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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"

45534 results found.

  1. GRB 260510B: EP-FXT follow-up observation
  2. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  3. GRB 260510C: Fermi GBM Observation
  4. GRB 260509A: SAO RAS optical observations
  5. GRB 260511A: REM near-infrared detection
  6. GRB 260511B: GROWTH-India Telescope optical observations
  7. GRB 260511B: AstroSat CZTI detection
  8. GRB 260506B: Glowbug gamma-ray detection
  9. GRB 260506A: Glowbug gamma-ray detection of a short burst
  10. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  11. GRB 260511B: NuSTAR detection of prompt emission
  12. GRB 260511A: NuSTAR detection of prompt emission
  13. GRB 260511B: Fermi GBM Detection
  14. GRB 260511C: Fermi GBM Final Real-time Localization
  15. GRB 260511B: SVOM/VT optical observation with VHF data
  16. GRB 260511B: TRT optical observation
  17. GRB 260510B: SVOM/ECLAIRs refined analysis
  18. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  19. GRB 260511A: Fermi GBM Detection
  20. GRB 260511B SVOM/C-GFT optical counterpart detection
  21. EP260509a: LCO optical upper limits
  22. GRB 260511A: UTGO H50 optical afterglow observation
  23. GRB 260510C: AstroSat CZTI detection
  24. GRB 260511B: SVOM detection of a burst
  25. GRB 260511B: Fermi GBM Final Real-time Localization
  26. GRB 260510C: EP-FXT follow-up observation
  27. GRB 260510C: SVOM/VT optical counterpart confirmation
  28. EP260509a: EP-FXT non-detection and upper limit
  29. GRB 260511A: SVOM/VT optical observation with VHF data
  30. Fermi GRB 260511A: Global MASTER-Net observations report
  31. GRB 260511A: KAIT optical afterglow observations
  32. GRB 260511A: LCO optical afterglow detection
  33. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  34. GRB 260511A: TRT optical counterpart detection
  35. GRB 260511A: SVOM detection of a bright burst
  36. GRB 260511A: BALROG localization (Fermi Trigger 800172815 / GRB 260511259)
  37. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  38. GRB 260511A: Fermi GBM Final Real-time Localization
  39. GRB 260510B: SVOM/VT optical upper limits
  40. GRB 260510C: SVOM/VT optical upper limits
  41. GRB 260510C: MAXI/GSC detection
  42. EP260509a: Global MASTER-Net observations report
  43. Fermi GBM Sub-Threshold Detection of GRB 260510B
  44. GRB 260510D: Fermi GBM Final Real-time Localization
  45. GRB 260510B: GOTO early upper limit
  46. GRB 260510C: SVOM detection of a burst
  47. GRB 260510C: Fermi GBM Final Real-time Localization
  48. GRB 260510A: GECAM-B observation
  49. GRB 260510B: LCO optical upper limits
  50. EP260509a: Einstein Probe detection of an X-ray transient
  51. GRB 260509A: Liverpool Telescope optical observations
  52. GRB 260510B: SVOM detection of a burst
  53. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  54. GRB 260509A: LCO optical observations
  55. SVOM GRB 260509A: MASTER-OAFA optical observation
  56. Fermi GRB 260510A: Global MASTER-Net observations report
  57. GRB 260509A: KAIT optical observations
  58. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  59. GRB 260510A: Fermi GBM Final Real-time Localization
  60. GRB 260509A: SVOM/VT optical candidate with VHF data
  61. GRB 260509A: LCO optical counterpart detection
  62. GRB 260509A: GOTO optical counterpart candidate
  63. GRB 260509A: SVOM detection of a burst
  64. GRB 260506B: AstroSat CZTI detection
  65. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  66. EP260507a: REM optical/NIR observations
  67. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  68. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  69. EP260507a: COLIBRÍ optical observations
  70. EP260507a: SVOM/VT optical observations
  71. EP260507a: NOT optical observations
  72. EP260507a: further Liverpool Telescope observations
  73. EP260507a: Liverpool Telescope optical upper limits
  74. GRB 260507A: Fermi GBM Final Real-time Localization
  75. EP260507a: GOTO optical counterpart detection
  76. EP260507a: TRT optical counterpart detection
  77. EP260507a: Kinder optical counterpart candidate
  78. EP260507a: LCO optical counterpart
  79. EP260507a: Einstein Probe detection of an X-ray transient
  80. GRB 260504B: AstroSat CZTI detection
  81. GRB 260504B: SVOM/ECLAIRs refined analysis
  82. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  83. GRB 260506B: Fermi GBM Final Real-time Localization
  84. EP260502a is likely a flaring star
  85. Fermi GRB 260506A: Global MASTER-Net observations report
  86. GRB 260506A: Fermi GBM Final Real-time Localization
  87. GRB 260503A: GECAM-B observation of a burst
  88. IceCube Alert 260505A: Global MASTER-Net observations report
  89. GRB 260430B: Glowbug gamma-ray detection
  90. GRB 260504B: SVOM/VT optical upper limits
  91. GRB 260421B: radio observation with the VLA
  92. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  93. Konus-Wind detection of GRB 260504B (short/hard)
  94. GRB 260504B: GECAM-B detection
  95. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  96. GRB 260504C: SVOM/GRM observation of short GRB
  97. GRB 260504B: SVOM/GRM spectral analysis
  98. GRB 260430B: AstroSat CZTI detection of a long burst
  99. GRB 260504B: SVOM/MXT refined analysis and potential detection
  100. GRB 260504B: EP-FXT upper limit

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