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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"

24 results found.

  1. SN 2026stf / GRB 260708A: ATLAS forced photometry
  2. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  3. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  4. GRB 260515A: LCO optical counterpart detection
  5. GRB 260511B: LCO optical counterpart detection
  6. GRB 260421B: LCO optical counterpart detection
  7. EP260403a: LCO optical counterpart detection
  8. EP260214b: LCO optical counterpart detection
  9. GRB 260208A: LCO detection of the optical counterpart
  10. GRB 260101A: LCO detection of the optical counterpart
  11. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  12. GRB 251214B: LCO detection of the optical counterpart
  13. GRB 251205A: ZTF and ATLAS optical afterglow detections
  14. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  15. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  16. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  17. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  18. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  19. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  20. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  21. GRB 251017A : RAPAS follow-up observations
  22. GRB 241128A : RAPAS follow-up observations
  23. GRB 241113B : RAPAS follow-up observation
  24. GRB 240809A : RAPAS follow-up observations

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Download all Circulars as a .tar.gz archive (updated once a day):
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