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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"

32550 results found.

  1. EP260327a: Global MASTER-Net observations report
  2. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  3. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  4. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  5. IPN triangulation of GRB 260320A
  6. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  7. GRB 260326A: Fermi GBM Detection
  8. EP260321a: JinShan near-infrared observations
  9. EP260321a: Upper limits from a neutrino search with IceCube
  10. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  11. IPN triangulation of GRB 260316B
  12. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  13. GRID detection of GRB 260320A
  14. EP260321a: Gemini-South confirmation of a supernova (duplicate submission)
  15. EP260321a: Gemini-South confirmation of a supernova
  16. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  17. GRB 260310A: LBT optical observations
  18. EP260321A: Mondy optical observations
  19. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  20. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  21. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  22. Fermi GRB 260323A: Global MASTER-Net observations report
  23. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  24. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  25. GRB 260320A: Glowbug gamma-ray detection
  26. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  27. EP260321a: COLIBRÍ further optical observations and brightening
  28. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  29. EP260214b: ATCA 6 GHz detection
  30. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  31. GRB 260321A: EP-FXT follow-up observation
  32. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  33. EP260321a: GOTO detection of blue variable source
  34. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  35. EP260321a: further Kinder optical observations
  36. GRB 260321A: SVOM/VT optical upper limits
  37. EP260321a: Las Cumbres upper limit
  38. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  39. GRB 260320A: Insight-HXMT/HE detection
  40. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  41. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  42. EP260321a: SVOM/VT optical upper limit
  43. GRB 260310A: continued optical observation at Mondy
  44. Fermi GBM Sub-Threshold Detection of GRB 260321A
  45. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  46. EP260321a: Global MASTER-Net observations report
  47. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  48. GRB 260318A: Glowbug gamma-ray detection
  49. GRB 260310A / AT 2026fgk: KAIT optical observations
  50. GRB 260320A: NuSTAR detection of prompt emission
  51. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  52. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  53. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  54. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  55. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  56. GRB 260310A/AT2026fgk: LBT near-infrared observations
  57. NOEMA Detection of GRB 260310A / AT 2026fgk
  58. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  59. GRB 260318A: SVOM/GRM observation
  60. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  61. GRB 260318A: GECAM-B observation
  62. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  63. Fermi GRB 260318A: Global MASTER-Net observations report
  64. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  65. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  66. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  67. GRB 260310A / AT 2026fgk: radio detection with the VLA
  68. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  69. GRB 260310A / AT2026fgk: LCO optical observations
  70. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  71. GRB 260316B: GECAM-B observation
  72. GRB 260316B: SVOM/GRM observation
  73. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  74. EP260316a: COLIBRÍ faint optical counterpart candidate
  75. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  76. GRB 260316B: AstroSat CZTI detection
  77. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  78. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  79. EP260316a: Xinglong optical upper limit
  80. EP260316a: optical upper limit with Kinder observations
  81. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  82. GRB 260314A: Glowbug gamma-ray detection
  83. IceCube-260315A: COLIBRÍ optical observations
  84. EP260314a: Xinglong optical upper limit
  85. EP260314a: optical upper limit with Kinder observations
  86. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  87. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  88. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  89. GRB 260310A / AT 2026fgk: iTelescope optical observations
  90. EP260314a: COLIBRÍ optical upper limit
  91. GRID detection of GRB 260312B
  92. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  93. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  94. EP260314a: Global MASTER-Net observations report
  95. EP260314a: SVOM/VT optical candidate
  96. GRB 260314A: GECAM-B observation of a burst
  97. GRB 260310A / AT2026fgk: SAO RAS optical observations
  98. GRB 260310A/AT2026fgk: radio detection at 15GHz
  99. GRB 260310A / AT2026fgk: TNG NIR detection
  100. GRB 260310A / AT2026fgk: OASDG optical observations

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