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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"

29121 results found.

  1. Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
  2. GRB 251103B: Fermi GBM observation
  3. GRB 251104A: SVOM detection of a burst
  4. GRB 251028A: Insight-HXMT/HE detection
  5. EP251102a: FTW optical and NIR observations
  6. GRB 251103A: WFST optical observations
  7. GRB 251103A: OHP/T193 optical observations
  8. GRB 251103A: Xinglong 2.16m optical detection
  9. GRB 251103A: Insight-HXMT detection
  10. GRB 251103A: KAIT optical observations
  11. GRB 251103B: Nanshan/HMT optical upper limit
  12. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  13. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  14. GRB 251103B: MITSuME Akeno optical upper limits
  15. GRB 251103B: Swift-XRT refined Analysis
  16. Fermi GRB 251103A: Global MASTER-Net observations report
  17. EP251102a: NIR observations with WINTER
  18. GRB 251103A: J-band detection with WINTER
  19. Swift GRB 251103B: Global MASTER-Net observations report
  20. GRB 251103B: GROWTH-India Telescope optical upper limits
  21. GRB 251103A: Kilonova-Catcher optical afterglow detection
  22. GRB 251103B: Swift detection of a burst
  23. GRB 251103B: Fermi GBM Final Real-time Localization
  24. GRB 251103A: Swift/UVOT Detection
  25. GRB 251103A: Fermi GBM Observation
  26. GRB 251103A: SVOM/GRM observation
  27. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  28. EP251102a: Einstein Probe detection of a fast X-ray transient
  29. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  30. GRB 251103A: LCO optical observation
  31. EP251102.890: COLIBRÍ optical counterpart candidate
  32. GRB 251103A: GOTO optical afterglow detection
  33. GRB 251102A: AstroSat CZTI detection
  34. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  35. GRB 251103A: NOT spectroscopic redshift z = 0.76
  36. GRB 251103A: BOOTES-2/TELMA optical afterglow
  37. GRB 251103A: LCO optical afterglow detection
  38. GRB 251103A: Fermi GBM Final Localization
  39. GRB 251103A: NOT optical afterglow candidate
  40. GRB 251103A: SVOM detection of a bright burst
  41. GRB 251102B: Fermi GBM Final Real-time Localization
  42. Fermi GRB 251102A: Global MASTER-Net observations report
  43. GRB 251102A: Fermi GBM Final Real-time Localization
  44. GRB 251031A: Fermi GBM Observation
  45. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  46. Konus-Wind detection of GRB 251028A
  47. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  48. GRB 251031A: Fermi GBM Final Real-time Localization
  49. GRB 251025C: SVOM/GRM observation
  50. GRB 251028A: GECAM-B detection
  51. GRB 251028A: SVOM/GRM observation
  52. GRB 251028A: Fermi GBM Observation
  53. GRB 251022A: Swift-XRT confirmation of fading
  54. GRB 251026B: LBT near-infrared observations
  55. GRB 250926B: VZLUSAT-2 detection
  56. GRB 250926A: VZLUSAT-2 detection
  57. GRB 251026B: Fermi GBM Observation
  58. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  59. GRB 251026A/EP251026a: EP-FXT follow-up observation
  60. The EP-WXT trigger 01709247588 is likely a flaring star
  61. GRB 251028B: Fermi/GBM observation
  62. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  63. GRB 251028B: Glowbug gamma-ray detection
  64. GRB 251028A: Glowbug gamma-ray detection
  65. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  66. Fermi GRB 251028B: Global MASTER-Net observations report
  67. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  68. GRB 251028B: Fermi GBM Final Localization Correction
  69. GRB251026B: PRIME H-band upper limit
  70. GRB251025B: 3.6m DOT Optical Observations
  71. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  72. GRB 251028A: Fermi GBM Final Real-time Localization
  73. The EP-WXT trigger 01709247525 is not a real source
  74. SVOM trigger sb25102702/GRB 251027A is not a GRB
  75. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  76. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  77. GRB 251025C: Glowbug gamma-ray detection
  78. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  79. Konus-Wind detection of GRB 251022A
  80. GRB 251027A: Swift-XRT observations
  81. EP251027.145: COLIBRÍ optical upper limits
  82. GRB 251022A: SVOM/GRM observation
  83. GRB 251026B: Swift ToO observations
  84. GRB 251027A: LCO optical upper limit
  85. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. Konus-Wind detection of GRB 251016A (short/hard)
  87. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  88. GRB 251027A: SVOM detection of a faint burst
  89. GRB 251026B: Tentative GOTO optical counterpart candidate
  90. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  91. Fermi GRB 251026B: Global MASTER-Net observations report
  92. Fermi GRB 251025C: Global MASTER-Net observations report
  93. GRB 251026A: Swift-XRT observations
  94. GRB 251025B: J-band detection with WINTER
  95. IceCube-251025A: DDOTI Optical Upper Limit
  96. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  97. GRB 251026B: Fermi GBM Final Localization
  98. GRB 251026A: SVOM detection of a long burst
  99. GRB 251025B: SVOM/VT optical bump
  100. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart

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