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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"

32560 results found.

  1. GRB 260310A: Gemini-North Spectral Confirmation of Supernova Features
  2. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  3. EP260327a: SVOM/VT optical upper limits
  4. SMA Detection of GRB 260310A / AT 2026fgk
  5. GRB 260307B: ATCA Radio Upper Limits
  6. EP260327a: WINTER J-band upper limit
  7. EP260327a: COLIBRÍ optical upper limits
  8. EP260327a: Gemini-North optical upper limits
  9. EP260324a: GROWTH-India Telescope optical observation
  10. EP260327a: Global MASTER-Net observations report
  11. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  12. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  13. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  14. IPN triangulation of GRB 260320A
  15. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  16. GRB 260326A: Fermi GBM Detection
  17. EP260321a: JinShan near-infrared observations
  18. EP260321a: Upper limits from a neutrino search with IceCube
  19. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  20. IPN triangulation of GRB 260316B
  21. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  22. GRID detection of GRB 260320A
  23. EP260321a: Gemini-South confirmation of a supernova (duplicate submission)
  24. EP260321a: Gemini-South confirmation of a supernova
  25. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  26. GRB 260310A: LBT optical observations
  27. EP260321A: Mondy optical observations
  28. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  29. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  30. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  31. Fermi GRB 260323A: Global MASTER-Net observations report
  32. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  33. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  34. GRB 260320A: Glowbug gamma-ray detection
  35. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  36. EP260321a: COLIBRÍ further optical observations and brightening
  37. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  38. EP260214b: ATCA 6 GHz detection
  39. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  40. GRB 260321A: EP-FXT follow-up observation
  41. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  42. EP260321a: GOTO detection of blue variable source
  43. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  44. EP260321a: further Kinder optical observations
  45. GRB 260321A: SVOM/VT optical upper limits
  46. EP260321a: Las Cumbres upper limit
  47. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  48. GRB 260320A: Insight-HXMT/HE detection
  49. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  50. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  51. EP260321a: SVOM/VT optical upper limit
  52. GRB 260310A: continued optical observation at Mondy
  53. Fermi GBM Sub-Threshold Detection of GRB 260321A
  54. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  55. EP260321a: Global MASTER-Net observations report
  56. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  57. GRB 260318A: Glowbug gamma-ray detection
  58. GRB 260310A / AT 2026fgk: KAIT optical observations
  59. GRB 260320A: NuSTAR detection of prompt emission
  60. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  61. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  62. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  63. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  64. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  65. GRB 260310A/AT2026fgk: LBT near-infrared observations
  66. NOEMA Detection of GRB 260310A / AT 2026fgk
  67. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  68. GRB 260318A: SVOM/GRM observation
  69. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  70. GRB 260318A: GECAM-B observation
  71. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  72. Fermi GRB 260318A: Global MASTER-Net observations report
  73. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  74. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  75. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  76. GRB 260310A / AT 2026fgk: radio detection with the VLA
  77. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  78. GRB 260310A / AT2026fgk: LCO optical observations
  79. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  80. GRB 260316B: GECAM-B observation
  81. GRB 260316B: SVOM/GRM observation
  82. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  83. EP260316a: COLIBRÍ faint optical counterpart candidate
  84. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  85. GRB 260316B: AstroSat CZTI detection
  86. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  87. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  88. EP260316a: Xinglong optical upper limit
  89. EP260316a: optical upper limit with Kinder observations
  90. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  91. GRB 260314A: Glowbug gamma-ray detection
  92. IceCube-260315A: COLIBRÍ optical observations
  93. EP260314a: Xinglong optical upper limit
  94. EP260314a: optical upper limit with Kinder observations
  95. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  96. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  97. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  98. GRB 260310A / AT 2026fgk: iTelescope optical observations
  99. EP260314a: COLIBRÍ optical upper limit
  100. GRID detection of GRB 260312B

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