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"

23578 results found.

  1. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  2. GRB 260511B: LCO optical counterpart detection
  3. GRB 260511B: GOTO optical counterpart detection
  4. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  5. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  6. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  7. GRB 260511A: REM near-infrared detection
  8. GRB 260511B: AstroSat CZTI detection
  9. GRB 260506B: Glowbug gamma-ray detection
  10. GRB 260506A: Glowbug gamma-ray detection of a short burst
  11. GRB 260511B: TRT optical observation
  12. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  13. GRB 260511B SVOM/C-GFT optical counterpart detection
  14. GRB 260510C: AstroSat CZTI detection
  15. GRB 260511B: SVOM detection of a burst
  16. GRB 260511A: SVOM/VT optical observation with VHF data
  17. GRB 260511A: KAIT optical afterglow observations
  18. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  19. GRB 260511A: TRT optical counterpart detection
  20. GRB 260511A: SVOM detection of a bright burst
  21. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  22. GRB 260510C: MAXI/GSC detection
  23. GRB 260510B: GOTO early upper limit
  24. GRB 260510A: GECAM-B observation
  25. GRB 260509A: KAIT optical observations
  26. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  27. GRB 260509A: GOTO optical counterpart candidate
  28. GRB 260509A: SVOM detection of a burst
  29. GRB 260506B: AstroSat CZTI detection
  30. EP260507a: REM optical/NIR observations
  31. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  32. EP260507a: COLIBRÍ optical observations
  33. EP260507a: NOT optical observations
  34. EP260507a: GOTO optical counterpart detection
  35. EP260507a: TRT optical counterpart detection
  36. EP260507a: Kinder optical counterpart candidate
  37. GRB 260504B: AstroSat CZTI detection
  38. GRB 260504B: SVOM/ECLAIRs refined analysis
  39. GRB 260506B: Fermi GBM Final Real-time Localization
  40. GRB 260506A: Fermi GBM Final Real-time Localization
  41. GRB 260430B: Glowbug gamma-ray detection
  42. GRB 260504B: SVOM/VT optical upper limits
  43. GRB 260421B: radio observation with the VLA
  44. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  45. Konus-Wind detection of GRB 260504B (short/hard)
  46. GRB 260430B: AstroSat CZTI detection of a long burst
  47. GRB 260504B: SVOM/MXT refined analysis and potential detection
  48. Konus-Wind detection of GRB 260415C
  49. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  50. Konus-Wind detection of GRB 260411C
  51. GRB 260504B: REM optical/NIR observations
  52. IPN triangulation of GRB 260429A
  53. IPN triangulation of GRB 260428A
  54. GRB 260504B: SVOM detection of a short burst
  55. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  56. GRB 260429B / EP260429a: AstroSat CZTI detection
  57. EP260502a: BOOTES-7: early optical upper limit
  58. GRB 260424B: AstroSat CZTI detection
  59. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  60. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  61. GRB 260429A: Fermi GBM Detection
  62. GRB 260428A: AstroSat CZTI detection
  63. Fermi GRB 260428A: Global MASTER-Net observations report
  64. GRB 260424B: Glowbug gamma-ray detection of a short burst
  65. GRB 260424B: COLIBRÍ optical upper limit
  66. Konus-Wind detection of GRB 260424B
  67. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  68. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  69. GRB 260401A: cubesat Avion detection
  70. GRB 260424A: AstroSat CZTI detection of a long burst
  71. GRB 260421B: Kilonova-Catcher optical afterglow detection
  72. The EP-WXT trigger 01709258652: Mondy optical observations
  73. GRB 260421B: SVOM/ECLAIRs refined analysis
  74. EP260416a: ZTSh R band observations
  75. GRB 260419A: AstroSat CZTI detection
  76. GRB 260421B: J-band upper limit with WINTER
  77. GRB 260421B: LCO optical counterpart detection
  78. GRB 260421A: AstroSat CZTI detection
  79. GRB 260412A: SVOM/ECLAIRs refined analysis
  80. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  81. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  82. GRB 260421B: BOOTES-7 early optical afterglow detection
  83. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  84. GRB 260421B: TRT optical counterpart detection
  85. EP260321a: VLA radio follow-up
  86. EP260416a: Optical follow-up observations with Kinder
  87. EP-WXT trigger 01709260303: KAIT optical observations
  88. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  89. EP260416a: Ondrejov D50 optical detection
  90. Konus-Wind detection of GRB 260411B
  91. GRB 260417A: AstroSat CZTI detection
  92. IPN triangulation of GRB 260411B
  93. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  94. EP260417a: TRT optical counterpart detection
  95. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  96. EP-WXT trigger 01709259586: KAIT optical observations
  97. EP260416a: KAIT optical upper limit
  98. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  99. GRB 260415B: Glowbug gamma-ray detection
  100. GRB 260411B: Glowbug gamma-ray detection

Advanced

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