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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

36143 results found.

  1. GRB 251105A: AstroSat CZTI detection
  2. GRB 251108A: Fermi GBM Final Localization Correction
  3. GRB 251102B: SVOM/GRM observation
  4. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  5. IPN triangulation of GRB 251105B (possible sGRB with EE)
  6. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  7. GRB 251106B: SVOM/GRM observation of a short burst
  8. GRB 251106A: Swift-XRT afterglow detection
  9. GRB 251106A: Kilonova-Catcher optical upper limit
  10. Fermi GBM Sub-Threshold Detection of GRB 251106A
  11. GRB 251106A: Swift/BAT arcminute localization of a burst
  12. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  13. GRB 251106A: MASTER optical observations
  14. GRB 251106A: SVOM detection of a burst
  15. GRB 251103B: AstroSat CZTI detection
  16. GRB 251025C: TERI Gamma-ray detection
  17. GRB 251016B: TERI Gamma-ray detection
  18. GRB 251016A: TERI Gamma-ray detection of a short burst
  19. GRB 250920C: TERI Gamma-ray detection
  20. Fermi Gamma-ray Burst Monitor trigger 784109140/251106337 is not a GRB
  21. GRB 251105A: Fermi GBM Observation
  22. GRB 251105C: Fermi GBM Final Localization Correction
  23. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  24. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  25. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  26. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  27. Fermi GBM Sub-Threshold Detection of GRB 251105B
  28. GRB 251103B: Swift/UVOT Upper Limits
  29. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  30. Fermi GRB 251105A: Global MASTER-Net observations report
  31. GRB 251105A: Fermi GBM Final Real-time Localization
  32. Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
  33. GRB 251103B: Fermi GBM observation
  34. GRB 251104A: SVOM detection of a burst
  35. GRB 251028A: Insight-HXMT/HE detection
  36. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  37. GRB 251103A: WFST optical observations
  38. EP251102a: OHP/T193 optical observations
  39. GRB 251103A: OHP/T193 optical observations
  40. GRB 251103A: Xinglong 2.16m optical detection
  41. GRB 251103A: Insight-HXMT detection
  42. GRB 251103A: KAIT optical observations
  43. GRB 251103B: Nanshan/HMT optical upper limit
  44. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  45. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  46. GRB 251103B: MITSuME Akeno optical upper limits
  47. GRB 251103B: Swift-XRT refined Analysis
  48. Fermi GRB 251103A: Global MASTER-Net observations report
  49. GRB 251103A: J-band detection with WINTER
  50. Swift GRB 251103B: Global MASTER-Net observations report
  51. GRB 251103B: GROWTH-India Telescope optical upper limits
  52. GRB 251103A: Kilonova-Catcher optical afterglow detection
  53. GRB 251103B: Enhanced Swift-XRT position
  54. GRB 251103B: Prompt enhanced Swift-XRT position
  55. GRB 251103B: Swift detection of a burst
  56. GRB 251103B: Fermi GBM Final Real-time Localization
  57. GRB 251103A: Swift/UVOT Detection
  58. GRB 251103A: Fermi GBM Observation
  59. GRB 251103A: SVOM/GRM observation
  60. GRB 251103A: Swift-XRT afterglow detection
  61. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  62. GRB 251025B: OHP/T193 optical upper limit
  63. GRB 251103A: LCO optical observation
  64. GRB 251103A: GOTO optical afterglow detection
  65. GRB 251102A: AstroSat CZTI detection
  66. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  67. GRB 251103A: NOT spectroscopic redshift z = 0.76
  68. GRB 251103A: BOOTES-2/TELMA optical afterglow
  69. GRB 251103A: LCO optical afterglow detection
  70. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  71. GRB 251103A: Fermi GBM Final Localization
  72. GRB 251103A: NOT optical afterglow candidate
  73. GRB 251103A: SVOM detection of a bright burst
  74. GRB 251102B: Fermi GBM Final Real-time Localization
  75. Fermi GRB 251102A: Global MASTER-Net observations report
  76. GRB 251102A: Fermi GBM Final Real-time Localization
  77. GRB 251031A: Fermi GBM Observation
  78. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  79. Konus-Wind detection of GRB 251028A
  80. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  81. GRB 251031A: Fermi GBM Final Real-time Localization
  82. GRB 251025C: SVOM/GRM observation
  83. GRB 251028A: GECAM-B detection
  84. GRB 251028A: SVOM/GRM observation
  85. GRB 251028A: Fermi GBM Observation
  86. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  87. GRB 251022A: Swift-XRT confirmation of fading
  88. GRB 251026B: LBT near-infrared observations
  89. GRB 250926B: VZLUSAT-2 detection
  90. GRB 250926A: VZLUSAT-2 detection
  91. GRB 250925A: VZLUSAT-2 detection
  92. GRB 251026B: Fermi GBM Observation
  93. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  94. GRB 251026A/EP251026a: EP-FXT follow-up observation
  95. GRB 251028B: Fermi/GBM observation
  96. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  97. GRB 251028B: Glowbug gamma-ray detection
  98. GRB 251028A: Glowbug gamma-ray detection
  99. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  100. Fermi GRB 251028B: Global MASTER-Net observations report

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