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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"

23 results found.

  1. EP250226a/GRB 250226A: KAIT optical observations
  2. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  3. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  4. GRB 250226A: GRANDMA Optical Observations
  5. Konus-Wind detection of GRB 250226A
  6. GRB 250226A: KAO Optical Upper Limit
  7. GRB 250226A: AbAO AS-32 Optical Upper Limit
  8. GRB 250226A: Fermi GBM Observation
  9. GRB 250226A / EP250226a: LCO detection of the afterglow
  10. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  11. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  12. EP250226a / GRB 250226A: SVOM/VT optical observations
  13. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  14. EP250226a/GRB 250226A: 1.6m Mephisto observations
  15. EP250226a/GRB 250226A: Kinder optical follow-up observations
  16. GRB 250226A: GECAM-B detection
  17. EP250226a/GRB 250226A: GSP detects optical counterpart
  18. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  19. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  20. EP250226a / GRB 250226A: TRT optical counterpart observation
  21. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  22. Fermi GRB 250226A: Global MASTER-Net observations report
  23. GRB 250226A: Fermi GBM Final Real-time Localization

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