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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"

27772 results found.

  1. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  2. GRB 260525A: Fermi GBM Final Real-time Localization
  3. GRB 260523B: AstroSat CZTI detection
  4. GRB 260523B: Fermi GBM Final Real-time Localization
  5. GRB 260523A: Fermi GBM Final Real-time Localization
  6. GRB 260522B: NuSTAR detection of prompt emission
  7. GRB 260522B: Fermi GBM Final Real-time Localization
  8. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  9. GRB 260522A: Fermi-LAT detection
  10. GRB 260522A: Fermi GBM Final Real-time Localization
  11. GRB 260511A: iTelescope T-75 optical detection
  12. GRB 260411B: TERI Gamma-ray detection
  13. GRB 260407A: TERI Gamma-ray detection
  14. GRB 260307A: TERI Gamma-ray detection
  15. GRB 260225D: TERI Gamma-ray detection
  16. GRB 251118A: TERI Gamma-ray detection
  17. GRB 251113A: TERI Gamma-ray detection
  18. GRB 260428A: TERI Gamma-ray detection
  19. Konus-Wind detection of GRB 260519C
  20. GRB 260520B: Fermi GBM Final Localization
  21. GRB 260520A: Fermi GBM Final Localization
  22. GRB 260519D: Fermi GBM Final Localization Correction
  23. GRB 260519C: NuSTAR detection of prompt emission
  24. Konus-Wind detection of GRB 260518A
  25. GRB 260519B: Fermi GBM Final Localization
  26. GRB 260519A: Fermi GBM Final Localization
  27. GRB 260518A: AstroSat CZTI detection of a long burst
  28. GRB 260421B: radio detection with the VLA
  29. GRID detection of GRB 260511A
  30. GRB 260516D: GOTO optical counterpart detection
  31. GRB 260516D: GROWTH-India Telescope optical detection
  32. GRB 260516D: FRAM-ORM optical limit
  33. GRB 260516D: SVOM possible detection of a burst
  34. GRB 260516C: Fermi GBM Final Real-time Localization
  35. Konus-Wind detection of GRB 260515A
  36. GRB 260515A: Liverpool Telescope optical detection
  37. GRB 260515A: LCO optical counterpart detection
  38. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  39. GRB 260516B: Fermi GBM Final Real-time Localization
  40. GRB 260516A: Fermi GBM Final Real-time Localization
  41. GRID detection of GRB 260507A
  42. GRB 260515A: LCO optical observations
  43. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  44. GRB 260515A: SVOM detection of a burst
  45. GRB 260510C: Glowbug gamma-ray detection
  46. Konus-Wind detection of GRB 260512A
  47. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  48. EP260514a: Einstein Probe detection of a fast X-ray transient
  49. EP260512a: LCO optical upper limits
  50. IPN triangulation of GRB 260512A
  51. GRB 260512A: AstroSat CZTI detection
  52. EP260512a: EP-FXT follow-up observation
  53. EP260507a: Xinglong Schmidt optical counterpart detection
  54. GRB 260514A: Fermi GBM Final Real-time Localization
  55. GRB 260513A: Fermi GBM Final Real-time Localization
  56. Konus-Wind detection of GRB 260511B
  57. EP260512a: Einstein Probe detection of an X-ray transient
  58. GRB 260512A: NuSTAR detection of prompt emission
  59. GRB 260512A: Fermi GBM Final Real-time Localization
  60. GRB 260511A: Glowbug gamma-ray detection
  61. Konus-Wind detection of GRB 260511A
  62. MASS-Cube (GRID 2.0) detection of GRB 260511A
  63. MASS-Cube (GRID 2.0) detection of GRB 260507A
  64. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  65. GRB 260511B: FRAM-ORM optical detection
  66. GRB 260511B: LCO optical counterpart detection
  67. GRB 260511B: GOTO optical counterpart detection
  68. GRB 260510A: AstroSat CZTI detection (Erroneous Submission)
  69. GRB 260511A: REM near-infrared detection
  70. GRB 260511B: AstroSat CZTI detection
  71. GRB 260506B: Glowbug gamma-ray detection
  72. GRB 260506A: Glowbug gamma-ray detection of a short burst
  73. GRB 260511B: NuSTAR detection of prompt emission
  74. GRB 260511A: NuSTAR detection of prompt emission
  75. GRB 260511B: Fermi GBM Detection
  76. GRB 260511C: Fermi GBM Final Real-time Localization
  77. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  78. GRB 260511A: Fermi GBM Detection
  79. GRB 260511B SVOM/C-GFT optical counterpart detection
  80. EP260509a: LCO optical upper limits
  81. GRB 260510C: AstroSat CZTI detection
  82. GRB 260511B: SVOM detection of a burst
  83. GRB 260511B: Fermi GBM Final Real-time Localization
  84. EP260509a: EP-FXT non-detection and upper limit
  85. GRB 260511A: LCO optical afterglow detection
  86. GRB 260511A: TRT optical counterpart detection
  87. GRB 260511A: SVOM detection of a bright burst
  88. GRB 260511A: Fermi GBM Final Real-time Localization
  89. GRB 260510B: SVOM/VT optical upper limits
  90. GRB 260510C: MAXI/GSC detection
  91. Fermi GBM Sub-Threshold Detection of GRB 260510B
  92. GRB 260510D: Fermi GBM Final Real-time Localization
  93. GRB 260510B: GOTO early upper limit
  94. GRB 260510C: SVOM detection of a burst
  95. GRB 260510C: Fermi GBM Final Real-time Localization
  96. EP260509a: Einstein Probe detection of an X-ray transient
  97. GRB 260510B: SVOM detection of a burst
  98. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  99. GRB 260510A: Fermi GBM Final Real-time Localization
  100. GRB 260509A: LCO optical counterpart detection

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