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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"

902 results found.

  1. EP260512a: COLIBRÍ optical upper limits
  2. EP260512a: Einstein Probe detection of an X-ray transient
  3. GRB 260511A: EP-FXT follow-up observation
  4. GRB 260511B: EP-FXT follow-up observation
  5. GRB 260510B: EP-FXT follow-up observation
  6. GRB 260510C: EP-FXT follow-up observation
  7. EP260509a: EP-FXT non-detection and upper limit
  8. EP260509a: Einstein Probe detection of an X-ray transient
  9. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  10. EP260507a: SVOM/VT optical observations
  11. EP260507a: Kinder optical counterpart candidate
  12. EP260507a: Einstein Probe detection of an X-ray transient
  13. EP260502a is likely a flaring star
  14. GRB 260504B: EP-FXT upper limit
  15. The EP-WXT trigger 01709261576 is likely a flaring star
  16. GRB 260429B / EP260429a: EP-FXT follow-up observation
  17. EP260502a: BOOTES-7: early optical upper limit
  18. EP260502a: Las Cumbres upper limit
  19. EP260502a: Einstein Probe detection of an X-ray transient
  20. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  21. EP260430a: Einstein Probe detection of an X-ray transient
  22. EP260429a: EP-WXT detection of a fast X-ray transient
  23. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  24. GRB 260421B: EP-FXT follow-up observation
  25. The EP-WXT trigger 01709260362 is likely a flaring star
  26. The EP-WXT trigger 01709260314 is likely a flaring star
  27. EP260416a: Optical follow-up observations with Kinder
  28. The EP-WXT trigger 01709260303 is likely a flaring star
  29. EP260417a: GROWTH-India Telescope optical upper limit
  30. EP260417b: GROWTH-India Telescope optical upper limit
  31. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  32. EP260417a: Einstein Probe detection of an X-ray transient
  33. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  34. EP260417b: Einstein Probe detection of a fast X-ray transient
  35. EP260416a: WFST optical observations and rebrightening
  36. EP260416a: SVOM/VT optical observation
  37. EP260416a: Einstein Probe detection of an X-ray transient
  38. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  39. The EP-WXT trigger 01709260122 is likely a flaring star
  40. EP260321a: SVOM/VT optical observations and color changes around peak
  41. The EP-WXT trigger 01709260010 is likely a flaring star
  42. EP-WXT01709259790: Optical Upper limits with kinder observations
  43. The EP-WXT trigger 01709259790 is likely a flaring star
  44. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  45. The EP-WXT trigger 01709259773 is likely a flaring star
  46. EP260409a: SVOM/VT optical upper limits
  47. EP260409a: Einstein Probe detection of an X-ray transient
  48. GRB 260310A / AT2026fgk: X-ray rebrightening
  49. EP260402a / GRB 260402A: Mephisto optical upper limits
  50. EP260403a: Mephisto optical upper limits
  51. EP260405a: GMOS-N optical upper limits
  52. EP260405a: SVOM/VT optical upper limits
  53. EP260405a: Einstein Probe detection of a fast X-ray transient
  54. The EP-WXT trigger 01709259621 is likely a flaring star
  55. The EP-WXT trigger 01709259615 is likely a flaring star
  56. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  57. The EP-WXT trigger 01709259586 is likely a flaring star
  58. EP260403a: LCO optical counterpart detection
  59. EP260403a: Einstein Probe detection of an X-ray transient
  60. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  61. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  62. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  63. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  64. EP260329a: EP-FXT follow up observation
  65. EP260329a: NOT optical counterpart candidate
  66. EP260329b: Optical follow-up with Kinder observations
  67. EP260329a: Optical upper limit with Kinder observations
  68. EP260329b: Einstein Probe detection of an X-ray transient
  69. EP260329a: Einstein Probe detection of an X-ray transient
  70. EP-WXT trigger 01709259209: TRT optical counterpart detection
  71. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  72. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  73. EP260327a: SVOM/VT optical upper limits
  74. EP260327a: Einstein Probe detection of an X-ray transient
  75. The EP-WXT trigger 01709259173 is likely a flaring star
  76. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  77. EP260321a: Upper limits from a neutrino search with IceCube
  78. The EP-WXT trigger 01709259112 is likely a flaring star
  79. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  80. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  81. GRB 260321A: EP-FXT follow-up observation
  82. The EP-WXT trigger 01709259045 is likely a flaring star
  83. EP260321a: further Kinder optical observations
  84. EP260321a: Las Cumbres upper limit
  85. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  86. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  87. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  88. EP260321a: Einstein Probe detection of an X-ray transient
  89. The EP-WXT trigger 01709258989 is likely a flaring star
  90. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  91. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  92. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  93. EP260316a: optical upper limit with Kinder observations
  94. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  95. EP260314a: optical upper limit with Kinder observations
  96. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  97. EP260314a: BOOTES-6/DPR optical upper limits at early times
  98. EP260314a: SVOM/VT optical candidate
  99. EP260314a: Einstein Probe detection of an X-ray transient
  100. The EP-WXT trigger 01709258851: Las Cumbres upper limit

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