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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.

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').
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"

26 results found.

  1. GRB 240821A: further radio observations with the VLA
  2. GRB 240821A: Keck/LRIS spectroscopic observations
  3. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  4. GRB 240821A: radio observation with the VLA
  5. GRB 240821A: VLT spectroscopic observations
  6. GRB 240821A: PRIME near-infrared observations
  7. SVOM GRB 240821A: optical afterglow discovery
  8. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  9. GRB 240821A: Swift/UVOT observations of the XRT sources.
  10. GRB 240821A: Colibri Optical Upper Limit
  11. GRB 240821A: Swift-XRT observations
  12. GRB 240821A: REM optical/NIR upper limits
  13. GRB 240821A: LCO optical observations
  14. GRB 240821A: JinShan optical upper limits
  15. GRB 240821A: SVOM/VT follow-up and optical upper limit
  16. GRB 240821A: GMG Optical Upper Limit
  17. Fermi GRB 240821A: Global MASTER-Net observations report
  18. GRB 240821A: Fermi GBM Observation
  19. GRB 240821A: Swift ToO observations
  20. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  21. GRB 240821A: SVOM/GRM observation
  22. GRB 240821A: SVOM/GRM observation
  23. GRB 240821A: GRANDMA/LesMakes-T60 Upper Limit
  24. GRB 240821A: BALROG localization (Fermi Trigger 745958167 / GRB 240821775)
  25. GRB 240821A : a likely short GRB detected by SVOM/ECLAIRs
  26. GRB 240821A: Fermi GBM Final Real-time Localization

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