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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"

19663 results found.

  1. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  2. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  3. GRB 260924A: Enhanced Swift-XRT position
  4. GRB 260924A: Swift detection of a burst
  5. Trigger_21914: Swift ToO observations (retracted)
  6. GRB 260922A: Ondrejov D50 optical limit
  7. GRB 260922A: Swift-BAT refined analysis
  8. GRB 260922A: Swift/UVOT Upper Limits
  9. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  10. GRB 260922A: COLIBRÍ optical upper limits
  11. GRB 260922A: Swift-XRT refined Analysis
  12. GRB 260922A: Enhanced Swift-XRT position
  13. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  14. GRB 260922A: SVOM/C-GFT optical upper limit
  15. GRB 260922A: Swift detection of a burst
  16. GRB 260921A: AstroSat CZTI detection
  17. GRB 260921A: Swift-BAT refined analysis
  18. GRB 260921A: Fermi GBM Observation
  19. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  20. Swift GRB 260921A: Global MASTER-Net observations report
  21. GRB 260921A: Swift detection of a burst
  22. GRB 260915A: VLT optical and near-infrared upper limits
  23. GRB 260915A: Swift-XRT afterglow detection
  24. GRB 260909A: Swift-XRT observations
  25. GRB 260915A: Swift ToO observations
  26. GRB 260909A: Swift ToO observations
  27. GRB 260903A: Swift-XRT observations
  28. GRB 260903A: Swift ToO observations
  29. NuSTAR 260828: a 1100s hard X-ray transient
  30. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  31. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  32. AT2026nik: EP-FXT X-ray counterpart
  33. SVOM GRB 260515A: Global MASTER-Net observations report
  34. EP260321a: Chandra X-ray Non-detection
  35. Swift BAT trigger 1500295: A solar flare
  36. Swift BAT trigger 1500287: A solar flare
  37. Swift BAT trigger 1500148: A solar flare
  38. Retraction of GCN 43965: GRB is actually solar flare
  39. GRB 260312A: Swift detection of a burst
  40. GRB 260208A: radio detection with the VLA
  41. IPN triangulation of GRB 260212A
  42. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  43. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  44. GRB 260208A: Swift UVOT detection
  45. GRB 260208A: LCO detection of the optical counterpart
  46. GRB 260208B: refined analysis of the EP-FXT observation
  47. GRB 260204A: Swift-XRT afterglow detection
  48. GRB 260208A: Fermi GBM Observation
  49. GRB 260208B: Swift-XRT observations
  50. GRB 260204A: Swift/UVOT Upper Limits
  51. GRB 260208B: EP-FXT observation
  52. GRB 260208B: SVOM/VT optical candidate
  53. GRB 260208A: SVOM/VT optical observation
  54. GRB 260208A: Swift-XRT observations
  55. GRB 260208B: Swift ToO observations
  56. GRB 260208B: Fermi-LAT detection
  57. GRB 260208A: Fermi-LAT detection
  58. GRB 260208A: Swift ToO observations
  59. GRB 260206A: Swift-XRT observations
  60. GRB 260206A: Tiled Swift observations
  61. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  62. GRB 260204A: Swift-XRT observations
  63. GRB 260204A: SVOM/VT optical candidate
  64. GRB 251230A: MeerLICHT afterglow detection
  65. GRB 260127A: GECAM-B observation
  66. GRB 260127B: AstroSat CZTI detection
  67. IPN triangulation of GRB 260121A
  68. GRB 260127A: Swift-BAT refined analysis
  69. GRB 260127B: Swift-XRT observations
  70. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  71. GRB 260127A: Fermi GBM Observation
  72. GRB 260127A: COLIBRÍ optical observations
  73. GRB 260127B: Swift ToO observations
  74. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  75. GRB 260127A: Swift-XRT refined Analysis
  76. GRB 260127A: SVOM/C-GFT optical observations
  77. GRB 260127A: Enhanced Swift-XRT position
  78. GRB 260127A: Prompt enhanced Swift-XRT position
  79. Swift GRB 260127A: Global MASTER-Net observations report
  80. GRB 260127A: Swift detection of a burst
  81. GRB 260125A: Swift-XRT observations
  82. Konus-Wind detection of GRB 260120B
  83. GRB 260125A: Swift ToO observations
  84. GRB 260114A: SVOM/VT optical upper limits
  85. GRB 260122B: Swift-BAT refined analysis
  86. GRB 260120B: SVOM/GRM observation
  87. GRB 260120B: AstroSat CZTI detection
  88. GRB 260114A: Insight-HXMT/HE detection
  89. GRB 260122B: Swift detection of a burst
  90. Swift GRB260122.97: Global MASTER-Net observations report
  91. GRB 260120B: Swift-BAT refined analysis
  92. GRB 260120B: Swift-XRT refined Analysis
  93. GRB 260120B: Fermi GBM Observation
  94. GRB 260120B: Swift/UVOT Detection
  95. GRB 260120B: COLIBRÍ optical upper limits
  96. GRB 260120B: Enhanced Swift-XRT position
  97. GRB 260120B: SVOM/C-GFT optical counterpart detection
  98. GRB 260101A: 239Alferov CubeSat detection
  99. GRB 260120B: Swift detection of a burst
  100. Swift GRB260120B: Global MASTER-Net observations report

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