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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"

929 results found.

  1. EP260327a: Einstein Probe detection of an X-ray transient
  2. The EP-WXT trigger 01709259173 is likely a flaring star
  3. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  4. EP260321a: Upper limits from a neutrino search with IceCube
  5. The EP-WXT trigger 01709259112 is likely a flaring star
  6. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  7. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  8. GRB 260321A: EP-FXT follow-up observation
  9. The EP-WXT trigger 01709259045 is likely a flaring star
  10. EP260321a: further Kinder optical observations
  11. EP260321a: Las Cumbres upper limit
  12. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  13. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  14. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  15. EP260321a: Einstein Probe detection of an X-ray transient
  16. The EP-WXT trigger 01709258989 is likely a flaring star
  17. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  18. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  19. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  20. EP260316a: optical upper limit with Kinder observations
  21. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  22. EP260314a: optical upper limit with Kinder observations
  23. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  24. EP260314a: BOOTES-6/DPR optical upper limits at early times
  25. EP260314a: SVOM/VT optical candidate
  26. EP260314a: Einstein Probe detection of an X-ray transient
  27. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  28. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  29. The EP-WXT trigger 01709258843 is not a real source
  30. EP260302a: MeerKAT radio counterpart
  31. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  32. EP260306a: Einstein Probe detection of an X-ray transient
  33. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  34. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  35. EP260302a: analysis of the follow-up EP-FXT observation
  36. EP260302a: BOOTES-7 optical counterpart detection at early times
  37. GRB 260228A: EP-FXT follow-up observation
  38. EP260302a: Einstein Probe detection of an X-ray transient
  39. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  40. EP260227A: 3.6m DOT optical afterglow detection
  41. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  42. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  43. The EP-WXT trigger 01709258652 is likely a flaring star
  44. EP260214a: VLA 6 GHz detection
  45. GRB 260225A: EP-FXT follow-up observation
  46. EP260126a: VLA 6 GHz detection
  47. EP260224a: Einstein Probe detection of an X-ray transient
  48. The EP-WXT trigger 01709258631 is likely a flaring star
  49. EP260223a: EP-FXT follow-up observation
  50. EP260223a: Einstein Probe detection of an X-ray transient
  51. EP260221a: Optical upper limit with Kinder observations
  52. EP260221a: EP-FXT follow-up observation
  53. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  54. EP260221a: Einstein Probe detection of an X-ray transient
  55. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  56. The EP-WXT trigger 01709258455 is likely a flaring star
  57. EP-WXT 01709258455: NOT optical upper limits
  58. EP260214b: Optical upper limit with Kinder observations
  59. EP260214a: Optical upper limits with Kinder observations
  60. EP260214b: EP-FXT follow-up observation
  61. EP260214b: GROWTH-India Telescope optical upper limit
  62. EP260214b: SVOM/VT optical observation
  63. EP260214a: refined analysis of the EP-FXT observation
  64. EP260214a: SVOM/VT optical upper limits
  65. EP260214b: Einstein Probe detection of a fast X-ray transient
  66. EP260214a: Einstein Probe detection of an X-ray transient
  67. EP260213a: Optical upper limits with Kinder observations
  68. EP260213a: SVOM/VT optical upper limit
  69. EP260213a: refined analysis of the EP-FXT observation
  70. EP260213a: Einstein Probe detection of a fast X-ray transient
  71. GRB 260211A: EP-FXT follow-up observation
  72. EP260210a: refined analysis of the EP-FXT observation
  73. EP260209a: Einstein Probe detection of a fast X-ray transient
  74. EP260210a: Optical upper limits with Kinder observations
  75. EP260210a: SVOM/VT optical upper limit
  76. GRB 260208B: refined analysis of the EP-FXT observation
  77. EP260210a: Einstein Probe detection of an X-ray transient
  78. GRB 260208B: EP-FXT observation
  79. Konus-Wind detection of GRB 260128A / EP260128a
  80. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  81. EP260131a: Las Cumbres detection of an optical counterpart
  82. EP260131a: Einstein Probe detection of an X-ray transient
  83. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  84. EP260128a: Einstein Probe detection of an X-ray transient
  85. EP260126a: Seimei/TriCCS optical upper limit
  86. The EP-WXT trigger 01709253145 is likely a flaring star
  87. EP260126a: EP-FXT follow-up observation
  88. EP260126a: Optical upper limit with Kinder observations
  89. EP260126a: Einstein Probe detection of a fast X-ray transient
  90. The EP-WXT trigger 01709251871 is likely a flaring star
  91. GRB 251202A: further radio observations with the VLA
  92. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  93. EP260119a: update of EP-FXT follow-up observation
  94. EP260119a: preliminary result from the EP-FXT observation
  95. EP260119a: EP-WXT detection of a fast X-ray transient
  96. EP260116a: Einstein Probe detection of an X-ray transient
  97. GRB 251222A: radio detection with the VLA
  98. Konus-Wind detection of GRB 251230A / EP251230a
  99. EP260110a: TRT optical upper limits
  100. The EP-WXT trigger 01709251266 is likely a flaring star

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