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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"

6788 results found.

  1. IceCube-260610A: EP-FXT follow-up observation
  2. GRB 260610B / AT2026owq: OASDG optical observations
  3. GRB 260610B / AT2026owq: SAO RAS optical observations
  4. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  5. GRB 260608A: Fermi GRB Observation
  6. GRB 260604C: further SAO RAS optical observations
  7. EP260605a: EP-FXT follow-up observation
  8. GRB 260607B: Fermi GBM Observation
  9. GRB 260607B: Fermi-LAT detection
  10. GRB 260604C: SAO RAS optical observations
  11. EP260602d: EP-FXT follow-up observation
  12. EP260602c: EP-FXT follow-up observation
  13. GRB 260604C: Fermi GBM Observation
  14. EP260602a: EP-FXT follow-up observation
  15. EP260602d: Optical Upper limits with kinder observations
  16. GRB 260603A: EP-FXT follow-up observation
  17. EP260601a/GRB 260601B: EP-FXT follow-up observation
  18. EP260602b: EP-FXT follow-up observation
  19. EP260602a: Optical upper limits with Kinder observations
  20. GRB 260601A: Fermi GBM Observation
  21. AT2026nik: EP-FXT X-ray counterpart
  22. EP260527a/GRB 260527A: EP-FXT follow-up observation
  23. EP260526a: EP-FXT follow-up observation
  24. GRB 260522A: Fermi GBM Observation
  25. GRB 260522A: Fermi-LAT detection
  26. Konus-Wind detection of GRB 260515A
  27. GRB 260515A: EP-FXT follow-up observation
  28. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  29. GRB 260515A: NOT optical observations.
  30. GRB 260511B: Mephisto multi-band optical followup
  31. EP260512a: EP-FXT follow-up observation
  32. Konus-Wind detection of GRB 260511B
  33. GRB 260511B: SAO RAS optical observations
  34. GRB 260511B: EP-FXT follow-up observation
  35. GRB 260511B: LCO optical counterpart detection
  36. GRB 260510B: EP-FXT follow-up observation
  37. GRB 260510C: Fermi GBM Observation
  38. GRB 260509A: SAO RAS optical observations
  39. GRB 260511B: Fermi GBM Detection
  40. GRB 260511A: Fermi GBM Detection
  41. Fermi GRB 260511A: Global MASTER-Net observations report
  42. EP260507a: NOT optical observations
  43. EP260507a: Kinder optical counterpart candidate
  44. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  45. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  46. GRB 260429A: Fermi GBM Detection
  47. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  48. GRB 260421B: Fermi GBM Observation
  49. GRB 260310A: Late-time Chandra X-ray Detection
  50. EP260416a: Optical follow-up observations with Kinder
  51. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  52. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  53. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  54. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  55. GRB 260410A: Insight-HXMT/HE detection
  56. GRB 260412A: Fermi GBM Observation
  57. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  58. GRB 260411B: Fermi-LAT detection
  59. GRB 260410B: Fermi GBM Observation
  60. GRB 260409A: Insight-HXMT/HE detection
  61. GRB 260411B: Fermi GBM Detection
  62. EP-WXT01709259790: Optical Upper limits with kinder observations
  63. GRB 260410A: Fermi GBM Observation
  64. GRB 260410A: Fermi-LAT detection
  65. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  66. EP260321a: Chandra X-ray Non-detection
  67. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  68. GRB 260401A: Fermi GBM Observation
  69. EP260321a :Xinglong optical observations
  70. EP260329a: NOT optical counterpart candidate
  71. EP260329b: Optical follow-up with Kinder observations
  72. EP260329a: Optical upper limit with Kinder observations
  73. EP260329b: LCO optical observations of the counterpart
  74. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  75. GRB 260326A: Fermi GBM Detection
  76. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  77. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  78. EP260321a: further Kinder optical observations
  79. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  80. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  81. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  82. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  83. EP260316a: optical upper limit with Kinder observations
  84. EP260314a: optical upper limit with Kinder observations
  85. GRB 260310A / AT 2026fgk: iTelescope optical observations
  86. Fermi trigger No 795185313: Global MASTER-Net observations report
  87. IceCube Alert 260315A: Global MASTER-Net observations report
  88. GRB 260310A / AT2026fgk: SAO RAS optical observations
  89. GRB 260310A / AT2026fgk: OASDG optical observations
  90. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  91. Fermi GRB 260314A: Global MASTER-Net observations report
  92. GRB 260310A: Fermi GBM Observation
  93. GRB 260303A: 1.3m DFOT optical upper limit
  94. EP260302a: LCO observations
  95. EP260227a: further LCO observations
  96. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  97. GRB 260226A : GROWTH-India Telescope optical observations
  98. GRB 260226A: Fermi GBM observation
  99. GRB 260226A: Fermi-LAT refined analysis
  100. GRB 260226A: Fermi-LAT detection of a bright burst

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