106.2. Use query results as user uploads for cross-matching

For the Portal Aspect of the Rubin Science Platform at data.lsst.cloud.

Data Release: Data Preview 2

Last verified to run: 2026-09-10

Learning objective: How to use TAP query results as a custom table in a subsequent query.

LSST data products: Object table

Credit: Originally developed by the Rubin Community Science team. Please consider acknowledging them if this tutorial is used for the preparation of journal articles, software releases, or other tutorials. DOI: 10.11578/rubin/dc.20250909.20

Get Support: Everyone is encouraged to ask questions or raise issues in the Support Category of the Rubin Community Forum. Rubin staff will respond to all questions posted there.

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1. Log in to the RSP and enter the Portal Aspect. In a web browser go to data.lsst.cloud, select the Portal Aspect, and log in.

2. Select Multi-archive TAP tab. On the Portal landing page, click on the menu icon (three horizontal lines at upper left) to open the sidebar menu. Under “Other archive searches,” select “Multi-archive TAP” if it is not already in your default tab list.

Figure 1: A portion of the sidebar menu in the Portal Aspect, showing available options for archive searches.

3. Query using Gaia TAP service. Select the Gaia TAP service from the drop-down menu next to “Select TAP service” near the top left and ensure gaiadr3.gaia_source table is selected from the “Tables” drop-down menu. Under the “Spatial” section, as an example, enter “225, -40” for coordinates and set the search radius to 0.5 degrees. At the bottom left, click the blue button named “Search”.

4. Upload the TAP query result as a custom table. In the results interface, click the “Actions” icon (circled in Figure 2) and select the “Use table as an upload to TAP search” option.

Figure 2: A screenshot showing available action items when clicking the “Actions” icon.

5. Switch to the Rubin TAP service. Once the query result is successfully uploaded as a custom table, the result interface is switched to the “Multi-archive TAP” tab and the custom table appears under the “Spatial” section. Switch to the Rubin TAP service by selecting “Rubin Tap” from the drop-down menu and ensure the Object table is selected.

Figure 3: The expected view of the Portal interface following the successful upload of a custom table and selection of the Rubin TAP service.

6. Use the custom table in a new TAP query. Under the “Spatial” section, ensure the position columns are set to ra and dec for the uploaded table, and coord_ra and coord_dec for the DP2 Object table. Set the search radius to 1 arcsecond to define a cross-matching tolerance. To include the photo_g_mean_mag and br_rp columns from the uploaded Gaia table in the final output, click the highlighted part next to “Rows: 45637” (circled in Figure 4). Select the two photometry columns from the pop-up window, and click “OK”. Finally, click “Search” in the lower-left corner of the page.

Figure 4: The Portal search interface fully configured prior to execution. The spatial cross-match parameters, the 1-arcsecond search radius, and the additional output columns from the uploaded Gaia table are properly set.

7. Review the results. The search returns ~100 matches from the user-uploaded table.