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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"

27578 results found.

  1. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  2. GRB 260414A: Fermi GBM Final Real-time Localization
  3. The EP-WXT trigger 01709260122 is likely a flaring star
  4. Fermi GRB 260413A: Global MASTER-Net observations report
  5. GRB 260413A: Fermi GBM Final Real-time Localization
  6. EP260321a: SVOM/VT optical observations and color changes around peak
  7. The EP-WXT trigger 01709260010 is likely a flaring star
  8. Fermi GRB 260412A: Global MASTER-Net observations report
  9. GRB 260412A: Fermi GBM Observation
  10. GRB 260411B: Fermi-LAT detection
  11. GRB 260412A: SVOM detection of a long burst
  12. GRB 260412A: Fermi GBM Final Real-time Localization
  13. GRB 260411B: COLIBRÍ optical observations
  14. GRB 260410B: Fermi GBM Observation
  15. GRB 260411B: Ondrejov D50 optical afterglow detection
  16. GRB260411B: 3.6m DOT optical observation
  17. GRB 260407B: SVOM/GRM detection of a possible magnetar X-ray burst
  18. GRB 260411B: SVOM/GRM observation of a long burst
  19. GRB 260411B: Fermi GBM Detection
  20. GRB 260411B: GOTO optical counterpart candidate
  21. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  22. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  23. GRB 260411B: Fermi GBM Final Real-time Localization
  24. GRB 260411A: Fermi GBM Final Real-time Localization
  25. GRB 260410A: COLIBRÍ optical upper limit
  26. EP-WXT01709259790: Optical Upper limits with kinder observations
  27. GRB 260410A: Fermi GBM Observation
  28. The EP-WXT trigger 01709259790 is likely a flaring star
  29. GRB 260410B: Fermi GBM Final Real-time Localization
  30. EP-WXT01709259790: Xinglong optical upper limit
  31. GRB 260410A: Fermi-LAT detection
  32. GRB 260410A: Fermi GBM Final Real-time Localization
  33. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  34. EP260321a: Chandra X-ray Non-detection
  35. GRB 260409A: Fermi GBM Final Real-time Localization
  36. The EP-WXT trigger 01709259773 is likely a flaring star
  37. EP260409a: SVOM/VT optical upper limits
  38. EP260409a: COLIBRÍ optical upper limits
  39. EP260409a: Global MASTER-Net observations report
  40. EP260321a: VLA radio detection
  41. GRB 260404A: Fermi GBM Final Localization
  42. GRB 260402A: SVOM/ECLAIRs refined analysis
  43. EP260402a / GRB 260402A: Mephisto optical upper limits
  44. EP-WXT01709259586: Xinglong optical upper limit
  45. EP260403a: Mephisto optical upper limits
  46. EP260402a/GRB 260402A: Xinglong optical upper limit
  47. EP260321a: Upper limits from VLA radio observations
  48. EP260321a: uGMRT observations
  49. GRB 260407A: Fermi GBM Final Real-time Localization
  50. EP260405a: GMOS-N optical upper limits
  51. EP260405a: SVOM/VT optical upper limits
  52. EP260405a: Global MASTER-Net observations report
  53. EP260405a: Einstein Probe detection of a fast X-ray transient
  54. The EP-WXT trigger 01709259621 is likely a flaring star
  55. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  56. The EP-WXT trigger 01709259615 is likely a flaring star
  57. Fermi trigger No 797039833: Global MASTER-Net observations report
  58. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  59. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  60. The EP-WXT trigger 01709259586 is likely a flaring star
  61. GRB 260330B: SVOM/VT further optical observation
  62. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  63. GRB 260330B: SVOM/ECLAIRs refined analysis
  64. EP260403a: LCO optical observations of the counterpart
  65. EP260403a: LCO optical counterpart detection
  66. EP260403a: COLIBRÍ optical counterpart candidate
  67. GRB 260330B: SVOM/VT optical candidate
  68. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  69. EP260324A / AT 2026hir: COLIBRÍ optical observations
  70. GRB 260403A: Fermi GBM Final Real-time Localization
  71. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  72. GRB 260402B: Fermi GBM Final Real-time Localization
  73. GRB 260402A: WINTER J-band upper limit
  74. GRB260402A: GROWTH-India Telescope optical upper limit
  75. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  76. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  77. GRB 260401A: SVOM/GRM observation
  78. GRB 260402A: MASTER optical observations
  79. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  80. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  81. GRB 260402A: SVOM detection of a burst
  82. Fermi GRB 260401A: Global MASTER-Net observations report
  83. GRB 260401A: Fermi GBM Observation
  84. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  85. GRB 260401A: Fermi GBM Final Real-time Localization
  86. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  87. EP260321a :Xinglong optical observations
  88. EP260327a: Xinglong optical upper limit
  89. EP260329b: GOTO detection of optical counterpart
  90. GRB 260330B: SVOM/VT optical upper limits
  91. GRB 260321A: SVOM/ECLAIRs refined analysis
  92. EP260329b: J-band upper limits with WINTER
  93. EP260329a: J-band upper limit with WINTER
  94. Fermi GBM Sub-Threshold Detection of GRB 260330B
  95. GRB 260330B: LCO optical upper limits
  96. GRB 260330B: SVOM detection of a burst
  97. EP260329a: COLIBRÍ optical upper limit
  98. EP260329a: EP-FXT follow up observation
  99. EP260329a: NOT optical counterpart candidate
  100. GRB 260330A: Fermi GBM Final Real-time Localization

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