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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"

3296 results found.

  1. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  2. The EP-WXT trigger 01709266272 is likely a flaring star
  3. AT2026nik: EP-FXT X-ray counterpart
  4. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  5. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  6. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  7. GRB 260527A/EP260527a: Insight-HXMT detection
  8. EP260526a: SVOM/VT optical upper limits
  9. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  10. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  11. EP260527a/GRB 260527A: EP-FXT follow-up observation
  12. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  13. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  14. EP260526a: EP-FXT follow-up observation
  15. EP260527a: COLIBRÍ optical detection
  16. EP260527a: Einstein Probe detection of a fast X-ray transient
  17. The EP-WXT trigger 01709266172 is likely a flaring star
  18. The EP-WXT trigger 01709266147 is likely a flaring star
  19. EP260526a: LCO optical upper limits
  20. EP260526a: Einstein Probe detection of a fast X-ray transient
  21. The EP-WXT trigger 01709266106 is not a real source
  22. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  23. EP-WXT 01709266106: NOT optical upper limits
  24. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  25. Konus-Wind detection of GRB 260519C
  26. Konus-Wind detection of GRB 260518A
  27. GRB 260516D: SVOM/ECLAIRs refined analysis
  28. GRB 260516D: EP-FXT follow-up observation
  29. Konus-Wind detection of GRB 260515A
  30. GRB 260515A: LCO optical counterpart detection
  31. GRB 260515A: EP-FXT follow-up observation
  32. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  33. EP260514a: NOT optical counterpart confirmation
  34. EP260514a: TRT optical counterpart candidate
  35. Konus-Wind detection of GRB 260512A
  36. EP260514a: Global MASTER-Net observations report
  37. EP260514a: Einstein Probe detection of a fast X-ray transient
  38. EP260512a: LCO optical upper limits
  39. The EP-WXT trigger 01709262077 is likely a flaring star
  40. EP260512a: EP-FXT follow-up observation
  41. EP260507a: Xinglong Schmidt optical counterpart detection
  42. EP260512a: Global MASTER-Net observations report
  43. GRB 260511B: further SAO RAS optical observations
  44. Konus-Wind detection of GRB 260511B
  45. The EP-WXT trigger 01709262036 is likely a flaring star
  46. EP260512a: Einstein Probe detection of an X-ray transient
  47. Konus-Wind detection of GRB 260511A
  48. GRB 260511B: SAO RAS optical observations
  49. GRB 260511A: EP-FXT follow-up observation
  50. GRB 260511B: EP-FXT follow-up observation
  51. GRB 260510B: EP-FXT follow-up observation
  52. GRB 260510C: Fermi GBM Observation
  53. EP260509a: LCO optical upper limits
  54. GRB 260510C: EP-FXT follow-up observation
  55. EP260509a: EP-FXT non-detection and upper limit
  56. EP260509a: Global MASTER-Net observations report
  57. EP260509a: Einstein Probe detection of an X-ray transient
  58. EP260507a: REM optical/NIR observations
  59. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  60. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  61. EP260507a: NOT optical observations
  62. EP260507a: GOTO optical counterpart detection
  63. EP260507a: TRT optical counterpart detection
  64. EP260507a: Kinder optical counterpart candidate
  65. EP260507a: LCO optical counterpart
  66. EP260507a: Einstein Probe detection of an X-ray transient
  67. EP260502a is likely a flaring star
  68. GRB 260504B: SVOM/VT optical upper limits
  69. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  70. Konus-Wind detection of GRB 260504B (short/hard)
  71. GRB 260504B: EP-FXT upper limit
  72. Konus-Wind detection of GRB 260415C
  73. Konus-Wind detection of GRB 260411C
  74. The EP-WXT trigger 01709261576 is likely a flaring star
  75. GRB 260429B / EP260429a: EP-FXT follow-up observation
  76. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  77. EP260502a: BOOTES-7: early optical upper limit
  78. EP260502a: Las Cumbres upper limit
  79. EP260502a: Einstein Probe detection of an X-ray transient
  80. EP260429a: Global MASTER-Net observations report
  81. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  82. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  83. EP260429a: LCO optical upper limits
  84. EP260430a: LCO optical upper limits
  85. EP260430a: Global MASTER-Net observations report
  86. EP260430a: Einstein Probe detection of an X-ray transient
  87. EP260429a: EP-WXT detection of a fast X-ray transient
  88. Konus-Wind detection of GRB 260424B
  89. The EP-WXT trigger 01709258652: Mondy optical observations
  90. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  91. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  92. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  93. GRB 260421B: EP-FXT follow-up observation
  94. The EP-WXT trigger 01709260362 is likely a flaring star
  95. The EP-WXT trigger 01709260314 is likely a flaring star
  96. EP260416a: Optical follow-up observations with Kinder
  97. EP-WXT trigger 01709260303: KAIT optical observations
  98. The EP-WXT trigger 01709260303 is likely a flaring star
  99. GRB 260417A: SVOM/GRM observation
  100. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT

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