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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"

37956 results found.

  1. GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
  2. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  3. GRB 260510A: AstroSat CZTI detection (Erroneous Submission)
  4. GRB 260511B: SVOM/VT optical observations
  5. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  6. GRB 260510B: EP-FXT follow-up observation
  7. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  8. GRB 260510C: Fermi GBM Observation
  9. GRB 260509A: SAO RAS optical observations
  10. GRB 260511A: REM near-infrared detection
  11. GRB 260511B: GROWTH-India Telescope optical observations
  12. GRB 260511B: AstroSat CZTI detection
  13. GRB 260506B: Glowbug gamma-ray detection
  14. GRB 260506A: Glowbug gamma-ray detection of a short burst
  15. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  16. GRB 260511B: NuSTAR detection of prompt emission
  17. GRB 260511A: NuSTAR detection of prompt emission
  18. GRB 260511B: Fermi GBM Detection
  19. GRB 260511C: Fermi GBM Final Real-time Localization
  20. GRB 260511B: SVOM/VT optical observation with VHF data
  21. GRB 260511B: TRT optical observation
  22. GRB 260510B: SVOM/ECLAIRs refined analysis
  23. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  24. GRB 260511A: Fermi GBM Detection
  25. GRB 260511B SVOM/C-GFT optical counterpart detection
  26. GRB 260511A: UTGO H50 optical afterglow observation
  27. GRB 260510C: AstroSat CZTI detection
  28. GRB 260511B: SVOM detection of a burst
  29. GRB 260511B: Fermi GBM Final Real-time Localization
  30. GRB 260510C: EP-FXT follow-up observation
  31. GRB 260510C: SVOM/VT optical counterpart confirmation
  32. GRB 260511A: SVOM/VT optical observation with VHF data
  33. Fermi GRB 260511A: Global MASTER-Net observations report
  34. GRB 260511A: KAIT optical afterglow observations
  35. GRB 260511A: LCO optical afterglow detection
  36. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  37. GRB 260511A: TRT optical counterpart detection
  38. GRB 260511A: SVOM detection of a bright burst
  39. GRB 260511A: BALROG localization (Fermi Trigger 800172815 / GRB 260511259)
  40. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  41. GRB 260511A: Fermi GBM Final Real-time Localization
  42. GRB 260510B: SVOM/VT optical upper limits
  43. GRB 260510C: SVOM/VT optical upper limits
  44. GRB 260510C: MAXI/GSC detection
  45. EP260509a: Global MASTER-Net observations report
  46. Fermi GBM Sub-Threshold Detection of GRB 260510B
  47. GRB 260510D: Fermi GBM Final Real-time Localization
  48. GRB 260510B: GOTO early upper limit
  49. GRB 260510C: SVOM detection of a burst
  50. GRB 260510C: Fermi GBM Final Real-time Localization
  51. GRB 260510A: GECAM-B observation
  52. GRB 260510B: LCO optical upper limits
  53. GRB 260509A: Liverpool Telescope optical observations
  54. GRB 260510B: SVOM detection of a burst
  55. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  56. GRB 260509A: LCO optical observations
  57. SVOM GRB 260509A: MASTER-OAFA optical observation
  58. Fermi GRB 260510A: Global MASTER-Net observations report
  59. GRB 260509A: KAIT optical observations
  60. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  61. GRB 260510A: Fermi GBM Final Real-time Localization
  62. GRB 260509A: SVOM/VT optical candidate with VHF data
  63. GRB 260509A: LCO optical counterpart detection
  64. GRB 260509A: GOTO optical counterpart candidate
  65. GRB 260509A: SVOM detection of a burst
  66. GRB 260506B: AstroSat CZTI detection
  67. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  68. GRB 260507A: Fermi GBM Final Real-time Localization
  69. GRB 260504B: AstroSat CZTI detection
  70. GRB 260504B: SVOM/ECLAIRs refined analysis
  71. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  72. GRB 260506B: Fermi GBM Final Real-time Localization
  73. Fermi GRB 260506A: Global MASTER-Net observations report
  74. GRB 260506A: Fermi GBM Final Real-time Localization
  75. GRB 260503A: GECAM-B observation of a burst
  76. IceCube Alert 260505A: Global MASTER-Net observations report
  77. GRB 260430B: Glowbug gamma-ray detection
  78. GRB 260504B: SVOM/VT optical upper limits
  79. GRB 260421B: radio observation with the VLA
  80. Konus-Wind detection of GRB 260504B (short/hard)
  81. GRB 260504B: GECAM-B detection
  82. GRB 260504C: SVOM/GRM observation of short GRB
  83. GRB 260504B: SVOM/GRM spectral analysis
  84. GRB 260430B: AstroSat CZTI detection of a long burst
  85. GRB 260504B: SVOM/MXT refined analysis and potential detection
  86. GRB 260504B: EP-FXT upper limit
  87. GRB 260502A: SVOM/GRM observation of a short GRB
  88. GRB 260503A: SVOM/GRM observation of a GRB
  89. Konus-Wind detection of GRB 260415C
  90. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  91. Konus-Wind detection of GRB 260411C
  92. GRB 260504B: REM optical/NIR observations
  93. IPN triangulation of GRB 260429A
  94. IPN triangulation of GRB 260428A
  95. GRB 260504B: AST3-2 i-band upper limit
  96. GRB 260504B: LCO z-band upper limit
  97. SVOM GRB 260504B: MASTER-OAFA optical observations
  98. GRB 260504B: SVOM detection of a short burst
  99. Fermi GRB 260504A: Global MASTER-Net observations report
  100. GRB 260504A: Fermi GBM Final Real-time Localization

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