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 251205A: Liverpool Telescope optical follow-up observations
- GRB 251203C: Swift/UVOT Upper Limit
- Konus-Wind detection of GRB 251118A
- GRB 251205A: Zeiss-1000 Koshka observatory optical observations
- GRB 251205A: COLIBRÍ optical observations
- GRB 251205A: GOTO optical afterglow detection
- GRB 251205A: NOT optical observations
- GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
- GRB 251205A: Enhanced Swift-XRT position
- Swift GRB 251205A : MASTER OT detection with host galaxy
- GRB 251205A: Swift detection of a burst with an optical afterglow
- Swift GRB251205A: Global MASTER-Net observations report
- GRB 251126B: Fermi GBM Final Localization
- GRB 251203A: Insight-HXMT/HE detection
- GRB 251203C: SVOM/ECLAIRs refined analysis
- SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
- GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
- GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251202A: SVOM/GRM observation
- GRB 251203A: GECAM-B observation of a burst
- GRB 251203A: SVOM/GRM observation
- GRB 251201B: SALT spectroscopic redshift z = 1.599
- GRB 251203C: J-band observations with WINTER
- GRB 251129B: Glowbug gamma-ray detection of a short burst
- GRB 251203A: AstroSat CZTI detection
- EP251130a: JinShan near-infrared observations
- Fermi Gamma-ray Burst Monitor trigger 786496343/251203967 is not a GRB
- GRB 251203C: LCO optical afterglow confirmation
- GRB 251203C: SVOM/VT optical counterpart
- GRB 251203C: EP-FXT follow-up observation
- GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
- GRB 251129B: GECAM-B observation of a burst
- GRB 251203B: Swift-XRT observations
- GRB 251203B: confirmation of a stellar flare by BOOTES-2
- GRB 251203B : SVOM trigger sb25120304 is not a GRB
- GRB 251203C: LCO optical upper limits
- GRB 251203B: LCO optical upper limits
- GRB 251203B: SVOM/VT optical observation
- GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
- GRB 251203C: SVOM detection of a burst
- SVOM GRB251203.77: Global MASTER-Net observations report
- SVOM GRB251203B: Global MASTER-Net observations report
- GRB 251203B: SVOM detection of a burst
- GRB 251129A / EP251129a: SVOM/VT optical color bluer
- GRB 251201B: Insight-HXMT/HE detection
- EP251202a / GRB 251202A: Insight-HXMT/HE detection
- EP251130a: MAO/AZT-22 optical observations
- GRB 251203A: Fermi GBM Final Real-time Localization
- EP251202a / GRB251202A: AstroSat CZTI detection
- GRB 251202A / EP251202a: SVOM/VT optical observation
- GRB 251201B: Fermi GBM Observation
- EP251202a/GRB 251202A: KAIT optical observations
- EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
- Fermi GRB 251202B: Global MASTER-Net observations report
- GRB 251202B: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 251129B (short/hard)
- GRB251129A/EP251129a: Swift UVOT detection
- GRB 251129B: AstroSat CZTI detection
- GRB 251202A: Fermi GBM Observation
- GRB 251202A: Swift/UVOT Detection
- GRB 251201B: Kilonova-Catcher optical afterglow detection
- GRB 251201B: Swift/UVOT Detection
- GRB 251130B: Glowbug gamma-ray detection
- GRB 251201B: GECAM-B observation of a long burst
- EP251130a: continued NOT optical observations indicate steep fading phase
- GRB 251122A/EP251122a: CrAO ZTSh optical observations
- Fermi-LAT Gamma-ray Observations of IceCube-251130A
- EP251202a / GRB 251202A: LCO r- and i-band optical detection
- GRB 251202A: GOTO optical afterglow detection
- EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
- GRB 251201A: GECAM-B observation of a burst
- GRB 251126A: SAO RAS optical marginal detection
- GRB 251202A: Swift-XRT afterglow detection
- EP251129a/GRB 251129A: NOWT Detection
- GRB 251126A: SVOM/VT optical observation
- EP251130a: SVOM/VT optical observation
- EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
- Fermi GRB 251202A: Global MASTER-Net observations report
- EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
- GRB 251201B: Swift-XRT refined Analysis
- IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
- EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
- GRB 251202A: Fermi GBM Final Real-time Localization
- GRB 251201A: SVOM/GRM observation of a burst
- GRB 251201B: SVOM/VT optical fading
- Swift GRB 251201B : MASTER optical counterpart detection
- GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
- Swift GRB 251201B: Global MASTER-Net observations report
- GRB 251201B: Enhanced Swift-XRT position
- EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
- GRB 251130B: AstroSat CZTI detection
- GRB 251201B: Swift detection of a burst with an optical counterpart
- GRB 251201B: Fermi GBM Final Real-time Localization
- EP251130a: Mondy optical observations
- EP251130a: Optical detections with Kinder observations
- SVOM GRB251201.19: Global MASTER-Net observations report
- EP251130a: SAO RAS optical observations
- EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
- EP251130a: KAIT optical observations
- EP251130A: Optical observation from 1.3m DFOT