DASCH “DRnext”

This page documents the data currently available through the DASCH data access services. These services are not versioned by data release, so the results of any queries or downloads will change as scanning proceeds and the data processing pipeline is updated. We refer to this “rolling data release” as “DRnext”.

Noteworthy changes in the data will be logged on the news page.

This documentation is under development along with the daschlab analysis toolkit. It is known to be incomplete. Please bear with us as we work to improve it, and email the DASCH Astrophysics email list with any requests, questions, or comments.

2024 July 25: Recent changes in daschlab include a necessary but disruptive rename of plates() to exposures(). Please migrate your notebooks. There is also now support for mitigating source splitting with the new function daschlab.lightcurves.merge(), demonstrated in the new HD 5501 tutorial below.

Getting Started: About DASCH DRnext

The Introduction to DASCH slide deck presents an overview of DASCH from an astronomer’s perspective.

View the slides

We recommend that astronomers retrieve and analyze DASCH data using Jupyter notebooks and the daschlab Python package. The Introduction to daschlab video gives an overview of what this is like.

Watch the video

The DRnext Scope document summarizes the contents of DRnext at a high level.

Read: Scope

The DRnext Data Products document lists the specific data products provided in DRnext.

Read: Data Products

Users of DASCH data are encouraged to subscribe to the DASCH Astrophysics email list for discussion and announcements.

Sign Up

Accessing and Using DASCH DRnext

Because the DASCH pipeline is always evolving, the available data may contain undocumented errors or limitations. Use them cautiously, and do not hesitate to reach out to the DASCH Astrophysics email list if you have any questions or concerns.

Likewise, the material here is, inevitably, provisional. If you find any inaccuracies, please bring them to the attention of the DASCH Astrophysics email list. For documentation that has been vetted but may be out-of-date, see the most recent snapshot data release: Data Release 6 (January 31, 2019).

Launch a cloud-based quicklook notebook to investigate a source. (Assumes familiarity with DASCH and daschlab.)

Open a Cloud Quicklook

The “Cannon” portal is the classical way to get DASCH data. daschlab and StarGlass are now recommended, but Cannon will be maintained indefinitely.

Go to the Cannon Portal

StarGlass is a portal for exploring the HCO plate collection. Among other features, it provides full-plate FITS mosaic downloads.

Go to StarGlass

For bulk data access, reach out to the email list.

Tutorials

If you’re not sure where to start, try a tutorial.

RY Cnc
This tutorial slide deck shows you how to recreate the daschlab analysis shown in the introductory video using a cloud-based notebook. If you’re running the software locally, you can download the notebook to your computer (right-click and “Save Link As” since GitHub just shows you the JSON).
HD 5501 - Handling Source Splitting
This tutorial notebook shows how to use daschlab to address the “source splitting” Known Issue. The link at left will launch a cloud-based version of the notebook, which might be slow. If you’re running the software locally, you can download the notebook to your computer (right-click and “Save Link As” since GitHub just shows you the JSON).

How-to Guides

Install daschlab
For substantial DRnext data analysis, you will probably want to install daschlab in your own computing environment. This guide explains how to do that.
Reduce Lightcurves
Recommended procedures for reducing DASCH lightcurve data.
Cite & Acknowledge DASCH
If you are writing a scholarly manuscript based on DASCH data, you should mention DASCH in the acknowledgments section and cite the relevant DASCH papers.

Explainers

These documents provide additional information about the DASCH DRnext data.

Known Issues
As with any survey, the DASCH data display various known issues. This page summarizes them and provides links to more in-depth discussions.
Legacy Data Guide
The Legacy Data Guide is an older document that is, frankly, quite confusing, but it contains details that have not yet been documented anywhere else. It may be helpful in deciphering obscure aspects of the DASCH data.
Pipeline Overview
An overview of DASCH data processing. Note: this document needs to be updated.
DASCH Data Access
A summary of different methods for accessing the DASCH data.

Reference Information

Lightcurve Columns
Definitions of columns in DASCH lightcurve tables, anchored to the naming conventions used by daschlab.
Exposure List Columns
Definitions of columns in DASCH exposure lists, anchored to the naming conventions used by daschlab.
(other table column definitions)
Not written yet! Ask on the email list.

daschlab API Docs
API reference documentation for the daschlab Python package.
StarGlass API Docs
Documentation of the StarGlass API, which can be used for automated retrieval of most DASCH data (but not lightcurves; for those, use daschlab).

Other Resources