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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"

20502 results found.

  1. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  2. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  3. GRB 260401A: SVOM/GRM observation
  4. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  5. GRB 260402A: Kilonova-Catcher optical upper limit
  6. GRB 260402A: MASTER optical observations
  7. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  8. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  9. GRB 260402A: SVOM detection of a burst
  10. EP260329b: Mondy and Assy-Turgen optical upper limits
  11. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  12. EP260321a :Xinglong optical observations
  13. EP260327a: Xinglong optical upper limit
  14. GRB 260330B: SVOM/VT optical upper limits
  15. GRB 260321A: SVOM/ECLAIRs refined analysis
  16. EP260329b: J-band upper limits with WINTER
  17. EP260329a: J-band upper limit with WINTER
  18. GRB 260310A: VLA Multi-frequency Radio Observations
  19. GRB 260330B: LCO optical upper limits
  20. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  21. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  22. EP260329a: COLIBRÍ optical upper limit
  23. EP260329a: EP-FXT follow up observation
  24. EP260329a: NOT optical counterpart candidate
  25. EP260329b: Optical follow-up with Kinder observations
  26. EP 260329b: COLIBRÍ optical observations
  27. EP260329a: Optical upper limit with Kinder observations
  28. EP260329b: LCO optical observations of the counterpart
  29. EP260329b: Einstein Probe detection of an X-ray transient
  30. EP260329a: Einstein Probe detection of an X-ray transient
  31. EP-WXT trigger 01709259209: TRT optical counterpart detection
  32. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  33. GRID detection of GRB 260326A
  34. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  35. EP260327a: SVOM/VT optical upper limits
  36. EP260327a: WINTER J-band upper limit
  37. EP260327a: COLIBRÍ optical upper limits
  38. GRB 260327A: AstroSat CZTI detection of a long burst
  39. EP260327a: Gemini-North optical upper limits
  40. EP260324a: GROWTH-India Telescope optical observation
  41. EP260327a: Einstein Probe detection of an X-ray transient
  42. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  43. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  44. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  45. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  46. EP260321a: JinShan near-infrared observations
  47. EP260321a: Upper limits from a neutrino search with IceCube
  48. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  49. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  50. GRID detection of GRB 260320A
  51. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  52. EP260321a: COLIBRÍ further optical observations and brightening
  53. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  54. EP260214b: ATCA 6 GHz detection
  55. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  56. The EP-WXT trigger 01709259045 is likely a flaring star
  57. EP260321a: GOTO detection of blue variable source
  58. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  59. EP260321a: further Kinder optical observations
  60. GRB 260321A: SVOM/VT optical upper limits
  61. EP260321a: Las Cumbres upper limit
  62. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  63. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  64. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  65. EP260321a: SVOM/VT optical upper limit
  66. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  67. EP260321a: Einstein Probe detection of an X-ray transient
  68. GRB 260310A / AT 2026fgk: KAIT optical observations
  69. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  70. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  71. GRB 260318A: SVOM/GRM observation
  72. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  73. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  74. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  75. GRB 260310A / AT 2026fgk: radio detection with the VLA
  76. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  77. GRB 260310A / AT2026fgk: LCO optical observations
  78. GRB 260316B: SVOM/GRM observation
  79. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  80. EP260316a: COLIBRÍ faint optical counterpart candidate
  81. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  82. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  83. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  84. EP260316a: Xinglong optical upper limit
  85. EP260316a: optical upper limit with Kinder observations
  86. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  87. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  88. IceCube-260315A: COLIBRÍ optical observations
  89. EP260314a: Xinglong optical upper limit
  90. EP260314a: optical upper limit with Kinder observations
  91. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  92. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  93. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  94. GRB 260310A / AT 2026fgk: iTelescope optical observations
  95. EP260314a: COLIBRÍ optical upper limit
  96. GRID detection of GRB 260312B
  97. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  98. EP260314a: SVOM/VT optical candidate
  99. EP260314a: Einstein Probe detection of an X-ray transient
  100. GRB 260310A / AT2026fgk: SAO RAS optical observations

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