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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"
  1. GRB 260211A: LAST optical upper limit
  2. GRB 260210A: SVOM/GRM observation
  3. Fermi GBM Sub-Threshold Detection of GRB 260211A
  4. Konus-Wind detection of GRB 260207B
  5. GRB 260128B: SVOM/ECLAIRs refined analysis
  6. GRID detection of GRB 260207B
  7. GRB 260211A: LCO optical upper limits
  8. GRB260131A/B: 3.6m DOT Optical Observations
  9. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  10. Fermi trigger No 792537871: Global MASTER-Net observations report
  11. GRB 260211A: SVOM detection of a burst
  12. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  13. Konus-Wind detection of GRB 260209B
  14. GRB 260208A: Swift UVOT detection
  15. Konus-Wind detection of GRB 260127B
  16. EP260209a: COLIBRÍ optical upper limit
  17. Fermi GRB 260210C: Global MASTER-Net observations report
  18. EP260209a: LCO optical upper limits
  19. EP260210a: Global MASTER-Net observations report
  20. EP260210a: refined analysis of the EP-FXT observation
  21. EP260209a: Global MASTER-Net observations report
  22. GRB 260208A: LCO detection of the optical counterpart
  23. EP260209a: Einstein Probe detection of a fast X-ray transient
  24. EP260210a: Optical upper limits with Kinder observations
  25. IPN triangulation of GRB 260207B (short/hard with EE)
  26. GRB 260210C: Fermi GBM Final Real-time Localization
  27. GRB 260210A: Glowbug gamma-ray detection
  28. GRB 260210B: Fermi GBM Final Real-time Localization
  29. EP260210a: SVOM/VT optical upper limit
  30. GRB 260210A: AstroSat CZTI detection
  31. GRB 260208C: AstroSat CZTI detection
  32. EP260210a: COLIBRÍ optical upper limit
  33. EP260210a: SVOM/C-GFT upper limit
  34. GRB 260208B: refined analysis of the EP-FXT observation
  35. EP260210a: Einstein Probe detection of an X-ray transient
  36. GRB 260207B: AstroSat CZTI detection
  37. GRB 260208C: SVOM/GRM observation
  38. GRB 260204A: Swift-XRT afterglow detection
  39. GRB 260208B: AstroSat CZTI detection of a bright long burst
  40. GRB260208A: Liverpool Telescope optical follow-up observations
  41. GRB 260208A: Glowbug gamma-ray detection
  42. GRB 260208A: NuSTAR detection of prompt emission
  43. GRB 260208A: Fermi GBM Observation
  44. Fermi GRB 260209A: Global MASTER-Net observations report
  45. GRB 260208B: Swift-XRT observations
  46. GRB 260131A/B: continued Mondy optical observations
  47. GRB 260204A: Swift/UVOT Upper Limits
  48. GRB 260208B: COLIBRÍ optical observations
  49. GRB 260208A: Mondy optical observations (duplicate submission)
  50. GRB 260208A: Mondy optical observations
  51. GRB 260208A: 1.3m DFOT optical detection
  52. GRB 260208A: COLIBRÍ optical observations
  53. GRB 260208B: EP-FXT observation
  54. GRB 260208A: NOT spectroscopic redshift z = 2.36
  55. GRB 260208A: Liverpool Telescope optical detection
  56. Fermi GRB 260208C: Global MASTER-Net observations report
  57. GRB 260208B: SVOM/VT optical candidate
  58. GRB 260208A: GECAM-B observation of a bright burst
  59. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  60. GRB 260209A: Fermi GBM Final Real-time Localization
  61. GRB 260208A: SVOM/VT optical observation
  62. Fermi GRB 260208D: Global MASTER-Net observations report
  63. GRB 260208D: Fermi GBM Final Real-time Localization
  64. GRB 260208A: Swift-XRT observations
  65. GRB 260208B: Swift ToO observations
  66. GRB 260208B: SVOM/GRM observation of a bright burst
  67. GRB 260208B: Fermi GBM Detection
  68. LAT GRB 260208B: Global MASTER-Net observations report
  69. GRB 260208B: Fermi-LAT detection
  70. GRB 260208C: Fermi GBM Final Real-time Localization
  71. GRB 260208A: Fermi-LAT detection
  72. GRB 260207B: GECAM-B observation
  73. GRB 260208A: Swift ToO observations
  74. GRB 260208A: Fermi GBM Classification Correction
  75. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  76. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  77. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  78. GRB 260208B: Fermi GBM Final Real-time Localization
  79. Fermi GRB 260208A: Global MASTER-Net observations report
  80. Fermi Gamma-ray Burst Monitor trigger 792220053/260208214 is not a GRB
  81. GRB 260208A: Fermi GBM Final Real-time Localization
  82. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  83. GRB 260207A : MASTER optical counterpart discovery
  84. GRB 260131A/B: Mondy and Terskol optical observations
  85. Fermi GRB 260207B: Global MASTER-Net observations report
  86. GRB 260206A: Swift-XRT observations
  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. EP260131a: VLA detection
  91. GRB 260206A: Tiled Swift observations
  92. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  93. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  94. GRB 260204A: Swift-XRT observations
  95. GRB 260204A: LCO optical afterglow detection
  96. GRB 260204A: SVOM/VT optical candidate
  97. GRB 260204A : MASTER Global robotic net optical observations
  98. Fermi GBM Sub-Threshold Detection of GRB 260204A
  99. GRB 260204A: GOTO optical upper limit
  100. GRB 260204A: LCO optical upper limits

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