| | 52 | ==== DVO ==== |
| | 53 | Occasionally the DVO catalogs are made available to the community. These consist of calibrated measurements |
| | 54 | and object associations of individual exposures. We currently have no method of directly tracking in the |
| | 55 | IPP database whether or not the measurements for a particular exposure were "released" in a given DVO |
| | 56 | catalog or for remembering the results of the calibrations performed by the DVO programs. This information |
| | 57 | can be figured out from the DVO tables, but since they are subject to change this information can become |
| | 58 | "stale". |
| | 59 | |
| | 60 | ==== "Grand" Reprocessing ==== |
| | 61 | As time goes on and the algorithms of the IPP improve and the exposures are reprocessed from scratch. |
| | 62 | This is commonly known as the grand reprocessing. Internally the IPP team refers to this process for |
| | 63 | the 3Pi survey as "Large Area Processing". For the medium deep fields, the terminology has changed |
| | 64 | over time but the concepts are somewhat similar. |
| | 65 | |
| | 66 | The results of this processing are added to a new DVO database and from there into PSPS. We currently |
| | 67 | do not have an efficient method of tracking which sets of processed pixels went into a given PSPS database. |
| | 68 | |
| | 69 | ==== Various Test runs ==== |
| | 70 | We currently have no way of tracking which of the various processing runs are intended for end user use |
| | 71 | and those that are the results of testing. The postage stamp server currently attempts to work around this |
| | 72 | problem but the results have been mixed. By specifically identifying the data that should be released this |
| | 73 | problem will be solved. |
| | 74 | |
| | 75 | |
| | 76 | === Stacked Images === |
| | 77 | The warped images are combined to form stacked images. While for single frames the logical unit |
| | 78 | is the exposure, stacks are performed on areas of the sky we call skycells. A skycell has a tessellation ID |
| | 79 | and a skycell number. For example (RINGS.V3, skycell.1406.016) or (MD09.V3, skycell.042) |
| | 80 | |
| | 81 | Three types of stacks have been identified |
| | 82 | * Nightly Stacks - constructed from exposures on a single night |
| | 83 | * Reference Stacks - constructed from exposures with good image quality that provide good coverage of a region of the sky |
| | 84 | * Deep Stacks - constructed from virtually all "good" exposures for a given area of the sky |
| | 85 | |
| | 86 | For the medium deep surveys all three stack types are used. |
| | 87 | Deep Stacks provide the greatest sensitivity, while reference stacks are used as templates for difference imaging and science that requires the highest resolution. Nightly stacks are used for transient detection. |
| | 88 | |
| | 89 | For the 3PI survey the stacks are produced in the LAP processes. For the purposes of this discussion they are |
| | 90 | considered "Deep Stacks" even though they are made from significantly fewer input exposures. |
| | 91 | |
| | 92 | Right now the various "releases" of stacks are managed in an ad hoc manner. It is very difficult for a user |
| | 93 | without access to the IPP database and detailed knowlege of the schema to track what data corresponds |
| | 94 | to a particular release. |
| | 95 | |
| | 96 | === Difference Images === |
| | 97 | Management of difference images is a subject for further research and will be discussed later. |
