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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.

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

26501 results found.

  1. SVOM GRB 260509A: MASTER-OAFA optical observation
  2. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  3. GRB 260509A: SVOM/VT optical candidate with VHF data
  4. GRB 260509A: LCO optical counterpart detection
  5. GRB 260509A: GOTO optical counterpart candidate
  6. GRB 260509A: SVOM detection of a burst
  7. GRB 260506B: AstroSat CZTI detection
  8. EP260507a: REM optical/NIR observations
  9. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  10. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  11. EP260507a: COLIBRÍ optical observations
  12. EP260507a: SVOM/VT optical observations
  13. EP260507a: NOT optical observations
  14. EP260507a: GOTO optical counterpart detection
  15. EP260507a: TRT optical counterpart detection
  16. EP260507a: Einstein Probe detection of an X-ray transient
  17. GRB 260504B: AstroSat CZTI detection
  18. GRB 260504B: SVOM/ECLAIRs refined analysis
  19. EP260502a is likely a flaring star
  20. GRB 260503A: GECAM-B observation of a burst
  21. GRB 260430B: Glowbug gamma-ray detection
  22. GRB 260504B: SVOM/VT optical upper limits
  23. GRB 260421B: radio observation with the VLA
  24. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  25. Konus-Wind detection of GRB 260504B (short/hard)
  26. GRB 260504B: GECAM-B detection
  27. GRB 260504C: SVOM/GRM observation of short GRB
  28. GRB 260504B: SVOM/GRM spectral analysis
  29. GRB 260430B: AstroSat CZTI detection of a long burst
  30. GRB 260504B: SVOM/MXT refined analysis and potential detection
  31. GRB 260502A: SVOM/GRM observation of a short GRB
  32. GRB 260503A: SVOM/GRM observation of a GRB
  33. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  34. Konus-Wind detection of GRB 260415C
  35. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  36. Konus-Wind detection of GRB 260411C
  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. GRB 260504B: SVOM detection of a short burst
  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: Einstein Probe detection of an X-ray transient
  52. GRB 260429A: SVOM/GRM observation of a short burst
  53. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  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. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  58. GRB 260429A: Fermi GBM Detection
  59. EP260430a: Einstein Probe detection of an X-ray transient
  60. EP260429a: EP-WXT detection of a fast X-ray transient
  61. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  62. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  63. GRB 260428A: AstroSat CZTI detection
  64. GRB 260424B: Glowbug gamma-ray detection of a short burst
  65. GRB 260424B: COLIBRÍ optical upper limit
  66. Konus-Wind detection of GRB 260424B
  67. IPN triangulation of GRB 260424B (short)
  68. GRB 260424B: SVOM/GRM detection of a short burst
  69. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  70. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  71. GRB 260401A: cubesat Avion detection
  72. GRB 260424A: AstroSat CZTI detection of a long burst
  73. EP260321a: Upper limits from ATCA radio observations
  74. GRB 260421B: Kilonova-Catcher optical afterglow detection
  75. GRB 260421B: Insight-HXMT/HE detection
  76. The EP-WXT trigger 01709258652: Mondy optical observations
  77. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  78. GRB 260421B: SVOM/ECLAIRs refined analysis
  79. EP260416a: ZTSh R band observations
  80. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  81. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  82. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  83. GRB 260419A: AstroSat CZTI detection
  84. GRB 260421B: SVOM/GRM observation
  85. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  86. GRB 260421B: EP-FXT follow-up observation
  87. GOTO26djh/AT2026jpw: ATCA radio detection
  88. GRB 260421B: J-band upper limit with WINTER
  89. GRB 260421B: LCO optical counterpart detection
  90. GRB 260421B: Fermi GBM Observation
  91. GRB 260421A: AstroSat CZTI detection
  92. GRB 260412A: SVOM/ECLAIRs refined analysis
  93. GRB 260421B: SVOM/VT optical observations
  94. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  95. GRB 260310A: Late-time Chandra X-ray Detection
  96. GRB 260418A: Insight-HXMT/HE detection
  97. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  98. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  99. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  100. GRB 260421B: BOOTES-7 early optical afterglow detection

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