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"

23436 results found.

  1. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  2. GRB 260310A / AT 2026fgk: iTelescope optical observations
  3. EP260314a: COLIBRÍ optical upper limit
  4. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  5. EP260314a: SVOM/VT optical candidate
  6. EP260314a: Einstein Probe detection of an X-ray transient
  7. GRB 260310A / AT2026fgk: SAO RAS optical observations
  8. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  9. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  10. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  11. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  12. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  13. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  14. GRB 260310A: NOT optical polarimetry
  15. GRB 260312B: AstroSat CZTI detection
  16. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  17. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  18. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  19. GRB 260312B: Glowbug gamma-ray detection
  20. GRB 260310A: potential optical counterpart
  21. GRB 260312A: Swift detection of a burst
  22. GRB 260131A/B: radio detection with the VLA
  23. EP260302a: MeerKAT radio counterpart
  24. GRB 260308A: SVOM/GRM observation of a short GRB
  25. EP260306a: Mondy optical upper limit
  26. GRB 260208A: radio detection with the VLA
  27. GRB 260307A: Glowbug gamma-ray detection
  28. GRB 260307B: Mephisto optical upper limits
  29. GRB 260307B: possible NOT optical counterpart
  30. GRB 260307B: SVOM/VT upper limit with X band data analysis
  31. GRB260307B: GROWTH-India Telescope optical upper limit
  32. GRB 260307B: SVOM/VT optical candidate
  33. GRB 260307B: SVOM/C-GFT upper limit
  34. GRB 260307B: SVOM detection of a burst
  35. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  36. GRB 260207A: TESS Detection and Possible VLA Counterpart
  37. EP260302a: SVOM/VT optical observation
  38. EP260306a: SVOM/VT optical observation
  39. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  40. EP260306a: Einstein Probe detection of an X-ray transient
  41. GRB 260303A: 1.3m DFOT optical upper limit
  42. EP260214b: ATCA 6 GHz observations
  43. GRB 260303B: AstroSat CZTI detection
  44. GRB 260304A: AstroSat CZTI detection of a long burst
  45. GRB 260303A: SVOM/VT optical observations
  46. GRB 260303A: J-band observations with WINTER
  47. GRB 260303B: Fermi GBM Final Real-time Localization
  48. EP260302a: analysis of the follow-up EP-FXT observation
  49. EP260302a: LCO observations
  50. EP260302a: BOOTES-7 optical counterpart detection at early times
  51. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  52. GRB 260303A: SVOM detection of a burst
  53. EP260302a: Einstein Probe detection of an X-ray transient
  54. GRB 251130B: TERI Gamma-ray detection
  55. GRB 260208A: TERI Gamma-ray detection
  56. EP260227a: Mondy optical observations
  57. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  58. EP260227a: Mephisto optical detection
  59. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  60. EP260227a: SVOM/VT optical observation
  61. GRB 260228A: SVOM/VT optical upper limits
  62. GRB 260225D: SVOM/GRM observation
  63. EP260227A: 3.6m DOT optical afterglow detection
  64. GRB 260225B: SVOM/GRM observation
  65. EP260227a: Liverpool Telescope optical observations
  66. EP260227a: LCOGT Optical Observations
  67. GRB 260226A: Asiago r-band upper limit
  68. EP260227a: Liverpool Telescope observations
  69. EP260227a: COLIBRÍ optical observations
  70. EP260227a: NOT optical observations
  71. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  72. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  73. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  74. EP260214a: VLT/FORS2 optical observations
  75. GRB 260225A: WINTER J-band upper limit
  76. GRB 260226A: COLIBRÍ optical upper limits
  77. GRB 260226A: LCOGT Optical Upper Limit
  78. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  79. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  80. GRB 260226A: Glowbug gamma-ray detection
  81. GRB 260226A : GROWTH-India Telescope optical observations
  82. GRB 260226A: LAST optical upper limit
  83. The EP-WXT trigger 01709258652 is likely a flaring star
  84. EP260224a: LCO optical upper limits
  85. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  86. GRB 260225A: SVOM/VT optical upper limits
  87. EP260223a: Liverpool Telescope upper limits
  88. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  89. EP260224a: Einstein Probe detection of an X-ray transient
  90. EP 260225.148: COLIBRÍ Confirmation of flaring star
  91. EP260223a: Xinglong optical upper limit
  92. GRB 260223A: Glowbug gamma-ray detection
  93. EP260213a: Mephisto optical upper limits
  94. sb26021801: SVOM/VT optical upper limits
  95. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  96. sb26021801: SVOM/C-GFT upper limit
  97. EP260223a: COLIBRÍ optical upper limits
  98. EP260223a: Einstein Probe detection of an X-ray transient
  99. GRB 260223A: SVOM/GRM observation
  100. GRB 260223A: COLIBRÍ further optical observations and a brightening

Advanced

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