Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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"

12084 results found.

  1. GRB 260509A: SVOM detection of a burst
  2. GRB 260506B: AstroSat CZTI detection
  3. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  4. EP260507a: Liverpool Telescope optical upper limits
  5. GRB 260507A: Fermi GBM Final Real-time Localization
  6. EP260507a: Kinder optical counterpart candidate
  7. EP260507a: Einstein Probe detection of an X-ray transient
  8. GRB 260504B: AstroSat CZTI detection
  9. IceCube Alert 260505A: Global MASTER-Net observations report
  10. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  11. Konus-Wind detection of GRB 260504B (short/hard)
  12. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  13. GRB 260430B: AstroSat CZTI detection of a long burst
  14. Konus-Wind detection of GRB 260415C
  15. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  16. Konus-Wind detection of GRB 260411C
  17. IPN triangulation of GRB 260429A
  18. IPN triangulation of GRB 260428A
  19. GRB 260503A: Fermi GBM Final Real-time Localization
  20. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  21. IPN triangulation of a bright burst from SGR 1E1841-045
  22. GRB 260429B / EP260429a: AstroSat CZTI detection
  23. EP260502a: Einstein Probe detection of an X-ray transient
  24. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  25. GRB 260424B: AstroSat CZTI detection
  26. GRB 260429A: Fermi GBM Detection
  27. Fermi GRB 260429A: Global MASTER-Net observations report
  28. EP260430a: Global MASTER-Net observations report
  29. EP260430a: Einstein Probe detection of an X-ray transient
  30. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  31. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  32. GRB 260428A: AstroSat CZTI detection
  33. Fermi GRB 260428A: Global MASTER-Net observations report
  34. EP260416a: Mondy and Terskol optical upper limits
  35. Konus-Wind detection of GRB 260424B
  36. GRB 260428A: Fermi GBM Final Real-time Localization
  37. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  38. GRB 260401A: cubesat Avion detection
  39. GRB 260424A: AstroSat CZTI detection of a long burst
  40. GRB 260421B: Kilonova-Catcher optical afterglow detection
  41. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  42. GRB 260421B: SVOM/ECLAIRs refined analysis
  43. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  44. GRB 260419A: AstroSat CZTI detection
  45. EP260416a: 1.3m DFOT optical observation
  46. Fermi GRB 260421B: Global MASTER-Net observations report
  47. Fermi GRB 260421A: Global MASTER-Net observations report
  48. GRB 260412A: LCOGT Optical Upper Limits
  49. EP260416a: Optical follow-up observations with Kinder
  50. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  51. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  52. GRB 260417A: SVOM/GRM observation
  53. Fermi trigger No 798275385: Global MASTER-Net observations report
  54. Fermi GRB 260417B: Global MASTER-Net observations report
  55. EP260416a: Ondrejov D50 optical detection
  56. GRB 260418B: Fermi GBM Final Real-time Localization
  57. EP260417a: Global MASTER-Net observations report
  58. Fermi GRB 260417A: Global MASTER-Net observations report
  59. Konus-Wind detection of GRB 260411B
  60. GRB 260417A: AstroSat CZTI detection
  61. IPN triangulation of GRB 260411B
  62. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  63. EP260417a: Einstein Probe detection of an X-ray transient
  64. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  65. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  66. EP260416a: COLIBRÍ optical counterpart candidate
  67. EP260416a: Global MASTER-Net observations report
  68. EP260416a: Einstein Probe detection of an X-ray transient
  69. GRB 260415B: NuSTAR detection of long prompt emission
  70. Fermi trigger No 797912738: Global MASTER-Net observations report
  71. EP260321a: CMO SAI J,K observations
  72. Konus-Wind detection of GRB 260410A (short/hard)
  73. GRB 260411B: Fermi-LAT detection
  74. GRB260411B: 3.6m DOT optical observation
  75. GRB 260411B: SVOM/GRM observation of a long burst
  76. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  77. EP-WXT01709259790: Optical Upper limits with kinder observations
  78. GRB 260410A: Fermi-LAT detection
  79. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  80. EP260409a: Einstein Probe detection of an X-ray transient
  81. GRB 260402A: SVOM/ECLAIRs refined analysis
  82. EP260402a / GRB 260402A: Mephisto optical upper limits
  83. EP260405a: Einstein Probe detection of a fast X-ray transient
  84. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  85. EP260403a: COLIBRÍ optical counterpart candidate
  86. EP260403a: Einstein Probe detection of an X-ray transient
  87. GRB 260403A: AstroSat CZTI detection
  88. GRB 260402C: AstroSat CZTI detection of a long burst
  89. EP260324A / AT 2026hir: COLIBRÍ optical observations
  90. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  91. GRB 260402A: SVOM detection of a burst
  92. Fermi GRB 260401A: Global MASTER-Net observations report
  93. GRB 260401A: MAXI/GSC detection
  94. EP260329b: Mondy and Assy-Turgen optical upper limits
  95. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  96. EP260327a: Xinglong optical upper limit
  97. EP260329b: GOTO detection of optical counterpart
  98. Konus-Wind detection of GRB 260320A
  99. Konus-Wind detection of GRB 260316B
  100. GRB 260330B: SVOM detection of a burst

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov