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"35943 results found.
- GRB 260607B: AstroSat CZTI detection
- GRB 260608A: SVOM detection of a burst
- GRB 260608A: Fermi GBM Final Real-time Localization (duplicate submission)
- GRB 260608A: Fermi GBM Final Real-time Localization
- 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 260604C: Mondy optical observations: evidence of a possible brightening
- 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 260605A: Insight-HXMT/HE detection
- GRB260603A: SVOM/ECLAIRs refined analysis
- GRB 260604A: Glowbug gamma-ray detection
- GRB 260604C: LCO optical upper limit
- GRB 260604C: Liverpool Telescope optical detection
- GRB 260601B / EP260601a: AstroSat CZTI detection
- GRB 260527A/EP260527a: 6 GHz VLA observations
- GRB 260604C: GOTO detections of the optical afterglow
- GRB 260604C: Correction to GCN 44828
- 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
- GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
- 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 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
- GRB 260604A: Fermi GBM Final Real-time Localization
- GRB 260603B: Fermi GBM Final Localization
- Konus-Wind detection of GRB 260601B/EP260601a
- GRB 260603A: EP-FXT follow-up observation
- EP260601a/GRB 260601B: EP-FXT follow-up observation
- GRB 260601B / EP260601a: Mondy optical upper limit
- GRB 260601B/EP260601a: Glowbug gamma-ray detection
- GRB 260603A: Kilonova-Catcher optical upper limit
- GRB 260603A: SVOM/VT optical observations
- GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
- GRB 260601A: SVOM/GRM observation of a short burst
- GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
- GRB 260603A: SVOM detection of a burst
- GRB 260601B/EP260601a: Insight-HXMT detection
- 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 260601B/EP260601a: J-band upper limit with WINTER
- EP260530a/AT 2026nwl: KAIT optical observations
- GRB 260602A: Fermi GBM Final Real-time Localization
- GRB 260601B: CALET Gamma-Ray Burst Monitor detection
- GRB 260601B / EP260601a: NuSTAR detection of prompt emission
- GRB 260601B/EP260601a: SVOM/VT optical observations
- GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
- GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
- GRB 260601A: Glowbug gamma-ray detection of a short burst
- GRB 260531B: Glowbug gamma-ray detection
- GRB 260516D: VLA radio detection
- GRB 260601A: Fermi GBM Observation
- GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
- GRB 260527A/EP260527a: Glowbug gamma-ray detection
- Fermi GRB 260601A: Global MASTER-Net observations report
- GRB 260601A: Fermi GBM Final Real-time Localization
- GRB 260531B: GECAM-B observation
- GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
- GRB 260531C: Fermi GBM Final Localization Correction
- Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
- GRB 260531B: Fermi GBM Final Real-time Localization
- GRB 260531A: MAXI/GSC detection
- AT 2026nuz: COLIBRÍ optical observations
- IPN triangulation of GRB 260527A / EP260527a
- EP260527a/GRB 260527A: further FTW optical and NIR observations
- GRB 260530B: SVOM/GRM detection of a possible bright short GRB
- GRB 260530A: Fermi GBM Final Real-time Localization
- GRB 260527A / EP260527a: VLA radio detection
- EP260527a/GRB 260527A: optical upper limit with Kinder observations
- GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
- GRB 260529A: GOTO tentative optical afterglow candidate
- GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
- GRB 260527A/EP260527a: Insight-HXMT detection
- Fermi GRB 260529A: Global MASTER-Net observations report
- GRB 260529A: Fermi GBM Final Real-time Localization
- GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
- EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart