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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"

28247 results found.

  1. EP260329b: Mondy and Assy-Turgen optical upper limits
  2. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  3. EP260321a :Xinglong optical observations
  4. EP260327a: Xinglong optical upper limit
  5. GRB 260330B: SVOM/VT optical upper limits
  6. Konus-Wind detection of GRB 260320A
  7. GRB 260321A: SVOM/ECLAIRs refined analysis
  8. EP260329b: J-band upper limits with WINTER
  9. EP260329a: J-band upper limit with WINTER
  10. GRB 260330A: Glowbug gamma-ray detection
  11. Fermi GBM Sub-Threshold Detection of GRB 260330B
  12. GRB 260330B: LCO optical upper limits
  13. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  14. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  15. EP260329a: COLIBRÍ optical upper limit
  16. EP260329a: EP-FXT follow up observation
  17. EP260329a: NOT optical counterpart candidate
  18. EP260329b: Global MASTER-Net observations report
  19. Fermi trigger No 796485221: Global MASTER-Net observations report
  20. GRB 260327A: Insight-HXMT/HE detection
  21. EP260329b: Optical follow-up with Kinder observations
  22. EP 260329b: COLIBRÍ optical observations
  23. EP260329a: Optical upper limit with Kinder observations
  24. EP260329b: LCO optical observations of the counterpart
  25. GRB 260326A: Insight-HXMT/HE detection
  26. EP260329b: Einstein Probe detection of an X-ray transient
  27. EP260329a: Einstein Probe detection of an X-ray transient
  28. EP-WXT trigger 01709259209: TRT optical counterpart detection
  29. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  30. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  31. EP260327a: SVOM/VT optical upper limits
  32. EP260327a: WINTER J-band upper limit
  33. EP260327a: COLIBRÍ optical upper limits
  34. EP260327a: Gemini-North optical upper limits
  35. EP260324a: GROWTH-India Telescope optical observation
  36. EP260327a: Global MASTER-Net observations report
  37. EP260327a: Einstein Probe detection of an X-ray transient
  38. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  39. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  40. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  41. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  42. GRB 260326A: Fermi GBM Detection
  43. EP260321a: JinShan near-infrared observations
  44. EP260321a: Upper limits from a neutrino search with IceCube
  45. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  46. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  47. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  48. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  49. Fermi GRB 260323A: Global MASTER-Net observations report
  50. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  51. GRB 260320A: Glowbug gamma-ray detection
  52. EP260321a: COLIBRÍ further optical observations and brightening
  53. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  54. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  55. GRB 260321A: EP-FXT follow-up observation
  56. EP260321a: GOTO detection of blue variable source
  57. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  58. EP260321a: further Kinder optical observations
  59. GRB 260321A: SVOM/VT optical upper limits
  60. EP260321a: Las Cumbres upper limit
  61. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  63. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  64. EP260321a: SVOM/VT optical upper limit
  65. Fermi GBM Sub-Threshold Detection of GRB 260321A
  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: Global MASTER-Net observations report
  68. EP260321a: Einstein Probe detection of an X-ray transient
  69. GRB 260318A: Glowbug gamma-ray detection
  70. GRB 260310A / AT 2026fgk: KAIT optical observations
  71. GRB 260320A: NuSTAR detection of prompt emission
  72. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  73. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  74. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  75. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  76. GRB 260318A: SVOM/GRM observation
  77. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  78. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  79. Fermi GRB 260318A: Global MASTER-Net observations report
  80. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  81. GRB 260310A / AT 2026fgk: radio detection with the VLA
  82. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  83. GRB 260310A / AT2026fgk: LCO optical observations
  84. GRB 260316B: SVOM/GRM observation
  85. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  86. EP260316a: COLIBRÍ faint optical counterpart candidate
  87. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  88. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  89. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  90. EP260316a: Xinglong optical upper limit
  91. EP260316a: optical upper limit with Kinder observations
  92. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  93. GRB 260314A: Glowbug gamma-ray detection
  94. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  95. IceCube-260315A: COLIBRÍ optical observations
  96. EP260314a: Xinglong optical upper limit
  97. EP260314a: optical upper limit with Kinder observations
  98. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  99. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  100. GRB 260310A / AT 2026fgk: iTelescope optical observations

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