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"
6098 results found.
- GRB 200925B: Swift-XRT refined analysis update
- GRB 200925B: Swift-XRT refined Analysis
- GRB 200925B: OSN Afterglow Candidate Discovery
- Fermi-LAT Gamma-ray Observations of IceCube-200921A and detection of a new gamma-ray source, Fermi J1256.9+2630
- IceCube-200921A: no significant detection in HAWC observations
- GRB 200922A: Swift-XRT refined Analysis
- IceCube-200921A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 200914A: Swift-XRT further observations
- Swift GRB200919.08: Global MASTER-Net observations report
- GRB 200917A: GROWTH-India Telescope optical upper limit.
- Swift-XRT observations of IceCube 200916A
- IceCube-200916A: No significant detection in HAWC
- GRB 200917A: Swift-XRT refined Analysis
- IceCube-200916A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Fermi-LAT Gamma-ray Observations of IceCube-200916A
- Swift-XRT observations of IceCube 200911A
- GRB 200914A: Swift-XRT observations
- GRB 200914A: Fermi GBM observation
- 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
- IceCube-200911A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 200829A: T100 observations
- GRB 200907B: Swift-XRT refined Analysis
- GRB 200906A: LBT near-infrared upper limit
- GRB 200906A: Swift-XRT refined Analysis
- GRB 200906A: Fermi GBM detection
- GRB 200903A: Fermi GBM detection
- GRB 200901B: Swift-XRT refined Analysis
- GRB 200901A: Swift-XRT refined Analysis
- GRB 200901A: Fermi GBM observation
- GRB 200901A: Swift-XRT observations
- GRB 200829A: further SAO RAS optical observations
- GRB 200829A: Fermi GBM detection
- GRB 200829A: SAO RAS optical observations
- GRB 200829A: Swift-XRT refined Analysis
- GRB 200826A: Swift-XRT afterglow detection
- GRB 200826B: Fermi GBM detection
- GRB 200826A: Fermi GBM observation
- Swift Trigger 992444 is due to detector noise
- IceCube-200806A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Swift Trigger 992444: a possible GRB 200821A
- GRB 200819A: Optical Observations from HCT
- GRB 200819A: Swift-XRT refined Analysis
- Swift Trigger 990358 is due to detector noise
- Swift Trigger 989458 is due to detector noise
- Alert from the HAWC Burst Monitor HAWC-200814A
- IceCube200806A: No significant detection in HAWC
- GRB 200809B: Fermi GBM detection
- GRB 200809B: Swift-XRT afterglow detection
- GRB 200806A: Swift/UVOT Possible Detection
- GRB 200806A: Swift-XRT refined Analysis
- Fermi-LAT Gamma-ray Observations of IceCube-200806A
- GRB 200803A: Fermi GBM detection
- GRB 200803A: Swift-XRT afterglow detection
- GRB 200803A: Fermi-LAT detection
- GRB 200729A: Swift-XRT refined Analysis
- GRB 200714E: Swift-XRT afterglow detection
- GRB 200716C: Optical observations from HCT
- GRB 200716C: Fermi GBM detection
- GRB 200716C: Swift-XRT refined analysis correction
- GRB 200716C: Fermi-LAT detection
- GRB 200716C: Swift-XRT refined Analysis
- GRB 200716A: Fermi GBM detection
- GRB 200715A: Swift-XRT afterglow detection
- GRB 200714E: Fermi GBM observation
- GRB 200714E: Swift-XRT observations
- GRB 200713A: Swift-XRT refined Analysis
- GRB 200711A: Fermi-LAT marginal detection
- GRB 200711A: Swift-XRT refined Analysis
- GRB 200711A: Fermi GBM detection
- Update of alert from the HAWC Burst Monitor HAWC-200709A
- GRB 200709B/HAWC-200907A: Swift-XRT further observations
- GRB 200709B: Swift-XRT observations
- GRB 200630A: Swift-XRT refined Analysis
- GRB 200623A: Swift XRT further observations
- GRB 200630A: Fermi GBM detection
- GRB 200625A: Fermi-LAT detection is likely a flare from PKS 1127-14
- GRB 200623A: Swift-XRT observations
- GRB 200623A: Fermi GBM observation
- IceCube-200620A: No significant detection in HAWC
- Fermi-LAT Gamma-ray Observations of IceCube-200620A
- GRB 200613A: R-band observations from HCT
- GRB 200619A: Fermi GBM observation
- GRB 200613A: SAO RAS optical observations
- Swift-XRT observations of IceCube 200615A
- IceCube-200615A: No significant detection in HAWC
- Fermi-LAT Gamma-ray Observations of IceCube-200615A
- IceCube-200614A: No significant detection in HAWC
- Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132
- IceCube-200615A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- IceCube-200614A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- GRB 200613A: Swift-XRT afterglow detection
- GRB 200613A: Candidate afterglow from OAJ
- GRB 200612A: Fermi GBM detection
- GRB 200613A: Fermi-LAT detection
- GRB 200613A: Fermi GBM observation
- GRB 200612A: Swift-XRT refined Analysis
- GRB 200530A: Fermi GBM detection
- GRB 200530A: Fermi-LAT detection
- Fermi-LAT Gamma-ray Observations of IceCube-200530A