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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"

38586 results found.

  1. GRB 260506B: Fermi GBM Final Real-time Localization
  2. EP260502a is likely a flaring star
  3. GRB 260506A: Fermi GBM Final Real-time Localization
  4. GRB 260503A: GECAM-B observation of a burst
  5. GRB 260430B: Glowbug gamma-ray detection
  6. GRB 260504B: SVOM/VT optical upper limits
  7. GRB 260421B: radio observation with the VLA
  8. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  9. Konus-Wind detection of GRB 260504B (short/hard)
  10. GRB 260504B: GECAM-B detection
  11. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  12. GRB 260504C: SVOM/GRM observation of short GRB
  13. GRB 260504B: SVOM/GRM spectral analysis
  14. GRB 260430B: AstroSat CZTI detection of a long burst
  15. GRB 260504B: SVOM/MXT refined analysis and potential detection
  16. GRB 260504B: EP-FXT upper limit
  17. GRB 260502A: SVOM/GRM observation of a short GRB
  18. GRB 260503A: SVOM/GRM observation of a GRB
  19. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  20. Konus-Wind detection of GRB 260415C
  21. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  22. Konus-Wind detection of GRB 260411C
  23. GRB 260504B: REM optical/NIR observations
  24. IPN triangulation of GRB 260429A
  25. IPN triangulation of GRB 260428A
  26. GRB 260504B: AST3-2 i-band upper limit
  27. GRB 260504B: LCO z-band upper limit
  28. SVOM GRB 260504B: MASTER-OAFA optical observations
  29. GRB 260504B: SVOM detection of a short burst
  30. GRB 260504A: Fermi GBM Final Real-time Localization
  31. GRB 260503A: Fermi GBM Final Real-time Localization
  32. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  33. GRB 260502A: GECAM-B observation of a short burst
  34. IPN triangulation of a bright burst from SGR 1E1841-045
  35. GRB 260502A: Fermi GBM Final Localization
  36. The EP-WXT trigger 01709261576 is likely a flaring star
  37. GRB 260429B / EP260429a: EP-FXT follow-up observation
  38. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  39. GRB 260429B / EP260429a: AstroSat CZTI detection
  40. EP260502a: BOOTES-7: early optical 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. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  45. GRB 260424B: AstroSat CZTI detection
  46. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  47. EP260429a: LCO optical upper limits
  48. EP260430a: LCO optical upper limits
  49. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  50. GRB 260429A: Fermi GBM Detection
  51. EP260430a: Einstein Probe detection of an X-ray transient
  52. EP260429a: EP-WXT detection of a fast X-ray transient
  53. GRB 260429A: Fermi GBM Final Real-time Localization
  54. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  55. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  56. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  57. GRB 260428A: AstroSat CZTI detection
  58. EP260416a: Mondy and Terskol optical upper limits
  59. GRB 260424B: Glowbug gamma-ray detection of a short burst
  60. GRB 260424B: COLIBRÍ optical upper limit
  61. Konus-Wind detection of GRB 260424B
  62. GRB 260428A: Fermi GBM Final Real-time Localization
  63. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  64. GRB 260424C: Fermi GBM Final Localization
  65. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  66. IPN triangulation of GRB 260424B (short)
  67. GRB 260424B: SVOM/GRM detection of a short burst
  68. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  69. GRB 260401A: cubesat Avion detection
  70. GRB 260424A: AstroSat CZTI detection of a long burst
  71. EP260321a: Upper limits from ATCA radio observations
  72. GRB 260421B: Kilonova-Catcher optical afterglow detection
  73. GRB 260421B: Insight-HXMT/HE detection
  74. The EP-WXT trigger 01709258652: Mondy optical observations
  75. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  76. EP260416a: Mondy optical observations
  77. GRB 260421B: SVOM/ECLAIRs refined analysis
  78. GRB 260421B: 3.6m DOT optical observation
  79. EP260416a: ZTSh R band observations
  80. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  81. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  82. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  83. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  84. GRB 260419A: AstroSat CZTI detection
  85. GRB 260421B: SVOM/GRM observation
  86. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  87. GRB 260421B: EP-FXT follow-up observation
  88. The EP-WXT trigger 01709260362 is likely a flaring star
  89. GOTO26djh/AT2026jpw: ATCA radio detection
  90. GRB 260421B: LCO optical counterpart detection
  91. GRB 260421B: Fermi GBM Observation
  92. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  93. GRB 260421A: AstroSat CZTI detection
  94. GRB 260412A: SVOM/ECLAIRs refined analysis
  95. GRB 260421B: SVOM/VT optical observations
  96. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  97. GRB 260310A: Late-time Chandra X-ray Detection
  98. GRB 260418A: Insight-HXMT/HE detection
  99. EP260416a: 1.3m DFOT optical observation
  100. GRB 260415A: CALET Gamma-Ray Burst Monitor detection

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