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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"

28081 results found.

  1. GRB 260506A: Glowbug gamma-ray detection of a short burst
  2. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  3. GRB 260511B: NuSTAR detection of prompt emission
  4. GRB 260511A: NuSTAR detection of prompt emission
  5. GRB 260511B: Fermi GBM Detection
  6. GRB 260511B: SVOM/VT optical observation with VHF data
  7. GRB 260511B: TRT optical observation
  8. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  9. GRB 260511A: Fermi GBM Detection
  10. GRB 260511B SVOM/C-GFT optical counterpart detection
  11. EP260509a: LCO optical upper limits
  12. GRB 260511A: UTGO H50 optical afterglow observation
  13. GRB 260511B: SVOM detection of a burst
  14. GRB 260510C: EP-FXT follow-up observation
  15. EP260509a: EP-FXT non-detection and upper limit
  16. GRB 260511A: SVOM/VT optical observation with VHF data
  17. Fermi GRB 260511A: Global MASTER-Net observations report
  18. GRB 260511A: KAIT optical afterglow observations
  19. GRB 260511A: LCO optical afterglow detection
  20. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  21. GRB 260511A: TRT optical counterpart detection
  22. GRB 260511A: SVOM detection of a bright burst
  23. GRB 260511A: BALROG localization (Fermi Trigger 800172815 / GRB 260511259)
  24. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  25. GRB 260510C: MAXI/GSC detection
  26. EP260509a: Global MASTER-Net observations report
  27. Fermi GBM Sub-Threshold Detection of GRB 260510B
  28. GRB 260510C: SVOM detection of a burst
  29. GRB 260510B: LCO optical upper limits
  30. EP260509a: Einstein Probe detection of an X-ray transient
  31. GRB 260509A: Liverpool Telescope optical observations
  32. GRB 260510B: SVOM detection of a burst
  33. GRB 260509A: LCO optical observations
  34. SVOM GRB 260509A: MASTER-OAFA optical observation
  35. Fermi GRB 260510A: Global MASTER-Net observations report
  36. GRB 260509A: KAIT optical observations
  37. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  38. GRB 260509A: SVOM/VT optical candidate with VHF data
  39. GRB 260509A: LCO optical counterpart detection
  40. GRB 260509A: SVOM detection of a burst
  41. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  42. EP260507a: REM optical/NIR observations
  43. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  44. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  45. EP260507a: COLIBRÍ optical observations
  46. EP260507a: NOT optical observations
  47. EP260507a: further Liverpool Telescope observations
  48. EP260507a: Liverpool Telescope optical upper limits
  49. EP260507a: TRT optical counterpart detection
  50. EP260507a: Kinder optical counterpart candidate
  51. EP260507a: LCO optical counterpart
  52. EP260507a: Einstein Probe detection of an X-ray transient
  53. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  54. Fermi GRB 260506A: Global MASTER-Net observations report
  55. IceCube Alert 260505A: Global MASTER-Net observations report
  56. GRB 260430B: Glowbug gamma-ray detection
  57. GRB 260421B: radio observation with the VLA
  58. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  59. GRB 260430B: AstroSat CZTI detection of a long burst
  60. GRB 260502A: SVOM/GRM observation of a short GRB
  61. GRB 260503A: SVOM/GRM observation of a GRB
  62. Konus-Wind detection of GRB 260411C
  63. GRB 260504B: REM optical/NIR observations
  64. GRB 260504B: LCO z-band upper limit
  65. SVOM GRB 260504B: MASTER-OAFA optical observations
  66. GRB 260504B: SVOM detection of a short burst
  67. Fermi GRB 260504A: Global MASTER-Net observations report
  68. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  69. GRB 260429B / EP260429a: EP-FXT follow-up observation
  70. EP260502a: Einstein Probe detection of an X-ray transient
  71. GRB 260429A: SVOM/GRM observation of a short burst
  72. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  73. EP260429a: Global MASTER-Net observations report
  74. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  75. GRB 260424B: AstroSat CZTI detection
  76. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  77. EP260429a: LCO optical upper limits
  78. EP260430a: LCO optical upper limits
  79. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  80. GRB 260429A: Fermi GBM Detection
  81. Fermi GRB 260429A: Global MASTER-Net observations report
  82. EP260430a: Global MASTER-Net observations report
  83. EP260430a: Einstein Probe detection of an X-ray transient
  84. EP260429a: EP-WXT detection of a fast X-ray transient
  85. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  86. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  87. Fermi GRB 260428A: Global MASTER-Net observations report
  88. EP260416a: Mondy and Terskol optical upper limits
  89. GRB 260424B: Glowbug gamma-ray detection of a short burst
  90. GRB 260424B: COLIBRÍ optical upper limit
  91. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  92. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  93. IceCube Alert 260425A: Global MASTER-Net observations report
  94. Fermi trigger No 798737427: Global MASTER-Net observations report
  95. GRB 260401A: cubesat Avion detection
  96. EP260321a: Upper limits from ATCA radio observations
  97. GRB 260421B: Kilonova-Catcher optical afterglow detection
  98. The EP-WXT trigger 01709258652: Mondy optical observations
  99. EP260416a: Mondy optical observations
  100. GRB 260421B: 3.6m DOT optical observation

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