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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"

905 results found.

  1. The EP-WXT trigger 01709262077 is likely a flaring star
  2. EP260512a: EP-FXT follow-up observation
  3. The EP-WXT trigger 01709262036 is likely a flaring star
  4. EP260512a: COLIBRÍ optical upper limits
  5. EP260512a: Einstein Probe detection of an X-ray transient
  6. GRB 260511A: EP-FXT follow-up observation
  7. GRB 260511B: EP-FXT follow-up observation
  8. GRB 260510B: EP-FXT follow-up observation
  9. GRB 260510C: EP-FXT follow-up observation
  10. EP260509a: EP-FXT non-detection and upper limit
  11. EP260509a: Einstein Probe detection of an X-ray transient
  12. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  13. EP260507a: SVOM/VT optical observations
  14. EP260507a: Kinder optical counterpart candidate
  15. EP260507a: Einstein Probe detection of an X-ray transient
  16. EP260502a is likely a flaring star
  17. GRB 260504B: EP-FXT upper limit
  18. The EP-WXT trigger 01709261576 is likely a flaring star
  19. GRB 260429B / EP260429a: EP-FXT follow-up observation
  20. EP260502a: BOOTES-7: early optical upper limit
  21. EP260502a: Las Cumbres upper limit
  22. EP260502a: Einstein Probe detection of an X-ray transient
  23. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  24. EP260430a: Einstein Probe detection of an X-ray transient
  25. EP260429a: EP-WXT detection of a fast X-ray transient
  26. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  27. GRB 260421B: EP-FXT follow-up observation
  28. The EP-WXT trigger 01709260362 is likely a flaring star
  29. The EP-WXT trigger 01709260314 is likely a flaring star
  30. EP260416a: Optical follow-up observations with Kinder
  31. The EP-WXT trigger 01709260303 is likely a flaring star
  32. EP260417a: GROWTH-India Telescope optical upper limit
  33. EP260417b: GROWTH-India Telescope optical upper limit
  34. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  35. EP260417a: Einstein Probe detection of an X-ray transient
  36. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  37. EP260417b: Einstein Probe detection of a fast X-ray transient
  38. EP260416a: WFST optical observations and rebrightening
  39. EP260416a: SVOM/VT optical observation
  40. EP260416a: Einstein Probe detection of an X-ray transient
  41. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  42. The EP-WXT trigger 01709260122 is likely a flaring star
  43. EP260321a: SVOM/VT optical observations and color changes around peak
  44. The EP-WXT trigger 01709260010 is likely a flaring star
  45. EP-WXT01709259790: Optical Upper limits with kinder observations
  46. The EP-WXT trigger 01709259790 is likely a flaring star
  47. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  48. The EP-WXT trigger 01709259773 is likely a flaring star
  49. EP260409a: SVOM/VT optical upper limits
  50. EP260409a: Einstein Probe detection of an X-ray transient
  51. GRB 260310A / AT2026fgk: X-ray rebrightening
  52. EP260402a / GRB 260402A: Mephisto optical upper limits
  53. EP260403a: Mephisto optical upper limits
  54. EP260405a: GMOS-N optical upper limits
  55. EP260405a: SVOM/VT optical upper limits
  56. EP260405a: Einstein Probe detection of a fast X-ray transient
  57. The EP-WXT trigger 01709259621 is likely a flaring star
  58. The EP-WXT trigger 01709259615 is likely a flaring star
  59. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  60. The EP-WXT trigger 01709259586 is likely a flaring star
  61. EP260403a: LCO optical counterpart detection
  62. EP260403a: Einstein Probe detection of an X-ray transient
  63. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  64. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  65. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  66. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  67. EP260329a: EP-FXT follow up observation
  68. EP260329a: NOT optical counterpart candidate
  69. EP260329b: Optical follow-up with Kinder observations
  70. EP260329a: Optical upper limit with Kinder observations
  71. EP260329b: Einstein Probe detection of an X-ray transient
  72. EP260329a: Einstein Probe detection of an X-ray transient
  73. EP-WXT trigger 01709259209: TRT optical counterpart detection
  74. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  75. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  76. EP260327a: SVOM/VT optical upper limits
  77. EP260327a: Einstein Probe detection of an X-ray transient
  78. The EP-WXT trigger 01709259173 is likely a flaring star
  79. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  80. EP260321a: Upper limits from a neutrino search with IceCube
  81. The EP-WXT trigger 01709259112 is likely a flaring star
  82. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  83. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  84. GRB 260321A: EP-FXT follow-up observation
  85. The EP-WXT trigger 01709259045 is likely a flaring star
  86. EP260321a: further Kinder optical observations
  87. EP260321a: Las Cumbres upper limit
  88. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  89. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  90. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  91. EP260321a: Einstein Probe detection of an X-ray transient
  92. The EP-WXT trigger 01709258989 is likely a flaring star
  93. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  94. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  95. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  96. EP260316a: optical upper limit with Kinder observations
  97. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  98. EP260314a: optical upper limit with Kinder observations
  99. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  100. EP260314a: BOOTES-6/DPR optical upper limits at early times

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