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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. The EP-WXT trigger 01709274151 is likely a flaring star
  2. The EP-WXT trigger 01709274141 is likely a flaring star
  3. The EP-WXT trigger 01709274014 is likely a flaring star
  4. GRB 260704A: EP-FXT follow-up observation
  5. EP260703a: EP-FXT follow-up observation
  6. EP260703a: EP-WXT detection of a fast X-ray transient
  7. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  8. EP260628a: EP-FXT follow-up observation
  9. EP260628a: EP-WXT detection of a fast X-ray transient
  10. The EP-WXT trigger 01709272671 is likely a flaring star
  11. EP260626a: EP-FXT follow-up observation
  12. EP260626a: Liverpool Telescope upper limits
  13. EP260626a: EP-WXT detection of a fast X-ray transient
  14. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  15. EP260623a: Optical follow-up observations with Kinder
  16. EP260623a: SVOM/VT optical observations
  17. EP260623a: Las Cumbres discovery of the optical counterpart
  18. EP260623a: Einstein Probe detection of an X-ray transient
  19. The EP-WXT trigger 01709271197 is likely a flaring star
  20. EP260618a: EP-FXT follow-up observation
  21. EP260618a: EP-WXT detection of an X-ray transient
  22. EP260616a/GRB 260616B: EP-FXT follow-up observation
  23. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  24. EP260616a: EP-WXT detection of a fast X-ray transient
  25. The EP-WXT trigger 01709270148 is likely a flaring star
  26. The EP-WXT trigger 01709269893 is likely a flaring star
  27. The EP-WXT trigger 01709269488 is likely a flaring star
  28. IceCube-260610A: EP-FXT follow-up observation
  29. The EP-WXT trigger 01709269176 is likely a flaring star
  30. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  31. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  32. EP260610b: SVOM/VT optical confirmation with blue color
  33. EP260610a: SVOM/VT optical upper limits
  34. EP260610b: Einstein Probe detection of an X-ray transient
  35. EP260610a: Einstein Probe detection of a fast X-ray transient
  36. EP260605a: EP-FXT follow-up observation
  37. EP260605a: Einstein Probe detection of a fast X-ray transient
  38. The EP-WXT trigger 01709267001 is likely a flaring star
  39. EP260602d: EP-FXT follow-up observation
  40. EP260602c: EP-FXT follow-up observation
  41. GRB 260601B / EP260601a: AstroSat CZTI detection
  42. The EP-WXT trigger 01709266798 is likely a flaring star
  43. EP260602a: EP-FXT follow-up observation
  44. EP260603a: Einstein Probe detection of a fast X-ray transient
  45. EP260602d: Optical Upper limits with kinder observations
  46. GRB 260603A: EP-FXT follow-up observation
  47. EP260601a/GRB 260601B: EP-FXT follow-up observation
  48. EP260602b: EP-FXT follow-up observation
  49. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  50. EP260602d: Einstein Probe detection of a fast X-ray transient
  51. EP260602c: Einstein Probe detection of a fast X-ray transient
  52. EP260602b: Einstein Probe detection of a fast X-ray transient
  53. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  54. EP260602a: SVOM/VT optical candidate
  55. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  56. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  57. EP260602a: Optical upper limits with Kinder observations
  58. EP260602a: Einstein Probe detection of a fast X-ray transient
  59. GRB 260601B/EP260601a: SVOM/VT optical observations
  60. EP260601a: Einstein Probe detection of an X-ray transient
  61. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  62. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  63. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  64. The EP-WXT trigger 01709266272 is likely a flaring star
  65. AT2026nik: EP-FXT X-ray counterpart
  66. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  67. EP260526a: SVOM/VT optical upper limits
  68. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  69. EP260527a/GRB 260527A: EP-FXT follow-up observation
  70. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  71. EP260526a: EP-FXT follow-up observation
  72. EP260527a: SVOM/VT optical observation
  73. EP260527a: Einstein Probe detection of a fast X-ray transient
  74. The EP-WXT trigger 01709266172 is likely a flaring star
  75. The EP-WXT trigger 01709266147 is likely a flaring star
  76. EP260526a: Einstein Probe detection of a fast X-ray transient
  77. The EP-WXT trigger 01709266106 is not a real source
  78. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  79. EP-WXT 01709266106: NOT optical upper limits
  80. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  81. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  82. GRB 260421B: radio detection with the VLA
  83. GRB 260516D: EP-FXT follow-up observation
  84. GRB 260515A: LCO optical counterpart detection
  85. GRB 260515A: EP-FXT follow-up observation
  86. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  87. EP260514a: SVOM/VT optical candidate
  88. EP260514a: COLIBRÍ optical upper limits
  89. EP260514a: Einstein Probe detection of a fast X-ray transient
  90. The EP-WXT trigger 01709262077 is likely a flaring star
  91. EP260512a: EP-FXT follow-up observation
  92. The EP-WXT trigger 01709262036 is likely a flaring star
  93. EP260512a: COLIBRÍ optical upper limits
  94. EP260512a: Einstein Probe detection of an X-ray transient
  95. GRB 260511A: EP-FXT follow-up observation
  96. GRB 260511B: EP-FXT follow-up observation
  97. GRB 260510B: EP-FXT follow-up observation
  98. GRB 260510C: EP-FXT follow-up observation
  99. EP260509a: EP-FXT non-detection and upper limit
  100. EP260509a: Einstein Probe detection of an X-ray transient

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