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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"

1095 results found.

  1. EP250916a: EP-FXT follow-up observation
  2. The EP-WXT trigger 01709241037 is likely a flaring star
  3. EP250916a: Einstein Probe detection of an X-ray transient
  4. The EP-WXT trigger 01709240768 is likely a flaring star
  5. EP250911a: Upper limit from Fermi-GBM Observations
  6. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  7. EP250911a: Swift-XRT observations
  8. EP250911a: Einstein Probe detection of an X-ray transient
  9. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  10. EP250908C: GROND observation of the fading optical counterpart
  11. EP#01709240653: Swift-XRT observations
  12. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  13. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  14. The EP-WXT trigger EP250908a/01709240652 is not a real source
  15. EP250908c: Einstein Probe detection of an X-ray transient
  16. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  17. EP250905b: EP-FXT follow-up observation
  18. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  19. EP250905b: EP-WXT detection of a fast X-ray transient
  20. EP250905a: JinShan likely optical counterpart detection
  21. EP250905a: Einstein Probe detection of an X-ray transient
  22. EP detected a brightening of LMXB 1ES 1735-26.9
  23. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  24. EP250903a: Swift-XRT observations
  25. EP#01709201209: Swift-XRT observations
  26. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  27. The EP-WXT trigger 01709201209 is likely a flaring star
  28. GRB 250903A: EP-FXT counterpart detection
  29. EP250903a: Einstein Probe detection of an X-ray transient
  30. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  31. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  32. GRB 250901A: EP-FXT follow-up observation
  33. EP250901a: Swift-XRT observations
  34. EP250827b: Gemini Spectroscopy of AT 2025wkm
  35. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  36. EP250901a: Einstein Probe detection of an X-ray transient
  37. EP250831a: EP-FXT follow-up observation
  38. EP250831a: Swift-XRT observations
  39. EP250831a: EP-WXT detection of a fast X-ray transient
  40. GRB 250830B: Swift-XRT observations
  41. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  42. The EP-WXT trigger 01709200994 is likely a flaring star
  43. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  44. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  45. EP250828a: Seimei/TriCCS optical counterpart detection
  46. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  47. EP250828a: Einstein Probe detection of an X-ray transient
  48. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  49. EP250827a: confirmation of optical rebrightening with LCO
  50. EP250827A: An optical rebrightening was detected by LCO.
  51. EP250827a: Swift-XRT counterpart detection
  52. The EP-WXT trigger 01709200800 is likely a flaring star
  53. EP250827a: BOOTES-7 early optical dectection
  54. EP250827a: Einstein Probe detection of an X-ray transient
  55. EP250821a: MeerKAT radio counterpart
  56. The EP-WXT trigger 01709200707 is likely a flaring star
  57. The EP-WXT trigger 01709200706 is likely a flaring star
  58. EP250821a: Swift/UVOT further observations.
  59. EP250821a: VLT X-shooter spectroscopic redshift z = 0.577
  60. EP250821a: Rapidly fading optical source detected in Las Cumbres followup
  61. EP250821a: Swift XRT and UVOT counterpart detection
  62. EP250821a: Preliminary analysis of the EP-WXT and EP-FXT observations
  63. LIGO/Virgo/KAGRA S250818k: EP/FXT observation of AT 2025ulz
  64. EP250821a: Einstein Probe detection of an X-ray transient
  65. GRB 250818B: EP-FXT counterpart detection
  66. GRB 250813B: EP-FXT counterpart detection
  67. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  68. GRB 250812A: EP-FXT counterpart detection
  69. EP250812a: Swift-XRT counterpart detection
  70. EP250812a: Einstein Probe detection of an X-ray transient
  71. EP250807a: EP-FXT follow-up observation upper limit
  72. GRB 250806A: SVOM/MXT refined analysis
  73. EP250807a: EP-WXT detection of a fast X-ray transient
  74. EP250806a: Upper limit from Fermi-GBM Observations
  75. GRB 250806A: EP-FXT observation
  76. EP#01709198415/EP250806a: Swift-XRT observations
  77. EP250802a: EP-FXT follow-up observation
  78. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  79. EP250806a: Einstein Probe detection of an X-ray transient
  80. EP250802a: Einstein Probe detection of an X-ray transient
  81. The EP-WXT trigger 01709198251 is likely a flaring star
  82. The EP-WXT trigger 01709198202 is likely a flaring star
  83. EP250730a: Einstein Probe detection of an X-ray transient
  84. GRB 250727A: EP-FXT follow-up observation
  85. GRB 250727A: EP-FXT counterpart detection
  86. The EP-WXT trigger 01709195487 is likely a flaring star
  87. GRB 250713A: EP-FXT counterpart detection
  88. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  89. GRB 250702B,D,E / EP250702a: ALMA detection
  90. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  91. The EP-WXT trigger 01709181970 is likely a flaring star
  92. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  93. IceCube-250706A: EP-FXT follow-up observations
  94. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  95. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  96. The EP-WXT trigger 01709181580 is likely a flaring star
  97. GRB 250704B: Swift-XRT refined Analysis
  98. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  99. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  100. GRB250702F: afterglow detected by joint EP-ZTF shadowing program

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