Enhance the ALeRCE broker to add LSST and solar system support via TAP

docs/data_services/alerce.rst

@@ -0,0 +1,83 @@
+ALeRCE: ZTF and LSST
+--------------------
+
+The ALeRCE data service queries the `ALeRCE <https://alerce.online/>`_ broker for objects from
+both ZTF and the Rubin Observatory's LSST. Choose the survey with the **Survey** field on the
+query form.
+
+How ALeRCE is queried
+*********************
+
+* **ZTF** searches use the ALeRCE REST API through the ``alerce`` Python client, as before.
+* **LSST** searches, and the classifier lists for both surveys, use ALeRCE's
+  `TAP service <https://tap.alerce.online/tap>`_ through ``pyvo``. The REST API can list LSST
+  objects, but it cannot yet filter them by classifier or list the LSST classifiers, and asteroid
+  (ssObject) searches need the MPC orbits that are only available through TAP.
+* **Light curves** for both surveys come from the REST API.
+
+If the TAP service is unavailable, the query form still loads without the classifier fields, and
+LSST searches report an error instead of failing the page.
+
+Searching for LSST objects
+**************************
+
+With **Survey** set to LSST, choose an **LSST Object Type**:
+
+``diaObject``
+    A static-sky transient or variable, for example a supernova candidate.
+
+``ssObject``
+    A known Solar System object, linked by the MPC to an orbit.
+
+The **Object ID** field takes a diaObjectId, an ssObjectId, or an asteroid designation such as
+``2010 WX64``. A designation is looked up in ALeRCE's copy of the MPC orbits, which takes about
+a second. Without an Object ID, the cone search, first and last detection MJD, and number of
+detections fields filter the search, as they do for ZTF. There are also three LSST-specific
+options:
+
+* **Classifiers** filter diaObjects by class and minimum probability, for example ``SN`` from
+  ``stamp_classifier_rubin_beta``. ssObjects are not offered here, because ALeRCE assigns every
+  known ssObject the asteroid class with probability 1 rather than classifying it.
+* **Max. Detection Time Span (days)** limits the time between the first and last detection.
+  Together with the stamp classifier's asteroid class, a span of less than a day finds candidate
+  new moving objects that are not yet linked to an ssObject.
+* **Max. Results**, **Sort By** and **Sort Order** control the size and order of the results.
+  When you filter by classifier, the limit applies to each classifier separately, and results
+  are sorted by probability by default.
+
+Each result links to the object's page on the ALeRCE Explorer.
+
+Creating targets
+****************
+
+* A **diaObject** becomes a sidereal target named by its diaObjectId, at ALeRCE's mean position.
+* An **ssObject** becomes a non-sidereal target named by its ssObjectId, with orbital elements
+  taken from its MPC orbit. Bound orbits use the ``MPC_MINOR_PLANET`` scheme; unbound ones use
+  ``MPC_COMET``. The target's aliases include its provisional designation and, where the MPC has
+  assigned them, its permanent number, name and any secondary designations. That way you can find
+  it under whichever name you know.
+
+Photometry
+**********
+
+LSST light curves report difference-image PSF fluxes in nJy. These are converted to AB
+magnitudes, with a zero point of 31.4, and their times are converted from TAI to UTC. Detections
+with zero or negative difference flux have no magnitude and are skipped. LSST photometry is
+recorded with the telescope ``Rubin`` and the instrument ``LSSTCam``.
+
+Updating the data for a target again leaves the photometry already stored unchanged, even if ALeRCE
+has since revised a measurement's uncertainty.
+
+Updating targets from other sources
+***********************************
+
+A target doesn't have to come from ALeRCE for ALeRCE to update its data. The data service finds
+the ALeRCE object from the target's name and aliases, in this order:
+
+#. A name that is already a ZTF object ID or an LSST diaObjectId/ssObjectId.
+#. A TNS name (e.g. ``SN 2025abc``), resolved to its ZTF or LSST internal name through TNS.
+   This needs the TNS data service to be configured; otherwise TNS names are skipped.
+#. An MPC designation (e.g. ``2010 WX64``), resolved to its LSST ssObjectId.
+
+This means, for example, that an asteroid target created from the MPC can pick up its LSST
+photometry.

docs/data_services/index.rst

@@ -7,6 +7,7 @@ Data Services
   :hidden:
 
   Add a data service <create_dataservice>
+  ALeRCE: ZTF and LSST <alerce>
   Available data services <../api/tom_dataservices/data_services>
   Data service views <../api/tom_dataservices/views>
 
@@ -20,4 +21,6 @@ A TOM Toolkit Data Service Module contains the logic for querying a remote broke
 
 :doc:`Data Service Modules <../api/tom_dataservices/data_services>` - Take a look at the supported Data Services.
 
+:doc:`ALeRCE: ZTF and LSST <alerce>` - Search ALeRCE for ZTF and LSST objects, including LSST asteroids, and ingest their light curves.
+
 :doc:`Data Service Views <../api/tom_dataservices/views>` - Familiarize yourself with the available Data Service Views.

pyproject.toml

@@ -72,6 +72,7 @@ dependencies = [
     "importlib-resources >=6.4.5,<6.5.0",
     "django-tasks (>=0.6.1,<0.7.0)",
     "alerce >=2.3.1,<3.0",
+    "pyvo >=1.5,<2",
 ]
 
 [tool.poetry]