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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

20519 results found.

  1. EP260316a: Xinglong optical upper limit
  2. EP260316a: optical upper limit with Kinder observations
  3. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  4. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  5. IceCube-260315A: COLIBRÍ optical observations
  6. EP260314a: Xinglong optical upper limit
  7. EP260314a: optical upper limit with Kinder observations
  8. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  9. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  10. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  11. GRB 260310A / AT 2026fgk: iTelescope optical observations
  12. EP260314a: COLIBRÍ optical upper limit
  13. GRID detection of GRB 260312B
  14. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  15. EP260314a: SVOM/VT optical candidate
  16. EP260314a: Einstein Probe detection of an X-ray transient
  17. GRB 260310A / AT2026fgk: SAO RAS optical observations
  18. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  19. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  20. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  21. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  22. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  23. GRB 260312B: AstroSat CZTI detection
  24. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  25. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  26. GRB 260310A: potential optical counterpart
  27. Fermi GRB 260311B: Global MASTER-Net observations report
  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 260307B: SVOM/ECLAIRs refined analysis
  33. GRB 260208A: radio detection with the VLA
  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 260303A: SVOM/ECLAIRs refined analysis
  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 260228A: SVOM/ECLAIRs refined analysis
  54. GRB 260225A: SVOM/ECLAIRs refined analysis
  55. EP260302a: analysis of the follow-up EP-FXT observation
  56. EP260302a: LCO observations
  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. EP260227a: Mondy optical observations
  61. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. EP260227a: Mephisto optical detection
  63. GRID detection of GRB 260225D
  64. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  65. EP260227a: SVOM/VT optical observation
  66. GRB 260228A: SVOM/VT optical upper limits
  67. GRB 260225D: SVOM/GRM observation
  68. EP260227A: 3.6m DOT optical afterglow detection
  69. GRB 260225B: SVOM/GRM observation
  70. EP260227a: Liverpool Telescope optical observations
  71. EP260227a: LCOGT Optical Observations
  72. GRB 260226A: Asiago r-band upper limit
  73. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  74. EP260227a: Liverpool Telescope observations
  75. EP260227a: COLIBRÍ optical observations
  76. EP260227a: NOT optical observations
  77. GRID detection of GRB 260223A
  78. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  79. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  80. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  81. Konus-Wind detection of GRB 260226A
  82. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  83. EP260214a: VLT/FORS2 optical observations
  84. GRB 260225A: WINTER J-band upper limit
  85. GRB 260226A: COLIBRÍ optical upper limits
  86. GRB 260226A: LCOGT Optical Upper Limit
  87. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  88. GRB 260226A : GROWTH-India Telescope optical observations
  89. GRB 260226A: LAST optical upper limit
  90. GRB 260226A: Fermi-LAT refined analysis
  91. GRB 260226A: AstroSat CZTI detection of bright long burst
  92. EP260214a: VLA 6 GHz detection
  93. EP260224a: LCO optical upper limits
  94. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  95. GRB 260225A: SVOM/VT optical upper limits
  96. EP260126a: VLA 6 GHz detection
  97. EP260223a: Liverpool Telescope upper limits
  98. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  99. EP260224a: Einstein Probe detection of an X-ray transient
  100. EP 260225.148: COLIBRÍ Confirmation of flaring star

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