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 200922A: Swift detection of a burst with possible optical counterpart
- IceCube-200921A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- IceCube-200921A: Upper limits from Fermi-GBM Observations
- IceCube-200921A: IceCube observation of a high-energy neutrino candidate event
- IPN triangulation of GRB 200920B (short)
- GRB 200914A: Swift-XRT further observations
- IceCube-200916A - ZTF20acaapwk/SN2020tno classified as SN Ia
- GRB 200920B: AGILE/MCAL detection of a burst
- GRB 200920A: Fermi GBM Final Real-time Localization
- Fermi GRB 200919C: Global MASTER-Net observations report
- GRB 200919C: Fermi GBM Final Real-time Localization
- GRB 200919A: CrAO/ZTSh early optical upper limit
- Fermi GRB 200919B: Global MASTER-Net observations report
- GRB 200919A: Swift-BAT refined analysis
- GRB 200919B: Fermi GBM Final Real-time Localization
- GRB 200916B: MASTER optical observation
- Swift GRB200919.08: Global MASTER-Net observations report
- GRB 200919A: Swift detection of a burst
- IceCube-200916A: AbAO observations of optical candidates ZTF20acaapwk/AT2020tno, ZTF20acaapwo/AT2020tnp
- IceCube-200916A: Upper limits from a search for additional neutrino events in IceCube
- GRB 200916B: AstroSat CZTI detection
- GRB 200917A: GROWTH-India Telescope optical upper limit.
- Swift-XRT observations of IceCube 200916A
- IceCube-200916A: No significant detection in HAWC
- GRB 200917A: Swift-BAT refined analysis
- IceCube-200916A: No neutrino counterpart candidates in ANTARES search
- Fermi-GBM Sub-Threshold Detection of GRB 200917A
- GRB 200917A: Swift-XRT refined Analysis
- IceCube-200916A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Swift GRB 200917A: Global MASTER-Net observations report
- IceCube-200916A: Two Candidate Counterparts from the Zwicky Transient Facility
- IPN triangulation of GRB 200916B (short)
- IceCube-200916A: Upper limits from Fermi-GBM Observations
- Fermi-LAT Gamma-ray Observations of IceCube-200916A
- IceCube Alert 200916.86: Global MASTER-Net observations report
- GRB 200917A: Enhanced Swift-XRT position
- GRB 200917A: Swift detection of a burst
- Swift-XRT observations of IceCube 200911A
- IceCube-200916A - IceCube observation of a high-energy neutrino candidate track-like event
- Fermi GRB 200916A: Global MASTER-Net observations report
- GRB 200916A: Fermi GBM Final Real-time Localization
- Fermi trigger No 621893860: Global MASTER-Net observations report
- Fermi trigger No 621833240: Global MASTER-Net observations report
- Integral GRB200914.53: Global MASTER-Net observations report
- Fermi GRB 200914A: Global MASTER-Net observations report
- GRB 200914A: AGILE detection
- GRB 200914A: Swift-XRT observations
- GRB 200914A: Fermi GBM observation
- IceCube Alert 200914.00: Global MASTER-Net observations report
- IceCube-200911A: No significant detection in HAWC
- Fermi-LAT Gamma-ray Observations of IceCube-200911A and detection of a new gamma-ray source, Fermi J0330.1+3743
- GRB 200914A: Swift ToO observations
- GRB 200914A : A long GRB detected by INTEGRAL
- GRB 200914A: BALROG localization (Fermi Trigger 621780515 / GRB 200914534)
- GRB 200914A: Fermi GBM Final Real-time Localization
- IceCube-200911A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-200911A: No neutrino counterpart candidates in ANTARES search
- IceCube Alert 200911.60: Global MASTER-Net observations report
- IceCube-200911A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- IceCube-200911A: not observable by Fermi-GBM
- IceCube-200911A: IceCube observation of a high-energy neutrino candidate event
- GRB 200826A: uGMRT radio upper limit at 1.25 GHz
- IPN triangulation of GRB 200907A (short)
- GRB 200909B: Swift-BAT refined analysis
- Swift GRB200909.97: Global MASTER-Net observations report
- GRB 200909B: Swift detection of a burst
- GRB 200909A: AstroSat CZTI detection
- GRB 200829A: T100 observations
- Fermi GRB 200909A: Global MASTER-Net observations report
- GRB 200909A: BALROG localization (Fermi Trigger 621316887 / GRB 200909168)
- GRB 200909A: Fermi GBM Final Real-time Localization
- GRB 200907B: Swift/UVOT Upper Limits
- Fermi GRB 200908A: Global MASTER-Net observations report
- GRB 200907B: Swift-BAT refined analysis
- Konus-Wind detection of GRB 200903E
- GRB 200908A: Fermi GBM Final Real-time Localization
- GRB 200907B: AstroSat CZTI detection
- GRB 200907B: Swift-XRT refined Analysis
- GRB 200907B: MITSuME Okayama optical upper limits
- Swift GRB 200907B: Global MASTER-Net observations report
- GRB 200907B: Enhanced Swift-XRT position
- Fermi GRB 200907C: Global MASTER-Net observations report
- GRB 200907C: Fermi GBM Final Real-time Localization
- Correction to GCN 28387: GRB 200907B GROWTH-India optical upper limit
- GRB200907A: GROWTH-India optical upper limit
- Fermi GRB 200906A: Global MASTER-Net observations report
- GRB 200907B: Prompt enhanced Swift-XRT position
- GRB 200907B: Swift detection of a short burst
- IPN triangulation of GRB 200903E
- GRB 200906A: EMIR/GTC NIR upper limit
- GRB 200906A: LBT near-infrared upper limit
- GRB 200906A: Swift-BAT refined analysis
- GRB 200906A: Swift/UVOT Upper Limits
- GRB 200907A: AGILE/MCAL detection of a burst
- GRB 200906A: GROWTH-India Telescope (GIT) optical r band upper limit
- GRB 200906A: OSN 1.5m Upper Limit
- GRB 200906A: Swift-XRT refined Analysis
- GRB 200906A: Fermi GBM detection
- GRB 200906A: Enhanced Swift-XRT position
- GRB 200906A: Nanshan/NEXT optical upper limit