| | 20 | * This was another week working on psphotStack. Progress was finally made on the memory usage problem. The primary issue is that in busy skycells (near the galacitc plane or containing a globular cluster) many large footprints that contain many sources are being created. In the merge process, where the "missing" sources found in one filter but not in another are prepared for forced photometry analysis, these footprints were being copied for each "missing" source. Since some of these were so large - as big as the input images - and complex - hundreds of thousands of spans, and contained tens of thousands of sources, these consumed all memory and swap space. Implemented a cache so only one copy is made for each input and this eliminatedd. However there are certain places in the code which handle these large footprints sub-optimally. For one skycell in the galactic plane it took about 18 hours to complete the analysis. But it did complete. |
| | 21 | * Another issue that needs to be resolved is duplicate sources being reported at the position of sources found in pass 1 of the psphot analysis. I found several cases where isolated stars were detected in pass 1, and another weak source was detected in pass 2 which finds detections on an image where the pass 1 sources have been subtracted off. During the psphot matching stage sometimes a perfectly good star is matched with the perfectly good star in other filters, but sometimes one good detection gets matched with the pass 2 source. Thus in the output we will have 2 sources with very different measurements in the different filters. |
| | 22 | * Added a feature to the postage stamp extractor program to return an entire copy of the input image. This is useful for two reasons. |
| | 23 | * The LAP stacks are stored with ASIN scaling of the pixel values. The output from ppstamp is linear scaling so it "undoes" that which is useful for examining stack images. |
| | 24 | * The stamp outputs for chip stage replace the inaccurate WCS solution from the telescope, with the astrometric solution from the camera stage. |
