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"23406 results found.
- GRB 260310A / AT2026fgk: Late-time Chandra Detection
- GRB 260714B: COLIBRÍ optical counterpart candidate
- sb26071506: SVOM detection of a X-ray transient
- EP260703a: SVOM/ECLAIRs Upper Limit
- GRB 260709A: AstroSat CZTI detection
- GRB 260714B: AstroSat CZTI detection
- GRB 260714B: Fermi GBM Detection
- IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
- EP260713a: Einstein Probe detection of an X-ray transient
- EP260623a: KAIT optical observations
- EP260711a: EP-FXT follow-up observation
- GRB 260708A: GRANDMA Optical Observations
- GRB 260708A: LCO optical observations
- EP260711a: Einstein Probe detection of an X-ray transient
- GRB 260710A: Fermi GBM Detection
- GRB 260709A: SVOM/GRM detection
- IceCube-260708A: Observations with the Vera C. Rubin Observatory
- EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
- GRB 260708A: Glowbug gamma-ray detection
- GRB 260706A : GRANDMA Upper limits
- GRB 260708A: Kilonova-Catcher optical afterglow detection
- IceCube-260708A: One candidate from the Zwicky Transient Facility
- Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
- GRB 260705B: SVOM/GRM observation
- GRB 260706A: Further EP-FXT follow-up observation
- EP260707a (by EP-FXT): NOT optical upper limit
- EP260707a is not a real source
- EP260707a: LCOGT Optical Upper Limit
- EP260707a: TRT optical upper limit
- EP260707a: Einstein Probe detection of an X-ray transient
- GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
- GRB 260705C: Glowbug gamma-ray detection of a short burst
- GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
- GRB 260706A: REM optical/NIR observations
- GRB 260706A: LCO optical upper limit
- IPN triangulation of GRB 260627A
- IceCube260704A: OHP/T193 optical observations
- GRB 260705A: LCO optical upper limits
- GRB 260704A: NOT optical upper limits
- GRB 260629A: SVOM/GRM observation of a short burst
- GRB 260704A: SVOM detection of a possible GRB
- EP260703a: EP-WXT detection of a fast X-ray transient
- EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
- GRB 260623A: Glowbug gamma-ray detection
- GRB 260614B: ATCA Radio Upper Limits
- EP260628a: EP-WXT detection of a fast X-ray transient
- EP260626a: further Liverpool Telescope optical upper limits
- EP260626a: COLIBRÍ optical upper limit
- EP260626a: Liverpool Telescope upper limits
- EP260626a: EP-WXT detection of a fast X-ray transient
- EP260623a: TNG NIR afterglow detection
- EP260623a: Liverpool Telescope optical observations
- EP260623a:refined analysis of the EP-WXT and EP-FXT observation
- EP260623a: WINTER J-band observations
- GRB 260617A: Glowbug gamma-ray detection of a short burst
- IPN triangulation of GRB 260605A
- EP260623a: Optical follow-up observations with Kinder
- EP260623a: SVOM/VT optical observations
- EP260623a: TRT optical observations
- EP260623a: REM optical/NIR afterglow detection
- EP 260623a: COLIBRÍ optical observations
- EP260623a: Las Cumbres discovery of the optical counterpart
- EP260623a: Einstein Probe detection of an X-ray transient
- EP260618a: Liverpool Telescope optical observations
- GRB 260618B: LCO optical observations
- EP260618a: JinShan optical observations
- GRB 260616B/EP260616a: SVOM/GRM detection of a burst
- GRB 260619A: TRT optical counterpart confirmation
- GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
- GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- Konus-Wind detection of GRB 260617A
- GRB 260616B: AstroSat CZTI detection
- GRB 260616A: AstroSat CZTI detection
- GRB 260616A: SVOM/GRM observation
- EP260618a: OHP/T193 optical observations
- GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
- GRB 260619A: Kilonova-Catcher optical upper limit
- EP260618a: EP-FXT follow-up observation
- EP260618a: LCO optical counterpart confirmation
- EP260618a: COLIBRÍ optical counterpart candidate
- GRB 260619A: SVOM possible detection of a faint burst
- IPN triangulation of GRB 260617A (short)
- EP260618a: EP-WXT detection of an X-ray transient
- GRB 260610B: AbAO optical observations
- GRB 260506B: cubesat Avion detection
- EP260616a/GRB260616B: COLIBRÍ optical upper limit
- GRB 260616A: GECAM-B observation
- GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
- GRB 260429A: cubesat Avion detection
- GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
- GRB 260614A: AstroSat CZTI detection
- EP260616a: EP-WXT detection of a fast X-ray transient
- GRB 260610B: Terskol optical observations
- GRB 260610B: SVOM/GRM observation
- GRB 260614B: SVOM/VT optical candidate from VHF data
- GRB 260614B: SVOM detection of a burst
- GRB 260611B: SVOM/GRM detection
- GRB 260610B: further Liverpool Telescope optical observations
- GRB 260610B / AT2026owq: GRANDMA optical observations
- GRB 260610B / AT2026owq: further SAO RAS optical observations