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 251209A: NuSTAR detection of prompt emission
- EP251212a : COLIBRÍ optical upper limit
- EP251212a: Einstein Probe detection of an X-ray transient
- Fermi-LAT Gamma-ray Observations of IceCube-251210A
- IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
- Fermi GRB 251211B: Global MASTER-Net observations report
- GRB 251211B: Fermi GBM Final Real-time Localization
- IceCube-251210A: DDOTI Optical Upper Limit
- SVOM GRB251211.12: Global MASTER-Net observations report
- GRB 251211A: Fermi GBM Final Real-time Localization
- GRB 251209A: Fermi GBM observation
- GRB 251205A: 1.3m DFOT optical upper limit
- GRB 251209A: AstroSat CZTI detection
- IceCube Alert 251210.46: Global MASTER-Net observations report
- IceCube-251210A - IceCube observation of a high-energy neutrino candidate track-like event
- EP251124a: Mondy optical upper limit
- GRB 251129A/EP251129a: AbAO and Mondy optical observations
- EP251130a: Mondy and AbAO optical observations
- GRB 251208A: AstroSat CZTI detection
- Fermi GBM Sub-Threshold Detection of GRB 251205A
- GRB 251208A: Glowbug gamma-ray detection
- GRB 251208B: COLIBRÍ optical upper limits
- EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
- GRB 251208C: GECAM-B observation of a short burst
- GRB 251208A: GECAM-B observation of a short burst
- Fermi GRB 251209A: Global MASTER-Net observations report
- Fermi GRB 251208C: Global MASTER-Net observations report
- GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251208B: Swift-XRT afterglow detection
- GRB 251208D: LAST optical upper limit
- GRB 251209A: Fermi GBM Final Real-time Localization
- GRB 251208D: LCO analysis of the XRT sources
- GRB 251208B: Fermi GBM Observation
- GRB 251208B: GROWTH-India Telescope optical upper limits
- GRB 251205A: J-band detection with WINTER
- GRB 251208D: Swift-XRT observations
- GRB 251208A: SVOM/GRM observation of a short burst
- GRB 251208C: SVOM/GRM observation of a short burst
- GRB 251129A: e-MERLIN C-band observations
- LAT GRB251208.43: Global MASTER-Net observations report
- GRB 251205A: Liverpool Telescope further optical follow-up observations
- GRB 251208D: LCO optical upper limits
- SVOM GRB251208D: Global MASTER-Net observations report
- GRB 251208B: Swift ToO observations
- GRB 251208B: Fermi-LAT detection
- GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
- GRB 251208D: SVOM possible detection of a faint burst
- GRB 251206A: SVOM detection of a burst through offline search
- GRB 251208C: Fermi GBM Final Real-time Localization
- GRB 251205A : MITSuME Akeno optical afterglow candidate detection
- GRB 251208B: Fermi GBM Final Real-time Localization
- GRB 251208A: Fermi GBM Final Real-time Localization
- GRB 251205A: FTW optical and NIR observations
- EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
- GRB 251205A: Liverpool Telescope further optical follow-up observations
- SVOM GRB251206.86: Global MASTER-Net observations report
- EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
- The EP-WXT trigger 01709249380 is likely a flaring star
- GRB 251205A: ZTF and ATLAS optical afterglow detections
- GRB 251205A: GROWTH-India Telescope optical observations
- GRB 251205A: Swift-BAT refined analysis
- GRB 251205A: Swift-XRT refined Analysis
- GRB 251205A: Swift/UVOT Detection
- 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