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"

14824 results found.

  1. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  2. EP260314a: BOOTES-6/DPR optical upper limits at early times
  3. EP260314a: Einstein Probe detection of an X-ray transient
  4. GRB 260310A/AT2026fgk: radio detection at 15GHz
  5. GRB 260310A / AT2026fgk: TNG NIR detection
  6. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  7. GRB 260314A: Fermi GBM Final Real-time Localization
  8. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  9. GRB 260310B: Insight-HXMT/HE detection
  10. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  11. GRB 260312B: AstroSat CZTI detection
  12. GRB 260313A: Fermi GBM Final Real-time Localization
  13. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  14. GRB 260308A: Insight-HXMT/HE detection
  15. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  16. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  17. GRB 260312B: Glowbug gamma-ray detection
  18. GRB 260310A: potential optical counterpart
  19. GRB 260312B: Fermi GBM Final Real-time Localization
  20. GRB 260312A: Swift detection of a burst
  21. GRB 260311B: Fermi GBM Final Real-time Localization
  22. GRB 260131A/B: radio detection with the VLA
  23. GRB 260310A: AstroSat CZTI detection of a long burst
  24. GRB 260311A: Fermi GBM Final Real-time Localization
  25. GRB 260310B: Fermi GBM Final Real-time Localization
  26. GRB 260208A: radio detection with the VLA
  27. GRB 260310A: Fermi GBM Final Real-time Localization
  28. GRB 260307A: Glowbug gamma-ray detection
  29. GRB 260308A: Fermi GBM Final Real-time Localization
  30. Fermi GBM Sub-Threshold Detection of GRB 260307B
  31. GRB 260307B: Mephisto optical upper limits
  32. GRB 260307B: possible NOT optical counterpart
  33. GRB 260307B: SVOM/VT upper limit with X band data analysis
  34. GRB 260307B: SVOM/VT optical candidate
  35. GRB 260307B: SVOM detection of a burst
  36. GRB 260307A: Fermi GBM Final Localization
  37. GRB 260207A: TESS Detection and Possible VLA Counterpart
  38. EP260306a: Gemini-North redshift z = 4.773
  39. EP260306a: Einstein Probe detection of an X-ray transient
  40. GRB 260303A: 1.3m DFOT optical upper limit
  41. EP260214b: ATCA 6 GHz observations
  42. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  43. GRB 260305A: Fermi GBM Final Real-time Localization
  44. GRB 260303B: AstroSat CZTI detection
  45. GRB 260304A: AstroSat CZTI detection of a long burst
  46. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  47. GRB 260303B: NuSTAR detection of prompt emission
  48. GRB 260303B: Fermi GBM Final Real-time Localization
  49. EP260302a: BOOTES-7 optical counterpart detection at early times
  50. GRB 260303A: SVOM detection of a burst
  51. EP260302a: Einstein Probe detection of an X-ray transient
  52. GRB 251130B: TERI Gamma-ray detection
  53. GRB 260208A: TERI Gamma-ray detection
  54. GRB 260302A: Fermi GBM Final Real-time Localization
  55. GRB 260228A: CAHA 2.2m telescope optical upper limit
  56. EP260227a: Mephisto optical detection
  57. GRID detection of GRB 260225D
  58. EP260227A: 3.6m DOT optical afterglow detection
  59. GRB 260228A: SVOM detection of a burst
  60. GRB 260226A: Asiago r-band upper limit
  61. EP260227a: Liverpool Telescope observations
  62. EP260227a: NOT optical observations
  63. GRID detection of GRB 260223A
  64. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  65. IceCube cascade alert 142200_1517143 retraction
  66. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  67. Konus-Wind detection of GRB 260226A
  68. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  69. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  70. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  71. GRB 260226A: Glowbug gamma-ray detection
  72. GRB 260226A: NuSTAR detection of bright prompt emission
  73. GRB 260226A: AstroSat CZTI detection of bright long burst
  74. EP260214a: VLA 6 GHz detection
  75. GRB 260226A: Fermi-LAT detection of a bright burst
  76. GRB 260226A: Fermi GBM Final Real-time Localization
  77. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  78. GRB 260225C: Fermi GBM Final Real-time Localization
  79. GRB 260225A: SVOM/VT optical upper limits
  80. GRB 260225B: Fermi GBM Final Real-time Localization
  81. EP260126a: VLA 6 GHz detection
  82. EP260223a: Liverpool Telescope upper limits
  83. GRB 260225A: SVOM detection of a burst
  84. EP260224a: Einstein Probe detection of an X-ray transient
  85. EP260223a: Xinglong optical upper limit
  86. GRB 260223A: Glowbug gamma-ray detection
  87. EP260213a: Mephisto optical upper limits
  88. EP260223a: EP-FXT follow-up observation
  89. sb26021801: SVOM/VT optical upper limits
  90. EP260223a: Einstein Probe detection of an X-ray transient
  91. EP260221a: Optical upper limit with Kinder observations
  92. GRB 260223A: Fermi GBM Final Real-time Localization
  93. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  94. EP260221a: COLIBRÍ optical counterpart candidate
  95. EP260221a: Gemini South z-band upper limit
  96. GRB 260222A: Fermi GBM Final Real-time Localization
  97. GRB 260221B: Fermi GBM Final Real-time Localization
  98. EP-WXT01709258519: Xinglong optical upper limit
  99. EP260221a: Xinglong optical upper limit
  100. GRB 260221A: 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