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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"

28070 results found.

  1. Fermi GRB 260510A: Global MASTER-Net observations report
  2. GRB 260510A: Fermi GBM Final Real-time Localization
  3. GRB 260509A: SVOM/VT optical candidate with VHF data
  4. GRB 260509A: LCO optical counterpart detection
  5. GRB 260509A: GOTO optical counterpart candidate
  6. GRB 260509A: SVOM detection of a burst
  7. GRB 260506B: AstroSat CZTI detection
  8. EP260507a: REM optical/NIR observations
  9. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  10. EP260507a: COLIBRÍ optical observations
  11. EP260507a: SVOM/VT optical observations
  12. EP260507a: Liverpool Telescope optical upper limits
  13. GRB 260507A: Fermi GBM Final Real-time Localization
  14. EP260507a: GOTO optical counterpart detection
  15. EP260507a: TRT optical counterpart detection
  16. EP260507a: Kinder optical counterpart candidate
  17. EP260507a: LCO optical counterpart
  18. GRB 260504B: SVOM/ECLAIRs refined analysis
  19. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  20. GRB 260506B: Fermi GBM Final Real-time Localization
  21. EP260502a is likely a flaring star
  22. Fermi GRB 260506A: Global MASTER-Net observations report
  23. GRB 260506A: Fermi GBM Final Real-time Localization
  24. GRB 260503A: GECAM-B observation of a burst
  25. IceCube Alert 260505A: Global MASTER-Net observations report
  26. GRB 260504B: SVOM/VT optical upper limits
  27. GRB 260421B: radio observation with the VLA
  28. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  29. GRB 260504C: SVOM/GRM observation of short GRB
  30. GRB 260504B: SVOM/MXT refined analysis and potential detection
  31. GRB 260502A: SVOM/GRM observation of a short GRB
  32. GRB 260503A: SVOM/GRM observation of a GRB
  33. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  34. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  35. GRB 260504B: REM optical/NIR observations
  36. IPN triangulation of GRB 260429A
  37. IPN triangulation of GRB 260428A
  38. GRB 260504B: LCO z-band upper limit
  39. SVOM GRB 260504B: MASTER-OAFA optical observations
  40. GRB 260504B: SVOM detection of a short burst
  41. Fermi GRB 260504A: Global MASTER-Net observations report
  42. GRB 260504A: Fermi GBM Final Real-time Localization
  43. GRB 260503A: Fermi GBM Final Real-time Localization
  44. GRB 260502A: GECAM-B observation of a short burst
  45. GRB 260502A: Fermi GBM Final Localization
  46. The EP-WXT trigger 01709261576 is likely a flaring star
  47. GRB 260429B / EP260429a: EP-FXT follow-up observation
  48. EP260502a: BOOTES-7: early optical upper limit
  49. EP260502a: Las Cumbres upper limit
  50. GRB 260429A: SVOM/GRM observation of a short burst
  51. EP260429a: Global MASTER-Net observations report
  52. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  53. EP260429a: LCO optical upper limits
  54. EP260430a: LCO optical upper limits
  55. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  56. GRB 260429A: Fermi GBM Detection
  57. Fermi GRB 260429A: Global MASTER-Net observations report
  58. EP260430a: Global MASTER-Net observations report
  59. EP260430a: Einstein Probe detection of an X-ray transient
  60. GRB 260429A: Fermi GBM Final Real-time Localization
  61. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  62. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  63. GRB 260428A: AstroSat CZTI detection
  64. Fermi GRB 260428A: Global MASTER-Net observations report
  65. GRB 260424B: COLIBRÍ optical upper limit
  66. GRB 260428A: Fermi GBM Final Real-time Localization
  67. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  68. GRB 260424C: Fermi GBM Final Localization
  69. GRB 260424B: SVOM/GRM detection of a short burst
  70. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  72. IceCube Alert 260425A: Global MASTER-Net observations report
  73. Fermi trigger No 798737427: Global MASTER-Net observations report
  74. GRB 260401A: cubesat Avion detection
  75. GRB 260421B: Kilonova-Catcher optical afterglow detection
  76. GRB 260421B: Insight-HXMT/HE detection
  77. The EP-WXT trigger 01709258652: Mondy optical observations
  78. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  79. GRB 260421B: SVOM/ECLAIRs refined analysis
  80. GRB 260421B: 3.6m DOT optical observation
  81. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  82. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  83. GRB 260419A: AstroSat CZTI detection
  84. GRB 260421B: SVOM/GRM observation
  85. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  86. GRB 260421B: EP-FXT follow-up observation
  87. The EP-WXT trigger 01709260362 is likely a flaring star
  88. GRB 260421B: J-band upper limit with WINTER
  89. GRB 260421B: LCO optical counterpart detection
  90. GRB 260421B: Fermi GBM Observation
  91. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  92. GRB 260421A: AstroSat CZTI detection
  93. GRB 260412A: SVOM/ECLAIRs refined analysis
  94. GRB 260421B: SVOM/VT optical observations
  95. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  96. GRB 260310A: Late-time Chandra X-ray Detection
  97. GRB 260418A: Insight-HXMT/HE detection
  98. EP260416a: 1.3m DFOT optical observation
  99. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  100. GRB 260415B: CALET Gamma-Ray Burst Monitor detection

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