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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"

45899 results found.

  1. IPN triangulation of GRB 260320A
  2. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  3. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  4. GRB 260326A: Fermi GBM Detection
  5. EP260321a: JinShan near-infrared observations
  6. GRB 260325A: Fermi GBM Final Localization
  7. GRB 260326A: Fermi GBM Final Real-time Localization
  8. EP260321a: Upper limits from a neutrino search with IceCube
  9. Fermi Gamma-ray Burst Monitor trigger 796145512/260325647 is not a GRB
  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. Fermi Gamma-ray Burst Monitor trigger 796060650/260324665 is not a GRB
  17. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  18. GRB 260310A: LBT optical observations
  19. EP260321A: Mondy optical observations
  20. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  21. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  22. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  23. The EP-WXT trigger 01709259112 is likely a flaring star
  24. Fermi GRB 260323A: Global MASTER-Net observations report
  25. GRB 260323A: Fermi GBM Final Real-time Localization
  26. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  27. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  28. GRB 260322A: Fermi GBM Final Localization
  29. GRB 260320A: Glowbug gamma-ray detection
  30. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  31. EP260321a: COLIBRÍ further optical observations and brightening
  32. Fermi Gamma-ray Burst Monitor trigger 795918973/260323025 is not a GRB
  33. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  34. EP260214b: ATCA 6 GHz detection
  35. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  36. GRB 260321A: EP-FXT follow-up observation
  37. The EP-WXT trigger 01709259045 is likely a flaring star
  38. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  39. EP260321a: GOTO detection of blue variable source
  40. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  41. EP260321a: further Kinder optical observations
  42. GRB 260321A: SVOM/VT optical upper limits
  43. EP260321a: Las Cumbres upper limit
  44. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  45. GRB 260320A: Insight-HXMT/HE detection
  46. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  47. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  48. EP260321a: SVOM/VT optical upper limit
  49. GRB 260310A: continued optical observation at Mondy
  50. Fermi GBM Sub-Threshold Detection of GRB 260321A
  51. GRB 260321A: SVOM detection of a burst
  52. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  53. EP260321a: Global MASTER-Net observations report
  54. EP260321a: Einstein Probe detection of an X-ray transient
  55. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  56. GRB 260318A: Glowbug gamma-ray detection
  57. GRB 260310A / AT 2026fgk: KAIT optical observations
  58. GRB 260320A: NuSTAR detection of prompt emission
  59. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  60. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  61. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  62. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  63. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  64. GRB 260310A/AT2026fgk: LBT near-infrared observations
  65. NOEMA Detection of GRB 260310A / AT 2026fgk
  66. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  67. GRB 260318A: SVOM/GRM observation
  68. The EP-WXT trigger 01709258989 is likely a flaring star
  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. GRB 260318A: Fermi GBM Final Real-time Localization
  74. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  75. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  76. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  77. GRB 260310A / AT 2026fgk: radio detection with the VLA
  78. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  79. GRB 260310A / AT2026fgk: LCO optical observations
  80. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  81. GRB 260317A: Fermi GBM Final Localization
  82. GRB 260316B: GECAM-B observation
  83. GRB 260316B: SVOM/GRM observation
  84. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  85. EP260316a: COLIBRÍ faint optical counterpart candidate
  86. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  87. GRB 260316B: AstroSat CZTI detection
  88. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  89. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  90. EP260316a: Xinglong optical upper limit
  91. GRB 260316B: Fermi GBM Final Real-time Localization
  92. EP260316a: optical upper limit with Kinder observations
  93. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  94. GRB 260314A: Glowbug gamma-ray detection
  95. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  96. IceCube-260315A: COLIBRÍ optical observations
  97. EP260314a: Xinglong optical upper limit
  98. EP260314a: optical upper limit with Kinder observations
  99. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  100. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations

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