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"19 results found.
- GRB 250920B: AstroSat CZTI detection
- GRB 250920B: AbAO optical upper limits
- GRB 250920B: CrAO ZTSH optical observations
- GRB 250920B: SAO RAS optical observations
- GRB 250920B: NIR observations with WINTER
- Konus-Wind detection of GRB 250920B
- GRB 250920B: Glowbug gamma-ray detection
- GRB 250920B: Asiago optical observations
- GRB 250920B: Kitab-ISON optical upper limit
- GRB 250920B: Swift-BAT refined analysis
- GRB 250920B: Fermi GBM Observation
- GRB 250920B: Swift/UVOT Detection
- GRB 250920B: FTW optical and NIR observations of the counterpart
- GRB 250920B: Enhanced Swift-XRT position
- GRB 250920B: Swift-XRT refined Analysis
- GRB 250920B: SVOM/C-GFT optical observations
- Swift GRB 250920B: Global MASTER-Net observations report
- GRB 250920B: Swift detection of a burst with a bright optical counterpart.
- GRB 250920B: Fermi GBM Final Real-time Localization