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"- 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
- VIRT optical transient detection
- GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
- GRB 230307A: iTelescope optical upper limit (likely)
- GRB 230414B: Montarrenti Observatory late time optical afterglow detection
- IceCube-230416A: IceCube observation of a high-energy neutrino candidate
- Fermi trigger No 703284533: Global MASTER-Net observations report
- GRB 230414B: Lulin 40cm-SLT optical limit
- GRB 230414B: Bassano Bresciano Observatory optical observations
- GRB 230414B: Redshift from OSIRIS/GTC
- GRB 230414B: AbAO optical observations
- GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
- GRB 230414B: Swift-XRT refined Analysis
- GRB 230414B: Dabancheng/GHOST optical observations
- AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230414A
- GRB 230414B: slow optical light curve decay
- GRB 230414B: SAO RAS optical observations
- GRB 230414B: Enhanced Swift-XRT position
- GRB 230414B: 1.3m DFOT Optical observations
- Fermi GRB 230414A: Global MASTER-Net observations report
- GRB 230414B: GROWTH India Telescope afterglow confirmation
- GRB 230414B (correction GRB name in the GCN 33615): Mondy optical afterglow candidate
- GRB 230414B: Nanshan/HMT optical afterglow detection
- GRB 230414A: Mondy optical afterglow candidate
- Swift GRB 230414B: Global MASTER-Net observations report
- GRB 230414B: Prompt enhanced Swift-XRT position
- GRB 230414B: Swift detection of a burst
- IceCube-230405A: BOOTES-4/MET Optical Upper Limits
- GRB 230414A: Fermi GBM Final Real-time Localization
- GRB 230328B: redshift lower limit estimating
- GRB 230409B: Mondy optical upper limit
- GRB 230409B: OHP/T193 optical upper limit
- GRB 230410B: VZLUSAT-2 detection
- GRB 230409D: VZLUSAT-2 detection
- GRB 230410B: AGILE detection of a burst
- GRB 230410A: Fermi GBM Final Real-time Localization
- Fermi GRB 230409C: Global MASTER-Net observations report
- Fermi GRB 230409A: Global MASTER-Net observations report
- GRB 230409C: Fermi GBM Final Real-time Localization
- GRB 230409B: Swift-XRT refined Analysis
- GRB 230409B: Swift-BAT refined analysis
- Fermi trigger No 702745263: Global MASTER-Net observations report
- Swift GRB 230409B: Global MASTER-Net observations report
- GRB 230409B: Swift/UVOT Detection
- GRB 230409B: Enhanced Swift-XRT position
- MAXI GRB230408.82: Global MASTER-Net observations report
- GRB 230409B: Swift detection of a burst
- GRB 230409A: Fermi GBM Final Real-time Localization
- GRB 230405B: VZLUSAT-2 detection
- IceCube-230405A: Upper limits from a search for additional neutrino events in IceCube
- Fermi-LAT gamma-ray observations of IceCube-230405A
- Konus-Wind detection of GRB 230405B
- GRB 230405B: AGILE detection
- GRB 230405B: Swift-XRT refined Analysis
- GRB 230405B: Fermi GBM Observation
- GRB 230405B: MeerLICHT upper limits
- IceCube Alert 230405.56: Global MASTER-Net observations report
- GRB 230307A: JWST NIRSpec observations, possible higher redshift
- GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
- GRB 230307A: good match with kilonova models
- GRB 230307A: short mininum variability timescale compatible with a merger origin
- GRB 230405B: Swift/UVOT Upper Limits
- GRB 230405B: AstroSat CZTI detection
- GRB 230405B: Enhanced Swift-XRT position
- Swift GRB 230405B: Global MASTER-Net observations report
- GRB 230405B: Prompt enhanced Swift-XRT position
- GRB 230405B: Swift detection of a burst
- GRB 230405B: Fermi GBM Final Real-time Localization
- GRB 230307A: JWST observations consistent with the presence of a kilonova
- Fermi GRB 230405A: Global MASTER-Net observations report
- IceCube-230405A: IceCube observation of a high-energy neutrino candidate
- GRB 230405A: Fermi GBM Final Real-time Localization
- GRB 230404A: AstroSat CZTI detection
- GRB 230404A: Fermi GBM Final Real-time Localization
- GRB 230402A: CALET Gamma-Ray Burst Monitor detection
- GRB 230402A: AstroSat CZTI detection
- Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
- IceCube-230401A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230328B: Multa observatory optical afterglow observation
- GRB 230307A: Chandra late-time detection of the X-ray afterglow
- GRB 230228A: detection by GTC of the potential host galaxy
- GRB 230328B: Swift/UVOT Detection
- GRB 230402A: AGILE detection
- Fermi GRB 230402A: Global MASTER-Net observations report
- GRB 230402A: Fermi GBM Final Real-time Localization
- IceCube-230401A: IceCube observation of a high-energy neutrino candidate
- GRB 230307A: Bad Time Intervals for Fermi GBM data
- GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
- GRB 230328B: CAHA 2.2m/CAFOS detection
- IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230328B: 3.6m DOT multiband optical observation
- Fermi trigger No 701883729: Global MASTER-Net observations report