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"18 results found.
- GRB 250920C: SALT redshift confirmation
- GRB 250920C: COLIBRÍ optical observations
- GRB 250920C: NIR observations with WINTER
- GRB 250920C: PRIME near-infrared detection
- GRB 250920C: Swift-XRT refined Analysis
- GRB 250920C: SVOM/GRM observation
- GRB 250920C: GTC/OSIRIS+ spectroscopic redshift z = 1.40
- GRB 250920C: GROWTH-India Telescope optical observations
- GRB 250920C: Swift-BAT refined analysis
- GRB 250920C: Enhanced Swift-XRT position
- GRB 250920C: Swift/UVOT Detection
- GRB 250920C: Fermi GBM Observation
- Swift GRB 250920C: Global MASTER-Net observations report
- GRB 250920C: Optical counterpart detection by LCO
- GRB250920C: LCOGT Optical Detection
- GRB 250920C: GOTO optical counterpart candidate
- GRB 250920C: Swift detection of a burst
- GRB 250920C: Fermi GBM Final Real-time Localization