DASCH Data Access

You can search and download the DASCH data products through the “Cannon” data portal.

These three interfaces let you do the following:

Search Plates
Locate plates by identifier or by sky location (using coordinates or object names); download plate imagery and metadata.
Search Lightcurves
Find and view lightcurves using coordinates or object names; download data tables, postage stamps.
Browse Logbooks
Browse and download photographs of the observing logs associated with the plates.

Note: temporary data access restrictions are in place to prevent crawlers from overloading the Cannon data portal. See below for how to request access.

At this time, the DASCH data are not versioned by data release — the portal will always deliver you the latest results. This means that the same query may yield different results as the DASCH data evolve. The DRnext overview page provides a best-effort summary of what is currently being served. See in particular the summary of known issues.

If you make use of DASCH data in scholarly work, you should properly cite and acknowledge DASCH.

If you’re interested in a specific plate, you can pull up its information directly:

Some of the main pieces of data documentation are:

Temporary Data Access Restrictions

The DASCH “Cannon” data access portal currently does not allow downloads of whole-plate FITS images to prevent webcrawlers from overloading the server. Tabular lightcurve data, image cutouts, photos, and plate metadata are all available.

Separately, the most recent formal data release, DR6, was restricted to data at galactic latitudes b > 0. At the moment, retrieval of sky-based data is still subject to this restriction.

Our goal is to make all products available for direct download as soon as possible. As of December 2023, a new cloud-based data portal with rate-limiting functionality is nearly ready for launch. Once it is running, we will migrate this site to source its data from there, allowing us to remove the file download restrictions. The new data portal will also enable us to provide more modern, standardized data access methods, including bulk downloads and API-based retrieval.

We intend to remove the DR6 spatial restriction as soon as we can validate that our recompiled data retrieval programs behave correctly.

In the meantime, data are available upon request to the technical contact. This isn’t one of those “please go away” situations — we really do want people to get their hands on the files! It’s just that the Cannon site isn’t sophisticated enough to handle wide-open web traffic.

Members of the DASCH team have access to the private version of the Cannon portal.