GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"- GRB 261104A: SVOM/ECLAIRs refined analysis
- EP261105a: LCO optical upper limits
- GRB 261104A: SVOM/VT optical upper limits
- EP261105a: SVOM/VT optical candidate
- IPN triangulation of GRB 261029C (short / bright)
- IPN triangulation of GRB 261025B (short)
- GRB 261103A: SVOM/C-GFT optical upper limit
- IPN triangulation of GRB 261024A
- EP261105a: Einstein Probe detection of an X-ray transient
- GRB 261104A: LCO optical upper limits
- EP261015a/SN 2026ahoa: MMT optical counterpart detection
- SVOM GRB261104.86: Global MASTER-Net observations report
- EP241208a: SVOM/ECLAIRs refined analysis
- GRB 261104A: SVOM detection of burst
- GRB 260924A: CrAO ZTSh optical observations
- EP261103a: NTT optical observation
- GRB 261029A : MITSuME Akeno optical afterglow detection
- GRB 261030C: AstroSat CZTI detection
- EP261103a: SVOM/VT optical observation
- EP261103a: BOOTES-6/DPRT early optical upper limits
- EP261103a: NOT optical counterpart candidate
- EP261103a: Einstein Probe detection of an X-ray transient
- GRB 261029A: VST/OmegaCAM detection of the optical afterglow at 3 days
- EP Alert 261103.85: Global MASTER-Net observations report
- GRB 261029A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
- GRB 261103A: LCO optical upper limits
- GRB 261103A: SVOM/ECLAIRs detection of a burst through on-ground search
- Konus-Wind detection of GRB 261029A
- EP Alert 261102.98: Global MASTER-Net observations report
- EP-WXT trigger 01709322206: confirmation of a stellar flare by BOOTES-5
- GRB 261029A: SAO RAS optical observations
- The EP-WXT trigger 01709322206 is likely a flaring star
- EP261015a/SN 2026ahoa: VLT/FORS2 discovery of a pre-peak type Ic-BL supernova at a tentative spectroscopic redshift z=0.31
- GRB 261102A: Fermi GBM Detection
- GRB 261029C: AstroSat CZTI detection of a short burst
- GRB 261102A: Fermi GBM Final Real-time Localization
- GRB 261101B: BALROG localization (Fermi Trigger 815240277 / GRB 261101651)
- GRB 261101B: Fermi GBM Final Real-time Localization
- EP261030a: EP-FXT follow-up observation
- EP261030a: GROWTH-India Telescope Upper Limit
- GRB 261101A: Fermi GBM Final Real-time Localization
- EP261030a: Global MASTER-Net observations report
- EP261030a: Einstein Probe detection of a fast X-ray transient
- GRB 261030A: Fermi GBM Detection
- Fermi GRB 261030B: Global MASTER-Net observations report
- GRB 261030B: Fermi GBM Final Real-time Localization
- GRB 261029A: SVOM/ECLAIRs refined analysis
- The EP-WXT trigger 01709321980: KAIT confirmation of a stellar flare
- GRB 261030A: BALROG localization (Fermi Trigger 815070447 / GRB 261030686)
- GRB 261030A: Fermi GBM Final Real-time Localization
- GRB 261029A / AT 2026ahaw: Optical upper limits from the PKU 60cm Telescope
- GRB 261029A: Glowbug gamma-ray detection
- GRB 261024D: SVOM/GRM observation
- GRB 261026A: Mondy, SAO RAS and Terskol optical observations
- GRB 261029A : SVOM/GWAC-F60 observations
- GRB 261029A: GECAM-B detection of a bright burst
- EP-WXT trigger 01709321980: confirmation of a stellar flare by BOOTES-5
- The EP-WXT trigger 01709321980 is likely a flaring star
- EP Alert 261030.22: Global MASTER-Net observations report
- GRB 261029A: WFST optical observations
- GRB 261029A: ULL-ASTRO-MASTER observations with LCO 1-m telescope at Siding Spring Observatory
- GRB 261029A: Ondrejov D50 optical observations, possible rebrightening
- GRB 261029A: Liverpool Telescope observations
- GRB 261029A: NuSTAR detection of bright prompt emission
- GRB 261029A: Optical detection with 60cm Panzhihua Telescope
- GRB 261029A: Fermi GBM Observation
- GRB 261029A: FRAM-ORM and FRAM-Auger optical afterglow light curve
- GRB 261029A: SVOM/GRM observation of a bright burst
- GRB 261029A: CALET Gamma-Ray Burst Monitor detection
- IPN triangulation of GRB 261024D
- GRB261029A: Infrared fading detected with MDM/MIRAGE
- GRB 261029A: SVOM/VT optical observation
- GRB 261029B : AstroSat CZTI detection
- GRB 261029A / AT2026ahaw: r- and i-band optical follow-up with the PKU 60cm Telescope
- GRB 261029A : AstroSat CZTI detection
- GRB 261029A: SVOM/C-GFT optical observations
- EP261010a: Xinglong optical follow-up
- GRB 261029A: EP-FXT follow-up observation
- GRB 261029A: Fermi-LAT detection
- GRB 261029A: LCO optical observations (correction to GCN 46082)
- GRB 261029A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 261029A: LCO optical observations
- GRB 261029A: NOT imaging and spectroscopic redshift z = 3.27
- GRB261029A: Early infrared detection with MDM/MIRAGE
- GRB 261029A: KAIT optical observations
- GRB 261029A: TRT optical observations
- EP261006a / AT 2026aetp: Xinglong 2.16-m optical follow-up
- EP261025a: EP-FXT follow-up observations
- GRB 261029B: Fermi GBM Final Real-time Localization
- GRB 261028B / MAXI J1609-487: MAXI GSC detection
- GRB 261029A: GOTO optical counterpart candidate
- GRB 261029A: SVOM detection of a burst
- GRB 261029A: Fermi GBM Final Real-time Localization
- GRB 261021A: Glowbug gamma-ray detection
- GRB 261028A: Fermi GBM Final Localization
- GRB 261026A: SVOM/ECLAIRs refined analysis
- GRB 261024C: GECAM-B observation
- GRB 261026B: AstroSat CZTI detection
- GRB 261024D: Insight-HXMT/HE detection
- GRB261026A: Infrared detection with MDM/MIRAGE