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"
32132 results found.
- GRB 240501B: GRBAlpha detection
- GRB 240430A: GRBAlpha detection
- GRB 240502B: Fermi GBM Final Real-time Localization
- GRB 240502A long GRB detected by INTEGRAL
- GRB 240502A: Fermi GBM Final Real-time Localization
- Fermi GRB 240501A: Global MASTER-Net observations report
- GRB 240426A: VZLUSAT-2 detection
- GRB 240425A: VZLUSAT-2 detection
- GRB240430A: Fermi GBM Final Localization
- GRB 240501B: AstroSat CZTI detection
- GRB 240501A: Fermi GBM Final Real-time Localization
- GRB 240408B: VZLUSAT-2 detection
- GRB 240407A: VZLUSAT-2 detection
- X-ray transient EP240414a: Detection of associated supernova
- GRB 240425A: GRBAlpha detection
- GRB 240429A: Fermi GBM Final Real-time Localization
- Fermi GRB 240428A: Global MASTER-Net observations report
- GRB 240428A: Fermi GBM Final Real-time Localization
- GRB 240426A: AstroSat CZTI detection
- GRB 240414A: NOEMA detection
- LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
- GRB 240425A: Fermi GBM Final Real-time Localization
- GRB 240419B: Swift-BAT refined analysis
- GRB 240421B: Swift-BAT refined analysis
- GRB 240422A: Glowbug gamma-ray detection
- IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 240421B: GRBAlpha detection
- GRB 240419A: Swift-BAT refined analysis
- GRB 240418A: Swift-BAT refined analysis
- LXT240402A/GRB240402B: Chandra X-ray detection
- GRB 240419A: Possible ATCA radio detection
- GRB 240421B: ATCA radio observations
- LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
- LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
- GRB 240421A: Glowbug gamma-ray detection
- GRB 240414A: radio detection with the VLA
- GRB 240414A: AMI-LA radio observations
- GRB 240414A: LBT optical detection
- GRB 240419B : MITSuME Akeno optical upper limits
- GRB 240415B: Swift-XRT observations
- GRB 240415A: Swift-XRT refined Analysis
- Fermi GRB 240422A: Global MASTER-Net observations report
- GRB 240421B: AstroSat CZTI detection
- GRB 240422A: Fermi GBM Final Real-time Localization
- GRB240421B: Zadko Observations
- Fermi GRB 240421B: Global MASTER-Net observations report
- Swift GRB 240421B: Global MASTER-Net observations report
- GRB 240421B: Fermi GBM Observation
- GRB 240421B: Swift-XRT refined Analysis
- GRB240421B: BOOTES-5/JGT optical upper limit
- GRB 240421B: J-band upper limits from WINTER
- GRB 240421B: Swift/UVOT Upper Limits
- GRB 240421B: Enhanced Swift-XRT position
- Fermi GRB 240421A: Global MASTER-Net observations report
- GRB 240421B: Swift detection of a burst
- EP240420a: Nanshan optical counterpart observations
- GRB 240421A: Fermi GBM Final Real-time Localization
- GRB240419A: Skynet Optical Afterglow Analysis
- GRB240418A - Candidate afterglow from NIRES
- GRB 240419B: Swift/UVOT Upper Limits
- GRB 240419A: Swift/UVOT Upper Limits
- GRB 240419B: Swift-XRT refined Analysis
- GRB 240419B: optical afterglow from the NOT
- Swift GRB 240419B: Global MASTER-Net observations report
- EP240414A: Terskol Zeiss-2000 optical upper limit
- GRB 240419B: Enhanced Swift-XRT position
- Swift GRB 240419A: Global MASTER-Net observations report
- GRB 240418A: Swift/UVOT Upper Limits
- GRB 240419A: REM NIR afterglow detection
- GRB 240419A: Swift-XRT refined Analysis
- GRB 240418A: Swift-XRT refined Analysis
- GRB 240419B: Swift detection of a burst
- GRB 240411B: Swift/UVOT Detection
- GRB240418A: YAHPT Upper Limits
- GRB 240419A: VLT/UVES redshift of z = 5.178
- GRB 240419A: VLT optical afterglow detection
- GRB 240419A: Enhanced Swift-XRT position
- GRB 240419A: Prompt enhanced Swift-XRT position
- GRB 240419A: Swift detection of a burst
- GRB 240418A: TSHAO Zeiss-1000 optical upper limit
- GRB 240418A: NOT optical upper limits
- GRB 240418A: Enhanced Swift-XRT position
- GRB 240418A: AKO Upper Limit
- GRB 240411A: GOTO early optical upper limits
- GRB 240418A: Swift detection of a burst
- Fermi GRB 240417A: Global MASTER-Net observations report
- EP240416A: Terskol Zeiss-2000 optical upper limit
- EP240416A: Khureltogoot optical upper limit
- Improved IPN triangulation of GRB 240411A
- GRB 240417A: Fermi GBM Final Real-time Localization
- GRB 240415A: Glowbug gamma-ray detection
- GRB 240414A: Glowbug gamma-ray detection
- GRB 240415B: GECAM-B detection
- EP 240416a: Xinglong and NOT decaying optical counterpart
- GRB 240415A: Swift-BAT refined analysis
- GRB 240411A: Glowbug gamma-ray detection
- GRB 240414A: Swift-BAT refined analysis
- GRB 240414A: AbAO optical upprer limit