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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"

32569 results found.

  1. EP260329b: Global MASTER-Net observations report
  2. GRB 260327A: Insight-HXMT/HE detection
  3. EP260329b: Optical follow-up with Kinder observations
  4. EP 260329b: COLIBRÍ optical observations
  5. EP260329a: Optical upper limit with Kinder observations
  6. EP260329b: LCO optical observations of the counterpart
  7. GRB 260326A: Insight-HXMT/HE detection
  8. EP260329b: Einstein Probe detection of an X-ray transient
  9. EP-WXT trigger 01709259209: TRT optical counterpart detection
  10. GRID detection of GRB 260326A
  11. GRB 260310A: Gemini-North Spectral Confirmation of Supernova Features
  12. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  13. EP260327a: SVOM/VT optical upper limits
  14. SMA Detection of GRB 260310A / AT 2026fgk
  15. GRB 260307B: ATCA Radio Upper Limits
  16. EP260327a: WINTER J-band upper limit
  17. EP260327a: COLIBRÍ optical upper limits
  18. EP260327a: Gemini-North optical upper limits
  19. EP260324a: GROWTH-India Telescope optical observation
  20. EP260327a: Global MASTER-Net observations report
  21. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  22. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  23. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  24. IPN triangulation of GRB 260320A
  25. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  26. GRB 260326A: Fermi GBM Detection
  27. EP260321a: JinShan near-infrared observations
  28. EP260321a: Upper limits from a neutrino search with IceCube
  29. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  30. IPN triangulation of GRB 260316B
  31. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  32. GRID detection of GRB 260320A
  33. EP260321a: Gemini-South confirmation of a supernova (duplicate submission)
  34. EP260321a: Gemini-South confirmation of a supernova
  35. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  36. GRB 260310A: LBT optical observations
  37. EP260321A: Mondy optical observations
  38. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  39. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  40. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  41. Fermi GRB 260323A: Global MASTER-Net observations report
  42. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  43. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  44. GRB 260320A: Glowbug gamma-ray detection
  45. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  46. EP260321a: COLIBRÍ further optical observations and brightening
  47. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  48. EP260214b: ATCA 6 GHz detection
  49. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  50. GRB 260321A: EP-FXT follow-up observation
  51. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  52. EP260321a: GOTO detection of blue variable source
  53. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  54. EP260321a: further Kinder optical observations
  55. GRB 260321A: SVOM/VT optical upper limits
  56. EP260321a: Las Cumbres upper limit
  57. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  58. GRB 260320A: Insight-HXMT/HE detection
  59. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  60. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  61. EP260321a: SVOM/VT optical upper limit
  62. GRB 260310A: continued optical observation at Mondy
  63. Fermi GBM Sub-Threshold Detection of GRB 260321A
  64. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  65. EP260321a: Global MASTER-Net observations report
  66. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  67. GRB 260318A: Glowbug gamma-ray detection
  68. GRB 260310A / AT 2026fgk: KAIT optical observations
  69. GRB 260320A: NuSTAR detection of prompt emission
  70. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  71. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  72. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  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. GRB 260310A/AT2026fgk: LBT near-infrared observations
  76. NOEMA Detection of GRB 260310A / AT 2026fgk
  77. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  78. GRB 260318A: SVOM/GRM observation
  79. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  80. GRB 260318A: GECAM-B observation
  81. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  82. Fermi GRB 260318A: Global MASTER-Net observations report
  83. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  84. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  85. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  86. GRB 260310A / AT 2026fgk: radio detection with the VLA
  87. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  88. GRB 260310A / AT2026fgk: LCO optical observations
  89. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  90. GRB 260316B: GECAM-B observation
  91. GRB 260316B: SVOM/GRM observation
  92. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  93. EP260316a: COLIBRÍ faint optical counterpart candidate
  94. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  95. GRB 260316B: AstroSat CZTI detection
  96. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  97. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  98. EP260316a: Xinglong optical upper limit
  99. EP260316a: optical upper limit with Kinder observations
  100. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection

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