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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

1096 results found.

  1. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  2. EP260302a: analysis of the follow-up EP-FXT observation
  3. EP260302a: BOOTES-7 optical counterpart detection at early times
  4. GRB 260228A: EP-FXT follow-up observation
  5. EP260302a: Einstein Probe detection of an X-ray transient
  6. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  7. EP260227A: 3.6m DOT optical afterglow detection
  8. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  9. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  10. The EP-WXT trigger 01709258652 is likely a flaring star
  11. EP260214a: VLA 6 GHz detection
  12. GRB 260225A: EP-FXT follow-up observation
  13. EP260126a: VLA 6 GHz detection
  14. EP260224a: Einstein Probe detection of an X-ray transient
  15. The EP-WXT trigger 01709258631 is likely a flaring star
  16. EP260223a: EP-FXT follow-up observation
  17. EP260223a: Einstein Probe detection of an X-ray transient
  18. EP260221a: Optical upper limit with Kinder observations
  19. EP260221a: EP-FXT follow-up observation
  20. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  21. EP260221a: Einstein Probe detection of an X-ray transient
  22. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  23. The EP-WXT trigger 01709258455 is likely a flaring star
  24. EP-WXT 01709258455: NOT optical upper limits
  25. EP260214b: Optical upper limit with Kinder observations
  26. EP260214a: Optical upper limits with Kinder observations
  27. EP260214b: EP-FXT follow-up observation
  28. EP260214b: GROWTH-India Telescope optical upper limit
  29. EP260214b: SVOM/VT optical observation
  30. EP260214a: refined analysis of the EP-FXT observation
  31. EP260214a: SVOM/VT optical upper limits
  32. EP260214b: Einstein Probe detection of a fast X-ray transient
  33. EP260214a: Einstein Probe detection of an X-ray transient
  34. EP260213a: Optical upper limits with Kinder observations
  35. EP260213a: SVOM/VT optical upper limit
  36. EP260213a: refined analysis of the EP-FXT observation
  37. EP260213a: Einstein Probe detection of a fast X-ray transient
  38. GRB 260211A: EP-FXT follow-up observation
  39. EP260210a: refined analysis of the EP-FXT observation
  40. EP260209a: Einstein Probe detection of a fast X-ray transient
  41. EP260210a: Optical upper limits with Kinder observations
  42. EP260210a: SVOM/VT optical upper limit
  43. GRB 260208B: refined analysis of the EP-FXT observation
  44. EP260210a: Einstein Probe detection of an X-ray transient
  45. GRB 260208B: EP-FXT observation
  46. Konus-Wind detection of GRB 260128A / EP260128a
  47. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  48. EP260131a: Las Cumbres detection of an optical counterpart
  49. EP260131a: Einstein Probe detection of an X-ray transient
  50. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  51. EP260128a: Einstein Probe detection of an X-ray transient
  52. EP260126a: Seimei/TriCCS optical upper limit
  53. The EP-WXT trigger 01709253145 is likely a flaring star
  54. EP260126a: EP-FXT follow-up observation
  55. EP260126a: Optical upper limit with Kinder observations
  56. EP260126a: Einstein Probe detection of a fast X-ray transient
  57. The EP-WXT trigger 01709251871 is likely a flaring star
  58. GRB 251202A: further radio observations with the VLA
  59. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  60. EP260119a: update of EP-FXT follow-up observation
  61. EP260119a: preliminary result from the EP-FXT observation
  62. EP260119a: EP-WXT detection of a fast X-ray transient
  63. EP260116a: Einstein Probe detection of an X-ray transient
  64. GRB 251222A: radio detection with the VLA
  65. Konus-Wind detection of GRB 251230A / EP251230a
  66. EP260110a: TRT optical upper limits
  67. The EP-WXT trigger 01709251266 is likely a flaring star
  68. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  69. EP260110a: Einstein Probe detection of an X-ray transient
  70. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  71. The EP-WXT trigger 01709251112 is likely a flaring star
  72. The EP-WXT trigger 01709251028 is likely a flaring star
  73. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  74. EP260104a: Einstein Probe detection of a fast X-ray transient
  75. EP260105a: Einstein Probe detection of an X-ray transient
  76. GRB 260102A: EP-FXT follow-up observation
  77. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  78. EP260101a: Einstein Probe detection of an X-ray transient
  79. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  80. EP251229a: Optical upper limit with Kinder observations
  81. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  82. EP251229a: BOOTES-2 early optical upper limit
  83. GRB 251230A: GOTO optical upper limit
  84. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  85. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  86. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  87. EP251229a: Einstein Probe detection of an X-ray transient
  88. The EP-WXT trigger 01709250662 is likely a flaring star
  89. The EP-WXT trigger 01709250617 is likely a flaring star
  90. GRB 251222A/EP251222b: Optical detection with Kinder observations
  91. EP251222a: Optical upper limit with Kinder observations
  92. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  93. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  94. EP251221a: PRIME upper limit
  95. GRB 251222A / EP251222b: GECAM-B observation
  96. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  97. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  98. Konus-Wind detection of GRB 251222A / EP251222b
  99. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  100. EP251222a: Einstein Probe detection of an X-ray transient

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