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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"

28209 results found.

  1. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  2. GRB 260326A: Fermi GBM Detection
  3. GRB 260325A: Fermi GBM Final Localization
  4. GRB 260326A: Fermi GBM Final Real-time Localization
  5. EP260321a: Upper limits from a neutrino search with IceCube
  6. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  7. IPN triangulation of GRB 260316B
  8. GRID detection of GRB 260320A
  9. EP260321a: Gemini-South confirmation of a supernova
  10. GRB 260310A: LBT optical observations
  11. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  12. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  13. GRB 260323A: Fermi GBM Final Real-time Localization
  14. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  15. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  16. GRB 260322A: Fermi GBM Final Localization
  17. GRB 260320A: Glowbug gamma-ray detection
  18. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  19. EP260321a: COLIBRÍ further optical observations and brightening
  20. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  21. EP260214b: ATCA 6 GHz detection
  22. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  23. EP260321a: GOTO detection of blue variable source
  24. EP260321a: further Kinder optical observations
  25. GRB 260320A: Insight-HXMT/HE detection
  26. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  27. Fermi GBM Sub-Threshold Detection of GRB 260321A
  28. GRB 260321A: SVOM detection of a burst
  29. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  30. EP260321a: Einstein Probe detection of an X-ray transient
  31. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  32. GRB 260318A: Glowbug gamma-ray detection
  33. GRB 260310A / AT 2026fgk: KAIT optical observations
  34. GRB 260320A: NuSTAR detection of prompt emission
  35. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  36. GRB 260310A/AT2026fgk: LBT near-infrared observations
  37. NOEMA Detection of GRB 260310A / AT 2026fgk
  38. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  39. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  40. GRB 260318A: Fermi GBM Final Real-time Localization
  41. GRB 260310A / AT 2026fgk: radio detection with the VLA
  42. GRB 260317A: Fermi GBM Final Localization
  43. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  44. GRB 260316B: AstroSat CZTI detection
  45. EP260316a: Xinglong optical upper limit
  46. GRB 260316B: Fermi GBM Final Real-time Localization
  47. EP260316a: optical upper limit with Kinder observations
  48. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  49. GRB 260314A: Glowbug gamma-ray detection
  50. EP260314a: Xinglong optical upper limit
  51. EP260314a: optical upper limit with Kinder observations
  52. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  53. GRB 260310A / AT 2026fgk: iTelescope optical observations
  54. GRID detection of GRB 260312B
  55. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  56. EP260314a: BOOTES-6/DPR optical upper limits at early times
  57. EP260314a: Einstein Probe detection of an X-ray transient
  58. GRB 260310A/AT2026fgk: radio detection at 15GHz
  59. GRB 260310A / AT2026fgk: TNG NIR detection
  60. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  61. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  62. GRB 260314A: Fermi GBM Final Real-time Localization
  63. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  64. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  65. GRB 260310B: Insight-HXMT/HE detection
  66. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  67. GRB 260312B: AstroSat CZTI detection
  68. Swift BAT trigger 1500295: A solar flare
  69. GRB 260313A: Fermi GBM Final Real-time Localization
  70. Swift BAT trigger 1500287: A solar flare
  71. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  72. GRB 260308A: Insight-HXMT/HE detection
  73. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  74. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  75. GRB260310A / AT2026fgk: P200 Spectroscopy
  76. GRB 260312B: Glowbug gamma-ray detection
  77. GRB 260310A: potential optical counterpart
  78. Swift BAT trigger 1500148: A solar flare
  79. GRB 260312B: Fermi GBM Final Real-time Localization
  80. GRB 260312A: Swift detection of a burst
  81. GRB 260311B: Fermi GBM Final Real-time Localization
  82. GRB 260131A/B: radio detection with the VLA
  83. GRB 260310A: AstroSat CZTI detection of a long burst
  84. GRB 260311A: Fermi GBM Final Real-time Localization
  85. GRB 260310B: Fermi GBM Final Real-time Localization
  86. GRB 260208A: radio detection with the VLA
  87. GRB 260310A: Fermi GBM Final Real-time Localization
  88. GRB 260307A: Glowbug gamma-ray detection
  89. GRB 260308A: Fermi GBM Final Real-time Localization
  90. Fermi GBM Sub-Threshold Detection of GRB 260307B
  91. GRB 260307B: Mephisto optical upper limits
  92. GRB 260307B: possible NOT optical counterpart
  93. GRB 260307B: SVOM/VT upper limit with X band data analysis
  94. GRB 260307B: SVOM/VT optical candidate
  95. GRB 260307B: SVOM detection of a burst
  96. GRB 260307A: Fermi GBM Final Localization
  97. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  98. GRB 260207A: TESS Detection and Possible VLA Counterpart
  99. EP260306a: Gemini-North redshift z = 4.773
  100. EP260306a: Einstein Probe detection of an X-ray transient

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