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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"

41190 results found.

  1. GRB 260211A: SVOM detection of a burst
  2. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  3. Konus-Wind detection of GRB 260209B
  4. Konus-Wind detection of GRB 260127B
  5. EP260209a: COLIBRÍ optical upper limit
  6. Fermi GRB 260210C: Global MASTER-Net observations report
  7. EP260209a: LCO optical upper limits
  8. EP260210a: Global MASTER-Net observations report
  9. EP260210a: refined analysis of the EP-FXT observation
  10. EP260209a: Global MASTER-Net observations report
  11. GRB 260208A: LCO detection of the optical counterpart
  12. EP260209a: Einstein Probe detection of a fast X-ray transient
  13. EP260210a: Optical upper limits with Kinder observations
  14. IPN triangulation of GRB 260207B (short/hard with EE)
  15. GRB 260210C: Fermi GBM Final Real-time Localization
  16. GRB 260210A: Glowbug gamma-ray detection
  17. GRB 260210B: Fermi GBM Final Real-time Localization
  18. EP260210a: SVOM/VT optical upper limit
  19. GRB 260210A: AstroSat CZTI detection
  20. GRB 260208C: AstroSat CZTI detection
  21. EP260210a: COLIBRÍ optical upper limit
  22. EP260210a: SVOM/C-GFT upper limit
  23. GRB 260208B: refined analysis of the EP-FXT observation
  24. EP260210a: Einstein Probe detection of an X-ray transient
  25. GRB 260207B: AstroSat CZTI detection
  26. GRB 260208C: SVOM/GRM observation
  27. GRB 260204A: Swift-XRT afterglow detection
  28. GRB 260208B: AstroSat CZTI detection of a bright long burst
  29. GRB260208A: Liverpool Telescope optical follow-up observations
  30. GRB 260208A: Glowbug gamma-ray detection
  31. GRB 260208A: NuSTAR detection of prompt emission
  32. GRB 260208A: Fermi GBM Observation
  33. Fermi GRB 260209A: Global MASTER-Net observations report
  34. GRB 260208B: Swift-XRT observations
  35. GRB 260131A/B: continued Mondy optical observations
  36. GRB 260204A: Swift/UVOT Upper Limits
  37. GRB 260208B: COLIBRÍ optical observations
  38. GRB 260208A: Mondy optical observations (duplicate submission)
  39. GRB 260208A: Mondy optical observations
  40. GRB 260208A: 1.3m DFOT optical detection
  41. GRB 260208A: COLIBRÍ optical observations
  42. GRB 260208B: EP-FXT observation
  43. GRB 260208A: NOT spectroscopic redshift z = 2.36
  44. GRB 260208A: Liverpool Telescope optical detection
  45. Fermi GRB 260208C: Global MASTER-Net observations report
  46. GRB 260208B: SVOM/VT optical candidate
  47. GRB 260208A: GECAM-B observation of a bright burst
  48. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  49. GRB 260209A: Fermi GBM Final Real-time Localization
  50. GRB 260208A: SVOM/VT optical observation
  51. Fermi GRB 260208D: Global MASTER-Net observations report
  52. GRB 260208D: Fermi GBM Final Real-time Localization
  53. GRB 260208A: Swift-XRT observations
  54. GRB 260208B: Swift ToO observations
  55. GRB 260208B: SVOM/GRM observation of a bright burst
  56. GRB 260208B: Fermi GBM Detection
  57. LAT GRB 260208B: Global MASTER-Net observations report
  58. GRB 260208B: Fermi-LAT detection
  59. GRB 260208C: Fermi GBM Final Real-time Localization
  60. GRB 260208A: Fermi-LAT detection
  61. GRB 260207B: GECAM-B observation
  62. GRB 260208A: Swift ToO observations
  63. GRB 260208A: Fermi GBM Classification Correction
  64. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  65. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  66. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  67. GRB 260208B: Fermi GBM Final Real-time Localization
  68. Fermi GRB 260208A: Global MASTER-Net observations report
  69. GRB 260208A: Fermi GBM Final Real-time Localization
  70. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  71. GRB 260207A : MASTER optical counterpart discovery
  72. GRB 260131A/B: Mondy and Terskol optical observations
  73. Fermi GRB 260207B: Global MASTER-Net observations report
  74. GRB 260206A: Swift-XRT observations
  75. GRB 260207B: Fermi GBM Final Real-time Localization
  76. GRB 260207A: Fermi GBM Final Localization
  77. Fermi trigger No 792135758: Global MASTER-Net observations report
  78. EP260131a: VLA detection
  79. GRB 260206A: Tiled Swift observations
  80. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  81. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  82. GRB 260204A: Swift-XRT observations
  83. GRB 260204A: LCO optical afterglow detection
  84. GRB 260204A: SVOM/VT optical candidate
  85. GRB 260204A : MASTER Global robotic net optical observations
  86. Fermi GBM Sub-Threshold Detection of GRB 260204A
  87. GRB 260204A: GOTO optical upper limit
  88. GRB 260204A: LCO optical upper limits
  89. EP260110a: Late GTC/EMIR near-infrared observations
  90. GRB 260204B: Fermi GBM Final Real-time Localization
  91. GRB 260204A: SVOM detection of a burst
  92. GRB 260121A: 239Alferov CubeSat detection
  93. Konus-Wind detection of GRB 260121A
  94. GRB 260131A/B: OHP/T193 optical observations
  95. GRB 260131A: KAIT optical observations
  96. GRB 251230A: MeerLICHT afterglow detection
  97. GRB 260131A: FTW optical and NIR observations
  98. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  99. GRID detection of GRB 260131A/B
  100. GRB 260131A/B: GTC/OSIRIS+ redshift confimation

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