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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"

42872 results found.

  1. GRB 260310A: LBT optical observations
  2. EP260321A: Mondy optical observations
  3. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  4. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  5. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  6. The EP-WXT trigger 01709259112 is likely a flaring star
  7. Fermi GRB 260323A: Global MASTER-Net observations report
  8. GRB 260323A: Fermi GBM Final Real-time Localization
  9. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  10. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  11. GRB 260322A: Fermi GBM Final Localization
  12. GRB 260320A: Glowbug gamma-ray detection
  13. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  14. EP260321a: COLIBRÍ further optical observations and brightening
  15. Fermi Gamma-ray Burst Monitor trigger 795918973/260323025 is not a GRB
  16. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  17. EP260214b: ATCA 6 GHz detection
  18. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  19. GRB 260321A: EP-FXT follow-up observation
  20. The EP-WXT trigger 01709259045 is likely a flaring star
  21. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  22. EP260321a: GOTO detection of blue variable source
  23. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  24. EP260321a: further Kinder optical observations
  25. GRB 260321A: SVOM/VT optical upper limits
  26. EP260321a: Las Cumbres upper limit
  27. GRB 260320A: Insight-HXMT/HE detection
  28. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  29. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  30. EP260321a: SVOM/VT optical upper limit
  31. GRB 260310A: continued optical observation at Mondy
  32. Fermi GBM Sub-Threshold Detection of GRB 260321A
  33. GRB 260321A: SVOM detection of a burst
  34. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  35. EP260321a: Global MASTER-Net observations report
  36. EP260321a: Einstein Probe detection of an X-ray transient
  37. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  38. GRB 260318A: Glowbug gamma-ray detection
  39. GRB 260310A / AT 2026fgk: KAIT optical observations
  40. GRB 260320A: NuSTAR detection of prompt emission
  41. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  42. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  43. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  44. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  45. GRB 260310A/AT2026fgk: LBT near-infrared observations
  46. NOEMA Detection of GRB 260310A / AT 2026fgk
  47. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  48. GRB 260318A: SVOM/GRM observation
  49. The EP-WXT trigger 01709258989 is likely a flaring star
  50. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  51. GRB 260318A: GECAM-B observation
  52. Fermi GRB 260318A: Global MASTER-Net observations report
  53. GRB 260318A: Fermi GBM Final Real-time Localization
  54. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  55. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  56. GRB 260310A / AT 2026fgk: radio detection with the VLA
  57. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  58. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  59. GRB 260317A: Fermi GBM Final Localization
  60. GRB 260316B: GECAM-B observation
  61. GRB 260316B: SVOM/GRM observation
  62. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  63. EP260316a: COLIBRÍ faint optical counterpart candidate
  64. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  65. GRB 260316B: AstroSat CZTI detection
  66. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  67. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  68. EP260316a: Xinglong optical upper limit
  69. GRB 260316B: Fermi GBM Final Real-time Localization
  70. EP260316a: optical upper limit with Kinder observations
  71. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  72. GRB 260314A: Glowbug gamma-ray detection
  73. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  74. IceCube-260315A: COLIBRÍ optical observations
  75. EP260314a: Xinglong optical upper limit
  76. EP260314a: optical upper limit with Kinder observations
  77. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  78. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  79. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  80. EP260314a: COLIBRÍ optical upper limit
  81. GRID detection of GRB 260312B
  82. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  83. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  84. EP260314a: BOOTES-6/DPR optical upper limits at early times
  85. EP260314a: Global MASTER-Net observations report
  86. EP260314a: SVOM/VT optical candidate
  87. Fermi trigger No 795185313: Global MASTER-Net observations report
  88. IceCube Alert 260315A: Global MASTER-Net observations report
  89. EP260314a: Einstein Probe detection of an X-ray transient
  90. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  91. GRB 260314A: GECAM-B observation of a burst
  92. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  93. GRB 260310A / AT2026fgk: SAO RAS optical observations
  94. GRB 260310A/AT2026fgk: radio detection at 15GHz
  95. GRB 260310A / AT2026fgk: TNG NIR detection
  96. GRB 260310A / AT2026fgk: OASDG optical observations
  97. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  98. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  99. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  100. Fermi GRB 260314A: Global MASTER-Net observations report

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