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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"

1094 results found.

  1. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  2. EP260507a: SVOM/VT optical observations
  3. EP260507a: Kinder optical counterpart candidate
  4. EP260507a: Einstein Probe detection of an X-ray transient
  5. EP260502a is likely a flaring star
  6. GRB 260504B: EP-FXT upper limit
  7. The EP-WXT trigger 01709261576 is likely a flaring star
  8. GRB 260429B / EP260429a: EP-FXT follow-up observation
  9. EP260502a: BOOTES-7: early optical upper limit
  10. EP260502a: Las Cumbres upper limit
  11. EP260502a: Einstein Probe detection of an X-ray transient
  12. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  13. EP260430a: Einstein Probe detection of an X-ray transient
  14. EP260429a: EP-WXT detection of a fast X-ray transient
  15. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  16. GRB 260421B: EP-FXT follow-up observation
  17. The EP-WXT trigger 01709260362 is likely a flaring star
  18. The EP-WXT trigger 01709260314 is likely a flaring star
  19. EP260416a: Optical follow-up observations with Kinder
  20. The EP-WXT trigger 01709260303 is likely a flaring star
  21. EP260417a: GROWTH-India Telescope optical upper limit
  22. EP260417b: GROWTH-India Telescope optical upper limit
  23. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  24. EP260417a: Einstein Probe detection of an X-ray transient
  25. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  26. EP260417b: Einstein Probe detection of a fast X-ray transient
  27. EP260416a: WFST optical observations and rebrightening
  28. EP260416a: SVOM/VT optical observation
  29. EP260416a: Einstein Probe detection of an X-ray transient
  30. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  31. The EP-WXT trigger 01709260122 is likely a flaring star
  32. EP260321a: SVOM/VT optical observations and color changes around peak
  33. The EP-WXT trigger 01709260010 is likely a flaring star
  34. EP-WXT01709259790: Optical Upper limits with kinder observations
  35. The EP-WXT trigger 01709259790 is likely a flaring star
  36. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  37. The EP-WXT trigger 01709259773 is likely a flaring star
  38. EP260409a: SVOM/VT optical upper limits
  39. EP260409a: Einstein Probe detection of an X-ray transient
  40. GRB 260310A / AT2026fgk: X-ray rebrightening
  41. EP260402a / GRB 260402A: Mephisto optical upper limits
  42. EP260403a: Mephisto optical upper limits
  43. EP260405a: GMOS-N optical upper limits
  44. EP260405a: SVOM/VT optical upper limits
  45. EP260405a: Einstein Probe detection of a fast X-ray transient
  46. The EP-WXT trigger 01709259621 is likely a flaring star
  47. The EP-WXT trigger 01709259615 is likely a flaring star
  48. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  49. The EP-WXT trigger 01709259586 is likely a flaring star
  50. EP260403a: LCO optical counterpart detection
  51. EP260403a: Einstein Probe detection of an X-ray transient
  52. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  53. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  54. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  55. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  56. EP260329a: EP-FXT follow up observation
  57. EP260329a: NOT optical counterpart candidate
  58. EP260329b: Optical follow-up with Kinder observations
  59. EP260329a: Optical upper limit with Kinder observations
  60. EP260329b: Einstein Probe detection of an X-ray transient
  61. EP260329a: Einstein Probe detection of an X-ray transient
  62. EP-WXT trigger 01709259209: TRT optical counterpart detection
  63. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  64. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  65. EP260327a: SVOM/VT optical upper limits
  66. EP260327a: Einstein Probe detection of an X-ray transient
  67. The EP-WXT trigger 01709259173 is likely a flaring star
  68. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  69. EP260321a: Upper limits from a neutrino search with IceCube
  70. The EP-WXT trigger 01709259112 is likely a flaring star
  71. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  72. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  73. GRB 260321A: EP-FXT follow-up observation
  74. The EP-WXT trigger 01709259045 is likely a flaring star
  75. EP260321a: further Kinder optical observations
  76. EP260321a: Las Cumbres upper limit
  77. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  78. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  79. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  80. EP260321a: Einstein Probe detection of an X-ray transient
  81. The EP-WXT trigger 01709258989 is likely a flaring star
  82. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  83. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  84. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  85. EP260316a: optical upper limit with Kinder observations
  86. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  87. EP260314a: optical upper limit with Kinder observations
  88. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  89. EP260314a: BOOTES-6/DPR optical upper limits at early times
  90. EP260314a: SVOM/VT optical candidate
  91. EP260314a: Einstein Probe detection of an X-ray transient
  92. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  93. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  94. The EP-WXT trigger 01709258843 is not a real source
  95. EP260302a: MeerKAT radio counterpart
  96. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  97. EP260306a: Einstein Probe detection of an X-ray transient
  98. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  99. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  100. EP260302a: analysis of the follow-up EP-FXT observation

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