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.
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').
- Fermi-LAT gamma-ray observations of IceCube-230405A
- Konus-Wind detection of GRB 230405B
- GRB 230405B: AGILE detection
- GRB 230405B: Swift-XRT refined Analysis
- GRB 230405B: Fermi GBM Observation
- GRB 230405B: MeerLICHT upper limits
- IceCube Alert 230405.56: Global MASTER-Net observations report
- GRB 230307A: JWST NIRSpec observations, possible higher redshift
- GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
- GRB 230307A: good match with kilonova models
- GRB 230307A: short mininum variability timescale compatible with a merger origin
- GRB 230405B: Swift/UVOT Upper Limits
- GRB 230405B: AstroSat CZTI detection
- GRB 230405B: Enhanced Swift-XRT position
- Swift GRB 230405B: Global MASTER-Net observations report
- GRB 230405B: Prompt enhanced Swift-XRT position
- GRB 230405B: Swift detection of a burst
- GRB 230405B: Fermi GBM Final Real-time Localization
- GRB 230307A: JWST observations consistent with the presence of a kilonova
- Fermi GRB 230405A: Global MASTER-Net observations report
- IceCube-230405A: IceCube observation of a high-energy neutrino candidate
- GRB 230405A: Fermi GBM Final Real-time Localization
- GRB 230404A: AstroSat CZTI detection
- GRB 230404A: Fermi GBM Final Real-time Localization
- GRB 230402A: CALET Gamma-Ray Burst Monitor detection
- GRB 230402A: AstroSat CZTI detection
- Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
- IceCube-230401A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230328B: Multa observatory optical afterglow observation
- GRB 230307A: Chandra late-time detection of the X-ray afterglow
- GRB 230228A: detection by GTC of the potential host galaxy
- GRB 230328B: Swift/UVOT Detection
- GRB 230402A: AGILE detection
- Fermi GRB 230402A: Global MASTER-Net observations report
- GRB 230402A: Fermi GBM Final Real-time Localization
- IceCube-230401A: IceCube observation of a high-energy neutrino candidate
- GRB 230307A: Bad Time Intervals for Fermi GBM data
- GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
- GRB 230328B: CAHA 2.2m/CAFOS detection
- IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230328B: 3.6m DOT multiband optical observation
- Fermi trigger No 701883729: Global MASTER-Net observations report
- GRB 230330B: Fermi GBM Final Localization
- Konus-Wind detection of GRB 230328B
- GRB 230328B: GRBAlpha detection
- GRB 230330A: Fermi GBM Final Real-time Localization
- GRB 230328B: Swift-BAT refined analysis
- GRB 230328B: Nanshan/NEXT 2nd optical observation
- GRB 230328B NUTTelA-TAO / BSTI Early Measurements
- GRB 230328B: Liverpool Telescope afterglow detection
- GRB 230328B: OHP/T120 optical observations
- GRB 230328B: GIT optical follow-up
- GRB 230328B: OASDG optical observations
- GRB 230328B: Nanshan/NEXT optical upper limit
- GRB 230328B: Swift-XRT refined Analysis
- GRB 230328B: AstroSat CZTI detection
- GRB 230328B: Fermi GBM observation
- GRB 230328B: Mondy, AbAO and Kitab optical observations
- GRB 230328B: Enhanced Swift-XRT position
- GRB 230328B: Mondy optical afterglow confirmation
- GRB 230328B: Swift detection of a burst with an optical afterglow
- GRB 230328B: Fermi GBM Final Real-time Localization
- Fermi GRB 230328A: Global MASTER-Net observations report
- GRB 230328A: Fermi GBM Final Real-time Localization
- GRB 230325A: Swift-BAT refined analysis
- GRB 230325A: Swift/UVOT Upper Limits
- GRB 230325A: X-shooter optical afterglow and redshift
- GRB 230325A: Swift-XRT refined Analysis
- GRB 230322B: Swift-BAT refined analysis
- GRB 230325A: Enhanced Swift-XRT position
- GRB 230325A: Prompt enhanced Swift-XRT position
- GRB 230325A: Swift detection of a burst
- GRB 230320B: Fermi GBM Observation
- Fermi trigger No 701313046: Global MASTER-Net observations report
- Fermi trigger No 701321709: Global MASTER-Net observations report
- GRB 230322B: Swift/UVOT Detection
- Konus-Wind detection of GRB 230309A
- Konus-Wind detection of GRB 230308A
- Konus-Wind detection of GRB 230304B
- GRB 230322B: Swift-XRT refined Analysis
- GRB 230322B: Enhanced Swift-XRT position
- Swift GRB 230322B: Global MASTER-Net observations report
- GRB 230322B: Swift detection of a burst with optical counterpart
- GRB 230322A: Fermi GBM Final Real-time Localization
- GRB 230320B: GRBAlpha detection
- GRB 230321A: CALET Gamma-Ray Burst Monitor detection
- GRB 230320B: CALET Gamma-Ray Burst Monitor 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
- SGR 1806-20: Correction to GCN 33494
- INTEGRAL detection of a burst from SGR 1806-200
- GRB 230321B: AstroSat CZTI detection
- GRB 230320B: AstroSat CZTI detection
- GRB 230321A: BALROG localization (Fermi Trigger 701065308 / GRB 230321182)
- GRB 230321A: Fermi GBM Final Real-time Localization
- GRB 230320A: Fermi GBM Final Real-time Localization
- GRB 230314A: TURBO Optical Upper Limit