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"27015 results found.
- GRB 260610B: SVOM/GRM observation
- GRB 260614B: SVOM/VT optical afterglow confirmation
- GRB 260614B: Fermi GBM Observation
- GRB 260614A: GECAM-B observation
- GRB 260614B: SVOM/VT optical candidate from VHF data
- GRB 260614B: SVOM detection of a burst
- GRB 260614B: Fermi GBM Final Real-time Localization
- GRB 260611B: SVOM/GRM detection
- GRB 260614A: Fermi GBM Final Localization
- The EP-WXT trigger 01709269488 is likely a flaring star
- GRB 260610B: further Liverpool Telescope optical observations
- GRB 260610B: Fermi GBM Observation
- GRB 260610B / AT2026owq: GRANDMA optical observations
- EP260605a: COLIBRÍ optical upper limits
- GRB 260610b: Liverpool Telescope optical observations
- EP260610b: Liverpool Telescope optical upper limits
- IceCube-260610A: EP-FXT follow-up observation
- GRB 260611B: CALET Gamma-Ray Burst Monitor detection
- The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
- GRB 260610B / AT2026owq: SVOM/VT optical observations
- GRB 260610B / AT2026owq: OASDG optical observations
- GRB 260610B / AT2026owq: SAO RAS optical observations
- GRB 260611B: Fermi GBM Final Real-time Localization
- EP260610b: GTC likely spectroscopic redshift z = 1.10
- GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
- The EP-WXT trigger 01709269176 is likely a flaring star
- EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
- GRB 260610B / AT 2026owq: COLIBRÍ optical observations
- EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
- GRB 260611A: Fermi GBM Final Real-time Localization
- EP260610b: COLIBRÍ optical observations
- GRB 260610B: DDOTI optical observations
- GRB 260610B: GOTO optical counterpart candidate
- GRB 260610B: Fermi GBM Final Localization
- EP260610b: SVOM/VT optical confirmation with blue color
- GRB 260515A: SOAR optical observations
- EP260610a: SVOM/VT optical upper limits
- EP260610b: Einstein Probe detection of an X-ray transient
- IPN triangulation of GRB 260601A (short/hard)
- GRB 260610A: Fermi GBM Final Real-time Localization
- EP260610a: COLIBRÍ optical upper limits
- EP260610a: Einstein Probe detection of a fast X-ray transient
- GRB 260609A: Fermi GBM Final Localization
- GRB 260608A: Fermi GRB Observation
- IPN triangulation of GRB 260601B / EP260601a
- GRB 260604C: SVOM/ECLAIRs refined analysis
- GRB 260608A: SVOM/ECLAIRs refined analysis
- GRB 260607B: GECAM-B observation
- GRB 260608C: Fermi GBM Final Real-time Localization
- GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
- GRB 260608B: Fermi GBM Final Localization
- GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
- GRB 260604C: SVOM/C-GFT upper limit
- GRB 260608A: SVOM detection of a burst
- GRB 260608A: Fermi GBM Final Real-time Localization
- EP260605a: EP-FXT follow-up observation
- GRB 260607A: TRT optical observations
- GRB 260604C: GRANDMA further observations
- GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
- GRB 260604A: SVOM/GRM detection
- GRB 260607B: Fermi GBM Observation
- GRB 260607B: Fermi-LAT detection
- GRB 260607B: Fermi GBM Final Localization Correction
- GRB 260604C: OPD1.6m - GRANDMA observations - detection
- GRB 260607A: Fermi GBM Final Real-time Localization
- GRB 260604C: GECAM-B observation
- GRB 260604C: 6 GHz VLA observations
- GRB 260604C: GRANDMA observations
- GRB 260604B: SVOM/GRM detection
- GRB260603A: SVOM/ECLAIRs refined analysis
- EP260605a: Einstein Probe detection of a fast X-ray transient
- EP260603a: COLIBRÍ optical upper limit
- GRB 260604C: LCO optical upper limit
- The EP-WXT trigger 01709267001 is likely a flaring star
- EP260602d: EP-FXT follow-up observation
- EP260602c: EP-FXT follow-up observation
- GRB 260527A/EP260527a: 6 GHz VLA observations
- GRB 260604C: Kilonova-Catcher optical afterglow detection
- GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
- The EP-WXT trigger 01709266798 is likely a flaring star
- GRB 260604C: Fermi GBM Observation
- EP260602d: J-band upper limit with WINTER
- EP260602b: J-band upper limit with WINTER
- Fermi GRB 260604C: Global MASTER-Net observations report
- Fermi GRB 260604C: Global MASTER-Net observations report
- SVOM GRB260604.85: Global MASTER-Net observations report
- GRB 260604C: SVOM detection of a long burst
- GRB 260604C: Fermi GBM Final Real-time Localization
- GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
- GRB 260603A: NOT optical observations
- GRB 260603A: Simeiz Zeiss-1000 optical upper limit
- GRB 260604B: Fermi GBM Final Real-time Localization
- GRB 260601A: CALET Gamma-Ray Burst Monitor detection
- EP260602a: EP-FXT follow-up observation
- EP260603a: Global MASTER-Net observations report
- EP260603a: Einstein Probe detection of a fast X-ray transient
- GRB 260604A: Fermi GBM Final Real-time Localization
- EP260602b: Liverpool Telescope observations
- EP260602a: Liverpool Telescope optical upper limits
- GRB 260603B: Fermi GBM Final Localization