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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

45533 results found.

  1. GRB 260411B: GOTO optical counterpart candidate
  2. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  3. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  4. GRB 260411B: Fermi GBM Final Real-time Localization
  5. GRB 260411A: Fermi GBM Final Real-time Localization
  6. GRB 260410A: COLIBRÍ optical upper limit
  7. EP-WXT01709259790: Optical Upper limits with kinder observations
  8. GRB 260410A: Fermi GBM Observation
  9. GRB 260410B: SVOM/GRM detection of a short faint burst
  10. The EP-WXT trigger 01709259790 is likely a flaring star
  11. GRB 260410B: Fermi GBM Final Real-time Localization
  12. EP-WXT01709259790: Xinglong optical upper limit
  13. GRB 260410A: Fermi-LAT detection
  14. GRB 260410A: Fermi GBM Final Real-time Localization
  15. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  16. EP260321a: Chandra X-ray Non-detection
  17. GRB 260409A: Fermi GBM Final Real-time Localization
  18. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  19. The EP-WXT trigger 01709259773 is likely a flaring star
  20. GRB 260407A: GECAM-A detection
  21. GRB 260407A: Insight-HXMT/HE detection
  22. EP260409a: SVOM/VT optical upper limits
  23. EP260409a: COLIBRÍ optical upper limits
  24. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  25. EP260409a: Global MASTER-Net observations report
  26. EP260409a: Einstein Probe detection of an X-ray transient
  27. EP260321a: VLA radio detection
  28. GRB 260404A: Fermi GBM Final Localization
  29. GRB 260407A: Glowbug gamma-ray detection
  30. GRB 260402A: SVOM/ECLAIRs refined analysis
  31. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  32. GRB 260310A / AT2026fgk: X-ray rebrightening
  33. EP260402a / GRB 260402A: Mephisto optical upper limits
  34. EP-WXT01709259586: Xinglong optical upper limit
  35. EP260403a: Mephisto optical upper limits
  36. EP260402a/GRB 260402A: Xinglong optical upper limit
  37. EP260321a: Upper limits from VLA radio observations
  38. GRID detection of GRB 260401A
  39. EP260321a: uGMRT observations
  40. GRB 260407A: Fermi GBM Final Real-time Localization
  41. EP260405a: GMOS-N optical upper limits
  42. EP260405a: SVOM/VT optical upper limits
  43. EP260405a: Global MASTER-Net observations report
  44. EP260405a: Einstein Probe detection of a fast X-ray transient
  45. The EP-WXT trigger 01709259621 is likely a flaring star
  46. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  47. The EP-WXT trigger 01709259615 is likely a flaring star
  48. Fermi trigger No 797039833: Global MASTER-Net observations report
  49. GRB 260403A: GECAM-B observation of a long burst
  50. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  51. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  52. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  53. The EP-WXT trigger 01709259586 is likely a flaring star
  54. GRB 260330B: SVOM/VT further optical observation
  55. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  56. GRB 260330B: SVOM/ECLAIRs refined analysis
  57. EP260403a: LCO optical observations of the counterpart
  58. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  59. EP260403a: LCO optical counterpart detection
  60. EP260403a: COLIBRÍ optical counterpart candidate
  61. GRB 260330B: SVOM/VT optical candidate
  62. EP260403a: Einstein Probe detection of an X-ray transient
  63. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  64. GRB 260403A: AstroSat CZTI detection
  65. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  66. GRB 260402B: GECAM-B observation
  67. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  68. GRB 260402C: NuSTAR detection of prompt emission
  69. GRB 260402C: AstroSat CZTI detection of a long burst
  70. EP260324A / AT 2026hir: COLIBRÍ optical observations
  71. GRB 260403A: Fermi GBM Final Real-time Localization
  72. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  73. GRB 260402B: Fermi GBM Final Real-time Localization
  74. GRB 260402A: WINTER J-band upper limit
  75. GRB260402A: GROWTH-India Telescope optical upper limit
  76. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  77. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  78. GRB 260401A: SVOM/GRM observation
  79. GRB 260401A: GECAM-B observation
  80. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  81. GRB 260402A: Kilonova-Catcher optical upper limit
  82. GRB 260402A: MASTER optical observations
  83. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  84. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  85. GRB 260402A: SVOM detection of a burst
  86. Fermi GRB 260401A: Global MASTER-Net observations report
  87. GRB 260401A: Fermi GBM Observation
  88. GRB 260401A: NuSTAR detection of prompt emission
  89. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  90. GRB 260401A: MAXI/GSC detection
  91. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  92. GRB 260401A: Fermi GBM Final Real-time Localization
  93. EP260329b: Mondy and Assy-Turgen optical upper limits
  94. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  95. EP260321a :Xinglong optical observations
  96. EP260327a: Xinglong optical upper limit
  97. EP260329b: GOTO detection of optical counterpart
  98. GRB 260330B: SVOM/VT optical upper limits
  99. Konus-Wind detection of GRB 260320A
  100. Konus-Wind detection of GRB 260316B (duplicate submission)

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