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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').
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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"

3385 results found.

  1. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  2. The EP-WXT trigger 01709201209 is likely a flaring star
  3. GRB 250903A: EP-FXT counterpart detection
  4. EP250903a: SVOM/VT optical confirmation
  5. EP250901a: Mondy, Assy and SAO RAS optical limits
  6. EP250903a: LCO candidate counterpart discovery
  7. EP250903a: Global MASTER-Net observations report
  8. EP250903a: TRT optical observations
  9. EP250903a: Einstein Probe detection of an X-ray transient
  10. EP 250827B: Detection of supernova counterpart by LCO.
  11. EP/WXT01709201159: GOTO optical follow-up
  12. EP250827b / AT 2025wkm: TRT optical observations
  13. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  14. GRB 250830B: Swift-XRT afterglow detection
  15. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  16. GRB 250901A: EP-FXT follow-up observation
  17. EP250901a: Swift-XRT observations
  18. EP250831a: NOT optical observations and tentative afterglow candidate
  19. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  20. EP250901a: Mephisto optical upper limits
  21. EP250901a: Global MASTER-Net observations report
  22. EP250901a: Einstein Probe detection of an X-ray transient
  23. EP250831a: EP-FXT follow-up observation
  24. EP250831a: Swift-XRT observations
  25. EP250831a: Global MASTER-Net observations report
  26. EP250831a: EP-WXT detection of a fast X-ray transient
  27. GRB 250830B: Swift-XRT observations
  28. EP250830a: Global MASTER-Net observations report
  29. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  30. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  31. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  32. The EP-WXT trigger 01709200994 is likely a flaring star
  33. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  34. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  35. EP250828a: Optical counterpart detection with Kinder observations
  36. EP250828a: Liverpool Telescope upper limits
  37. EP250828a: Global MASTER-Net observations report
  38. EP-WXT trigger 01709200800 : KAIT optical observations
  39. EP250827a: Swift/UVOT Detection
  40. EP250828a: NOT optical counterpart confirmation
  41. EP250828a: SVOM/VT optical candidate
  42. EP250828a: Seimei/TriCCS optical counterpart detection
  43. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  44. EP250828a: Optical upper limit with Kinder observations
  45. EP250827a: LCO observations show fading optical counterpart
  46. EP250828a: Einstein Probe detection of an X-ray transient
  47. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  48. EP250827a: confirmation of optical rebrightening with LCO
  49. EP250827A: An optical rebrightening was detected by LCO.
  50. EP250827a: Swift-XRT counterpart detection
  51. The EP-WXT trigger 01709200800 is likely a flaring star
  52. EP250827a: TRT optical observations
  53. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  54. EP250827a: Gemini-South redshift z = 1.613
  55. EP250827a: Global MASTER-Net observations report
  56. EP250827a: Gemini-South optical counterpart detection
  57. EP250827a: Einstein Probe detection of an X-ray transient
  58. EP triggers 01709200706 and 01709200707: GOTO confirmation of flaring stars
  59. The EP-WXT trigger 01709200707 is likely a flaring star
  60. The EP-WXT trigger 01709200706 is likely a flaring star
  61. Konus-Wind detection of GRB 250821B
  62. EP250821a: Swift/XRT counterpart fading
  63. EP250821a: VLT X-shooter spectroscopic redshift z = 0.577
  64. EP250821a: SVOM/VT optical observation
  65. EP250821a: Rapidly fading optical source detected in Las Cumbres followup
  66. EP250821a: Swift XRT and UVOT counterpart detection
  67. EP250821a: Preliminary analysis of the EP-WXT and EP-FXT observations
  68. LIGO/Virgo/KAGRA S250818k: EP/FXT observation of AT 2025ulz
  69. EP250821a: Einstein Probe detection of an X-ray transient
  70. GRB 250818B: Kilonova-Catcher optical afterglow detection
  71. GRB 250818B: SAO RAS optical observations
  72. GRB 250818B: EP-FXT counterpart detection
  73. GRB 250813B: Liverpool Telescope optical upper limits
  74. GRB 250813B: SVOM/GRM observation
  75. GRB 250813B: SVOM/VT optical observations
  76. GRB 250813B: EP-FXT counterpart detection
  77. EP250812a: NOT, NTT, and GS observations
  78. EP250812a: Liverpool Telescope upper limits
  79. EP250812a: SVOM/VT optical counterpart
  80. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  81. GRB 250812A: EP-FXT counterpart detection
  82. EP 250812a: GOTO optical upper limit
  83. EP250812a: Swift-XRT counterpart detection
  84. EP250812a: Einstein Probe detection of an X-ray transient
  85. EP250807a: EP-FXT follow-up observation upper limit
  86. EP250807a: Global MASTER-Net observations report
  87. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  88. Konus-Wind detection of GRB 250807A
  89. GRB 250806A: SVOM/MXT refined analysis
  90. EP250807a: NTT z-band optical upper limit
  91. EP250807a: EP-WXT detection of a fast X-ray transient
  92. EP 250807.979: GOTO optical upper limit
  93. EP250807a: COLIBRÍ optical upper limit
  94. EP250806a: Upper limit from Fermi-GBM Observations
  95. EP250806a:SVOM/VT refined analysis
  96. EP250806a: Liverpool telescope optical upper limit
  97. GRB 250806A: EP-FXT observation
  98. EP#01709198415/EP250806a: Swift-XRT observations
  99. EP250806a: Global MASTER-Net observations report
  100. EP250802a: EP-FXT follow-up observation

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