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"
- IceCube-230511A: IceCube observation of a high-energy neutrino candidate
- GRB 230510B: AstroSat CZTI detection
- GRB 230511C: Fermi GBM Final Localization
- Fermi trigger No 705503315: Global MASTER-Net observations report
- GRB 230511B: Fermi GBM Final Real-time Localization
- Fermi trigger No 705496510: Global MASTER-Net observations report
- GRB 230511A: Fermi GBM Final Real-time Localization
- GRB 230510A: Fermi GBM detection
- Fermi trigger No 705446499: Global MASTER-Net observations report
- GRB 230510A: Gaoyazi/GOT optical upper limit
- GRB 230510B: CALET Gamma-Ray Burst Monitor detection
- GRB 230510A: CALET Gamma-Ray Burst Monitor detection
- GRB 230510A: Nanshan/NEXT optical afterglow detection
- GRB 230510B: MAXI/GSC detection
- GRB 230510B: Fermi GBM Final Real-time Localization
- GRB 230506B: Fermi GBM detection
- GRB 230510A: Swift-XRT refined Analysis
- GRB 230510A: Enhanced Swift-XRT position
- GRB 230506C: Fermi GBM detection
- Fermi trigger No 705413051: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 230510133/705381054 is not a GRB
- GRB 230510A: Swift detection of a burst
- GRB 230510A: Fermi GBM Final Real-time Localization
- GRB 230506B: Swift/UVOT further analysis
- GRB 230506C: T193-OHP MISTRAL tentative redshift
- GRB 230506C: SAO RAS optical observations
- GRB 230307A: JWST second-epoch observations
- IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
- Fermi-LAT gamma-ray observations of IceCube-230506A
- GRB 230506C: Swift-XRT refined Analysis
- GRB 230506C: Swift-BAT refined analysis
- GRB 230506B: Swift-BAT refined analysis
- GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
- GRB 230506B: LCOGT Optical Upper Limits
- GRB 230506C: Swift/UVOT Upper Limits
- GRB 230506C: NUTTelA-TAO / BSTI Early Optical Limits
- 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