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').
- GRB 230506B: Swift-XRT refined Analysis
- GRB 230506C: Swift-XRT analysis
- GRB 230506C: Candidate afterglow observation by D50
- GRB 230506C: TSHAO possible afterglow candidate
- GRB 230506B: Swift/UVOT Detection
- IceCube-230506A: IceCube observation of a high-energy neutrino candidate
- GRB 230506C: Swift detection of a burst
- Swift GRB230506.71: Global MASTER-Net observations report
- GRB 230506B: Swift detection of a burst
- GRB 230506B: MASTER optical observations
- GRB 230506B: Swift detection of a burst
- GRB 230506A: Fermi GBM Final Real-time Localization
- GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
- Fermi trigger No 704837952: Global MASTER-Net observations report
- GRB 230430A: A short GRB from a neutron star merger
- GRB 230427A: Swift-BAT refined analysis
- GRB 230503A: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 230430A
- IceCube-Cascade 230430A: Upper limits from a search for additional neutrino events in IceCube
- IPN triangulation of GRB 230430A (short)
- GRB 230420A: AROMA-N Optical Upper Limit
- GRB 230430B: Fermi GBM Final Localization
- GRB 230430A: Fermi GBM observation
- GRB 230430A: AstroSat CZTI detection
- GRB 230430A: Fermi GBM Final Real-time Localization
- GRB 230427A: NOT optical upper limit
- GRB 230427A: TSHAO, SAO RAS, AbAO optical upper limit
- GRB 230427A: Swift/UVOT Detection
- Duplicate of GCN 33369
- GRB 230427A: Gaoyazi/GOT optical upper limit
- GRB 230427A: OHP/T193 spectroscopy observations of WISEA J101316.01+481158.7
- GRB 230427A: Nanshan/HMT optical upper limit
- GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
- GRB 230427A: OSIRIS+/GTC observations
- GRB 230427A: Swift-XRT refined Analysis
- GRB 230426A: VZLUSAT-2 detection
- Fermi trigger No 704365743: Global MASTER-Net observations report
- GRB 230428A: Fermi GBM Final Real-time Localization
- GRB 230427A: GIT optical upper limit
- GRB 230427A: Bassano Bresciano Observatory upper limit
- GRB 230427A: GMG upper limit
- GRB 230427A : OHP/T193 optical upper limit
- GRB 230427A: BOOTES-5/JGT afterglow detection
- GRB 230423A(trigger #1165354): Swift-BAT refined analysis
- GRB 230427A: AKO Upper Limit
- Swift GRB230427.44: Global MASTER-Net observations report
- GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
- GRB 230427A: MITSuME Akeno optical upper limits
- GRB 230426A: Fermi GBM Detection
- GRB 230427A: Enhanced Swift-XRT position
- GRB 230427A: Swift detection of a burst with an optical counterpart
- GRB 230426A: AstroSat CZTI detection
- Fermi trigger No 704233744: Global MASTER-Net observations report
- GRB 230426A: Fermi GBM Final Real-time Localization
- GRB 230423A: Swift/UVOT Upper Limits
- GRB 230425A: Fermi GBM Final Real-time Localization
- GRB 230423A: Swift-XRT refined Analysis
- GRB 230420A: Lowell Discovery Telescope Optical Detection
- GRB 230423A: Swift-XRT afterglow detection
- Erroneous submission
- Swift Trigger 1165354 is probably not a GRB
- GRB 221009A: Late-time JWST Observations and Detection of Supernova Emission
- GRB 230421A: Fermi GBM observation
- Konus-Wind detection of GRB 230418A
- GRB 230420A: Swift/UVOT Upper Limits
- GRB 230421: Swift/BAT-GUANO arcminute localization
- GRB230420A: VLT optical observation
- GRB 230420A: Swift-BAT refined analysis
- Duplicate of GCN 33668
- GRB 230421A: Fermi GBM Final Real-time Localization
- GRB 230420A: Swift-XRT refined Analysis
- GRB 230420A: MITSuME Akeno optical observation
- GRB 230420A: NOT optical afterglow confirmation
- GRB 230420A: Gaoyazi/GOT optical upper limit
- GRB 230420A: BOOTES-5/JGT optical afterglow detection
- GRB 230420A: LCOGT Optical Upper Limit
- GRB 230420A: Enhanced Swift-XRT position
- GRB230414B: VIRT Optical Upper Limit
- IPN triangulation of GRB 230418A (short)
- GRB 230420A: Swift detection of a burst
- GRB 230418A: AstroSat CZTI detection
- GRB 230418A: AGILE detection
- GRB 230402A: Fermi GBM detection
- GRB 230419A: Fermi GBM Final Real-time Localization
- GRB 230418A: Swift/BAT-GUANO detection outside the coded FOV
- GRB 230418A: Fermi GBM Observation
- IceCube-Cascade 230417A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230402A: Fermi-LAT detection
- Fermi-LAT gamma-ray observations of IceCube-230416A
- GRB 230414B: Nickel and KAIT telescope optical observations
- Duplicate of GCN 33640
- Duplicate of GCN 33640
- GRB 230414B Swift-BAT refined analysis
- Duplicate of GCN 33642
- GRB 230415A: Fermi GBM detection
- GRB 230414B: Swift/UVOT Detection
- GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
- IceCube-230416A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230415A: Swift/BAT-GUANO detection
- New GCN Circulars Portal for Rapid Communications on Astronomical Transients is Online