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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"

40637 results found.

  1. EP260210a: Global MASTER-Net observations report
  2. EP260210a: refined analysis of the EP-FXT observation
  3. EP260209a: Global MASTER-Net observations report
  4. GRB 260208A: LCO detection of the optical counterpart
  5. EP260209a: Einstein Probe detection of a fast X-ray transient
  6. EP260210a: Optical upper limits with Kinder observations
  7. IPN triangulation of GRB 260207B (short/hard with EE)
  8. GRB 260210C: Fermi GBM Final Real-time Localization
  9. GRB 260210A: Glowbug gamma-ray detection
  10. GRB 260210B: Fermi GBM Final Real-time Localization
  11. EP260210a: SVOM/VT optical upper limit
  12. GRB 260210A: AstroSat CZTI detection
  13. GRB 260208C: AstroSat CZTI detection
  14. EP260210a: COLIBRÍ optical upper limit
  15. EP260210a: SVOM/C-GFT upper limit
  16. GRB 260208B: refined analysis of the EP-FXT observation
  17. EP260210a: Einstein Probe detection of an X-ray transient
  18. GRB 260207B: AstroSat CZTI detection
  19. GRB 260208C: SVOM/GRM observation
  20. GRB 260204A: Swift-XRT afterglow detection
  21. GRB 260208B: AstroSat CZTI detection of a bright long burst
  22. GRB260208A: Liverpool Telescope optical follow-up observations
  23. GRB 260208A: Glowbug gamma-ray detection
  24. GRB 260208A: NuSTAR detection of prompt emission
  25. GRB 260208A: Fermi GBM Observation
  26. Fermi GRB 260209A: Global MASTER-Net observations report
  27. GRB 260208B: Swift-XRT observations
  28. GRB 260131A/B: continued Mondy optical observations
  29. GRB 260204A: Swift/UVOT Upper Limits
  30. GRB 260208B: COLIBRÍ optical observations
  31. GRB 260208A: Mondy optical observations (duplicate submission)
  32. GRB 260208A: Mondy optical observations
  33. GRB 260208A: 1.3m DFOT optical detection
  34. GRB 260208A: COLIBRÍ optical observations
  35. GRB 260208B: EP-FXT observation
  36. GRB 260208A: NOT spectroscopic redshift z = 2.36
  37. GRB 260208A: Liverpool Telescope optical detection
  38. Fermi GRB 260208C: Global MASTER-Net observations report
  39. GRB 260208B: SVOM/VT optical candidate
  40. GRB 260208A: GECAM-B observation of a bright burst
  41. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  42. GRB 260209A: Fermi GBM Final Real-time Localization
  43. GRB 260208A: SVOM/VT optical observation
  44. Fermi GRB 260208D: Global MASTER-Net observations report
  45. GRB 260208D: Fermi GBM Final Real-time Localization
  46. GRB 260208A: Swift-XRT observations
  47. GRB 260208B: Swift ToO observations
  48. GRB 260208B: SVOM/GRM observation of a bright burst
  49. GRB 260208B: Fermi GBM Detection
  50. LAT GRB 260208B: Global MASTER-Net observations report
  51. GRB 260208B: Fermi-LAT detection
  52. GRB 260208C: Fermi GBM Final Real-time Localization
  53. GRB 260208A: Fermi-LAT detection
  54. GRB 260207B: GECAM-B observation
  55. GRB 260208A: Swift ToO observations
  56. GRB 260208A: Fermi GBM Classification Correction
  57. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  58. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  59. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  60. GRB 260208B: Fermi GBM Final Real-time Localization
  61. Fermi GRB 260208A: Global MASTER-Net observations report
  62. GRB 260208A: Fermi GBM Final Real-time Localization
  63. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  64. GRB 260207A : MASTER optical counterpart discovery
  65. GRB 260131A/B: Mondy and Terskol optical observations
  66. Fermi GRB 260207B: Global MASTER-Net observations report
  67. GRB 260206A: Swift-XRT observations
  68. GRB 260207B: Fermi GBM Final Real-time Localization
  69. GRB 260207A: Fermi GBM Final Localization
  70. Fermi trigger No 792135758: Global MASTER-Net observations report
  71. EP260131a: VLA detection
  72. GRB 260206A: Tiled Swift observations
  73. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  74. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  75. GRB 260204A: Swift-XRT observations
  76. GRB 260204A: LCO optical afterglow detection
  77. GRB 260204A: SVOM/VT optical candidate
  78. GRB 260204A : MASTER Global robotic net optical observations
  79. Fermi GBM Sub-Threshold Detection of GRB 260204A
  80. GRB 260204A: GOTO optical upper limit
  81. GRB 260204A: LCO optical upper limits
  82. EP260110a: Late GTC/EMIR near-infrared observations
  83. GRB 260204B: Fermi GBM Final Real-time Localization
  84. GRB 260204A: SVOM detection of a burst
  85. GRB 260121A: 239Alferov CubeSat detection
  86. Konus-Wind detection of GRB 260121A
  87. GRB 260131A/B: OHP/T193 optical observations
  88. GRB 260131A: KAIT optical observations
  89. GRB 251230A: MeerLICHT afterglow detection
  90. GRB 260131A: FTW optical and NIR observations
  91. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  92. GRID detection of GRB 260131A/B
  93. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  94. GRB 260130A: Insight-HXMT/HE detection
  95. GRB 260130A: GECAM-B observation of a short burst
  96. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  97. GRB 260131A/B: EP/FXT X-ray afterglow detection
  98. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  99. GRB 260127B: Insight-HXMT/HE detection
  100. GRB 260127B: GECAM-B observation of a short burst

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