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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"

23585 results found.

  1. EP260512a: COLIBRÍ optical upper limits
  2. EP260512a: Einstein Probe detection of an X-ray transient
  3. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  4. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  5. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  6. GRB 260511A: Glowbug gamma-ray detection
  7. Konus-Wind detection of GRB 260511A
  8. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  9. GRB 260511B: LCO optical counterpart detection
  10. GRB 260511B: GOTO optical counterpart detection
  11. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  12. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  13. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  14. GRB 260511A: REM near-infrared detection
  15. GRB 260511B: AstroSat CZTI detection
  16. GRB 260506B: Glowbug gamma-ray detection
  17. GRB 260506A: Glowbug gamma-ray detection of a short burst
  18. GRB 260511B: TRT optical observation
  19. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  20. GRB 260511B SVOM/C-GFT optical counterpart detection
  21. GRB 260510C: AstroSat CZTI detection
  22. GRB 260511B: SVOM detection of a burst
  23. GRB 260511A: SVOM/VT optical observation with VHF data
  24. GRB 260511A: KAIT optical afterglow observations
  25. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  26. GRB 260511A: TRT optical counterpart detection
  27. GRB 260511A: SVOM detection of a bright burst
  28. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  29. GRB 260510C: MAXI/GSC detection
  30. GRB 260510B: GOTO early upper limit
  31. GRB 260510A: GECAM-B observation
  32. GRB 260509A: KAIT optical observations
  33. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  34. GRB 260509A: GOTO optical counterpart candidate
  35. GRB 260509A: SVOM detection of a burst
  36. GRB 260506B: AstroSat CZTI detection
  37. EP260507a: REM optical/NIR observations
  38. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  39. EP260507a: COLIBRÍ optical observations
  40. EP260507a: NOT optical observations
  41. EP260507a: GOTO optical counterpart detection
  42. EP260507a: TRT optical counterpart detection
  43. EP260507a: Kinder optical counterpart candidate
  44. GRB 260504B: AstroSat CZTI detection
  45. GRB 260504B: SVOM/ECLAIRs refined analysis
  46. GRB 260506B: Fermi GBM Final Real-time Localization
  47. GRB 260506A: Fermi GBM Final Real-time Localization
  48. GRB 260430B: Glowbug gamma-ray detection
  49. GRB 260504B: SVOM/VT optical upper limits
  50. GRB 260421B: radio observation with the VLA
  51. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  52. Konus-Wind detection of GRB 260504B (short/hard)
  53. GRB 260430B: AstroSat CZTI detection of a long burst
  54. GRB 260504B: SVOM/MXT refined analysis and potential detection
  55. Konus-Wind detection of GRB 260415C
  56. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  57. Konus-Wind detection of GRB 260411C
  58. GRB 260504B: REM optical/NIR observations
  59. IPN triangulation of GRB 260429A
  60. IPN triangulation of GRB 260428A
  61. GRB 260504B: SVOM detection of a short burst
  62. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  63. GRB 260429B / EP260429a: AstroSat CZTI detection
  64. EP260502a: BOOTES-7: early optical upper limit
  65. GRB 260424B: AstroSat CZTI detection
  66. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  67. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  68. GRB 260429A: Fermi GBM Detection
  69. GRB 260428A: AstroSat CZTI detection
  70. Fermi GRB 260428A: Global MASTER-Net observations report
  71. GRB 260424B: Glowbug gamma-ray detection of a short burst
  72. GRB 260424B: COLIBRÍ optical upper limit
  73. Konus-Wind detection of GRB 260424B
  74. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  75. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  76. GRB 260401A: cubesat Avion detection
  77. GRB 260424A: AstroSat CZTI detection of a long burst
  78. GRB 260421B: Kilonova-Catcher optical afterglow detection
  79. The EP-WXT trigger 01709258652: Mondy optical observations
  80. GRB 260421B: SVOM/ECLAIRs refined analysis
  81. EP260416a: ZTSh R band observations
  82. GRB 260419A: AstroSat CZTI detection
  83. GRB 260421B: J-band upper limit with WINTER
  84. GRB 260421B: LCO optical counterpart detection
  85. GRB 260421A: AstroSat CZTI detection
  86. GRB 260412A: SVOM/ECLAIRs refined analysis
  87. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  88. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  89. GRB 260421B: BOOTES-7 early optical afterglow detection
  90. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  91. GRB 260421B: TRT optical counterpart detection
  92. EP260321a: VLA radio follow-up
  93. EP260416a: Optical follow-up observations with Kinder
  94. EP-WXT trigger 01709260303: KAIT optical observations
  95. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  96. EP260416a: Ondrejov D50 optical detection
  97. Konus-Wind detection of GRB 260411B
  98. GRB 260417A: AstroSat CZTI detection
  99. IPN triangulation of GRB 260411B
  100. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope

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