You can obtain DASCH data through several different channels: daschlab, the DASCH web APIs, or Starglass. The legacy “Cannon” data portal is still available, but its use is strongly discouraged. Whatever method you use, you are urged to join the DASCH Astrophysics email list to ensure that you can join in discussions relating to DASCH data analysis.
The DR7 documentation describes the official DASCH data products. See also the DR7 summary of known issues.
If you make use of DASCH data in scholarly work, you should properly cite and acknowledge DASCH.
daschlab
For DR7, the DASCH team has introduced a new system for accessing and analyzing DASCH data: a Python toolkit called daschlab. Cloud-based notebooks allow you to perform basic data retrievals and analysis with minimal need to understand Python and no required software installation. See the DR7: Getting Started section to, well, get started.
daschlab is now the recommended framework for retrieval and analysis of DASCH astronomical data.
Web APIs
Underlying daschlab are an assortment of web API endpoints that can be used to retrieve DR7 data. In many cases, daschlab is really only a thin layer on top of these APIs, which use a standard JSON-oriented, RESTful paradigm. The DR7 Web APIs page documents them and provides links to additional resources.
Starglass
The Starglass website provides a user interface and a programmatic API allowing access to DASCH plate-level data products and queries. While Starglass does not provide access to DASCH lightcurve data, it does provide plate photographs and full-plate FITS “mosaics”. If you sign up for a Starglass user account, you can obtain an API key allowing you to make requests, including mosaic retrievals, with much higher rate limits than are allowed for anonymous clients. Visit the Starglass site to see what it holds.
The web APIs that support Starglass are implemented in the same framework as the ones that support DASCH DR7 scientific data access. In addition to the resources linked above, you may wish to read the Starglass API docs to learn how to fetch data from Starglass systematically.
“Cannon” Data Portal
Alongside daschlab and Starglass, you can also access DASCH data through the classic “Cannon” data portal.
Use of the Cannon portal is strongly discouraged. Among other limitations, it only provides machine-readable data tables with difficulty at best, and its lightcurve display tool can produce misleading results. Harvard staff will attempt to keep the website running in good working order to the extent possible, but it may disappear without warning.
That being said, if you have not yet migrated to the preferred data access tools, the Cannon portal provides two main search mechanisms:
Data Access Restrictions
Historically, only subsets of DASCH data were accessible to the general public. As of 2024, all DASCH data access restrictions have been lifted.