GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"12 results found.
- GRB 250917B: iTelescope T-26 upper limit
- GRB 250917B: Mondy and Zeiss-1000 SAO RAS optical observations, optical observations, afterglow candidate
- GRB 250917B: KAIT optical upper limit
- GRB 250917B: VLT/HAWK-I near-infrared observations
- GRB 250917B: Swift-BAT refined analysis
- GRB 250917B: Swift/UVOT Upper Limits
- GRB250917B: WFST optical observations
- GRB 250917B: Fermi GBM Observation
- GRB 250917B: Swift-XRT observations
- Fermi GRB 250917B: Global MASTER-Net observations report
- GRB 250917B: Swift detection of a short burst
- GRB 250917B: Fermi GBM Final Real-time Localization