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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"

45535 results found.

  1. GRB 260503A: GECAM-B observation of a burst
  2. IceCube Alert 260505A: Global MASTER-Net observations report
  3. GRB 260430B: Glowbug gamma-ray detection
  4. GRB 260504B: SVOM/VT optical upper limits
  5. GRB 260421B: radio observation with the VLA
  6. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  7. Konus-Wind detection of GRB 260504B (short/hard)
  8. GRB 260504B: GECAM-B detection
  9. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  10. GRB 260504C: SVOM/GRM observation of short GRB
  11. GRB 260504B: SVOM/GRM spectral analysis
  12. GRB 260430B: AstroSat CZTI detection of a long burst
  13. GRB 260504B: SVOM/MXT refined analysis and potential detection
  14. GRB 260504B: EP-FXT upper limit
  15. GRB 260502A: SVOM/GRM observation of a short GRB
  16. GRB 260503A: SVOM/GRM observation of a GRB
  17. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  18. Konus-Wind detection of GRB 260415C
  19. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  20. Konus-Wind detection of GRB 260411C
  21. GRB 260504B: REM optical/NIR observations
  22. IPN triangulation of GRB 260429A
  23. IPN triangulation of GRB 260428A
  24. GRB 260504B: AST3-2 i-band upper limit
  25. GRB 260504B: LCO z-band upper limit
  26. SVOM GRB 260504B: MASTER-OAFA optical observations
  27. GRB 260504B: SVOM detection of a short burst
  28. Fermi GRB 260504A: Global MASTER-Net observations report
  29. GRB 260504A: Fermi GBM Final Real-time Localization
  30. GRB 260503A: Fermi GBM Final Real-time Localization
  31. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  32. GRB 260502A: GECAM-B observation of a short burst
  33. IPN triangulation of a bright burst from SGR 1E1841-045
  34. GRB 260502A: Fermi GBM Final Localization
  35. The EP-WXT trigger 01709261576 is likely a flaring star
  36. GRB 260429B / EP260429a: EP-FXT follow-up observation
  37. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  38. GRB 260429B / EP260429a: AstroSat CZTI detection
  39. EP260502a: BOOTES-7: early optical upper limit
  40. EP260502a: Las Cumbres upper limit
  41. EP260502a: Einstein Probe detection of an X-ray transient
  42. GRB 260429A: SVOM/GRM observation of a short burst
  43. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  44. EP260429a: Global MASTER-Net observations report
  45. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  46. GRB 260424B: AstroSat CZTI detection
  47. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  48. EP260429a: LCO optical upper limits
  49. EP260430a: LCO optical upper limits
  50. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  51. GRB 260429A: Fermi GBM Detection
  52. Fermi GRB 260429A: Global MASTER-Net observations report
  53. EP260430a: Global MASTER-Net observations report
  54. EP260430a: Einstein Probe detection of an X-ray transient
  55. EP260429a: EP-WXT detection of a fast X-ray transient
  56. GRB 260429A: Fermi GBM Final Real-time Localization
  57. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  58. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  59. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 260428A: AstroSat CZTI detection
  61. Fermi GRB 260428A: Global MASTER-Net observations report
  62. EP260416a: Mondy and Terskol optical upper limits
  63. GRB 260424B: Glowbug gamma-ray detection of a short burst
  64. GRB 260424B: COLIBRÍ optical upper limit
  65. Konus-Wind detection of GRB 260424B
  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. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  70. IPN triangulation of GRB 260424B (short)
  71. GRB 260424B: SVOM/GRM detection of a short burst
  72. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  73. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  74. IceCube Alert 260425A: Global MASTER-Net observations report
  75. Fermi trigger No 798737427: Global MASTER-Net observations report
  76. GRB 260401A: cubesat Avion detection
  77. GRB 260424A: AstroSat CZTI detection of a long burst
  78. EP260321a: Upper limits from ATCA radio observations
  79. GRB 260421B: Kilonova-Catcher optical afterglow detection
  80. GRB 260421B: Insight-HXMT/HE detection
  81. The EP-WXT trigger 01709258652: Mondy optical observations
  82. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  83. EP260416a: Mondy optical observations
  84. GRB 260421B: SVOM/ECLAIRs refined analysis
  85. GRB 260421B: 3.6m DOT optical observation
  86. EP260416a: ZTSh R band observations
  87. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  88. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  89. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  90. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  91. GRB 260419A: AstroSat CZTI detection
  92. GRB 260421B: SVOM/GRM observation
  93. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  94. GRB 260421B: EP-FXT follow-up observation
  95. The EP-WXT trigger 01709260362 is likely a flaring star
  96. GOTO26djh/AT2026jpw: ATCA radio detection
  97. GRB 260421B: J-band upper limit with WINTER
  98. GRB 260421B: LCO optical counterpart detection
  99. GRB 260421B: Fermi GBM Observation
  100. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB

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