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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').
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"

17555 results found.

  1. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  2. EP260321a: COLIBRÍ further optical observations and brightening
  3. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  4. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  5. GRB 260321A: EP-FXT follow-up observation
  6. The EP-WXT trigger 01709259045 is likely a flaring star
  7. EP260321a: GOTO detection of blue variable source
  8. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  9. EP260321a: further Kinder optical observations
  10. GRB 260321A: SVOM/VT optical upper limits
  11. EP260321a: Las Cumbres upper limit
  12. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  13. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  14. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  15. EP260321a: SVOM/VT optical upper limit
  16. GRB 260310A: continued optical observation at Mondy
  17. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  18. EP260321a: Einstein Probe detection of an X-ray transient
  19. GRB 260310A / AT 2026fgk: KAIT optical observations
  20. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  21. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  22. GRB 260318A: SVOM/GRM observation
  23. The EP-WXT trigger 01709258989 is likely a flaring star
  24. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  25. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  26. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  27. GRB 260310A / AT 2026fgk: radio detection with the VLA
  28. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  29. GRB 260310A / AT2026fgk: LCO optical observations
  30. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  31. GRB 260316B: SVOM/GRM observation
  32. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  33. EP260316a: COLIBRÍ faint optical counterpart candidate
  34. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  35. EP260316a: Xinglong optical upper limit
  36. EP260316a: optical upper limit with Kinder observations
  37. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  38. IceCube-260315A: COLIBRÍ optical observations
  39. EP260314a: Xinglong optical upper limit
  40. EP260314a: optical upper limit with Kinder observations
  41. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  42. GRB 260310A / AT 2026fgk: iTelescope optical observations
  43. EP260314a: COLIBRÍ optical upper limit
  44. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  45. EP260314a: SVOM/VT optical candidate
  46. EP260314a: Einstein Probe detection of an X-ray transient
  47. GRB 260310A / AT2026fgk: SAO RAS optical observations
  48. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  49. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  50. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  51. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  52. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  53. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  54. GRB 260310A: potential optical counterpart
  55. GRB 260131A/B: radio detection with the VLA
  56. EP260302a: MeerKAT radio counterpart
  57. GRB 260308A: SVOM/GRM observation of a short GRB
  58. EP260306a: Mondy optical upper limit
  59. GRB 260208A: radio detection with the VLA
  60. GRB 260307B: Mephisto optical upper limits
  61. GRB 260307B: possible NOT optical counterpart
  62. GRB 260307B: SVOM/VT upper limit with X band data analysis
  63. GRB260307B: GROWTH-India Telescope optical upper limit
  64. GRB 260307B: SVOM/VT optical candidate
  65. GRB 260307B: SVOM/C-GFT upper limit
  66. GRB 260307B: SVOM detection of a burst
  67. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  68. GRB 260207A: TESS Detection and Possible VLA Counterpart
  69. EP260302a: SVOM/VT optical observation
  70. EP260306a: SVOM/VT optical observation
  71. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  72. EP260306a: Einstein Probe detection of an X-ray transient
  73. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  74. GRB 260303A: 1.3m DFOT optical upper limit
  75. GRB 260304A: AstroSat CZTI detection of a long burst
  76. GRB 260303A: SVOM/VT optical observations
  77. GRB 260303A: J-band observations with WINTER
  78. EP260302a: analysis of the follow-up EP-FXT observation
  79. EP260302a: LCO observations
  80. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  81. GRB 260303A: SVOM detection of a burst
  82. GRB 260228A: EP-FXT follow-up observation
  83. EP260302a: Einstein Probe detection of an X-ray transient
  84. EP260227a: Mondy optical observations
  85. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. EP260227a: Mephisto optical detection
  87. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  88. EP260227a: SVOM/VT optical observation
  89. GRB 260228A: SVOM/VT optical upper limits
  90. GRB 260225D: SVOM/GRM observation
  91. EP260227A: 3.6m DOT optical afterglow detection
  92. GRB 260225B: SVOM/GRM observation
  93. EP260227a: Liverpool Telescope optical observations
  94. EP260227a: LCOGT Optical Observations
  95. GRB 260226A: Asiago r-band upper limit
  96. EP260227a: Liverpool Telescope observations
  97. EP260227a: COLIBRÍ optical observations
  98. EP260227a: NOT optical observations
  99. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  100. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow

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