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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"

32542 results found.

  1. GRB 260509A: LCO optical counterpart detection
  2. GRB 260509A: GOTO optical counterpart candidate
  3. GRB 260509A: SVOM detection of a burst
  4. GRB 260506B: AstroSat CZTI detection
  5. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  6. EP260507a: REM optical/NIR observations
  7. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  8. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  9. EP260507a: COLIBRÍ optical observations
  10. EP260507a: SVOM/VT optical observations
  11. EP260507a: NOT optical observations
  12. EP260507a: further Liverpool Telescope observations
  13. EP260507a: Liverpool Telescope optical upper limits
  14. EP260507a: GOTO optical counterpart detection
  15. EP260507a: TRT optical counterpart detection
  16. EP260507a: Kinder optical counterpart candidate
  17. EP260507a: LCO optical counterpart
  18. GRB 260504B: AstroSat CZTI detection
  19. GRB 260504B: SVOM/ECLAIRs refined analysis
  20. EP260502a is likely a flaring star
  21. Fermi GRB 260506A: Global MASTER-Net observations report
  22. GRB 260503A: GECAM-B observation of a burst
  23. GRB 260430B: Glowbug gamma-ray detection
  24. GRB 260504B: SVOM/VT optical upper limits
  25. GRB 260421B: radio observation with the VLA
  26. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  27. Konus-Wind detection of GRB 260504B (short/hard)
  28. GRB 260504B: GECAM-B detection
  29. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  30. GRB 260504B: SVOM/GRM spectral analysis
  31. GRB 260504B: SVOM/MXT refined analysis and potential detection
  32. GRB 260504B: EP-FXT upper limit
  33. GRB 260502A: SVOM/GRM observation of a short GRB
  34. GRB 260503A: SVOM/GRM observation of a GRB
  35. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  36. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  37. GRB 260504B: REM optical/NIR observations
  38. IPN triangulation of GRB 260429A
  39. IPN triangulation of GRB 260428A
  40. GRB 260504B: AST3-2 i-band upper limit
  41. GRB 260504B: LCO z-band upper limit
  42. SVOM GRB 260504B: MASTER-OAFA optical observations
  43. Fermi GRB 260504A: Global MASTER-Net observations report
  44. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  45. GRB 260502A: GECAM-B observation of a short burst
  46. IPN triangulation of a bright burst from SGR 1E1841-045
  47. GRB 260429B / EP260429a: EP-FXT follow-up observation
  48. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  49. GRB 260429B / EP260429a: AstroSat CZTI detection
  50. EP260502a: BOOTES-7: early optical upper limit
  51. EP260502a: Las Cumbres upper limit
  52. GRB 260429A: SVOM/GRM observation of a short burst
  53. EP260429a: Global MASTER-Net observations report
  54. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  55. GRB 260424B: AstroSat CZTI detection
  56. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  57. EP260429a: LCO optical upper limits
  58. EP260430a: LCO optical upper limits
  59. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  60. Fermi GRB 260429A: Global MASTER-Net observations report
  61. EP260430a: Global MASTER-Net observations report
  62. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  63. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  64. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  65. GRB 260428A: AstroSat CZTI detection
  66. Fermi GRB 260428A: Global MASTER-Net observations report
  67. EP260416a: Mondy and Terskol optical upper limits
  68. GRB 260424B: Glowbug gamma-ray detection of a short burst
  69. GRB 260424B: COLIBRÍ optical upper limit
  70. Konus-Wind detection of GRB 260424B
  71. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  72. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  73. IPN triangulation of GRB 260424B (short)
  74. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  75. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  76. GRB 260401A: cubesat Avion detection
  77. EP260321a: Upper limits from ATCA radio observations
  78. GRB 260421B: Kilonova-Catcher optical afterglow detection
  79. GRB 260421B: Insight-HXMT/HE detection
  80. The EP-WXT trigger 01709258652: Mondy optical observations
  81. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  82. EP260416a: Mondy optical observations
  83. GRB 260421B: SVOM/ECLAIRs refined analysis
  84. GRB 260421B: 3.6m DOT optical observation
  85. EP260416a: ZTSh R band observations
  86. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  87. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  88. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  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: EP-FXT follow-up observation
  93. GOTO26djh/AT2026jpw: ATCA radio detection
  94. GRB 260421B: J-band upper limit with WINTER
  95. GRB 260421B: LCO optical counterpart detection
  96. GRB 260421B: Fermi GBM Observation
  97. GRB 260421A: AstroSat CZTI detection
  98. GOTO26djh/AT2026jpw: radio detection at 15GHz
  99. GRB 260412A: SVOM/ECLAIRs refined analysis
  100. GRB 260421B: SVOM/VT optical observations

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