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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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

15250 results found.

  1. EP260507a: Xinglong Schmidt optical counterpart detection
  2. Konus-Wind detection of GRB 260511B
  3. EP260512a: COLIBRÍ optical upper limits
  4. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  5. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  6. Konus-Wind detection of GRB 260511A
  7. GRB 260511B: FRAM-ORM optical detection
  8. GRB 260511A: EP-FXT follow-up observation
  9. GRB 260511B: EP-FXT follow-up observation
  10. GRB 260511B: LCO optical counterpart detection
  11. GRB260511B: MAO/AZT-22 optical observations
  12. GRB 260511B: OHP/T193 spectroscopic observations
  13. GRB 260511B: GOTO optical counterpart detection
  14. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  15. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  16. GRB 260510C: Fermi GBM Observation
  17. GRB 260511B: GROWTH-India Telescope optical observations
  18. GRB 260511B: AstroSat CZTI detection
  19. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  20. GRB 260510B: SVOM/ECLAIRs refined analysis
  21. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  22. GRB 260510C: AstroSat CZTI detection
  23. GRB 260511B: SVOM detection of a burst
  24. GRB 260511A: SVOM detection of a bright burst
  25. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  26. GRB 260510B: SVOM/VT optical upper limits
  27. GRB 260510C: MAXI/GSC detection
  28. GRB 260510B: GOTO early upper limit
  29. GRB 260510C: SVOM detection of a burst
  30. GRB 260510A: GECAM-B observation
  31. GRB 260509A: Liverpool Telescope optical observations
  32. GRB 260510B: SVOM detection of a burst
  33. GRB 260509A: LCO optical observations
  34. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  35. GRB 260509A: LCO optical counterpart detection
  36. GRB 260509A: GOTO optical counterpart candidate
  37. GRB 260509A: SVOM detection of a burst
  38. GRB 260506B: AstroSat CZTI detection
  39. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  40. EP260507a: COLIBRÍ optical observations
  41. EP260507a: Kinder optical counterpart candidate
  42. GRB 260504B: AstroSat CZTI detection
  43. GRB 260504B: SVOM/ECLAIRs refined analysis
  44. GRB 260503A: GECAM-B observation of a burst
  45. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  46. Konus-Wind detection of GRB 260504B (short/hard)
  47. GRB 260504B: GECAM-B detection
  48. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  49. GRB 260504C: SVOM/GRM observation of short GRB
  50. GRB 260504B: SVOM/GRM spectral analysis
  51. GRB 260430B: AstroSat CZTI detection of a long burst
  52. GRB 260504B: SVOM/MXT refined analysis and potential detection
  53. GRB 260502A: SVOM/GRM observation of a short GRB
  54. GRB 260503A: SVOM/GRM observation of a GRB
  55. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  56. Konus-Wind detection of GRB 260415C
  57. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  58. Konus-Wind detection of GRB 260411C
  59. GRB 260504B: AST3-2 i-band upper limit
  60. GRB 260504B: SVOM detection of a short burst
  61. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  62. GRB 260502A: GECAM-B observation of a short burst
  63. GRB 260429B / EP260429a: EP-FXT follow-up observation
  64. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  65. GRB 260429B / EP260429a: AstroSat CZTI detection
  66. GRB 260429A: SVOM/GRM observation of a short burst
  67. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  68. GRB 260424B: AstroSat CZTI detection
  69. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  70. GRB 260429A: Fermi GBM Detection
  71. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  72. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  73. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  74. GRB 260428A: AstroSat CZTI detection
  75. GRB 260424B: COLIBRÍ optical upper limit
  76. Konus-Wind detection of GRB 260424B
  77. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  78. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  79. GRB 260424B: SVOM/GRM detection of a short burst
  80. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  81. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  82. GRB 260401A: cubesat Avion detection
  83. GRB 260424A: AstroSat CZTI detection of a long burst
  84. GRB 260421B: Insight-HXMT/HE detection
  85. The EP-WXT trigger 01709258652: Mondy optical observations
  86. GRB 260421B: SVOM/ECLAIRs refined analysis
  87. GRB 260421B: 3.6m DOT optical observation
  88. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  89. GRB 260419A: AstroSat CZTI detection
  90. GRB 260421B: SVOM/GRM observation
  91. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  92. GRB 260421B: LCO optical counterpart detection
  93. GRB 260421B: Fermi GBM Observation
  94. GRB 260421A: AstroSat CZTI detection
  95. GRB 260412A: SVOM/ECLAIRs refined analysis
  96. GRB 260418A: Insight-HXMT/HE detection
  97. GRB 260421B: BOOTES-7 early optical afterglow detection
  98. GRB 260421B: LCO optical afterglow confirmation
  99. GRB 260421B: SVOM detection of a long burst
  100. EP260416a: Optical follow-up observations with Kinder

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