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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"

1056 results found.

  1. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  2. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  3. GRB 260822A: SVOM/VT optical upper limits
  4. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  5. GRB 260822A: EP/FXT follow-up observations
  6. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  7. EP260822a: EP-FXT non-detection and upper limit
  8. EP260822a: Einstein Probe detection of a fast X-ray transient
  9. The EP-WXT trigger 01709287395 is likely a flaring star
  10. The EP-WXT trigger 01709286204 is likely a flaring star
  11. EP detected a brightening of LMXB 1ES 1735-26.9
  12. GRB 260818B: EP-FXT follow-up observation
  13. GRB260818A: EP-FXT follow-up observation
  14. EP260812a: AbAO optical upper limit
  15. The EP-WXT trigger 01709281429 is likely a flaring star
  16. EP260812a: AZT-22 optical upper limit
  17. EP260806a: WFST optical observations
  18. The EP-WXT trigger 01709280562 is likely a flaring star
  19. EP260812b: Optical upper limit with Kinder
  20. The EP-WXT trigger 01709279838 is likely a flaring star
  21. EP260812a: NOT and Liverpool Telescope upper limits:
  22. EP260812b: Liverpool Telescope observations
  23. EP260812b: GOTO detection of the optical counterpart
  24. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  25. EP260812b: Einstein Probe detection of an X-ray transient
  26. EP260812a: Einstein Probe detection of an X-ray transient
  27. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  28. The EP-WXT trigger 01709278015 is likely a flaring star
  29. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  30. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  31. EP260809a: Einstein Probe detection of an X-ray transient
  32. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  33. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  34. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  35. EP260806a: Einstein Probe detection of an X-ray transient
  36. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  37. The EP-WXT trigger 01709277420 is likely a flaring star
  38. EP260731a: Einstein Probe detection of an X-ray transient
  39. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  40. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  41. EP260729a: Einstein Probe detection of an X-ray transient
  42. EP260728a: EP-FXT follow-up observation
  43. EP260728a: Einstein Probe detection of a fast X-ray transient
  44. EP260727a: 1.5m OSN optical counterpart detection
  45. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  46. EP260727a: Liverpool Telescope confirmation of optical counterpart
  47. EP260727a: Einstein Probe detection of an X-ray transient
  48. EP260723a: further EP-FXT follow-up observation
  49. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  50. EP260725a: EP-WXT detection of an X-ray transient
  51. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  52. EP260723a: EP-FXT follow-up observation
  53. EP260723a: Liverpool Telescope likely optical counterpart
  54. EP260723a: EP-WXT detection of a fast X-ray transient
  55. GRB 260718A: EP-FXT follow-up observation
  56. EP260713a: Einstein Probe detection of an X-ray transient
  57. EP260711a: EP-FXT follow-up observation
  58. EP260711a: Einstein Probe detection of an X-ray transient
  59. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  60. EP260707a is not a real source
  61. EP260707a: Einstein Probe detection of an X-ray transient
  62. GRB 260706A: EP-FXT follow-up observation
  63. The EP-WXT trigger 01709274151 is likely a flaring star
  64. The EP-WXT trigger 01709274141 is likely a flaring star
  65. The EP-WXT trigger 01709274014 is likely a flaring star
  66. GRB 260704A: EP-FXT follow-up observation
  67. EP260703a: EP-FXT follow-up observation
  68. EP260703a: EP-WXT detection of a fast X-ray transient
  69. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  70. EP260628a: EP-FXT follow-up observation
  71. EP260628a: EP-WXT detection of a fast X-ray transient
  72. The EP-WXT trigger 01709272671 is likely a flaring star
  73. EP260626a: EP-FXT follow-up observation
  74. EP260626a: Liverpool Telescope upper limits
  75. EP260626a: EP-WXT detection of a fast X-ray transient
  76. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  77. EP260623a: Optical follow-up observations with Kinder
  78. EP260623a: SVOM/VT optical observations
  79. EP260623a: Las Cumbres discovery of the optical counterpart
  80. EP260623a: Einstein Probe detection of an X-ray transient
  81. The EP-WXT trigger 01709271197 is likely a flaring star
  82. EP260618a: EP-FXT follow-up observation
  83. EP260618a: EP-WXT detection of an X-ray transient
  84. EP260616a/GRB 260616B: EP-FXT follow-up observation
  85. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  86. EP260616a: EP-WXT detection of a fast X-ray transient
  87. The EP-WXT trigger 01709270148 is likely a flaring star
  88. The EP-WXT trigger 01709269893 is likely a flaring star
  89. The EP-WXT trigger 01709269488 is likely a flaring star
  90. IceCube-260610A: EP-FXT follow-up observation
  91. The EP-WXT trigger 01709269176 is likely a flaring star
  92. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  93. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  94. EP260610b: SVOM/VT optical confirmation with blue color
  95. EP260610a: SVOM/VT optical upper limits
  96. EP260610b: Einstein Probe detection of an X-ray transient
  97. EP260610a: Einstein Probe detection of a fast X-ray transient
  98. EP260605a: EP-FXT follow-up observation
  99. EP260605a: Einstein Probe detection of a fast X-ray transient
  100. The EP-WXT trigger 01709267001 is likely a flaring star

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