs out, leaving only the 2009 inputs. Overplotted on these are the psphot detections with the ipp-20130620 tag. The full set has more detections, but the density of sources is similar to that in the 2009 only data, showing that there is no evidence of the large increase in false positives. To directly show this, the bottom left panel shows the same central region of the full set stack, but with the detections generated with the prior version of psphot. This clearly shows that as the number of inputs drops, the combination of the V2/SOFTEN.VARIANCE choices drives up the S/N of small spikes, resulting in a massive amount of false detections. |
