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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"

2993 results found.

  1. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  2. Konus-Wind detection of GRB 260411B
  3. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  4. EP260417a: TRT optical counterpart detection
  5. EP260417a: Einstein Probe detection of an X-ray transient
  6. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  7. EP260417b: Einstein Probe detection of a fast X-ray transient
  8. EP-WXT trigger 01709259586: KAIT optical observations
  9. EP260416a: COLIBRÍ optical counterpart candidate
  10. EP260416a: Global MASTER-Net observations report
  11. EP260416a: Einstein Probe detection of an X-ray transient
  12. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  13. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  14. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  15. The EP-WXT trigger 01709260122 is likely a flaring star
  16. Konus-Wind detection of GRB 260410A (short/hard)
  17. The EP-WXT trigger 01709260010 is likely a flaring star
  18. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  19. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  20. EP-WXT01709259790: Optical Upper limits with kinder observations
  21. The EP-WXT trigger 01709259790 is likely a flaring star
  22. EP-WXT01709259790: Xinglong optical upper limit
  23. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  24. EP260321a: Chandra X-ray Non-detection
  25. The EP-WXT trigger 01709259773 is likely a flaring star
  26. EP260409a: SVOM/VT optical upper limits
  27. EP260409a: COLIBRÍ optical upper limits
  28. EP260409a: Global MASTER-Net observations report
  29. EP260409a: Einstein Probe detection of an X-ray transient
  30. GRB 260402A: SVOM/ECLAIRs refined analysis
  31. GRB 260310A / AT2026fgk: X-ray rebrightening
  32. EP260402a / GRB 260402A: Mephisto optical upper limits
  33. EP-WXT01709259586: Xinglong optical upper limit
  34. EP260402a/GRB 260402A: Xinglong optical upper limit
  35. EP260321a: uGMRT observations
  36. EP260405a: GMOS-N optical upper limits
  37. EP260405a: SVOM/VT optical upper limits
  38. EP260405a: Global MASTER-Net observations report
  39. EP260405a: Einstein Probe detection of a fast X-ray transient
  40. The EP-WXT trigger 01709259621 is likely a flaring star
  41. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  42. The EP-WXT trigger 01709259615 is likely a flaring star
  43. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  44. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  45. The EP-WXT trigger 01709259586 is likely a flaring star
  46. EP260403a: LCO optical observations of the counterpart
  47. EP260403a: LCO optical counterpart detection
  48. EP260403a: COLIBRÍ optical counterpart candidate
  49. GRB 260330B: SVOM/VT optical candidate
  50. EP260403a: Einstein Probe detection of an X-ray transient
  51. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  52. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  53. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  54. EP260324A / AT 2026hir: COLIBRÍ optical observations
  55. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  56. GRB 260402A: WINTER J-band upper limit
  57. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  58. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  59. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  60. EP260329b: Mondy and Assy-Turgen optical upper limits
  61. EP260321a :Xinglong optical observations
  62. EP260327a: Xinglong optical upper limit
  63. EP260329b: GOTO detection of optical counterpart
  64. Konus-Wind detection of GRB 260320A
  65. Konus-Wind detection of GRB 260316B
  66. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  67. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  68. EP260329a: COLIBRÍ optical upper limit
  69. EP260329a: EP-FXT follow up observation
  70. EP260329a: NOT optical counterpart candidate
  71. EP260329b: Global MASTER-Net observations report
  72. EP260329b: Optical follow-up with Kinder observations
  73. EP 260329b: COLIBRÍ optical observations
  74. EP260329a: Optical upper limit with Kinder observations
  75. EP260329b: Einstein Probe detection of an X-ray transient
  76. EP260329a: Einstein Probe detection of an X-ray transient
  77. EP-WXT trigger 01709259209: TRT optical counterpart detection
  78. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  79. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  80. EP260327a: SVOM/VT optical upper limits
  81. EP260327a: WINTER J-band upper limit
  82. EP260327a: COLIBRÍ optical upper limits
  83. EP260327a: Gemini-North optical upper limits
  84. EP260327a: Global MASTER-Net observations report
  85. EP260327a: Einstein Probe detection of an X-ray transient
  86. The EP-WXT trigger 01709259173 is likely a flaring star
  87. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  88. EP260321a: Gemini-South confirmation of a supernova
  89. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  90. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  91. The EP-WXT trigger 01709259112 is likely a flaring star
  92. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  93. EP260321a: COLIBRÍ further optical observations and brightening
  94. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  95. EP260214b: ATCA 6 GHz detection
  96. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  97. GRB 260321A: EP-FXT follow-up observation
  98. The EP-WXT trigger 01709259045 is likely a flaring star
  99. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  100. EP260321a: GOTO detection of blue variable source

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