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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"

18334 results found.

  1. GRB 260318A: SVOM/GRM observation
  2. The EP-WXT trigger 01709258989 is likely a flaring star
  3. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  4. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  5. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  6. GRB 260310A / AT 2026fgk: radio detection with the VLA
  7. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  8. GRB 260310A / AT2026fgk: LCO optical observations
  9. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  10. GRB 260316B: SVOM/GRM observation
  11. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  12. EP260316a: COLIBRÍ faint optical counterpart candidate
  13. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  14. EP260316a: Xinglong optical upper limit
  15. EP260316a: optical upper limit with Kinder observations
  16. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  17. IceCube-260315A: COLIBRÍ optical observations
  18. EP260314a: Xinglong optical upper limit
  19. EP260314a: optical upper limit with Kinder observations
  20. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  21. GRB 260310A / AT 2026fgk: iTelescope optical observations
  22. EP260314a: COLIBRÍ optical upper limit
  23. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  24. EP260314a: SVOM/VT optical candidate
  25. EP260314a: Einstein Probe detection of an X-ray transient
  26. GRB 260310A / AT2026fgk: SAO RAS optical observations
  27. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  28. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  29. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  30. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  31. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  32. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  33. GRB 260310A: potential optical counterpart
  34. GRB 260131A/B: radio detection with the VLA
  35. EP260302a: MeerKAT radio counterpart
  36. GRB 260308A: SVOM/GRM observation of a short GRB
  37. EP260306a: Mondy optical upper limit
  38. GRB 260208A: radio detection with the VLA
  39. GRB 260307B: Mephisto optical upper limits
  40. GRB 260307B: possible NOT optical counterpart
  41. GRB 260307B: SVOM/VT upper limit with X band data analysis
  42. GRB260307B: GROWTH-India Telescope optical upper limit
  43. GRB 260307B: SVOM/VT optical candidate
  44. GRB 260307B: SVOM/C-GFT upper limit
  45. GRB 260307B: SVOM detection of a burst
  46. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  47. GRB 260207A: TESS Detection and Possible VLA Counterpart
  48. EP260302a: SVOM/VT optical observation
  49. EP260306a: SVOM/VT optical observation
  50. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  51. EP260306a: Einstein Probe detection of an X-ray transient
  52. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  53. GRB 260303A: 1.3m DFOT optical upper limit
  54. GRB 260304A: AstroSat CZTI detection of a long burst
  55. GRB 260303A: SVOM/VT optical observations
  56. GRB 260303A: J-band observations with WINTER
  57. EP260302a: analysis of the follow-up EP-FXT observation
  58. EP260302a: LCO observations
  59. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  60. GRB 260303A: SVOM detection of a burst
  61. GRB 260228A: EP-FXT follow-up observation
  62. EP260302a: Einstein Probe detection of an X-ray transient
  63. EP260227a: Mondy optical observations
  64. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  65. EP260227a: Mephisto optical detection
  66. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  67. EP260227a: SVOM/VT optical observation
  68. GRB 260228A: SVOM/VT optical upper limits
  69. GRB 260225D: SVOM/GRM observation
  70. EP260227A: 3.6m DOT optical afterglow detection
  71. GRB 260225B: SVOM/GRM observation
  72. EP260227a: Liverpool Telescope optical observations
  73. EP260227a: LCOGT Optical Observations
  74. GRB 260226A: Asiago r-band upper limit
  75. EP260227a: Liverpool Telescope observations
  76. EP260227a: COLIBRÍ optical observations
  77. EP260227a: NOT optical observations
  78. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  79. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  80. Konus-Wind detection of GRB 260226A
  81. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  82. EP260214a: VLT/FORS2 optical observations
  83. GRB 260225A: WINTER J-band upper limit
  84. GRB 260226A: COLIBRÍ optical upper limits
  85. GRB 260226A: LCOGT Optical Upper Limit
  86. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  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: EP-FXT follow-up observation
  92. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  93. GRB 260225A: SVOM/VT optical upper limits
  94. EP260223a: Liverpool Telescope upper limits
  95. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  96. EP260224a: Einstein Probe detection of an X-ray transient
  97. EP 260225.148: COLIBRÍ Confirmation of flaring star
  98. EP260223a: Xinglong optical upper limit
  99. The EP-WXT trigger 01709258631 is likely a flaring star
  100. EP260213a: Mephisto optical upper limits

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