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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"

36352 results found.

  1. GRB 251111A: KAIT optical upper limit
  2. GRB 251111A: LCO optical observation
  3. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  4. GRB 251111A: SVOM detection of a soft burst
  5. GRB 251103B: Swift-BAT refined analysis
  6. GRB 251106A: Swift/UVOT Upper Limits
  7. GRB 251105B: Insight-HXMT/HE detection
  8. GRB 251106B: Insight-HXMT detection
  9. GRB 251105A: AstroSat CZTI detection
  10. GRB 251108A: Fermi GBM Final Localization Correction
  11. GRB 251102B: SVOM/GRM observation
  12. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  13. IPN triangulation of GRB 251105B (possible sGRB with EE)
  14. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  15. GRB 251106B: SVOM/GRM observation of a short burst
  16. GRB 251106A: Swift-XRT afterglow detection
  17. GRB 251106A: Kilonova-Catcher optical upper limit
  18. Fermi GBM Sub-Threshold Detection of GRB 251106A
  19. GRB 251106A: Swift/BAT arcminute localization of a burst
  20. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  21. GRB 251106A: MASTER optical observations
  22. GRB 251106A: SVOM detection of a burst
  23. GRB 251103B: AstroSat CZTI detection
  24. GRB 251025C: TERI Gamma-ray detection
  25. GRB 251016B: TERI Gamma-ray detection
  26. GRB 251016A: TERI Gamma-ray detection of a short burst
  27. GRB 250920C: TERI Gamma-ray detection
  28. Fermi Gamma-ray Burst Monitor trigger 784109140/251106337 is not a GRB
  29. GRB 251105A: Fermi GBM Observation
  30. GRB 251105C: Fermi GBM Final Localization Correction
  31. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  32. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  33. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  34. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  35. Fermi GBM Sub-Threshold Detection of GRB 251105B
  36. GRB 251103B: Swift/UVOT Upper Limits
  37. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  38. Fermi GRB 251105A: Global MASTER-Net observations report
  39. GRB 251105A: Fermi GBM Final Real-time Localization
  40. Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
  41. GRB 251103B: Fermi GBM observation
  42. GRB 251104A: SVOM detection of a burst
  43. GRB 251028A: Insight-HXMT/HE detection
  44. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  45. GRB 251103A: WFST optical observations
  46. EP251102a: OHP/T193 optical observations
  47. GRB 251103A: OHP/T193 optical observations
  48. GRB 251103A: Xinglong 2.16m optical detection
  49. GRB 251103A: Insight-HXMT detection
  50. GRB 251103A: KAIT optical observations
  51. GRB 251103B: Nanshan/HMT optical upper limit
  52. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  53. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  54. GRB 251103B: MITSuME Akeno optical upper limits
  55. GRB 251103B: Swift-XRT refined Analysis
  56. Fermi GRB 251103A: Global MASTER-Net observations report
  57. GRB 251103A: J-band detection with WINTER
  58. Swift GRB 251103B: Global MASTER-Net observations report
  59. GRB 251103B: GROWTH-India Telescope optical upper limits
  60. GRB 251103A: Kilonova-Catcher optical afterglow detection
  61. GRB 251103B: Enhanced Swift-XRT position
  62. GRB 251103B: Prompt enhanced Swift-XRT position
  63. GRB 251103B: Swift detection of a burst
  64. GRB 251103B: Fermi GBM Final Real-time Localization
  65. GRB 251103A: Swift/UVOT Detection
  66. GRB 251103A: Fermi GBM Observation
  67. GRB 251103A: SVOM/GRM observation
  68. GRB 251103A: Swift-XRT afterglow detection
  69. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  70. GRB 251025B: OHP/T193 optical upper limit
  71. GRB 251103A: LCO optical observation
  72. GRB 251103A: GOTO optical afterglow detection
  73. GRB 251102A: AstroSat CZTI detection
  74. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  75. GRB 251103A: NOT spectroscopic redshift z = 0.76
  76. GRB 251103A: BOOTES-2/TELMA optical afterglow
  77. GRB 251103A: LCO optical afterglow detection
  78. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  79. GRB 251103A: Fermi GBM Final Localization
  80. GRB 251103A: NOT optical afterglow candidate
  81. GRB 251103A: SVOM detection of a bright burst
  82. GRB 251102B: Fermi GBM Final Real-time Localization
  83. Fermi GRB 251102A: Global MASTER-Net observations report
  84. GRB 251102A: Fermi GBM Final Real-time Localization
  85. GRB 251031A: Fermi GBM Observation
  86. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  87. Konus-Wind detection of GRB 251028A
  88. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  89. GRB 251031A: Fermi GBM Final Real-time Localization
  90. GRB 251025C: SVOM/GRM observation
  91. GRB 251028A: GECAM-B detection
  92. GRB 251028A: SVOM/GRM observation
  93. GRB 251028A: Fermi GBM Observation
  94. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  95. GRB 251022A: Swift-XRT confirmation of fading
  96. GRB 251026B: LBT near-infrared observations
  97. GRB 250926B: VZLUSAT-2 detection
  98. GRB 250926A: VZLUSAT-2 detection
  99. GRB 250925A: VZLUSAT-2 detection
  100. GRB 251026B: Fermi GBM Observation

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