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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"

3300 results found.

  1. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  2. EP260601a: Einstein Probe detection of an X-ray transient
  3. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  4. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  5. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  6. The EP-WXT trigger 01709266272 is likely a flaring star
  7. AT2026nik: EP-FXT X-ray counterpart
  8. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  9. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  10. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  11. GRB 260527A/EP260527a: Insight-HXMT detection
  12. EP260526a: SVOM/VT optical upper limits
  13. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  14. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  15. EP260527a/GRB 260527A: EP-FXT follow-up observation
  16. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  17. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  18. EP260526a: EP-FXT follow-up observation
  19. EP260527a: COLIBRÍ optical detection
  20. EP260527a: Einstein Probe detection of a fast X-ray transient
  21. The EP-WXT trigger 01709266172 is likely a flaring star
  22. The EP-WXT trigger 01709266147 is likely a flaring star
  23. EP260526a: LCO optical upper limits
  24. EP260526a: Einstein Probe detection of a fast X-ray transient
  25. The EP-WXT trigger 01709266106 is not a real source
  26. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  27. EP-WXT 01709266106: NOT optical upper limits
  28. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  29. Konus-Wind detection of GRB 260519C
  30. Konus-Wind detection of GRB 260518A
  31. GRB 260516D: SVOM/ECLAIRs refined analysis
  32. GRB 260516D: EP-FXT follow-up observation
  33. Konus-Wind detection of GRB 260515A
  34. GRB 260515A: LCO optical counterpart detection
  35. GRB 260515A: EP-FXT follow-up observation
  36. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  37. EP260514a: NOT optical counterpart confirmation
  38. EP260514a: TRT optical counterpart candidate
  39. Konus-Wind detection of GRB 260512A
  40. EP260514a: Global MASTER-Net observations report
  41. EP260514a: Einstein Probe detection of a fast X-ray transient
  42. EP260512a: LCO optical upper limits
  43. The EP-WXT trigger 01709262077 is likely a flaring star
  44. EP260512a: EP-FXT follow-up observation
  45. EP260507a: Xinglong Schmidt optical counterpart detection
  46. EP260512a: Global MASTER-Net observations report
  47. GRB 260511B: further SAO RAS optical observations
  48. Konus-Wind detection of GRB 260511B
  49. The EP-WXT trigger 01709262036 is likely a flaring star
  50. EP260512a: Einstein Probe detection of an X-ray transient
  51. Konus-Wind detection of GRB 260511A
  52. GRB 260511B: SAO RAS optical observations
  53. GRB 260511A: EP-FXT follow-up observation
  54. GRB 260511B: EP-FXT follow-up observation
  55. GRB 260510B: EP-FXT follow-up observation
  56. GRB 260510C: Fermi GBM Observation
  57. EP260509a: LCO optical upper limits
  58. GRB 260510C: EP-FXT follow-up observation
  59. EP260509a: EP-FXT non-detection and upper limit
  60. EP260509a: Global MASTER-Net observations report
  61. EP260509a: Einstein Probe detection of an X-ray transient
  62. EP260507a: REM optical/NIR observations
  63. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  64. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  65. EP260507a: NOT optical observations
  66. EP260507a: GOTO optical counterpart detection
  67. EP260507a: TRT optical counterpart detection
  68. EP260507a: Kinder optical counterpart candidate
  69. EP260507a: LCO optical counterpart
  70. EP260507a: Einstein Probe detection of an X-ray transient
  71. EP260502a is likely a flaring star
  72. GRB 260504B: SVOM/VT optical upper limits
  73. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  74. Konus-Wind detection of GRB 260504B (short/hard)
  75. GRB 260504B: EP-FXT upper limit
  76. Konus-Wind detection of GRB 260415C
  77. Konus-Wind detection of GRB 260411C
  78. The EP-WXT trigger 01709261576 is likely a flaring star
  79. GRB 260429B / EP260429a: EP-FXT follow-up observation
  80. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  81. EP260502a: BOOTES-7: early optical upper limit
  82. EP260502a: Las Cumbres upper limit
  83. EP260502a: Einstein Probe detection of an X-ray transient
  84. EP260429a: Global MASTER-Net observations report
  85. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  86. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  87. EP260429a: LCO optical upper limits
  88. EP260430a: LCO optical upper limits
  89. EP260430a: Global MASTER-Net observations report
  90. EP260430a: Einstein Probe detection of an X-ray transient
  91. EP260429a: EP-WXT detection of a fast X-ray transient
  92. Konus-Wind detection of GRB 260424B
  93. The EP-WXT trigger 01709258652: Mondy optical observations
  94. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  95. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  96. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  97. GRB 260421B: EP-FXT follow-up observation
  98. The EP-WXT trigger 01709260362 is likely a flaring star
  99. The EP-WXT trigger 01709260314 is likely a flaring star
  100. EP260416a: Optical follow-up observations with Kinder

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