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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"

23442 results found.

  1. GRB 260314A: Glowbug gamma-ray detection
  2. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  3. IceCube-260315A: COLIBRÍ optical observations
  4. EP260314a: Xinglong optical upper limit
  5. EP260314a: optical upper limit with Kinder observations
  6. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  7. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  8. GRB 260310A / AT 2026fgk: iTelescope optical observations
  9. EP260314a: COLIBRÍ optical upper limit
  10. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  11. EP260314a: SVOM/VT optical candidate
  12. EP260314a: Einstein Probe detection of an X-ray transient
  13. GRB 260310A / AT2026fgk: SAO RAS optical observations
  14. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  15. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  16. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  17. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  18. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  19. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  20. GRB 260310A: NOT optical polarimetry
  21. GRB 260312B: AstroSat CZTI detection
  22. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  23. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  24. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  25. GRB 260312B: Glowbug gamma-ray detection
  26. GRB 260310A: potential optical counterpart
  27. GRB 260312A: Swift detection of a burst
  28. GRB 260131A/B: radio detection with the VLA
  29. EP260302a: MeerKAT radio counterpart
  30. GRB 260308A: SVOM/GRM observation of a short GRB
  31. EP260306a: Mondy optical upper limit
  32. GRB 260208A: radio detection with the VLA
  33. GRB 260307A: Glowbug gamma-ray detection
  34. GRB 260307B: Mephisto optical upper limits
  35. GRB 260307B: possible NOT optical counterpart
  36. GRB 260307B: SVOM/VT upper limit with X band data analysis
  37. GRB260307B: GROWTH-India Telescope optical upper limit
  38. GRB 260307B: SVOM/VT optical candidate
  39. GRB 260307B: SVOM/C-GFT upper limit
  40. GRB 260307B: SVOM detection of a burst
  41. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  42. GRB 260207A: TESS Detection and Possible VLA Counterpart
  43. EP260302a: SVOM/VT optical observation
  44. EP260306a: SVOM/VT optical observation
  45. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  46. EP260306a: Einstein Probe detection of an X-ray transient
  47. GRB 260303A: 1.3m DFOT optical upper limit
  48. EP260214b: ATCA 6 GHz observations
  49. GRB 260303B: AstroSat CZTI detection
  50. GRB 260304A: AstroSat CZTI detection of a long burst
  51. GRB 260303A: SVOM/VT optical observations
  52. GRB 260303A: J-band observations with WINTER
  53. GRB 260303B: Fermi GBM Final Real-time Localization
  54. EP260302a: analysis of the follow-up EP-FXT observation
  55. EP260302a: LCO observations
  56. EP260302a: BOOTES-7 optical counterpart detection at early times
  57. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  58. GRB 260303A: SVOM detection of a burst
  59. EP260302a: Einstein Probe detection of an X-ray transient
  60. GRB 251130B: TERI Gamma-ray detection
  61. GRB 260208A: TERI Gamma-ray detection
  62. EP260227a: Mondy optical observations
  63. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  64. EP260227a: Mephisto optical detection
  65. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  66. EP260227a: SVOM/VT optical observation
  67. GRB 260228A: SVOM/VT optical upper limits
  68. GRB 260225D: SVOM/GRM observation
  69. EP260227A: 3.6m DOT optical afterglow detection
  70. GRB 260225B: SVOM/GRM observation
  71. EP260227a: Liverpool Telescope optical observations
  72. EP260227a: LCOGT Optical Observations
  73. GRB 260226A: Asiago r-band upper limit
  74. EP260227a: Liverpool Telescope observations
  75. EP260227a: COLIBRÍ optical observations
  76. EP260227a: NOT optical observations
  77. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  78. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  79. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  80. EP260214a: VLT/FORS2 optical observations
  81. GRB 260225A: WINTER J-band upper limit
  82. GRB 260226A: COLIBRÍ optical upper limits
  83. GRB 260226A: LCOGT Optical Upper Limit
  84. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  85. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  86. GRB 260226A: Glowbug gamma-ray detection
  87. GRB 260226A : GROWTH-India Telescope optical observations
  88. GRB 260226A: LAST optical upper limit
  89. The EP-WXT trigger 01709258652 is likely a flaring star
  90. EP260224a: LCO optical upper limits
  91. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  92. GRB 260225A: SVOM/VT optical upper limits
  93. EP260223a: Liverpool Telescope upper limits
  94. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  95. EP260224a: Einstein Probe detection of an X-ray transient
  96. EP 260225.148: COLIBRÍ Confirmation of flaring star
  97. EP260223a: Xinglong optical upper limit
  98. GRB 260223A: Glowbug gamma-ray detection
  99. EP260213a: Mephisto optical upper limits
  100. sb26021801: SVOM/VT optical upper limits

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