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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"

45759 results found.

  1. GRB 260415A: Fermi GBM Final Real-time Localization
  2. Fermi trigger No 797912738: Global MASTER-Net observations report
  3. GRB 260414A: Glowbug gamma-ray detection
  4. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  5. EP260321a: CMO SAI J,K observations
  6. GRB 260412A: Insight-HXMT/HE detection
  7. GRB 260414A: Fermi GBM Final Real-time Localization
  8. The EP-WXT trigger 01709260122 is likely a flaring star
  9. Fermi GRB 260413A: Global MASTER-Net observations report
  10. GRB 260410A: Glowbug gamma-ray detection of a short burst
  11. GRB 260413A: Fermi GBM Final Real-time Localization
  12. GRB 260410B: Insight-HXMT/HE detection
  13. GRB 260410A: Insight-HXMT/HE detection
  14. Konus-Wind detection of GRB 260410A (short/hard)
  15. GRB 260411B: GECAM-B observation of a long burst
  16. EP260321a: SVOM/VT optical observations and color changes around peak
  17. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  18. The EP-WXT trigger 01709260010 is likely a flaring star
  19. GRB 260412A: GECAM-B observation of a long burst
  20. Fermi GRB 260412A: Global MASTER-Net observations report
  21. GRB 260412A: Fermi GBM Observation
  22. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  23. GRB 260411B: Fermi-LAT detection
  24. GRB 260412A: SVOM detection of a long burst
  25. GRB 260412A: Fermi GBM Final Real-time Localization
  26. GRB 260411B: COLIBRÍ optical observations
  27. GRB 260410B: Fermi GBM Observation
  28. GRB 260411B: Ondrejov D50 optical afterglow detection
  29. GRB260411B: 3.6m DOT optical observation
  30. GRB 260411A: SVOM/GRM observation
  31. GRB 260407B: SVOM/GRM detection of a possible magnetar X-ray burst
  32. GRB 260411B: SVOM/GRM observation of a long burst
  33. GRB 260409A: Insight-HXMT/HE detection
  34. GRB 260411B: Fermi GBM Detection
  35. GRB 260411B: GOTO optical counterpart candidate
  36. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  37. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  38. GRB 260411B: Fermi GBM Final Real-time Localization
  39. GRB 260411A: Fermi GBM Final Real-time Localization
  40. GRB 260410A: COLIBRÍ optical upper limit
  41. EP-WXT01709259790: Optical Upper limits with kinder observations
  42. GRB 260410A: Fermi GBM Observation
  43. GRB 260410B: SVOM/GRM detection of a short faint burst
  44. The EP-WXT trigger 01709259790 is likely a flaring star
  45. GRB 260410B: Fermi GBM Final Real-time Localization
  46. EP-WXT01709259790: Xinglong optical upper limit
  47. GRB 260410A: Fermi-LAT detection
  48. GRB 260410A: Fermi GBM Final Real-time Localization
  49. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  50. EP260321a: Chandra X-ray Non-detection
  51. GRB 260409A: Fermi GBM Final Real-time Localization
  52. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  53. The EP-WXT trigger 01709259773 is likely a flaring star
  54. GRB 260407A: GECAM-A detection
  55. GRB 260407A: Insight-HXMT/HE detection
  56. EP260409a: SVOM/VT optical upper limits
  57. EP260409a: COLIBRÍ optical upper limits
  58. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  59. EP260409a: Global MASTER-Net observations report
  60. EP260409a: Einstein Probe detection of an X-ray transient
  61. EP260321a: VLA radio detection
  62. GRB 260404A: Fermi GBM Final Localization
  63. GRB 260407A: Glowbug gamma-ray detection
  64. GRB 260402A: SVOM/ECLAIRs refined analysis
  65. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  66. GRB 260310A / AT2026fgk: X-ray rebrightening
  67. EP260402a / GRB 260402A: Mephisto optical upper limits
  68. EP-WXT01709259586: Xinglong optical upper limit
  69. EP260403a: Mephisto optical upper limits
  70. EP260402a/GRB 260402A: Xinglong optical upper limit
  71. EP260321a: Upper limits from VLA radio observations
  72. GRID detection of GRB 260401A
  73. EP260321a: uGMRT observations
  74. GRB 260407A: Fermi GBM Final Real-time Localization
  75. EP260405a: GMOS-N optical upper limits
  76. EP260405a: SVOM/VT optical upper limits
  77. EP260405a: Global MASTER-Net observations report
  78. EP260405a: Einstein Probe detection of a fast X-ray transient
  79. The EP-WXT trigger 01709259621 is likely a flaring star
  80. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  81. The EP-WXT trigger 01709259615 is likely a flaring star
  82. Fermi trigger No 797039833: Global MASTER-Net observations report
  83. GRB 260403A: GECAM-B observation of a long burst
  84. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  85. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  86. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  87. The EP-WXT trigger 01709259586 is likely a flaring star
  88. GRB 260330B: SVOM/VT further optical observation
  89. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  90. GRB 260330B: SVOM/ECLAIRs refined analysis
  91. EP260403a: LCO optical observations of the counterpart
  92. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  93. EP260403a: LCO optical counterpart detection
  94. EP260403a: COLIBRÍ optical counterpart candidate
  95. GRB 260330B: SVOM/VT optical candidate
  96. EP260403a: Einstein Probe detection of an X-ray transient
  97. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  98. GRB 260403A: AstroSat CZTI detection
  99. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  100. GRB 260402B: GECAM-B observation

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