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"

27015 results found.

  1. GRB 260411B: Fermi GBM Detection
  2. GRB 260411B: GOTO optical counterpart candidate
  3. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  4. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  5. GRB 260411B: Fermi GBM Final Real-time Localization
  6. GRB 260411A: Fermi GBM Final Real-time Localization
  7. GRB 260410A: COLIBRÍ optical upper limit
  8. EP-WXT01709259790: Optical Upper limits with kinder observations
  9. GRB 260410A: Fermi GBM Observation
  10. GRB 260410B: SVOM/GRM detection of a short faint burst
  11. The EP-WXT trigger 01709259790 is likely a flaring star
  12. GRB 260410B: Fermi GBM Final Real-time Localization
  13. EP-WXT01709259790: Xinglong optical upper limit
  14. GRB 260410A: Fermi-LAT detection
  15. GRB 260410A: Fermi GBM Final Real-time Localization
  16. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  17. EP260321a: Chandra X-ray Non-detection
  18. GRB 260409A: Fermi GBM Final Real-time Localization
  19. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  20. The EP-WXT trigger 01709259773 is likely a flaring star
  21. GRB 260407A: GECAM-A detection
  22. EP260409a: SVOM/VT optical upper limits
  23. EP260409a: COLIBRÍ optical upper limits
  24. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  25. EP260409a: Global MASTER-Net observations report
  26. EP260409a: Einstein Probe detection of an X-ray transient
  27. EP260321a: VLA radio detection
  28. GRB 260404A: Fermi GBM Final Localization
  29. GRB 260402A: SVOM/ECLAIRs refined analysis
  30. GRB 260310A / AT2026fgk: X-ray rebrightening
  31. EP260402a / GRB 260402A: Mephisto optical upper limits
  32. EP-WXT01709259586: Xinglong optical upper limit
  33. EP260403a: Mephisto optical upper limits
  34. EP260402a/GRB 260402A: Xinglong optical upper limit
  35. EP260321a: Upper limits from VLA radio observations
  36. GRID detection of GRB 260401A
  37. EP260321a: uGMRT observations
  38. GRB 260407A: Fermi GBM Final Real-time Localization
  39. EP260405a: GMOS-N optical upper limits
  40. EP260405a: SVOM/VT optical upper limits
  41. EP260405a: Global MASTER-Net observations report
  42. EP260405a: Einstein Probe detection of a fast X-ray transient
  43. The EP-WXT trigger 01709259621 is likely a flaring star
  44. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  45. The EP-WXT trigger 01709259615 is likely a flaring star
  46. Fermi trigger No 797039833: Global MASTER-Net observations report
  47. GRB 260403A: GECAM-B observation of a long burst
  48. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  49. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  50. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  51. The EP-WXT trigger 01709259586 is likely a flaring star
  52. GRB 260330B: SVOM/VT further optical observation
  53. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  54. GRB 260330B: SVOM/ECLAIRs refined analysis
  55. EP260403a: LCO optical observations of the counterpart
  56. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  57. EP260403a: LCO optical counterpart detection
  58. EP260403a: COLIBRÍ optical counterpart candidate
  59. GRB 260330B: SVOM/VT optical candidate
  60. EP260403a: Einstein Probe detection of an X-ray transient
  61. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  62. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  63. GRB 260402B: GECAM-B observation
  64. EP260324A / AT 2026hir: COLIBRÍ optical observations
  65. GRB 260403A: Fermi GBM Final Real-time Localization
  66. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  67. GRB 260402B: Fermi GBM Final Real-time Localization
  68. GRB 260402A: WINTER J-band upper limit
  69. GRB260402A: GROWTH-India Telescope optical upper limit
  70. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  71. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  72. GRB 260401A: SVOM/GRM observation
  73. GRB 260401A: GECAM-B observation
  74. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  75. GRB 260402A: Kilonova-Catcher optical upper limit
  76. GRB 260402A: MASTER optical observations
  77. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  79. GRB 260402A: SVOM detection of a burst
  80. Fermi GRB 260401A: Global MASTER-Net observations report
  81. GRB 260401A: Fermi GBM Observation
  82. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  83. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  84. GRB 260401A: Fermi GBM Final Real-time Localization
  85. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  86. EP260321a :Xinglong optical observations
  87. EP260327a: Xinglong optical upper limit
  88. EP260329b: GOTO detection of optical counterpart
  89. GRB 260330B: SVOM/VT optical upper limits
  90. GRB 260321A: SVOM/ECLAIRs refined analysis
  91. EP260329b: J-band upper limits with WINTER
  92. EP260329a: J-band upper limit with WINTER
  93. Fermi GBM Sub-Threshold Detection of GRB 260330B
  94. GRB 260330B: LCO optical upper limits
  95. GRB 260330B: SVOM detection of a burst
  96. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  97. EP260329a: COLIBRÍ optical upper limit
  98. EP260329a: EP-FXT follow up observation
  99. EP260329a: NOT optical counterpart candidate
  100. GRB 260330A: Fermi GBM Final Real-time Localization

Advanced

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