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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"

42893 results found.

  1. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  2. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  3. The EP-WXT trigger 01709259173 is likely a flaring star
  4. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  5. IPN triangulation of GRB 260320A
  6. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  7. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  8. GRB 260326A: Fermi GBM Detection
  9. EP260321a: JinShan near-infrared observations
  10. GRB 260325A: Fermi GBM Final Localization
  11. GRB 260326A: Fermi GBM Final Real-time Localization
  12. EP260321a: Upper limits from a neutrino search with IceCube
  13. Fermi Gamma-ray Burst Monitor trigger 796145512/260325647 is not a GRB
  14. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  15. IPN triangulation of GRB 260316B
  16. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  17. GRID detection of GRB 260320A
  18. EP260321a: Gemini-South confirmation of a supernova (duplicate submission)
  19. EP260321a: Gemini-South confirmation of a supernova
  20. Fermi Gamma-ray Burst Monitor trigger 796060650/260324665 is not a GRB
  21. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  22. GRB 260310A: LBT optical observations
  23. EP260321A: Mondy optical observations
  24. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  25. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  26. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  27. The EP-WXT trigger 01709259112 is likely a flaring star
  28. Fermi GRB 260323A: Global MASTER-Net observations report
  29. GRB 260323A: Fermi GBM Final Real-time Localization
  30. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  31. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  32. GRB 260322A: Fermi GBM Final Localization
  33. GRB 260320A: Glowbug gamma-ray detection
  34. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  35. EP260321a: COLIBRÍ further optical observations and brightening
  36. Fermi Gamma-ray Burst Monitor trigger 795918973/260323025 is not a GRB
  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. The EP-WXT trigger 01709259045 is likely a flaring star
  42. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  43. EP260321a: GOTO detection of blue variable source
  44. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  45. EP260321a: further Kinder optical observations
  46. GRB 260321A: SVOM/VT optical upper limits
  47. EP260321a: Las Cumbres 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. GRB 260321A: SVOM detection of a burst
  55. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  56. EP260321a: Global MASTER-Net observations report
  57. EP260321a: Einstein Probe detection of an X-ray transient
  58. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  59. GRB 260318A: Glowbug gamma-ray detection
  60. GRB 260310A / AT 2026fgk: KAIT optical observations
  61. GRB 260320A: NuSTAR detection of prompt emission
  62. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  63. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  64. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  65. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  66. GRB 260310A/AT2026fgk: LBT near-infrared observations
  67. NOEMA Detection of GRB 260310A / AT 2026fgk
  68. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  69. GRB 260318A: SVOM/GRM observation
  70. The EP-WXT trigger 01709258989 is likely a flaring star
  71. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  72. GRB 260318A: GECAM-B observation
  73. Fermi GRB 260318A: Global MASTER-Net observations report
  74. GRB 260318A: Fermi GBM Final Real-time Localization
  75. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  76. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  77. GRB 260310A / AT 2026fgk: radio detection with the VLA
  78. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  79. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  80. GRB 260317A: Fermi GBM Final Localization
  81. GRB 260316B: GECAM-B observation
  82. GRB 260316B: SVOM/GRM observation
  83. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  84. EP260316a: COLIBRÍ faint optical counterpart candidate
  85. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  86. GRB 260316B: AstroSat CZTI detection
  87. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  88. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  89. EP260316a: Xinglong optical upper limit
  90. GRB 260316B: Fermi GBM Final Real-time Localization
  91. EP260316a: optical upper limit with Kinder observations
  92. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  93. GRB 260314A: Glowbug gamma-ray detection
  94. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  95. IceCube-260315A: COLIBRÍ optical observations
  96. EP260314a: Xinglong optical upper limit
  97. EP260314a: optical upper limit with Kinder observations
  98. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  99. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  100. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations

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