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').
- Konus-Wind detection of GRB 240125A
- GRB 240205B: VLT/X-shooter redshift
- GRB 240205B: CALET Gamma-Ray Burst Monitor detection
- GRB 240205B: BOOTES-6 optical afterglow follow-up
- GRB 240205B: ATCA detection of radio counterpart
- GRB 240205B: REM detection of the optical/NIR afterglow
- GRB 240205B: Fermi GBM Observation
- GRB 240204A: AstroSat CZTI detection
- GRB 240204A: Mondy optical afterglow observations
- GRB 240204A : OHP/T193/T120 optical afterglow fading detection
- GRB 240205B: GECAM detection of a long burst
- GRB 240204A: Swift-BAT refined analysis
- GRB 240205B: Skynet Optical Afterglow Observations
- GRB 240205B: BOOTES-7 optical afterglow follow-up
- Fermi trigger No 728749569: Global MASTER-Net observations report
- GRB 240205B: MASTER OT J232550.14-550704.6 counterpart detection
- GRB 240205B: Swift detection of a burst
- GRB 240205B: Fermi GBM Final Real-time Localization
- Swift GRB240205.93: Global MASTER-Net observations report
- GRB 240204A: Fermi GBM Observation
- GRB 240205A: Fermi GBM Final Real-time Localization
- GRB 240204a: Liverpool Telescope optical afterglow detection
- GRB 240204A: Osservatorio Astronomico Nastro Verde upper limit
- IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
- Fermi Gamma-ray Burst Monitor trigger 728740048/240204491 is not a GRB
- Fermi trigger No 728796365: Global MASTER-Net observations report
- GRB 240204A: optical afterglow detection with LCOGT 1m telescopes at Sutherland and Teide Observatories
- GRB 240204A: Montarrenti Observatory optical observations
- GRB 240204A: Enhanced Swift-XRT position
- GRB 240204A: Mondy optical afterglow candidate
- Fermi Gamma-ray Burst Monitor trigger 728706420/240204102 is not a GRB
- Fermi GRB 240204A: Global MASTER-Net observations report
- Fermi trigger No 728706420: Global MASTER-Net observations report
- GRB 240204A: Swift detection of a burst
- IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 240204A: Fermi GBM Final Real-time Localization
- IceCube Alert 240204.38: Global MASTER-Net observations report
- Swift Trigger 1212791 is not an astrophysical event.
- Swift-BAT triggers 1212787, 1212789 are not astrophysical.
- GRB 230812B: Update on Bad Time Intervals for Fermi GBM data
- Konus-Wind detection of GRB 240124B
- Konus-Wind detection of GRB 240123C
- IPN triangulation of GRB 240124B
- GRB 240201A: AstroSat CZTI detection
- GRB 240129A: Fermi GBM Observation
- IPN triangulation of GRB 240125B (short)
- GRB 240129A: Swift/BAT-GUANO detection of a burst outside the coded FOV
- IPN triangulation of GRB 240125A (short)
- GRB 240128A: Glowbug gamma-ray detection
- GRB 240128A: Swift-XRT observations
- GRB 240128A: GRBAlpha detection
- GRB 240128A: Tiled Swift observations
- GRB 240128A: CALET Gamma-Ray Burst Monitor detection
- GRB 240128A: MAXI/GSC detection
- GRB 240125A: GRBAlpha detection
- Fermi GRB 240127A: Global MASTER-Net observations report
- GRB 240123C: GRBAlpha detection
- GRB 240122A: ATCA detection of radio counterpart
- GRB 240127A: Fermi GBM Final Real-time Localization
- IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
- GRB 240125A: CALET Gamma-Ray Burst Monitor detection
- Swift Trigger 1211211 and 1211212 are not astrophysical
- GRB 240125A: AstroSat CZTI detection of a short burst
- GRB 240124B: AstroSat CZTI detection
- GRB 240123C: AstroSat CZTI detection
- GRB 240125B: Fermi GBM Final Localization
- GRB240122A: PRIME near infrared detection
- GRB 240123B: Fermi GBM Observation
- GRB 240123A: Glowbug gamma-ray detection
- GRB 240125A (short): Glowbug gamma-ray detection
- GRB 240123B: Swift/BAT-GUANO detection of a long burst
- GRB 240123A: GRBAlpha detection
- IPN triangulation of GRB 240123C (short)
- Swift trigger 1210856 is not astrophysical
- Fermi-LAT gamma-ray observations of IceCube-240123A
- GRB 240123A: further SAO RAS optical observations
- GRB 240122B: CALET Gamma-Ray Burst Monitor detection
- GRB 240123A: Swift-BAT refined analysis
- IceCube Alert 240123.48: Global MASTER-Net observations report
- GRB 240123A: Mondy continued optical observations and the PL decay index
- GRB 240123A: SAO RAS optical observations
- GRB 240123A : MITSuME Akeno optical afterglow candidate detection
- Fermi/GBM trigger 727752941: BALROG analysis retraction
- GRB 240123A: Enhanced Swift-XRT position
- GRB 240124A?: BALROG localization (Fermi Trigger 727752941 / GRB 240124066)
- Fermi GRB 240123B: Global MASTER-Net observations report
- GRB 240122A: Swift/UVOT Upper Limits
- GRB 240123A: Swift-XRT refined Analysis
- GRB 240122A: BOOTES-2/TELMA optical upper limit and 1.5m OSN detection
- Fermi GBM Sub-Threshold Detection of GRB 240123A
- GRB 240123A: Mondy continued optical observations + correction of the GRB name in GCN 35605
- GRB 240123B: Fermi GBM Final Real-time Localization
- GRB 240118A: Swift/UVOT Upper Limits
- GRB 240122B: Glowbug gamma-ray detection
- GRB 240123A: Mondy optical afterglow observations
- IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
- Konus-Wind detection of GRB 240112A
- GRB 240123A: Swift detection of a burst with a possible optical counterpart
- Swift GRB240123.46: Global MASTER-Net observations report
- GRB 240122A: Swift-XRT afterglow detection