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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"

14824 results found.

  1. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  2. X-ray transient EP 240315a: Second epoch Chandra observations
  3. X-ray transient EP240315a: e-MERLIN radio observations
  4. X-ray transient EP240315a: Ondrejov D50 optical limit
  5. GRB 240320A: Glowbug gamma-ray detection
  6. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  7. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  8. GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  9. X-ray transient EP240315a: ATCA detection of radio counterpart
  10. GRB 240320A: Fermi GBM Final Real-time Localization
  11. GRB 240317B: Swift/BAT-GUANO Angular Error Correction
  12. X-ray transient EP 240315a: Chandra observations
  13. X-ray transient EP240315a: MeerKAT radio detection
  14. GRB 240318A: Glowbug gamma-ray detection
  15. GRB 240317C: Glowbug gamma-ray detection
  16. GRB 240318B: Glowbug gamma-ray detection
  17. X-ray transient EP240315a: PRIME near infrared detection
  18. X-ray transient EP240315a: 3.6 m TNG NIR detection
  19. X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
  20. GRB 240318A: Fermi GBM Final Real-time Localization
  21. GRB 240317A: AstroSat CZTI detection
  22. GRB 240315B: AstroSat CZTI detection
  23. GRB 240317B: Fermi GBM Final Real-time Localization
  24. GRB 240317A: Fermi GBM Final Real-time Localization
  25. X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
  26. X-ray transient EP240315a: GROND J-band detection
  27. X-ray transient EP240315a: VLT/X-shooter spectroscopic redshift of z = 4.859
  28. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  29. AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
  30. X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
  31. Einstein Probe detected of a fast X-ray transient EP240315a
  32. GRID detection of GRB 240306A
  33. Changes to the Fermi-GBM Triggering Thresholds
  34. GRB 240315A: Fermi GBM Final Real-time Localization
  35. GRB 240314A: Fermi GBM Final Real-time Localization
  36. GRB240204A: VIRT optical upper limit
  37. GRB 240312A: Glowbug gamma-ray detection
  38. GRB 240312A: GECAM detection of a long burst
  39. GRB 240303C: VZLUSAT-2 detection
  40. GRB 240310A: MASTER OT J200702.72-263928.7 inside 3sigma
  41. GRB 240310B: Glowbug gamma-ray detection
  42. GRB 240310A: Fermi GBM Final Real-time Localization
  43. GRB 240309A: MAXI/GSC detection
  44. GRID detection of GRB 240229A (Updated Report)
  45. GRID detection of GRB 240229A
  46. GRB 240308A: Fermi GBM Final Localization
  47. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  48. GRB 240229A: Glowbug gamma-ray detection
  49. GRB 240227A (short): Glowbug gamma-ray detection
  50. GRB 240229A: GRBAlpha detection
  51. Konus-Wind detection of GRB 231118A
  52. GRB 240306A: AstroSat CZTI detection
  53. GRB 240306A: Swift/BAT-GUANO detection of a burst
  54. GRB 240305C: AstroSat CZTI detection of a short burst
  55. GRB 240306A: Fermi GBM Final Real-time Localization
  56. GRB 240305C: Fermi GBM Final Real-time Localization
  57. GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
  58. GRB 240218A: ALMA detection
  59. GRB 240218A: Chandra Detection and Jet Break Confirmation
  60. GRB 240305B: Fermi GBM Final Localization
  61. Konus-Wind detection of GRB 240227A (short/hard)
  62. GRB 240303B: VZLUSAT-2 detection
  63. GRB 240229A: VZLUSAT-2 detection
  64. IPN triangulation of GRB 240229A
  65. GRB 240305A: Fermi GBM Final Real-time Localization
  66. GRB240218A: ATCA observation of the radio counterpart
  67. Transient EPW20240219aa: Optical observations with LDT
  68. Konus-Wind detection of GRB 240303B
  69. Swift Trigger 1218645: Another detection of Swift J151857.0-572147
  70. IPN triangulation of GRB 240303B
  71. GRB 240303B: Fermi GBM Detection
  72. GRB 240225B: Swift-XRT afterglow detection
  73. Swift detection of Swift J151857.0-572147
  74. GRB 240303B: CALET Gamma-Ray Burst Monitor detection
  75. GRB 240215A: Swift-XRT afterglow detection
  76. GRB 240303B: Fermi GBM Final Localization
  77. GRB 240303A: Swift detection of a burst
  78. GRB 240225B: Glowbug gamma-ray detection
  79. GRB 240225C: Glowbug gamma-ray detection
  80. GRB 240225A (short): Glowbug gamma-ray detection
  81. GRB 240218A: NOEMA upper limit
  82. GRB 240229A: CALET Gamma-Ray Burst Monitor detection
  83. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  84. Konus-Wind detection of GRB 240225B (long)
  85. GRB 240229A: Fermi GBM Final Real-time Localization
  86. GRB 240225B: VLT/X-shooter redshift
  87. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  88. GRB 240225B: 3.6m DOT observation
  89. GRB 240226A: GRBAlpha detection
  90. GRB 240225B: Liverpool Telescope afterglow observations
  91. Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up
  92. IPN triangulation of GRB 240227A (short)
  93. GRB 240227A: Fermi GBM Final Real-time Localization
  94. GRB 240225B: Nanshan/HMT optical afterglow detection
  95. GRB 240225B: CALET Gamma-Ray Burst Monitor detection
  96. GRB 240226B: Fermi GBM Final Real-time Localization
  97. GRB 240225C: CALET Gamma-Ray Burst Monitor detection
  98. GRB 240225B: GOTO detection of a candidate optical afterglow
  99. GRB 240226A: Fermi GBM Final Real-time Localization
  100. Transient EPW20240219aa: REM optical/NIR upper limits

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