Introduction

GraceDB in context

GraceDB serves as a communications hub and as a database for storing and displaying information about candidate gravitational-wave events and related electromagnetic events:

_images/annotations_flow_white.png

The primary responsibilities of GraceDB are to:

  • ingest and store information about events
  • expose that information to users and followup robots
  • send alerts about each new piece of information

As such, GraceDB curates content from many sources, but does not itself produce any original scientific content. The service is mainly geared toward low latency data analysis and electromagnetic followup, but need not be used exclusively for those purposes. The diagram above depicts a typical sequence of events:

  1. An LVC data analysis pipeline detects an interesting candidate gravitational wave (GW) event and submits it to GraceDB.
  2. GraceDB sends an LVAlert message which notifies LVC followup robots of the new event.
  3. The followup robots perform analyses and report results back to GraceDB. These results accumulate on the candidate event’s page.
  4. Eventually, a designated EM approval robot forwards the event to GCN/TAN.
  5. Astronomers receive a GCN Notice for the new event, perform followup observations, and report coordinates via GraceDB.

Overview of components

GraceDB consists of the server (gracedb.ligo.org) and a set of client tools. Two user interfaces are available: the web interface for browser access (i.e., the one you are using now), and the REST API. These interfaces represent the information in GraceDB in different ways: the web interface naturally represents information as HTML pages, whereas the REST interface delivers JSON-serialized data.

The client tools (available via pip, SL6 or Debian packages, and source build, see Installing the client) provide a way to interact via the REST API. These tools include a Python client class with methods for all common GraceDB operations. There is also a gracedb executable for the command line with much of the same functionality.

The GraceDB API conforms to the RESTful principles of “uniform interface” and “resource-oriented architecture”.

Where can I go for help?

This documentation is not as great as it could be, but we are working on it. For help with issues not addressed here, please send mail to uwm-help@ligo.org.