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"

12082 results found.

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

Advanced

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