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"
4713 results found.
- Fermi trigger No 701883729: Global MASTER-Net observations report
- GRB 230328B: GRBAlpha detection
- GRB 230328B: Nanshan/NEXT 2nd optical observation
- GRB 230328B NUTTelA-TAO / BSTI Early Measurements
- GRB 230328B: Liverpool Telescope afterglow detection
- GRB 230328B: GIT optical follow-up
- GRB 230328B: Nanshan/NEXT optical upper limit
- GRB 230328B: AstroSat CZTI detection
- GRB 230328B: Mondy, AbAO and Kitab optical observations
- GRB 230328B: Mondy optical afterglow confirmation
- Fermi GRB 230328A: Global MASTER-Net observations report
- GRB 230325A: Swift-BAT refined analysis
- GRB 230325A: Swift detection of a burst
- Fermi trigger No 701313046: Global MASTER-Net observations report
- Fermi trigger No 701321709: Global MASTER-Net observations report
- Swift GRB 230322B: Global MASTER-Net observations report
- GRB 230320B: GRBAlpha detection
- Fermi trigger No 701071944: Global MASTER-Net observations report
- GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
- Fermi GRB 230320A: Global MASTER-Net observations report
- Fermi GRB 230321A: Global MASTER-Net observations report
- Fermi trigger No 701058254: Global MASTER-Net observations report
- GRB 230321B: AstroSat CZTI detection
- GRB 230320B: AstroSat CZTI detection
- GRB 230314A: TURBO Optical Upper Limit
- Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
- Fermi trigger No 700976129: Global MASTER-Net observations report
- Fermi GRB 230316A: Global MASTER-Net observations report
- GRB 230304D: AstroSat CZTI detection
- IPN triangulation of GRB 230304B
- GRB 230313A: AstroSat CZTI detection
- GRB 230307A: Far off-axis NuSTAR detection of the GRB
- Fermi GRB 230314A: Global MASTER-Net observations report
- GRB 230307A: ATCA radio detection
- VZLUSAT-2 detection of SGR 1806-20
- GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
- AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
- Fermi GRB 230313A: Global MASTER-Net observations report
- GRB 230307A: soft X-ray detection with LEIA
- GRB 230309A: AstroSat CZTI detection of a bright long GRB
- Swift GRB230311.85: Global MASTER-Net observations report
- Swift GRB230311.83: Global MASTER-Net observations report
- Further improved IPN localization for GRB 230307A
- Swift GRB230311.81: Global MASTER-Net observations report
- GRB 230307A: SOAR/Goodman detection of the possible host galaxy
- Swift GRB230311.84: Global MASTER-Net observations report
- Swift GRB230311.82: Global MASTER-Net observations report
- TESS Detection of the Optical Afterglow of GRB230307A
- GRB 230310A: AstroSat CZTI detection
- GRB 230307A: GECKO optical observations and detections of the afterglow
- GRB 230307A: MAXI/GSC upper limit
- GRB 230307A: Gemini-South Confirmation of the Optical Afterglow
- Fermi GRB 230310A: Global MASTER-Net observations report
- GRB 230307A: AGILE/MCAL analysis
- GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
- GRB 230307A: Possible optical afterglow
- GRB 230307A: ASO-S/HXI detection
- GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
- GRB 230308A: AGILE/MCAL detection
- GRB 230307A: Upper limits from a neutrino search with IceCube
- Fermi GRB 230307A: Global MASTER-Net observations report
- GRB 230307A: VZLUSAT-2 detection
- Fermi GRB 230308A: Global MASTER-Net observations report
- GRB 230307A: Detection by GRBAlpha
- GRB 230305A: Detection by GRBAlpha
- GRB 230307A: AstroSat CZTI detection
- GRB 230307A: possibly the second highest GRB energy fluence ever identified
- GRB 230307A: AGILE/MCAL detection
- GRB 230307A: Fermi GBM Observation of a very bright burst
- Solar Orbiter STIX observation of GRB 230307A
- IceCube-230306A: Upper limits from a search for additional neutrino events in IceCube
- Fermi-LAT gamma-ray observations of IceCube-230306A
- GRB 230307A: GECAM detection of an extremely bright burst
- Fermi trigger No 699811746: Global MASTER-Net observations report
- IceCube-230306A - IceCube observation of a high-energy neutrino candidate
- IceCube Alert 230306.46: Global MASTER-Net observations report
- GRB 230304C: AstroSat CZTI detection
- GRB 230304B: AstroSat CZTI detection
- GRB 230304A: AstroSat CZTI detection
- GRB 230304B: Detection by GRBAlpha
- Fermi GRB 230301B: Global MASTER-Net observations report
- Fermi trigger No 699294715: Global MASTER-Net observations report
- GRB 230228A: OSN optical upper limit
- GRB 230227A: Fermi GBM Final Real-time Localization
- Fermi trigger No 699029364: Global MASTER-Net observations report
- GRB 230216A Mondy Observations
- IceCube-230220A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230216B: CALET Gamma-Ray Burst Monitor detection
- GRB 230216B: AstroSat CZTI detection
- Fermi trigger No 697904388: Global MASTER-Net observations report
- Fermi trigger No 697403223: Global MASTER-Net observations report
- Fermi trigger No 697396830: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor triggers due to recent activity of RX J0440.9+4431 (LS V +44 17)
- GRB 230205A: SVOM/C-GFT optical upper limit
- GRB 230205A: OHP/T193 optical observations
- GRB 230204B: Detection by GRBAlpha
- IceCube-230201A: BOOTES-4/MET Optical Upper Limits
- Fermi trigger No 697208885: Global MASTER-Net observations report
- GRB 230201B: TURBO Optical Upper Limits
- Fermi Gamma-ray Burst Monitor trigger 230203275 / 697098930 is not a GRB