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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"

48 results found.

  1. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  2. GRB 230307A: JWST second-epoch observations
  3. GRB 230307A: iTelescope optical upper limit (likely)
  4. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  5. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  6. GRB 230307A: good match with kilonova models
  7. GRB 230307A: short mininum variability timescale compatible with a merger origin
  8. GRB 230307A: JWST observations consistent with the presence of a kilonova
  9. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  10. GRB 230307A: Bad Time Intervals for Fermi GBM data
  11. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  12. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  13. GRB 230307A: ATCA radio detection
  14. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  15. GRB 230307A: Swift/UVOT detection
  16. GRB 230307A: soft X-ray detection with LEIA
  17. GRB 230307A: Swift-XRT afterglow detection
  18. Further improved IPN localization for GRB 230307A
  19. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  20. GRB 230307A: GECKO optical observations and detections of the afterglow
  21. GRB 230307A: MAXI/GSC upper limit
  22. GRB 230307A: Gemini-South Confirmation of the Optical Afterglow
  23. GRB 230307A: AGILE/MCAL analysis
  24. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  25. GRB 230307A: Erratum of the GCN 33441
  26. GRB 230307A: Possible optical afterglow
  27. GRB 230307A: ASO-S/HXI detection
  28. GRB 230307A: AstroSat LAXPC detection
  29. GRB 230307A: optical upper limit
  30. GRB 230307A: Swift/BAT upper limits on the early afterglow
  31. GRB 230307A: Upper limits from a neutrino search with IceCube
  32. GRB 230307A: Swift-XRT observations
  33. Fermi GRB 230307A: Global MASTER-Net observations report
  34. Konus-Wind detection of GRB 230307A
  35. Improved IPN localization for GRB 230307A
  36. GRB 230307A: VZLUSAT-2 detection
  37. GRB 230307A: Tiled Swift observations
  38. GRB 230307A: Detection by GRBAlpha
  39. GRB 230307A: BALROG localization (Fermi Trigger 699896651/ GRB 230307656)
  40. GRB 230307A: AstroSat CZTI detection
  41. GRB 230307A: possibly the second highest GRB energy fluence ever identified
  42. IPN triangulation of GRB 230307A (long/very bright)
  43. GRB 230307A: AGILE/MCAL detection
  44. GRB 230307A: Fermi GBM Observation of a very bright burst
  45. Solar Orbiter STIX observation of GRB 230307A
  46. GRB 230307A: Fermi GBM detection of a very bright GRB
  47. GRB 230307A: GECAM detection of an extremely bright burst
  48. GRB 230307A: Fermi GBM Final Real-time Localization

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