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"
3036 results found.
- GRB 201216C: Swift-XRT refined Analysis
- GRB 210102B: further Swift-XRT observations
- GW170817: HST observations at 3.4 years from merger
- GRB 210104A: Swift-XRT refined Analysis
- GRB 210104B: Swift-XRT refined Analysis
- GRB 210102B: Swift-XRT observations
- GRB 201227A: Swift-XRT observations
- GRB 201229A: Swift-XRT refined Analysis
- GRB 201223A: Swift-XRT refined Analysis
- Swift-XRT observations of Icecube 201222A
- Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
- GRB 201216A - further Swift-XRT observations
- GRB 201221D: Swift-XRT refined Analysis
- GRB 201221A: Swift-XRT refined Analysis
- GRB 201214A: Swift-XRT afterglow detection
- GRB 201216A: Swift-XRT observations
- Chandra observations of GW170817 at ~3.3 years since merger (Full report)
- GRB 201214B: Swift-XRT observations
- GRB 201214A: Swift-XRT observations
- Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
- Long-lasting X-ray emission from GW170817 detected by Chandra
- Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
- GRB 201208A: Swift-XRT afterglow detection
- GRB 201209A: Swift-XRT refined Analysis
- Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
- GRB 201203A: Swift-XRT afterglow detection
- GRB 201128B: Swift-XRT observations
- Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
- Swift-XRT observations of IceCube 201130A
- GRB 201128A: Swift-XRT refined Analysis
- IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
- IceCube 201114A: Swift followup of Fermi J0703.5+0505
- GRB 201116A: Swift-XRT afterglow detection
- 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
- 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
- Fermi GRB 201104A: Global MASTER-Net observations report
- IceCube 201021A: Swift follow-up of Fermi J1725.5+1312
- GRB 201029A: Swift-XRT refined Analysis
- GRB 201027A: Swift-XRT refined Analysis
- GRB 201026A: Swift-XRT refined Analysis
- GRB201024A: rebrightening after initial steep decline
- GRB 201024A: Swift-XRT refined Analysis
- GRB 201021C: Swift-XRT refined Analysis
- GRB 201020B: Swift-XRT afterglow detection
- Swift-XRT observations of IceCube 201021A
- GRB 201020A: Swift-XRT refined Analysis
- GRB 201017A: Swift-XRT refined Analysis
- GRB 201015A: Swift-XRT refined Analysis
- GRB 201008A: Swift-XRT afterglow detection
- GRB 201014A: Swift-XRT refined Analysis
- Swift-BAT trigger 1000255: XRT afterglow detection of GRB 201014A
- GRB 201013A: Swift-XRT refined Analysis
- GRB 201006A: Chandra upper limit on the X-ray afterglow
- GRB 201008A: Swift-XRT observations
- IceCube-200926A: Upper limits from Insight-HXMT Observations
- Swift-XRT observations of IceCube 201007A
- GRB 201006A: Swift-XRT refined Analysis
- GRB 201001A: Swift-XRT refined Analysis
- Swift-XRT observations of IceCube 200929A
- Swift-XRT observations of IceCube 200926A
- GRB 200925B: Swift-XRT refined analysis update
- GRB 200925B: Swift-XRT refined Analysis
- GRB 200922A: Swift-XRT refined Analysis
- GRB 200914A: Swift-XRT further observations
- Swift-XRT observations of IceCube 200916A
- GRB 200917A: Swift-XRT refined Analysis
- Swift-XRT observations of IceCube 200911A
- GRB 200914A: Swift-XRT observations
- GRB 200907B: Swift-XRT refined Analysis
- GRB 200906A: LBT near-infrared upper limit
- GRB 200906A: Swift-XRT refined Analysis
- GRB 200901B: Swift-XRT refined Analysis
- GRB 200901A: Swift-XRT refined Analysis
- GRB 200901A: Swift-XRT observations
- GRB 200829A: Swift-XRT refined Analysis
- GRB 200826A: Swift-XRT afterglow detection
- Swift Trigger 992444 is due to detector noise
- Swift Trigger 992444: a possible GRB 200821A
- GRB 200819A: Swift-XRT refined Analysis
- Swift Trigger 990358 is due to detector noise
- Swift Trigger 989458 is due to detector noise
- GRB 200809B: Swift-XRT afterglow detection
- GRB 200806A: Swift-XRT refined Analysis
- GRB 200803A: Swift-XRT afterglow detection
- GRB 200729A: Swift-XRT refined Analysis
- GRB 200714E: Swift-XRT afterglow detection
- GRB 200716C: Swift-XRT refined analysis correction
- GRB 200716C: Swift-XRT refined Analysis
- GRB 200715A: Swift-XRT afterglow detection
- GRB 200714E: Swift-XRT observations
- GRB 200713A: Swift-XRT refined Analysis
- GRB 200711A: Swift-XRT refined Analysis
- 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