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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"

11556 results found.

  1. GRB 260219A: Fermi GBM Final Real-time Localization
  2. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  3. GRB 260217A: Fermi GBM Final Localization
  4. Konus-Wind detection of GRB 260212A
  5. GRB 260208A: AbAO and Terskol optical upper limits
  6. GRB 260208A: continued Mondy optical observations
  7. IPN triangulation of GRB 260212A
  8. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  9. GRB 260213A: GECAM-B observation of a short burst
  10. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  11. GRB 260216A: Fermi GBM Final Real-time Localization
  12. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  13. GRB 260211A: SVOM/VT optical counterpart
  14. GRB 260212A: AstroSat CZTI detection
  15. GRB 260212A: Fermi GBM Observation
  16. GRB 260212A: GECAM-B observation
  17. GRB 260212A: SVOM/GRM observation of a long burst
  18. GRB 260213B: Fermi GBM Final Localization
  19. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  20. GRB 260211A - SVOM/ECLAIRs refined analysis
  21. GRB 260204A: SVOM/ECLAIRs refined analysis
  22. GRB 260213A: Fermi GBM Final Localization
  23. GRB 260211A: SVOM/VT optical observation
  24. GRB 260212A: Glowbug gamma-ray detection
  25. Fermi GRB 260212A: Global MASTER-Net observations report
  26. GRB 260212A: Fermi GBM Final Real-time Localization
  27. Fermi GBM Sub-Threshold Detection of GRB 260211A
  28. Konus-Wind detection of GRB 260207B
  29. GRID detection of GRB 260207B
  30. GRB260131A/B: 3.6m DOT Optical Observations
  31. Fermi trigger No 792537871: Global MASTER-Net observations report
  32. GRB 260208A: Swift UVOT detection
  33. Konus-Wind detection of GRB 260127B
  34. Fermi GRB 260210C: Global MASTER-Net observations report
  35. GRB 260208A: LCO detection of the optical counterpart
  36. IPN triangulation of GRB 260207B (short/hard with EE)
  37. GRB 260210C: Fermi GBM Final Real-time Localization
  38. GRB 260210B: Fermi GBM Final Real-time Localization
  39. GRB 260208C: AstroSat CZTI detection
  40. GRB 260208B: refined analysis of the EP-FXT observation
  41. GRB 260207B: AstroSat CZTI detection
  42. GRB 260208C: SVOM/GRM observation
  43. GRB 260208B: AstroSat CZTI detection of a bright long burst
  44. GRB260208A: Liverpool Telescope optical follow-up observations
  45. GRB 260208A: Glowbug gamma-ray detection
  46. GRB 260208A: NuSTAR detection of prompt emission
  47. GRB 260208A: Fermi GBM Observation
  48. Fermi GRB 260209A: Global MASTER-Net observations report
  49. GRB 260208B: Swift-XRT observations
  50. GRB 260131A/B: continued Mondy optical observations
  51. GRB 260208B: COLIBRÍ optical observations
  52. GRB 260208A: Mondy optical observations
  53. GRB 260208A: 1.3m DFOT optical detection
  54. GRB 260208A: COLIBRÍ optical observations
  55. GRB 260208B: EP-FXT observation
  56. GRB 260208A: NOT spectroscopic redshift z = 2.36
  57. GRB 260208A: Liverpool Telescope optical detection
  58. Fermi GRB 260208C: Global MASTER-Net observations report
  59. GRB 260208B: SVOM/VT optical candidate
  60. GRB 260208A: GECAM-B observation of a bright burst
  61. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  62. GRB 260209A: Fermi GBM Final Real-time Localization
  63. GRB 260208A: SVOM/VT optical observation
  64. Fermi GRB 260208D: Global MASTER-Net observations report
  65. GRB 260208D: Fermi GBM Final Real-time Localization
  66. GRB 260208A: Swift-XRT observations
  67. GRB 260208B: Swift ToO observations
  68. GRB 260208B: SVOM/GRM observation of a bright burst
  69. GRB 260208B: Fermi GBM Detection
  70. GRB 260208B: Fermi-LAT detection
  71. GRB 260208C: Fermi GBM Final Real-time Localization
  72. GRB 260208A: Fermi-LAT detection
  73. GRB 260207B: GECAM-B observation
  74. GRB 260208A: Swift ToO observations
  75. GRB 260208A: Fermi GBM Classification Correction
  76. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  77. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  78. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  79. GRB 260208B: Fermi GBM Final Real-time Localization
  80. Fermi GRB 260208A: Global MASTER-Net observations report
  81. Fermi Gamma-ray Burst Monitor trigger 792220053/260208214 is not a GRB
  82. GRB 260208A: Fermi GBM Final Real-time Localization
  83. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  84. GRB 260207A : MASTER optical counterpart discovery
  85. GRB 260131A/B: Mondy and Terskol optical observations
  86. Fermi GRB 260207B: Global MASTER-Net observations report
  87. GRB 260207B: Fermi GBM Final Real-time Localization
  88. GRB 260207A: Fermi GBM Final Localization
  89. Fermi trigger No 792135758: Global MASTER-Net observations report
  90. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  91. GRB 260204A : MASTER Global robotic net optical observations
  92. Fermi GBM Sub-Threshold Detection of GRB 260204A
  93. GRB 260204B: Fermi GBM Final Real-time Localization
  94. GRB 260131A/B: OHP/T193 optical observations
  95. GRB 260131A: KAIT optical observations
  96. GRB 260131A: FTW optical and NIR observations
  97. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  98. GRID detection of GRB 260131A/B
  99. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  100. GRB 260130A: Insight-HXMT/HE detection

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