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.
- Swift-XRT observations of IceCube 201130A
- GRB 201128A: Swift-XRT refined Analysis
- IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
- Fermi-LAT Gamma-ray Observations of IceCube-201120A
- IceCube-201120A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
- ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations
- IceCube 201114A: Swift followup of Fermi J0703.5+0505
- Fermi-LAT Gamma-ray Observations of IceCube-201114A
- GRB 201116A: NOT optical observations
- GRB 201116A: Swift-XRT afterglow detection
- IceCube-201115A: No significant detection in HAWC
- IceCube-201114A: No significant detection in HAWC
- GRB 201116A: Fermi-LAT detection
- IceCube-201115A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- IceCube-201114A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Fermi-LAT Gamma-ray Observations of IceCube-201115A
- Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
- Swift-XRT observations of IceCube 201114A
- Fermi-LAT Gamma-ray Observations of NuEm-201107A
- ZTF20acozryr (GRB 201103B): GROWTH-India Telescope optical observations
- GRB 201109A: Fermi GBM detection
- GRB 201104A: Swift-XRT observations
- Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
- GRB 201015A: Swift-XRT late time observations
- GRB 201104B: Swift-XRT refined Analysis
- GRB 201105B: Fermi GBM observation
- GRB 201104A: Fermi GBM observation
- GRB 201104A: Fermi-LAT detection
- IceCube 201021A: Swift follow-up of Fermi J1725.5+1312
- GRB 201029A: Fermi GBM detection
- GRB 201029A: Swift-XRT refined Analysis
- GRB 201027A: Swift-XRT refined Analysis
- GRB 201026A: Fermi GBM detection
- GRB 201026A: Swift-XRT refined Analysis
- GRB 201026A: Swift/UVOT Upper Limits
- GRB201024A: rebrightening after initial steep decline
- GRB 201020B: HCT and GIT continued optical follow-up observations
- GRB 201024A: Swift-XRT refined Analysis
- GRB 201020B: follow-up observations with Savelli Telescope
- GRB 201020B: follow-up observations at Konkoly
- IceCube-201021A: No significant detection in HAWC
- GRB 201021C: Swift-XRT refined Analysis
- GRB 201020B: GROWTH-India Telescope optical observations
- Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
- GRB 201020B: Konkoly Obs. optical detection
- GRB 201021C: Fermi GBM detection
- GRB 201020A: GROWTH-India Telescope late-time optical upper limit
- GRB 201014A: 2.0m HCT upper limit
- GRB 201020B: Swift-XRT afterglow detection
- IceCube-201021A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Swift-XRT observations of IceCube 201021A
- GRB 201020B: Fermi-LAT detection
- GRB 201020A: DOAO optical afterglow observations
- GRB 201020A: GROWTH-India Telescope optical observations
- GRB 201020B: Fermi GBM detection
- Alert from the HAWC Burst Monitor HAWC-201019A
- GRB 201020A: Swift-XRT refined Analysis
- GRB 201020A: Fermi GBM observation
- GRB 201014A: SAO RAS optical observations
- GRB 201017A: SAO RAS optical observations
- GRB 201017A: GROWTH-India optical upper limit
- GRB 201013A: 3.6m DOT Optical Observations
- GRB 201015A: GROWTH-India Telescope (GIT) upper limit
- GRB 201017A: Swift-XRT refined Analysis
- GRB 201017A: Fermi GBM detection
- GRB 201017A: Xinglong TNT upper limit
- GRB 201015A: Swift-XRT refined Analysis
- IceCube-201014A: No significant detection in HAWC
- GRB 201008A: Swift-XRT afterglow detection
- GRB 201016A: Fermi GBM detection
- GRB 201014A: Swift-XRT refined Analysis
- Swift-BAT trigger 1000255: XRT afterglow detection of GRB 201014A
- Fermi-LAT Gamma-ray Observations of IceCube-201014A
- IceCube-201014A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 201013A: Swift-XRT refined Analysis
- GRB 201011A: Fermi GBM detection of a likely Long GRB in the direction of SGR 1830-0645
- GRB 201006A: Chandra upper limit on the X-ray afterglow
- IceCube-201007A: No significant detection in HAWC
- GRB 201008A: Swift-XRT observations
- IceCube-200926A: Upper limits from Insight-HXMT Observations
- Fermi-LAT Gamma-ray Observations of IceCube-201007A
- Swift-XRT observations of IceCube 201007A
- IceCube-201007A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 201006A: GROWTH-India Telescope optical upper limit
- GRB 201006A: Swift-XRT refined Analysis
- GRB 201006A: Swift/UVOT Upper Limits
- GRB 201006A: Fermi GBM detection
- IceCube-200926B: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- IceCube-200929A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- IceCube-200929A: No significant detection in HAWC
- GRB 201001A: Swift-XRT refined Analysis
- GRB 201001A: Fermi GBM observation
- Swift-XRT observations of IceCube 200929A
- Fermi-LAT Gamma-ray Observations of IceCube-200929A
- IceCube-200926B: No significant detection in HAWC
- IceCube-200926A: No significant detection in HAWC
- Fermi-LAT Gamma-ray Observations of IceCube-200926B
- Swift-XRT observations of IceCube 200926A
- Fermi-LAT Gamma-ray Observations of IceCube-200926A