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').
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"- Retraction: Fermi GBM trigger 679932336.585264/220719587 is not a GRB
- GRB 220715A: CALET Gamma-Ray Burst Monitor detection
- GRB 220711B: CALET Gamma-Ray Burst Monitor detection
- GRB 220719A: Fermi GBM Final Real-time Localization
- GRB 220715B: Swift-BAT refined analysis
- GRB220714B: UVOT detections
- GRB 220715B: Fermi GBM detection
- GRB 220715B: Swift-XRT refined Analysis
- GRB 220715B: Swift/UVOT Upper Limits
- GRB 220715B: Enhanced Swift-XRT position
- GRB 220715B: BOOTES-network optical upper limits
- Swift GRB 220715B: Global MASTER-Net observations report
- GRB 220715B: Prompt enhanced Swift-XRT position
- GRB 220715B: Swift detection of a burst
- GRB 220715B: Fermi GBM Final Real-time Localization
- GRB 220714B: Swift-BAT refined analysis
- GRB 220714B: Fermi GBM observation
- GRB 220715A: AGILE/MCAL detection
- GRB 220714B: LCO Optical Observations
- GRB 220715A: Fermi GBM Final Real-time Localization
- GRB 220714B: Swift-XRT refined Analysis
- Swift/BAT Trigger 1116172 (=GRB 220714A) is not a real astrophysical event
- GRB 220714B: UVOT afterglow discovery
- GRB 220714B: Enhanced Swift-XRT position
- GRB 220713A: Fermi GBM Final Localization
- GRB 220714B: Swift detection of a burst
- GRB 220714B: Fermi GBM Final Real-time Localization
- GRB 220714A: Possible Swift detection of a burst
- GRB 220710A: Swift/UVOT Upper Limits
- GRB 220711C: Fermi GBM Observation
- Retraction of GRB 220711B: 10.4 m GTC(+EMIR) observations (GCN 32387)
- GRB 220711B: 10.4 m GTC(+EMIR) observations
- GRB 220711B: 10.4 m GTC(+EMIR) observations
- GRB 220710A: Swift-XRT afterglow detection
- GRB 220711C: Swift/BAT-GUANO detection outside the coded FOV
- GRB 220711B, GROND observations
- Konus-Wind detection of GRB 220711C
- GRB 220711B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
- GRB 220711B: GIT optical upper limits
- Fermi trigger No 679248723: Global MASTER-Net observations report
- Fermi GRB 220711B: Global MASTER-Net observations report
- GRB 220712B: NOT optical afterglow confirmation
- GRB 220710A: Swift ToO observations
- GRB 220710A: Swift/BAT-GUANO arcminute localization
- GRB 220711B: Swift-BAT refined analysis
- IPN triangulation of GRB 220711C (short)
- GRB 220711B: Swift-XRT refined Analysis
- GRB 220711B: Swift/UVOT Upper Limits
- GRB 220711B: Enhanced Swift-XRT position
- GRB 220711B: Fermi GBM Detection
- GRB 220711B: NOT optical observations
- GRB 220711B: LCO Optical Upper Limits
- GRB 220711B: Swift detection of a burst
- GRB 220711B: Fermi GBM Final Real-time Localization
- GRB 220707A: AstroSat CZTI detection
- GRB 220708B: GIT optical upper limits
- GRB 220711A: Fermi GBM Final Real-time Localization
- GRB 220708A: Swift-BAT refined analysis
- GRB 220708B: T193-OHP optical upper limit
- Konus-Wind detection of GRB 220708B (Correction to GCN 32358)
- Konus-Wind detection of GRB 220708B
- IceCube-220624A: Classification of AT2022nit as a type Ia supernova and AT2021bei as an AGN
- GRB 220708B: CALET Gamma-Ray Burst Monitor detection
- GRB 220708B: Nanshan/NEXT optical upper limits
- GRB 220708A: Swift/UVOT Upper Limits
- GRB 220706A : NICER detection of re-brightening 1 day after the Swift trigger
- GRB 220708A: Swift-XRT refined Analysis
- GRB 220706A: Swift/UVOT Upper Limits
- GRB 220708B: Swift-XRT afterglow detection
- GRB 220708A: BOOTES-5/JGT early optical upper limit
- GRB 220706A: Swift-BAT refined analysis
- GRB 220708A: Enhanced Swift-XRT position
- GRB 220708B: Swift ToO observations
- GRB 220708B: Swift/BAT-GUANO arcminute localization
- GRB 220708A: Swift-XRT observations
- GRB 220708A: Swift detection of a burst
- GRB 220706A: LCO Optical Upper Limits
- GRB 220627A: ATCA detection of radio counterpart
- GRB 220706A: Swift-XRT refined Analysis
- GRB 220706A, GROND observations
- GRB 220706A: Optical observations from NOT
- GRB 220706A: MAXI/GSC detection 84 minutes after the Swift Trigger
- GRB 220702B: AstroSat CZTI detection
- GRB 220706A: Nanshan/NEXT optical upper limits
- MAXI GRB220706.73: Global MASTER-Net observations report
- GRB 220706A: Enhanced Swift-XRT position
- Swift GRB 220706A: Global MASTER-Net observations report
- GRB 220706A: Zadko observatory - Gingin optical observations
- GRB 220706A: Prompt enhanced Swift-XRT position
- GRB 220706A: Swift detection of a burst
- GRB 220701A: Swift-BAT refined analysis
- GRB220408A: VIRT Optical Upper Limit
- GRB220412A: VIRT Optical Upper Limit
- GRB220701A: VIRT Optical Upper Limit
- GRB 220702B: Fermi GBM Final Localization
- GRB 220702A: Fermi GBM Final Localization
- GRB 220705A: Fermi GBM Final Localization
- Fermi trigger No 678635286: Global MASTER-Net observations report
- GRB 220701A: MITSuME Akeno optical upper limits
- Alert from the HAWC Burst Monitor HAWC-220702A