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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"

23443 results found.

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

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