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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. EP260707a: Einstein Probe detection of an X-ray transient
  2. GRB 260706A: EP-FXT follow-up observation
  3. The EP-WXT trigger 01709274151 is likely a flaring star
  4. The EP-WXT trigger 01709274141 is likely a flaring star
  5. The EP-WXT trigger 01709274014 is likely a flaring star
  6. GRB 260704A: EP-FXT follow-up observation
  7. EP260703a: EP-FXT follow-up observation
  8. EP260703a: EP-WXT detection of a fast X-ray transient
  9. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  10. EP260628a: EP-FXT follow-up observation
  11. EP260628a: EP-WXT detection of a fast X-ray transient
  12. The EP-WXT trigger 01709272671 is likely a flaring star
  13. EP260626a: EP-FXT follow-up observation
  14. EP260626a: Liverpool Telescope upper limits
  15. EP260626a: EP-WXT detection of a fast X-ray transient
  16. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  17. EP260623a: Optical follow-up observations with Kinder
  18. EP260623a: SVOM/VT optical observations
  19. EP260623a: Las Cumbres discovery of the optical counterpart
  20. EP260623a: Einstein Probe detection of an X-ray transient
  21. The EP-WXT trigger 01709271197 is likely a flaring star
  22. EP260618a: EP-FXT follow-up observation
  23. EP260618a: EP-WXT detection of an X-ray transient
  24. EP260616a/GRB 260616B: EP-FXT follow-up observation
  25. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  26. EP260616a: EP-WXT detection of a fast X-ray transient
  27. The EP-WXT trigger 01709270148 is likely a flaring star
  28. The EP-WXT trigger 01709269893 is likely a flaring star
  29. The EP-WXT trigger 01709269488 is likely a flaring star
  30. IceCube-260610A: EP-FXT follow-up observation
  31. The EP-WXT trigger 01709269176 is likely a flaring star
  32. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  33. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  34. EP260610b: SVOM/VT optical confirmation with blue color
  35. EP260610a: SVOM/VT optical upper limits
  36. EP260610b: Einstein Probe detection of an X-ray transient
  37. EP260610a: Einstein Probe detection of a fast X-ray transient
  38. EP260605a: EP-FXT follow-up observation
  39. EP260605a: Einstein Probe detection of a fast X-ray transient
  40. The EP-WXT trigger 01709267001 is likely a flaring star
  41. EP260602d: EP-FXT follow-up observation
  42. EP260602c: EP-FXT follow-up observation
  43. GRB 260601B / EP260601a: AstroSat CZTI detection
  44. The EP-WXT trigger 01709266798 is likely a flaring star
  45. EP260602a: EP-FXT follow-up observation
  46. EP260603a: Einstein Probe detection of a fast X-ray transient
  47. EP260602d: Optical Upper limits with kinder observations
  48. GRB 260603A: EP-FXT follow-up observation
  49. EP260601a/GRB 260601B: EP-FXT follow-up observation
  50. EP260602b: EP-FXT follow-up observation
  51. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  52. EP260602d: Einstein Probe detection of a fast X-ray transient
  53. EP260602c: Einstein Probe detection of a fast X-ray transient
  54. EP260602b: Einstein Probe detection of a fast X-ray transient
  55. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  56. EP260602a: SVOM/VT optical candidate
  57. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  58. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  59. EP260602a: Optical upper limits with Kinder observations
  60. EP260602a: Einstein Probe detection of a fast X-ray transient
  61. GRB 260601B/EP260601a: SVOM/VT optical observations
  62. EP260601a: Einstein Probe detection of an X-ray transient
  63. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  64. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  65. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  66. The EP-WXT trigger 01709266272 is likely a flaring star
  67. AT2026nik: EP-FXT X-ray counterpart
  68. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  69. EP260526a: SVOM/VT optical upper limits
  70. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  71. EP260527a/GRB 260527A: EP-FXT follow-up observation
  72. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  73. EP260526a: EP-FXT follow-up observation
  74. EP260527a: SVOM/VT optical observation
  75. EP260527a: Einstein Probe detection of a fast X-ray transient
  76. The EP-WXT trigger 01709266172 is likely a flaring star
  77. The EP-WXT trigger 01709266147 is likely a flaring star
  78. EP260526a: Einstein Probe detection of a fast X-ray transient
  79. The EP-WXT trigger 01709266106 is not a real source
  80. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  81. EP-WXT 01709266106: NOT optical upper limits
  82. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  83. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  84. GRB 260421B: radio detection with the VLA
  85. GRB 260516D: EP-FXT follow-up observation
  86. GRB 260515A: LCO optical counterpart detection
  87. GRB 260515A: EP-FXT follow-up observation
  88. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  89. EP260514a: SVOM/VT optical candidate
  90. EP260514a: COLIBRÍ optical upper limits
  91. EP260514a: Einstein Probe detection of a fast X-ray transient
  92. The EP-WXT trigger 01709262077 is likely a flaring star
  93. EP260512a: EP-FXT follow-up observation
  94. The EP-WXT trigger 01709262036 is likely a flaring star
  95. EP260512a: COLIBRÍ optical upper limits
  96. EP260512a: Einstein Probe detection of an X-ray transient
  97. GRB 260511A: EP-FXT follow-up observation
  98. GRB 260511B: EP-FXT follow-up observation
  99. GRB 260510B: EP-FXT follow-up observation
  100. GRB 260510C: EP-FXT follow-up observation

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