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.
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"12283 results found.
- GRB 260607B: Fermi GBM Observation
- GRB 260607B: Fermi-LAT detection
- GRB 260607B: Fermi GBM Final Localization Correction
- GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
- GRB 260604C: OPD1.6m - GRANDMA observations - detection
- GRB 260607A: Fermi GBM Final Real-time Localization (duplicate submission)
- GRB 260607A: Fermi GBM Final Real-time Localization
- GRB 260604C: GECAM-B observation
- GRB 260604C: 6 GHz VLA observations
- GRB 260604C: SAO RAS optical observations
- GRB 260604C: GRANDMA observations
- GRB 260604B: SVOM/GRM detection
- GRB 260604A: Glowbug gamma-ray detection
- GRB 260604C: LCO optical upper limit
- GRB 260604C: Liverpool Telescope optical detection
- GRB 260604C: GOTO detections of the optical afterglow
- GRB 260604C: Kilonova-Catcher optical afterglow detection
- GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 260604C: Jinshan optical observations
- GRB 260604C: Fermi GBM Observation
- GRB 260604C: LAST detection of optical counterpart candidate
- Fermi GRB 260604C: Global MASTER-Net observations report
- Fermi GRB 260604C: Global MASTER-Net observations report
- GRB 260604C: SVOM detection of a long burst
- GRB 260604C: Fermi GBM Final Real-time Localization
- GRB 260604B: Fermi GBM Final Real-time Localization
- GRB 260601A: CALET Gamma-Ray Burst Monitor detection
- GRB 260604A: Fermi GBM Final Real-time Localization
- GRB 260603B: Fermi GBM Final Localization
- Fermi trigger No 802141998: Global MASTER-Net observations report
- GRB 260601A: SVOM/GRM observation of a short burst
- Fermi GRB 260602B: Global MASTER-Net observations report
- Fermi GRB 260602B: Global MASTER-Net observations report
- GRB 260602B: Fermi GBM Final Localization
- GRB 260601A: GECAM-B observation of a short burst
- GRB 260602A: Fermi GBM Final Real-time Localization
- GRB 260601A: Glowbug gamma-ray detection of a short burst
- GRB 260531B: Glowbug gamma-ray detection
- GRB 260601A: Fermi GBM Observation
- Fermi GRB 260601A: Global MASTER-Net observations report
- GRB 260601A: Fermi GBM Final Real-time Localization
- GRB 260531B: GECAM-B observation
- GRB 260531C: Fermi GBM Final Localization Correction
- Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
- Fermi trigger No 801900520: Global MASTER-Net observations report
- GRB 260531B: Fermi GBM Final Real-time Localization
- AT 2026nuz: COLIBRÍ optical observations
- GRB 260530A: Fermi GBM Final Real-time Localization
- GRB 260529A: GOTO tentative optical afterglow candidate
- Fermi GRB 260529A: Global MASTER-Net observations report
- GRB 260529A: Fermi GBM Final Real-time Localization
- GRB 260526A: GECAM-B observation
- Fermi trigger No 801580882: Global MASTER-Net observations report
- GRB 260525A: AstroSat CZTI detection
- Fermi GRB 260526A: Global MASTER-Net observations report
- GRB 260526A: Fermi GBM Final Real-time Localization
- Fermi GRB 260525A: Global MASTER-Net observations report
- GRB 260525A: Fermi GBM Final Real-time Localization
- GRB 260523B: AstroSat CZTI detection
- GRB 260523B: GECAM-B observation
- Fermi GRB 260523A: Global MASTER-Net observations report
- GRB 260523B: Fermi GBM Final Real-time Localization
- GRB 260523A: Fermi GBM Final Real-time Localization
- GRB 260522A: Fermi GBM Observation
- GRB 260522B: NuSTAR detection of prompt emission
- GRB 260522B: Fermi GBM Final Real-time Localization
- GRB 260522A: GOTO optical upper limit
- Fermi trigger No 801135305: Global MASTER-Net observations report
- Fermi GRB 260522A: Global MASTER-Net observations report
- GRB 260522A: Fermi-LAT detection
- GRB 260522A: Fermi GBM Final Real-time Localization
- GRB 260511A: iTelescope T-75 optical detection
- GRB 260520B: SVOM/GRM observation
- GRB 260411B: TERI Gamma-ray detection
- GRB 260407A: TERI Gamma-ray detection
- GRB 260307A: TERI Gamma-ray detection
- GRB 251118A: TERI Gamma-ray detection
- GRB 251113A: TERI Gamma-ray detection
- GRB 260428A: TERI Gamma-ray detection
- GRB 260520B: Fermi GBM Final Localization
- GRB 260520A: Fermi GBM Final Localization
- GRB 260519D: Fermi GBM Final Localization Correction
- GRB 260519B: Fermi GBM Final Localization
- GRB 260519A: Fermi GBM Final Localization
- GRB 260421B: radio detection with the VLA
- GRID detection of GRB 260511A
- Fermi GRB 260516C: Global MASTER-Net observations report
- GRB 260516C: Fermi GBM Final Real-time Localization
- Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
- Fermi GRB 260516B: Global MASTER-Net observations report
- GRB 260516B: Fermi GBM Final Real-time Localization
- Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
- GRB 260516A: Fermi GBM Final Real-time Localization
- GRID detection of GRB 260507A
- GRB 260510C: Glowbug gamma-ray detection
- IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
- GRB 260511B: NOT optical observations
- Konus-Wind detection of GRB 260512A
- GRB 260510C: CALET Gamma-Ray Burst Monitor detection
- IPN triangulation of GRB 260512A