DM-31226: Add WCSFit task

.github/workflows/lint.yaml

@@ -13,7 +13,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v2
         with:
-          python-version: 3.7
+          python-version: "3.10"
 
       - name: Install
         run: pip install -r <(curl https://raw.githubusercontent.com/lsst/linting/main/requirements.txt)

doc/lsst.drp.tasks/tasks/lsst.drp.tasks.GbdesAstrometricFitTask.rst

@@ -0,0 +1,53 @@
+.. lsst-task-topic:: lsst.drp.tasks.GbdesAstrometricFitTask
+
+##########
+GbdesAstrometricFitTask
+##########
+
+``GbdesAstrometricFitTask`` fits an astrometric solution, or world coordinate system (WCS), for a series of visits.
+Sources in science images are matched with a reference catalog, which allows the fitting algorithm to break degeneracies in the astrometric model.
+The fit model is a series of mappings, which can include (but are not limited to) a per-detector polynomial mapping and a per-visit polynomial mapping.
+The fit is done using the `WCSFit` class from the `gbdes` package (https://github.com/lsst/gbdes/tree/lsst-dev), which is an implementation of the method described in Bernstein et al. (2017).
+
+This task requires source catalogs for the input images, a reference catalog, and a visit summary table, which provides a starting point for the WCS fit.
+The task produces the fitted WCSs, which are described in AST format and are held in `lsst.afw.table.ExposureCatalog`\s called `outputWcs`.
+The task also outputs a table for debugging, `outputCatalog`, which contains the sources used in the fit, along with their residuals with the best-fit model.
+
+.. _lsst.drp.tasks.GbdesAstrometricFitTask-summary:
+
+Processing summary
+==================
+
+``GbdesAstrometricFitTask`` runs this sequence of operations:
+
+#. Gathers information on the visit epochs, RAs and Decs, etc.
+
+#. Associates sources in science images and the reference catalog to make matched objects using a friends-of-friends algorithm.
+
+#. Uses the associated objects to fit the astrometric solution, which is a configurable sequence of mappings from the detector pixels to the sky.
+This uses `WCSFit` from the `gbdes` package (https://github.com/lsst/gbdes/tree/lsst-dev).
+
+#. Converts the internal astrometric mappings to AST format.
+The output is in the form of one `lsst.afw.table.ExposureCatalog` for each visit, with a row for each detector.
+The fit WCS is accessed by calling `getWCS()` on the catalog row corresponding to the desired visit and detector.
+
+.. _lsst.drp.tasks.GbdesAstrometricFit-api:
+
+Python API summary
+==================
+
+.. lsst-task-api-summary:: lsst.drp.tasks.GbdesAstrometricFitTask
+
+.. _lsst.drp.tasks.GbdesAstrometricFitTask-subtasks:
+
+Retargetable subtasks
+=====================
+
+.. lsst-task-config-subtasks:: lsst.drp.tasks.GbdesAstrometricFitTask
+
+.. _lsst.drp.tasks.GbdesAstrometricFitTask-configs:
+
+Configuration fields
+====================
+
+.. lsst-task-config-fields:: lsst.drp.tasks.GbdesAstrometricFitTask

python/lsst/drp/tasks/__init__.py

@@ -19,4 +19,5 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+from .gbdesAstrometricFit import *
 from .version import *  # Generated by sconsUtils