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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"

27039 results found.

  1. GRB 260511B: LCO optical observations
  2. GRB 260511B: GOTO optical counterpart detection
  3. GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
  4. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  5. GRB 260511B: SVOM/VT optical observations
  6. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  7. GRB 260510B: EP-FXT follow-up observation
  8. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  9. GRB 260510C: Fermi GBM Observation
  10. GRB 260509A: SAO RAS optical observations
  11. GRB 260511A: REM near-infrared detection
  12. GRB 260511B: GROWTH-India Telescope optical observations
  13. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  14. GRB 260511B: Fermi GBM Detection
  15. GRB 260511C: Fermi GBM Final Real-time Localization
  16. GRB 260511B: SVOM/VT optical observation with VHF data
  17. GRB 260511B: TRT optical observation
  18. GRB 260510B: SVOM/ECLAIRs refined analysis
  19. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  20. GRB 260511A: Fermi GBM Detection
  21. GRB 260511B SVOM/C-GFT optical counterpart detection
  22. GRB 260511A: UTGO H50 optical afterglow observation
  23. GRB 260511B: SVOM detection of a burst
  24. GRB 260511B: Fermi GBM Final Real-time Localization
  25. GRB 260510C: EP-FXT follow-up observation
  26. GRB 260510C: SVOM/VT optical counterpart confirmation
  27. EP260509a: EP-FXT non-detection and upper limit
  28. GRB 260511A: SVOM/VT optical observation with VHF data
  29. Fermi GRB 260511A: Global MASTER-Net observations report
  30. GRB 260511A: KAIT optical afterglow observations
  31. GRB 260511A: LCO optical afterglow detection
  32. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  33. GRB 260511A: SVOM detection of a bright burst
  34. GRB 260511A: BALROG localization (Fermi Trigger 800172815 / GRB 260511259)
  35. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  36. GRB 260511A: Fermi GBM Final Real-time Localization
  37. GRB 260510B: SVOM/VT optical upper limits
  38. GRB 260510C: SVOM/VT optical upper limits
  39. GRB 260510C: MAXI/GSC detection
  40. EP260509a: Global MASTER-Net observations report
  41. Fermi GBM Sub-Threshold Detection of GRB 260510B
  42. GRB 260510D: Fermi GBM Final Real-time Localization
  43. GRB 260510C: SVOM detection of a burst
  44. GRB 260510C: Fermi GBM Final Real-time Localization
  45. GRB 260510A: GECAM-B observation
  46. GRB 260510B: LCO optical upper limits
  47. EP260509a: Einstein Probe detection of an X-ray transient
  48. GRB 260509A: Liverpool Telescope optical observations
  49. GRB 260510B: SVOM detection of a burst
  50. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  51. SVOM GRB 260509A: MASTER-OAFA optical observation
  52. Fermi GRB 260510A: Global MASTER-Net observations report
  53. GRB 260510A: Fermi GBM Final Real-time Localization
  54. GRB 260509A: SVOM/VT optical candidate with VHF data
  55. GRB 260509A: LCO optical counterpart detection
  56. GRB 260509A: GOTO optical counterpart candidate
  57. GRB 260509A: SVOM detection of a burst
  58. EP260507a: REM optical/NIR observations
  59. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  60. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  61. EP260507a: COLIBRÍ optical observations
  62. EP260507a: SVOM/VT optical observations
  63. EP260507a: Liverpool Telescope optical upper limits
  64. GRB 260507A: Fermi GBM Final Real-time Localization
  65. EP260507a: GOTO optical counterpart detection
  66. EP260507a: TRT optical counterpart detection
  67. EP260507a: Kinder optical counterpart candidate
  68. EP260507a: LCO optical counterpart
  69. EP260507a: Einstein Probe detection of an X-ray transient
  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. EP260502a is likely a flaring star
  74. Fermi GRB 260506A: Global MASTER-Net observations report
  75. GRB 260506A: Fermi GBM Final Real-time Localization
  76. GRB 260503A: GECAM-B observation of a burst
  77. IceCube Alert 260505A: Global MASTER-Net observations report
  78. GRB 260504B: SVOM/VT optical upper limits
  79. GRB 260504B: GECAM-B detection
  80. GRB 260504C: SVOM/GRM observation of short GRB
  81. GRB 260504B: SVOM/GRM spectral analysis
  82. GRB 260504B: SVOM/MXT refined analysis and potential detection
  83. GRB 260504B: EP-FXT upper limit
  84. GRB 260502A: SVOM/GRM observation of a short GRB
  85. GRB 260503A: SVOM/GRM observation of a GRB
  86. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  87. GRB 260504B: REM optical/NIR observations
  88. IPN triangulation of GRB 260429A
  89. GRB 260504B: LCO z-band upper limit
  90. SVOM GRB 260504B: MASTER-OAFA optical observations
  91. GRB 260504B: SVOM detection of a short burst
  92. Fermi GRB 260504A: Global MASTER-Net observations report
  93. GRB 260504A: Fermi GBM Final Real-time Localization
  94. GRB 260503A: Fermi GBM Final Real-time Localization
  95. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  96. GRB 260502A: GECAM-B observation of a short burst
  97. GRB 260502A: Fermi GBM Final Localization
  98. The EP-WXT trigger 01709261576 is likely a flaring star
  99. GRB 260429B / EP260429a: EP-FXT follow-up observation
  100. EP260502a: BOOTES-7: early optical upper limit

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