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"
3039 results found.
- Possible HAWC-detected GRB 191210A: Fermi-LAT Upper Limits
- Possible HAWC-detected GRB 191210A: Swift-XRT observations
- Fermi trigger No 597737032: Global MASTER-Net observations report
- LIGO/Virgo S191205ah: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S191204r: No counterpart candidates in Fermi-LAT observations
- GRB 191130A: Swift-XRT observations
- LIGO/Virgo S191129u: No counterpart candidates in Fermi-LAT observations
- GRB 191123A: Swift-XRT refined Analysis
- GRB 191122A: Swift-XRT refined Analysis
- LIGO/Virgo S191110af: Swift XRT observations, no secure afterglow found
- LIGO/Virgo S191110af: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S191109d: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S191105e: No counterpart candidates in Fermi-LAT observations
- GRB 191106A: Swift-XRT refined Analysis
- GRB 191101A: Swift-XRT refined Analysis
- GRB 191031C: Swift-XRT refined Analysis
- GRB 191031D: Swift-XRT refined Analysis
- GRB 191029A: CORRECTED Swift-XRT refined analysis
- GRB 191029A: Swift/UVOT Upper Limits
- GRB 191029A: Swift-XRT refined Analysis
- Swift Trigger 931384: possible GRB 191025A
- GRB 191024A: Swift-XRT refined Analysis
- GRB 191019A: Swift-XRT updated analysis
- GRB 191019A: Swift-XRT refined Analysis
- GRB 191017B: Swift-XRT refined Analysis
- GRB 191016A: Swift-XRT afterglow detection
- GRB 191016A: Swift/UVOT Detection
- GRB 191011A: Swift-XRT refined Analysis
- LIGO/Virgo S190930t: Continued Swift observations of AT2019sbk
- LIGO/Virgo S190930t: Swift XRT observations, no secure afterglow found
- GRB 191004B: Swift-XRT refined Analysis
- GRB 191004A: Swift-XRT refined Analysis
- GRB 191001A: Swift-XRT observations
- LIGO/Virgo S190930t: Continued Swift/UVOT observations of Swift J221951-484240
- LIGO/Virgo S190930t: Transient found in Swift/UVOT counterpart search
- LIGO/Virgo S190930t: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190930s: No counterpart candidates in Fermi-LAT observations
- GRB 190926A: Swift-XRT refined Analysis
- LIGO/Virgo S190924h: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190923y: No counterpart candidates in Fermi-LAT observations
- GRB 190919B: Swift-XRT observations
- GRB 190919B: GROND detection of the NIR afterglow
- LIGO/Virgo S190915ak: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190910h: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190910d: No counterpart candidates in Fermi-LAT observations
- GRB 190823A: Swift-XRT afterglow detection
- Chandra observations of GW170817 ~740-743 days since merger
- LIGO/Virgo S190901ap: No counterpart candidates in Fermi-LAT observations
- GRB 190829A: TNG imaging of the NIR afterglow
- GRB 190829A: Fermi-LAT Upper Limits
- GRB 190829A: GROND detection of the Optical/NIR Afterglow
- GRB 190829A: Swift-XRT refined Analysis
- GRB 190828B: Swift-XRT refined Analysis
- GRB 190828A: Swift-XRT observations
- LIGO/Virgo S190828l: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190828j: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190814bv: no variation of DESGW candidates AT 2019onj and AT 2019okr from ENGRAVE VLT/HAWK-I observations, and archival detection
- GRB 190823A: Swift-XRT observations
- GRB 190816A: Swift-XRT afterglow detection
- GRB 190824A: Swift-XRT refined Analysis
- LIGO/Virgo S190814bv: GROND follow-up observations of AT2019npv
- LIGO/Virgo S190814bv: ENGRAVE VLT/HAWK-I observations and archival detection of the CFHT candidate
- GRB 190821A: Swift-XRT refined Analysis
- Fermi GBM-190816: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190814bv: No strong counterpart candidates in Swift/XRT observations
- GRB 190816A: Swift-XRT observations
- LIGO/Virgo S190814bv: Fermi-LAT search for a high-energy gamma-ray counterpart
- LIGO/Virgo S190814bv: GRAWITA TNG infrared imaging of desgw-190814e, DG19sevhc and selected galaxies
- LIGO/Virgo S190814bv: GRAWITA TNG infrared imaging of selected galaxies
- HAWC-190806A: Swift-XRT observations
- GRB 190804B: Swift-XRT afterglow detection
- GRB 190805B: Swift-XRT observations
- GRB 190804B: Swift-XRT observations
- GRB 190731A: Swift-XRT afterglow detection
- LIGO/Virgo S190728q: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190727h: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190718y: Swift XRT observations, 45 X-ray sources
- LIGO/Virgo S190720a: No counterpart candidates in Fermi-LAT observations
- GRB 190719C: Swift-XRT refined Analysis
- LIGO/Virgo S190718y: No counterpart candidates in Fermi-LAT observations
- GRB 190718A: Swift-XRT refined Analysis
- GRB 190714A: an X-ray flare from 2E 1624.6+1504/UCAC4 525-061488
- GRB 190708B: confirmation of the X-ray afterglow
- GRB 190708B: Swift-XRT observations
- LIGO/Virgo S190707q: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190706ai: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S190701ah: No counterpart candidates in Fermi-LAT observations
- GRB 190706B: Swift-XRT refined Analysis
- GRB 190701A: Swift-XRT refined Analysis
- GRB 190630C: Swift-XRT refined Analysis
- LIGO/Virgo S190630ag: No counterpart candidates in Fermi-LAT observations
- GRB 190630B: Swift-XRT refined Analysis
- GRB 190627A: Swift-XRT refined Analysis
- Swift Trigger 911102 is likely not an astrophysical event
- GRB 190610A: Swift-XRT observations
- GRB 190613B: Swift-XRT refined Analysis
- GRB 190613A: Swift-XRT refined Analysis
- GRB 190611A: Swift-XRT refined Analysis
- Fermi trigger No 581645543 Global MASTER-Net observations report
- GRB 190604B: Swift-XRT refined Analysis