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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28260 results found.

  1. GRB 260511A: SVOM detection of a bright burst
  2. GRB 260511A: BALROG localization (Fermi Trigger 800172815 / GRB 260511259)
  3. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  4. GRB 260510C: MAXI/GSC detection
  5. EP260509a: Global MASTER-Net observations report
  6. Fermi GBM Sub-Threshold Detection of GRB 260510B
  7. GRB 260510C: SVOM detection of a burst
  8. GRB 260510B: LCO optical upper limits
  9. EP260509a: Einstein Probe detection of an X-ray transient
  10. GRB 260509A: Liverpool Telescope optical observations
  11. GRB 260510B: SVOM detection of a burst
  12. GRB 260509A: LCO optical observations
  13. SVOM GRB 260509A: MASTER-OAFA optical observation
  14. Fermi GRB 260510A: Global MASTER-Net observations report
  15. GRB 260509A: KAIT optical observations
  16. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  17. GRB 260509A: SVOM/VT optical candidate with VHF data
  18. GRB 260509A: LCO optical counterpart detection
  19. GRB 260509A: SVOM detection of a burst
  20. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  21. EP260507a: REM optical/NIR observations
  22. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  23. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  24. EP260507a: COLIBRÍ optical observations
  25. EP260507a: NOT optical observations
  26. EP260507a: further Liverpool Telescope observations
  27. EP260507a: Liverpool Telescope optical upper limits
  28. EP260507a: TRT optical counterpart detection
  29. EP260507a: Kinder optical counterpart candidate
  30. EP260507a: LCO optical counterpart
  31. EP260507a: Einstein Probe detection of an X-ray transient
  32. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  33. Fermi GRB 260506A: Global MASTER-Net observations report
  34. IceCube Alert 260505A: Global MASTER-Net observations report
  35. GRB 260430B: Glowbug gamma-ray detection
  36. GRB 260421B: radio observation with the VLA
  37. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  38. GRB 260430B: AstroSat CZTI detection of a long burst
  39. GRB 260502A: SVOM/GRM observation of a short GRB
  40. GRB 260503A: SVOM/GRM observation of a GRB
  41. Konus-Wind detection of GRB 260411C
  42. GRB 260504B: REM optical/NIR observations
  43. GRB 260504B: LCO z-band upper limit
  44. SVOM GRB 260504B: MASTER-OAFA optical observations
  45. GRB 260504B: SVOM detection of a short burst
  46. Fermi GRB 260504A: Global MASTER-Net observations report
  47. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  48. GRB 260429B / EP260429a: EP-FXT follow-up observation
  49. EP260502a: Einstein Probe detection of an X-ray transient
  50. GRB 260429A: SVOM/GRM observation of a short burst
  51. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  52. EP260429a: Global MASTER-Net observations report
  53. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  54. GRB 260424B: AstroSat CZTI detection
  55. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  56. EP260429a: LCO optical upper limits
  57. EP260430a: LCO optical upper limits
  58. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  59. GRB 260429A: Fermi GBM Detection
  60. Fermi GRB 260429A: Global MASTER-Net observations report
  61. EP260430a: Global MASTER-Net observations report
  62. EP260430a: Einstein Probe detection of an X-ray transient
  63. EP260429a: EP-WXT detection of a fast X-ray transient
  64. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  65. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  66. Fermi GRB 260428A: Global MASTER-Net observations report
  67. EP260416a: Mondy and Terskol optical upper limits
  68. GRB 260424B: Glowbug gamma-ray detection of a short burst
  69. GRB 260424B: COLIBRÍ optical upper limit
  70. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  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. EP260321a: Upper limits from ATCA radio observations
  76. GRB 260421B: Kilonova-Catcher optical afterglow detection
  77. The EP-WXT trigger 01709258652: Mondy optical observations
  78. EP260416a: Mondy optical observations
  79. GRB 260421B: 3.6m DOT optical observation
  80. EP260416a: ZTSh R band observations
  81. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  82. GRB 260421B: SVOM/GRM observation
  83. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  84. GRB 260421B: EP-FXT follow-up observation
  85. GOTO26djh/AT2026jpw: ATCA radio detection
  86. GRB 260421B: J-band upper limit with WINTER
  87. GRB 260421B: LCO optical counterpart detection
  88. GRB 260421B: Fermi GBM Observation
  89. GOTO26djh/AT2026jpw: radio detection at 15GHz
  90. GRB 260421B: SVOM/VT optical observations
  91. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  92. GRB 260310A: Late-time Chandra X-ray Detection
  93. EP260416a: 1.3m DFOT optical observation
  94. Fermi GRB 260421C: Global MASTER-Net observations report
  95. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  96. Fermi GRB 260421B: Global MASTER-Net observations report
  97. GRB 260421B: LCO optical afterglow confirmation
  98. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  99. GRB 260421B: TRT optical counterpart detection
  100. GRB 260421B: SVOM detection of a long burst

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