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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"

11752 results found.

  1. Fermi GRB 260510A: Global MASTER-Net observations report
  2. GRB 260509A: SVOM detection of a burst
  3. GRB 260506B: AstroSat CZTI detection
  4. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  5. EP260507a: Liverpool Telescope optical upper limits
  6. GRB 260507A: Fermi GBM Final Real-time Localization
  7. EP260507a: Kinder optical counterpart candidate
  8. EP260507a: Einstein Probe detection of an X-ray transient
  9. GRB 260504B: AstroSat CZTI detection
  10. IceCube Alert 260505A: Global MASTER-Net observations report
  11. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  12. Konus-Wind detection of GRB 260504B (short/hard)
  13. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  14. GRB 260430B: AstroSat CZTI detection of a long burst
  15. Konus-Wind detection of GRB 260415C
  16. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  17. Konus-Wind detection of GRB 260411C
  18. IPN triangulation of GRB 260429A
  19. IPN triangulation of GRB 260428A
  20. GRB 260503A: Fermi GBM Final Real-time Localization
  21. GRB 260429B / EP260429a: AstroSat CZTI detection
  22. EP260502a: Einstein Probe detection of an X-ray transient
  23. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  24. GRB 260424B: AstroSat CZTI detection
  25. GRB 260429A: Fermi GBM Detection
  26. Fermi GRB 260429A: Global MASTER-Net observations report
  27. EP260430a: Global MASTER-Net observations report
  28. EP260430a: Einstein Probe detection of an X-ray transient
  29. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  30. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  31. GRB 260428A: AstroSat CZTI detection
  32. Fermi GRB 260428A: Global MASTER-Net observations report
  33. EP260416a: Mondy and Terskol optical upper limits
  34. Konus-Wind detection of GRB 260424B
  35. GRB 260428A: Fermi GBM Final Real-time Localization
  36. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  37. GRB 260401A: cubesat Avion detection
  38. GRB 260424A: AstroSat CZTI detection of a long burst
  39. GRB 260421B: Kilonova-Catcher optical afterglow detection
  40. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  41. GRB 260421B: SVOM/ECLAIRs refined analysis
  42. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  43. GRB 260419A: AstroSat CZTI detection
  44. EP260416a: 1.3m DFOT optical observation
  45. Fermi GRB 260421B: Global MASTER-Net observations report
  46. Fermi GRB 260421A: Global MASTER-Net observations report
  47. GRB 260412A: LCOGT Optical Upper Limits
  48. EP260416a: Optical follow-up observations with Kinder
  49. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  50. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  51. GRB 260417A: SVOM/GRM observation
  52. Fermi trigger No 798275385: Global MASTER-Net observations report
  53. Fermi GRB 260417B: Global MASTER-Net observations report
  54. EP260416a: Ondrejov D50 optical detection
  55. GRB 260418B: Fermi GBM Final Real-time Localization
  56. EP260417a: Global MASTER-Net observations report
  57. Fermi GRB 260417A: Global MASTER-Net observations report
  58. Konus-Wind detection of GRB 260411B
  59. GRB 260417A: AstroSat CZTI detection
  60. IPN triangulation of GRB 260411B
  61. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  62. EP260417a: Einstein Probe detection of an X-ray transient
  63. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  64. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  65. EP260416a: COLIBRÍ optical counterpart candidate
  66. EP260416a: Global MASTER-Net observations report
  67. EP260416a: Einstein Probe detection of an X-ray transient
  68. GRB 260415B: NuSTAR detection of long prompt emission
  69. Fermi trigger No 797912738: Global MASTER-Net observations report
  70. EP260321a: CMO SAI J,K observations
  71. Konus-Wind detection of GRB 260410A (short/hard)
  72. GRB 260411B: Fermi-LAT detection
  73. GRB260411B: 3.6m DOT optical observation
  74. GRB 260411B: SVOM/GRM observation of a long burst
  75. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  76. EP-WXT01709259790: Optical Upper limits with kinder observations
  77. GRB 260410A: Fermi-LAT detection
  78. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  79. EP260409a: Einstein Probe detection of an X-ray transient
  80. GRB 260402A: SVOM/ECLAIRs refined analysis
  81. EP260402a / GRB 260402A: Mephisto optical upper limits
  82. EP260405a: Einstein Probe detection of a fast X-ray transient
  83. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  84. EP260403a: COLIBRÍ optical counterpart candidate
  85. EP260403a: Einstein Probe detection of an X-ray transient
  86. GRB 260403A: AstroSat CZTI detection
  87. GRB 260402C: AstroSat CZTI detection of a long burst
  88. EP260324A / AT 2026hir: COLIBRÍ optical observations
  89. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  90. GRB 260402A: SVOM detection of a burst
  91. Fermi GRB 260401A: Global MASTER-Net observations report
  92. GRB 260401A: MAXI/GSC detection
  93. EP260329b: Mondy and Assy-Turgen optical upper limits
  94. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  95. EP260327a: Xinglong optical upper limit
  96. EP260329b: GOTO detection of optical counterpart
  97. Konus-Wind detection of GRB 260320A
  98. Konus-Wind detection of GRB 260316B
  99. GRB 260330B: SVOM detection of a burst
  100. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope

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