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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"

36145 results found.

  1. Fermi GBM Sub-Threshold Detection of GRB 260510B
  2. GRB 260510D: Fermi GBM Final Real-time Localization
  3. GRB 260510B: GOTO early upper limit
  4. GRB 260510C: SVOM detection of a burst
  5. GRB 260510C: Fermi GBM Final Real-time Localization
  6. GRB 260510A: GECAM-B observation
  7. GRB 260510B: LCO optical upper limits
  8. GRB 260509A: Liverpool Telescope optical observations
  9. GRB 260510B: SVOM detection of a burst
  10. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  11. GRB 260509A: LCO optical observations
  12. SVOM GRB 260509A: MASTER-OAFA optical observation
  13. Fermi GRB 260510A: Global MASTER-Net observations report
  14. GRB 260509A: KAIT optical observations
  15. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  16. GRB 260510A: Fermi GBM Final Real-time Localization
  17. GRB 260509A: SVOM/VT optical candidate with VHF data
  18. GRB 260509A: LCO optical counterpart detection
  19. GRB 260509A: GOTO optical counterpart candidate
  20. GRB 260509A: SVOM detection of a burst
  21. GRB 260506B: AstroSat CZTI detection
  22. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  23. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  24. GRB 260507A: Fermi GBM Final Real-time Localization
  25. GRB 260504B: AstroSat CZTI detection
  26. GRB 260504B: SVOM/ECLAIRs refined analysis
  27. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  28. GRB 260506B: Fermi GBM Final Real-time Localization
  29. Fermi GRB 260506A: Global MASTER-Net observations report
  30. GRB 260506A: Fermi GBM Final Real-time Localization
  31. GRB 260503A: GECAM-B observation of a burst
  32. GRB 260430B: Glowbug gamma-ray detection
  33. GRB 260504B: SVOM/VT optical upper limits
  34. GRB 260421B: radio observation with the VLA
  35. Konus-Wind detection of GRB 260504B (short/hard)
  36. GRB 260504B: GECAM-B detection
  37. GRB 260504C: SVOM/GRM observation of short GRB
  38. GRB 260504B: SVOM/GRM spectral analysis
  39. GRB 260430B: AstroSat CZTI detection of a long burst
  40. GRB 260504B: SVOM/MXT refined analysis and potential detection
  41. GRB 260504B: EP-FXT upper limit
  42. GRB 260502A: SVOM/GRM observation of a short GRB
  43. GRB 260503A: SVOM/GRM observation of a GRB
  44. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  45. Konus-Wind detection of GRB 260415C
  46. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  47. Konus-Wind detection of GRB 260411C
  48. GRB 260504B: REM optical/NIR observations
  49. IPN triangulation of GRB 260429A
  50. IPN triangulation of GRB 260428A
  51. GRB 260504B: AST3-2 i-band upper limit
  52. GRB 260504B: LCO z-band upper limit
  53. SVOM GRB 260504B: MASTER-OAFA optical observations
  54. GRB 260504B: SVOM detection of a short burst
  55. Fermi GRB 260504A: Global MASTER-Net observations report
  56. GRB 260504A: Fermi GBM Final Real-time Localization
  57. GRB 260503A: Fermi GBM Final Real-time Localization
  58. GRB 260502A: GECAM-B observation of a short burst
  59. IPN triangulation of a bright burst from SGR 1E1841-045
  60. GRB 260502A: Fermi GBM Final Localization
  61. GRB 260429B / EP260429a: EP-FXT follow-up observation
  62. GRB 260429B / EP260429a: AstroSat CZTI detection
  63. GRB 260429A: SVOM/GRM observation of a short burst
  64. GRB 260424B: AstroSat CZTI detection
  65. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  66. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  67. GRB 260429A: Fermi GBM Detection
  68. Fermi GRB 260429A: Global MASTER-Net observations report
  69. GRB 260429A: Fermi GBM Final Real-time Localization
  70. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  71. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  72. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  73. GRB 260428A: AstroSat CZTI detection
  74. Fermi GRB 260428A: Global MASTER-Net observations report
  75. EP260416a: Mondy and Terskol optical upper limits
  76. GRB 260424B: Glowbug gamma-ray detection of a short burst
  77. GRB 260424B: COLIBRÍ optical upper limit
  78. Konus-Wind detection of GRB 260424B
  79. GRB 260428A: Fermi GBM Final Real-time Localization
  80. GRB 260424C: Fermi GBM Final Localization
  81. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  82. IPN triangulation of GRB 260424B (short)
  83. GRB 260424B: SVOM/GRM detection of a short burst
  84. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  86. GRB 260401A: cubesat Avion detection
  87. GRB 260424A: AstroSat CZTI detection of a long burst
  88. GRB 260421B: Kilonova-Catcher optical afterglow detection
  89. GRB 260421B: Insight-HXMT/HE detection
  90. The EP-WXT trigger 01709258652: Mondy optical observations
  91. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  92. EP260416a: Mondy optical observations
  93. GRB 260421B: SVOM/ECLAIRs refined analysis
  94. GRB 260421B: 3.6m DOT optical observation
  95. EP260416a: ZTSh R band observations
  96. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  97. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  98. GRB 260419A: AstroSat CZTI detection
  99. GRB 260421B: SVOM/GRM observation
  100. GRB260421B: J band upper limit by SYSU 80cm infrared telescope

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