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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"

28105 results found.

  1. EP260321a: Upper limits from a neutrino search with IceCube
  2. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  3. IPN triangulation of GRB 260316B
  4. GRID detection of GRB 260320A
  5. EP260321a: Gemini-South confirmation of a supernova
  6. GRB 260310A: LBT optical observations
  7. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  8. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  9. GRB 260323A: Fermi GBM Final Real-time Localization
  10. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  11. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  12. GRB 260322A: Fermi GBM Final Localization
  13. GRB 260320A: Glowbug gamma-ray detection
  14. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  15. EP260321a: COLIBRÍ further optical observations and brightening
  16. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  17. EP260214b: ATCA 6 GHz detection
  18. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  19. EP260321a: GOTO detection of blue variable source
  20. EP260321a: further Kinder optical observations
  21. GRB 260320A: Insight-HXMT/HE detection
  22. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  23. Fermi GBM Sub-Threshold Detection of GRB 260321A
  24. GRB 260321A: SVOM detection of a burst
  25. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  26. EP260321a: Einstein Probe detection of an X-ray transient
  27. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  28. GRB 260318A: Glowbug gamma-ray detection
  29. GRB 260310A / AT 2026fgk: KAIT optical observations
  30. GRB 260320A: NuSTAR detection of prompt emission
  31. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  32. GRB 260310A/AT2026fgk: LBT near-infrared observations
  33. NOEMA Detection of GRB 260310A / AT 2026fgk
  34. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  35. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  36. GRB 260318A: Fermi GBM Final Real-time Localization
  37. GRB 260310A / AT 2026fgk: radio detection with the VLA
  38. GRB 260317A: Fermi GBM Final Localization
  39. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  40. GRB 260316B: AstroSat CZTI detection
  41. EP260316a: Xinglong optical upper limit
  42. GRB 260316B: Fermi GBM Final Real-time Localization
  43. EP260316a: optical upper limit with Kinder observations
  44. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  45. GRB 260314A: Glowbug gamma-ray detection
  46. EP260314a: Xinglong optical upper limit
  47. EP260314a: optical upper limit with Kinder observations
  48. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  49. GRB 260310A / AT 2026fgk: iTelescope optical observations
  50. GRID detection of GRB 260312B
  51. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  52. EP260314a: BOOTES-6/DPR optical upper limits at early times
  53. EP260314a: Einstein Probe detection of an X-ray transient
  54. GRB 260310A/AT2026fgk: radio detection at 15GHz
  55. GRB 260310A / AT2026fgk: TNG NIR detection
  56. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  57. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  58. GRB 260314A: Fermi GBM Final Real-time Localization
  59. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  60. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  61. GRB 260310B: Insight-HXMT/HE detection
  62. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  63. GRB 260312B: AstroSat CZTI detection
  64. Swift BAT trigger 1500295: A solar flare
  65. GRB 260313A: Fermi GBM Final Real-time Localization
  66. Swift BAT trigger 1500287: A solar flare
  67. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  68. GRB 260308A: Insight-HXMT/HE detection
  69. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  70. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  71. GRB260310A / AT2026fgk: P200 Spectroscopy
  72. GRB 260312B: Glowbug gamma-ray detection
  73. GRB 260310A: potential optical counterpart
  74. Swift BAT trigger 1500148: A solar flare
  75. GRB 260312B: Fermi GBM Final Real-time Localization
  76. GRB 260312A: Swift detection of a burst
  77. GRB 260311B: Fermi GBM Final Real-time Localization
  78. GRB 260131A/B: radio detection with the VLA
  79. GRB 260310A: AstroSat CZTI detection of a long burst
  80. GRB 260311A: Fermi GBM Final Real-time Localization
  81. GRB 260310B: Fermi GBM Final Real-time Localization
  82. GRB 260208A: radio detection with the VLA
  83. GRB 260310A: Fermi GBM Final Real-time Localization
  84. GRB 260307A: Glowbug gamma-ray detection
  85. GRB 260308A: Fermi GBM Final Real-time Localization
  86. Fermi GBM Sub-Threshold Detection of GRB 260307B
  87. GRB 260307B: Mephisto optical upper limits
  88. GRB 260307B: possible NOT optical counterpart
  89. GRB 260307B: SVOM/VT upper limit with X band data analysis
  90. GRB 260307B: SVOM/VT optical candidate
  91. GRB 260307B: SVOM detection of a burst
  92. GRB 260307A: Fermi GBM Final Localization
  93. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  94. GRB 260207A: TESS Detection and Possible VLA Counterpart
  95. EP260306a: Gemini-North redshift z = 4.773
  96. EP260306a: Einstein Probe detection of an X-ray transient
  97. EP260302a: Optical afterglow rebrightening
  98. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  99. GRB 260303A: 1.3m DFOT optical upper limit
  100. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate

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