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').
- 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