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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"

2963 results found.

  1. GRB 260515A: JinShan optical counterpart candidate
  2. Konus-Wind detection of GRB 260512A
  3. EP260514a: Global MASTER-Net observations report
  4. EP260514a: Einstein Probe detection of a fast X-ray transient
  5. EP260512a: LCO optical upper limits
  6. The EP-WXT trigger 01709262077 is likely a flaring star
  7. EP260512a: EP-FXT follow-up observation
  8. EP260507a: Xinglong Schmidt optical counterpart detection
  9. EP260512a: Global MASTER-Net observations report
  10. GRB 260511B: further SAO RAS optical observations
  11. Konus-Wind detection of GRB 260511B
  12. The EP-WXT trigger 01709262036 is likely a flaring star
  13. EP260512a: Einstein Probe detection of an X-ray transient
  14. Konus-Wind detection of GRB 260511A
  15. GRB 260511B: SAO RAS optical observations
  16. GRB 260511A: EP-FXT follow-up observation
  17. GRB 260511B: EP-FXT follow-up observation
  18. GRB 260510B: EP-FXT follow-up observation
  19. GRB 260510C: Fermi GBM Observation
  20. EP260509a: LCO optical upper limits
  21. GRB 260510C: EP-FXT follow-up observation
  22. EP260509a: EP-FXT non-detection and upper limit
  23. EP260509a: Global MASTER-Net observations report
  24. EP260509a: Einstein Probe detection of an X-ray transient
  25. EP260507a: REM optical/NIR observations
  26. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  27. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  28. EP260507a: NOT optical observations
  29. EP260507a: GOTO optical counterpart detection
  30. EP260507a: TRT optical counterpart detection
  31. EP260507a: Kinder optical counterpart candidate
  32. EP260507a: LCO optical counterpart
  33. EP260507a: Einstein Probe detection of an X-ray transient
  34. EP260502a is likely a flaring star
  35. GRB 260504B: SVOM/VT optical upper limits
  36. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  37. Konus-Wind detection of GRB 260504B (short/hard)
  38. GRB 260504B: EP-FXT upper limit
  39. Konus-Wind detection of GRB 260415C
  40. Konus-Wind detection of GRB 260411C
  41. The EP-WXT trigger 01709261576 is likely a flaring star
  42. GRB 260429B / EP260429a: EP-FXT follow-up observation
  43. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  44. EP260502a: BOOTES-7: early optical upper limit
  45. EP260502a: Las Cumbres upper limit
  46. EP260502a: Einstein Probe detection of an X-ray transient
  47. EP260429a: Global MASTER-Net observations report
  48. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  49. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  50. EP260429a: LCO optical upper limits
  51. EP260430a: LCO optical upper limits
  52. EP260430a: Global MASTER-Net observations report
  53. EP260430a: Einstein Probe detection of an X-ray transient
  54. EP260429a: EP-WXT detection of a fast X-ray transient
  55. Konus-Wind detection of GRB 260424B
  56. The EP-WXT trigger 01709258652: Mondy optical observations
  57. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  58. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  59. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  60. GRB 260421B: EP-FXT follow-up observation
  61. The EP-WXT trigger 01709260362 is likely a flaring star
  62. The EP-WXT trigger 01709260314 is likely a flaring star
  63. EP260416a: Optical follow-up observations with Kinder
  64. EP-WXT trigger 01709260303: KAIT optical observations
  65. The EP-WXT trigger 01709260303 is likely a flaring star
  66. GRB 260417A: SVOM/GRM observation
  67. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  68. EP260417b: GROWTH-India Telescope optical upper limit
  69. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  70. EP260417a: Global MASTER-Net observations report
  71. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  72. Konus-Wind detection of GRB 260411B
  73. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  74. EP260417a: TRT optical counterpart detection
  75. EP260417a: Einstein Probe detection of an X-ray transient
  76. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  77. EP260417b: Einstein Probe detection of a fast X-ray transient
  78. EP-WXT trigger 01709259586: KAIT optical observations
  79. EP260416a: COLIBRÍ optical counterpart candidate
  80. EP260416a: Global MASTER-Net observations report
  81. EP260416a: Einstein Probe detection of an X-ray transient
  82. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  83. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  84. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  85. The EP-WXT trigger 01709260122 is likely a flaring star
  86. Konus-Wind detection of GRB 260410A (short/hard)
  87. The EP-WXT trigger 01709260010 is likely a flaring star
  88. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  89. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  90. EP-WXT01709259790: Optical Upper limits with kinder observations
  91. The EP-WXT trigger 01709259790 is likely a flaring star
  92. EP-WXT01709259790: Xinglong optical upper limit
  93. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  94. EP260321a: Chandra X-ray Non-detection
  95. The EP-WXT trigger 01709259773 is likely a flaring star
  96. EP260409a: SVOM/VT optical upper limits
  97. EP260409a: COLIBRÍ optical upper limits
  98. EP260409a: Global MASTER-Net observations report
  99. EP260409a: Einstein Probe detection of an X-ray transient
  100. GRB 260402A: SVOM/ECLAIRs refined analysis

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