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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"

38586 results found.

  1. The EP-WXT trigger 01709259790 is likely a flaring star
  2. GRB 260410B: Fermi GBM Final Real-time Localization
  3. EP-WXT01709259790: Xinglong optical upper limit
  4. GRB 260410A: Fermi-LAT detection
  5. GRB 260410A: Fermi GBM Final Real-time Localization
  6. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  7. EP260321a: Chandra X-ray Non-detection
  8. GRB 260409A: Fermi GBM Final Real-time Localization
  9. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  10. The EP-WXT trigger 01709259773 is likely a flaring star
  11. GRB 260407A: GECAM-A detection
  12. GRB 260407A: Insight-HXMT/HE detection
  13. EP260409a: SVOM/VT optical upper limits
  14. EP260409a: COLIBRÍ optical upper limits
  15. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  16. EP260409a: Einstein Probe detection of an X-ray transient
  17. GRB 260404A: Fermi GBM Final Localization
  18. GRB 260407A: Glowbug gamma-ray detection
  19. GRB 260402A: SVOM/ECLAIRs refined analysis
  20. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  21. GRB 260310A / AT2026fgk: X-ray rebrightening
  22. EP260402a / GRB 260402A: Mephisto optical upper limits
  23. EP-WXT01709259586: Xinglong optical upper limit
  24. EP260403a: Mephisto optical upper limits
  25. EP260402a/GRB 260402A: Xinglong optical upper limit
  26. EP260321a: Upper limits from VLA radio observations
  27. GRID detection of GRB 260401A
  28. EP260321a: uGMRT observations
  29. GRB 260407A: Fermi GBM Final Real-time Localization
  30. EP260405a: GMOS-N optical upper limits
  31. EP260405a: SVOM/VT optical upper limits
  32. EP260405a: Einstein Probe detection of a fast X-ray transient
  33. The EP-WXT trigger 01709259621 is likely a flaring star
  34. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  35. The EP-WXT trigger 01709259615 is likely a flaring star
  36. GRB 260403A: GECAM-B observation of a long burst
  37. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  38. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  39. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  40. The EP-WXT trigger 01709259586 is likely a flaring star
  41. GRB 260330B: SVOM/VT further optical observation
  42. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  43. GRB 260330B: SVOM/ECLAIRs refined analysis
  44. EP260403a: LCO optical observations of the counterpart
  45. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  46. EP260403a: LCO optical counterpart detection
  47. EP260403a: COLIBRÍ optical counterpart candidate
  48. GRB 260330B: SVOM/VT optical candidate
  49. EP260403a: Einstein Probe detection of an X-ray transient
  50. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  51. GRB 260403A: AstroSat CZTI detection
  52. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  53. GRB 260402B: GECAM-B observation
  54. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  55. GRB 260402C: NuSTAR detection of prompt emission
  56. GRB 260402C: AstroSat CZTI detection of a long burst
  57. EP260324A / AT 2026hir: COLIBRÍ optical observations
  58. GRB 260403A: Fermi GBM Final Real-time Localization
  59. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  60. GRB 260402B: Fermi GBM Final Real-time Localization
  61. GRB 260402A: WINTER J-band upper limit
  62. GRB260402A: GROWTH-India Telescope optical upper limit
  63. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  64. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  65. GRB 260401A: SVOM/GRM observation
  66. GRB 260401A: GECAM-B observation
  67. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  68. GRB 260402A: Kilonova-Catcher optical upper limit
  69. GRB 260402A: MASTER optical observations
  70. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  71. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  72. GRB 260402A: SVOM detection of a burst
  73. GRB 260401A: Fermi GBM Observation
  74. GRB 260401A: NuSTAR detection of prompt emission
  75. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  76. GRB 260401A: MAXI/GSC detection
  77. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  78. GRB 260401A: Fermi GBM Final Real-time Localization
  79. EP260329b: Mondy and Assy-Turgen optical upper limits
  80. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  81. EP260321a :Xinglong optical observations
  82. EP260327a: Xinglong optical upper limit
  83. EP260329b: GOTO detection of optical counterpart
  84. GRB 260330B: SVOM/VT optical upper limits
  85. Konus-Wind detection of GRB 260320A
  86. Konus-Wind detection of GRB 260316B
  87. GRB 260321A: SVOM/ECLAIRs refined analysis
  88. GRB 260330A: Glowbug gamma-ray detection
  89. GRB 260310A: VLA Multi-frequency Radio Observations
  90. Fermi GBM Sub-Threshold Detection of GRB 260330B
  91. GRB 260330B: LCO optical upper limits
  92. GRB 260330B: SVOM detection of a burst
  93. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  94. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  95. EP260329a: COLIBRÍ optical upper limit
  96. EP260329a: EP-FXT follow up observation
  97. GRB 260330A: Fermi GBM Final Real-time Localization
  98. GRB 260327A: Insight-HXMT/HE detection
  99. EP260329b: Optical follow-up with Kinder observations
  100. EP 260329b: COLIBRÍ optical observations

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