GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"- GRB 210601A: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 210531A
- GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
- GRB 210531A: AstroSat CZTI detection
- Fermi trigger No 644155206: Global MASTER-Net observations report
- GRB 210531A: AGILE/MCAL detection (Fermi Trigger 644155206 / GRB 210531500)
- GRB 210531A: BALROG localization (Fermi Trigger 644155206 / GRB 210531500)
- GRB 210529B: DDOTI Upper Limits on the Afterglow
- Fermi GRB 210529A: Global MASTER-Net observations report
- Fermi GRB 210529B: Global MASTER-Net observations report
- GRB 210529B: Fermi GBM Final Real-time Localization
- GRB 210529A: Fermi GBM Final Real-time Localization
- GRB 210528A: Fermi GBM detection
- GRB 210528A: AstroSat CZTI detection
- GRB 210528B: DDOTI Upper Limits on the Afterglow
- GRB 210528B: MITSuME Akeno optical upper limits
- MAXI GRB210528.95: Global MASTER-Net observations report
- GRB 210528B: MAXI/GSC detection
- Fermi GRB 210528A: Global MASTER-Net observations report
- GRB 210527A: Swift-BAT refined analysis
- GRB 210528A: BALROG localization (Fermi Trigger 643903431 / GRB 210528586)
- GRB 210528A: Fermi GBM Final Real-time Localization
- GRB 210527A: Swift/UVOT Observations
- GRB 210527A: GIT optical upper limit
- GRB 210527A: MITSuME Akeno optical upper limits
- Swift GRB 210527A: Global MASTER-Net observations report
- GRB 210527A: Swift-XRT refined Analysis
- GRB 210527A: RATIR Optical and NIR Observations
- GRB 210527A: Enhanced Swift-XRT position
- GRB 210527A: Swift-XRT observations
- GRB 210527A: Swift detection of a burst
- GRB 210306A: LBT observations of the likely host galaxy
- ZTF21aayokph (AT2021lfa): LBT optical observations
- Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
- Konus-Wind detection of GRB 210524A
- IPN triangulation of GRB 210524A
- Fermi trigger No 643548039: Global MASTER-Net observations report
- GRB 210524B: Fermi GBM Final Real-time Localization
- GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208)
- Fermi GRB 210524A: Global MASTER-Net observations report
- GRB 210524A: Fermi GBM Final Real-time Localization
- GRB 210522A: GECAM detection
- GRB 210520A: Swift-XRT observations
- MAXI GRB210521.54: Global MASTER-Net observations report
- GRB 210521A: MAXI/GSC detection
- GRB210413B: further Swift-XRT observations
- GRB 210520A: Fermi GBM detection
- ZTF21aayokph (AT2021lfa): continued Assy optical observations
- GRB 210520A: Tiled Swift observations
- GRB 210520A: Fermi-LAT detection
- GRB 210520A: GECAM detection
- Fermi GRB 210520A: Global MASTER-Net observations report
- GRB 210520A: Fermi GBM Final Real-time Localization
- Fermi GBM observation of a bright burst from magneta
- GRB 210517A: KCT optical upper limit
- IceCube GCN alert 135302_36915486.amon retraction
- Fermi GRB 210519A: Global MASTER-Net observations report
- IceCube Alert 210519.86: Global MASTER-Net observations report
- IPN triangulation of GRB 210518A
- Fermi trigger No 643065622: Global MASTER-Net observations report
- GRB 210518.889: DDOTI Upper Limits on the Afterglow
- GRB 210519A: Fermi GBM Final Localization
- Fermi GRB 210518A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 210514A
- Fermi trigger No 642991619: Global MASTER-Net observations report
- Fermi-LAT Gamma-ray Observations of IceCube-210516A
- GRB 210518A: Fermi GBM Final Real-time Localization
- IceCube Alert 210515.01: Global MASTER-Net observations report
- GRB 210517A: Swift-BAT refined analysis
- GRB 210517A: Swift-XRT refined Analysis
- IceCube-210516A: No significant detection in HAWC
- GRB 210517A: Swift/UVOT Upper Limits
- GRB 210515C: Swift/UVOT Upper Limits
- IceCube-210516A: Upper limits from a search for additional neutrino events in IceCube
- GRB 210517A: VLT/X-shooter optical afterglow and redshift
- GRB 210517A: AGILE detection
- GRB 210514A: CALET Gamma-Ray Burst Monitor detection
- GRB 210517A: Enhanced Swift-XRT position
- Swift GRB 210517A: Global MASTER-Net observations report
- GRB 210517A: Swift detection of a burst
- Fermi GRB 210516A: Global MASTER-Net observations report
- GRB 210516A: Fermi GBM Final Real-time Localization
- IceCube Alert 210516.61: Global MASTER-Net observations report
- GRB 210515C: LCO Optical Upper Limit
- GRB 210504A: LCO Optical Afterglow Detection
- IceCube-210516A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 210514A: Swift/UVOT Upper Limits
- AMON IC_HAWC NuEm-210515A / NuEm-210515B : No neutrino counterpart detected with ANTARES
- GRB 210515C: Swift-XRT refined Analysis
- Swift GRB210515.83: Global MASTER-Net observations report
- GRB 210515C: Swift-BAT refined analysis
- GRB 210515C: Swift detection of a burst
- Fermi GRB 210515B: Global MASTER-Net observations report
- GRB 210514A: Swift-BAT refined analysis
- Fermi GRB 210515A: Global MASTER-Net observations report
- GRB 210515B: Fermi GBM Final Real-time Localization
- GRB 210515A: Fermi GBM Final Real-time Localization
- Swift GRB210514.71: Global MASTER-Net observations report
- GRB 210514A: Swift XRT light curve is fading
- GRB 210514A: Swift-XRT refined Analysis