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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"

28 results found.

  1. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  2. GRB 250309B/AT2025dws: further ATCA observations
  3. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  4. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  5. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  6. GRB 250309B: PRIME near-infrared detection
  7. GRB 250309B: SVOM/VT optical observation
  8. GRB 250309B / AT2025dws: further SAO RAS optical observations
  9. IceCube-250309A: Upper limits from Fermi-GBM Observations
  10. Konus-Wind detection of GRB 250309B
  11. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  12. IPN triangulation of GRB 250309B
  13. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  14. GRB 250309B: Swift-XRT refined Analysis
  15. GRB 250309B / IceCube-250309A: GECAM-B observations
  16. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  17. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  18. GRB 250309B / AT2025dws: SAO RAS optical observations
  19. GRB 250309B / AT2025dws: Swift-UVOT detection
  20. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  21. GRB 250309B: Fermi GBM Observation
  22. Fermi GRB 250309B: Global MASTER-Net observations report
  23. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  24. Fermi-LAT gamma-ray observations of IceCube-250309A
  25. GRB 250309B: Fermi GBM Final Localization
  26. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  27. GRB 230509B: Tiled Swift observations
  28. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)

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