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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"

28196 results found.

  1. EP260210a: Einstein Probe detection of an X-ray transient
  2. GRB 260207B: AstroSat CZTI detection
  3. GRB 260204A: Swift-XRT afterglow detection
  4. GRB 260208B: AstroSat CZTI detection of a bright long burst
  5. GRB 260208A: Glowbug gamma-ray detection
  6. GRB 260208A: NuSTAR detection of prompt emission
  7. GRB 260208A: Fermi GBM Observation
  8. GRB 260208B: Swift-XRT observations
  9. GRB 260204A: Swift/UVOT Upper Limits
  10. GRB 260208A: 1.3m DFOT optical detection
  11. GRB 260208B: EP-FXT observation
  12. GRB 260208A: NOT spectroscopic redshift z = 2.36
  13. GRB 260208A: Liverpool Telescope optical detection
  14. GRB 260208B: SVOM/VT optical candidate
  15. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  16. GRB 260209A: Fermi GBM Final Real-time Localization
  17. GRB 260208A: SVOM/VT optical observation
  18. GRB 260208D: Fermi GBM Final Real-time Localization
  19. GRB 260208A: Swift-XRT observations
  20. GRB 260208B: Swift ToO observations
  21. GRB 260208B: Fermi GBM Detection
  22. GRB 260208B: Fermi-LAT detection
  23. GRB 260208C: Fermi GBM Final Real-time Localization
  24. GRB 260208A: Fermi-LAT detection
  25. GRB 260208A: Swift ToO observations
  26. GRB 260208A: Fermi GBM Classification Correction
  27. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  28. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  29. GRB 260208B: Fermi GBM Final Real-time Localization
  30. GRB 260208A: Fermi GBM Final Real-time Localization
  31. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  32. GRB 260207A : MASTER optical counterpart discovery
  33. GRB 260206A: Swift-XRT observations
  34. GRB 260207B: Fermi GBM Final Real-time Localization
  35. GRB 260207A: Fermi GBM Final Localization
  36. EP260131a: VLA detection
  37. GRB 260206A: Tiled Swift observations
  38. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  39. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  40. GRB 260204A: Swift-XRT observations
  41. GRB 260204A: LCO optical afterglow detection
  42. GRB 260204A: SVOM/VT optical candidate
  43. Fermi GBM Sub-Threshold Detection of GRB 260204A
  44. GRB 260204B: Fermi GBM Final Real-time Localization
  45. GRB 260204A: SVOM detection of a burst
  46. GRB 260121A: 239Alferov CubeSat detection
  47. Konus-Wind detection of GRB 260121A
  48. GRB 260131A/B: OHP/T193 optical observations
  49. GRB 260131A: KAIT optical observations
  50. GRB 251230A: MeerLICHT afterglow detection
  51. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  52. GRID detection of GRB 260131A/B
  53. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  54. GRB 260130A: Insight-HXMT/HE detection
  55. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  56. GRB 260131A/B: EP/FXT X-ray afterglow detection
  57. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  58. GRB 260127B: Insight-HXMT/HE detection
  59. GRB 260131A: NOT spectroscopic redshift z = 1.434
  60. Konus-Wind detection of GRB 260128A / EP260128a
  61. GRB 260131A: Insight-HXMT/HE detection
  62. Konus-Wind detection of GRB 260131A/B
  63. EP260131a: Xinglong optical upper limit
  64. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  65. EP260131a: COLIBRÍ observations of slow optical fading
  66. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  67. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  68. GRB 260131B: MAXI/GSC detection
  69. GRB 260131A: Fermi GBM Final Real-time Localization
  70. EP260131a: Las Cumbres detection of an optical counterpart
  71. GRB 260127B: AstroSat CZTI detection
  72. GRB 260130A: Fermi GBM Detection
  73. EP260131a: Einstein Probe detection of an X-ray transient
  74. GRB 260127B: Fermi GBM Detection
  75. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  76. GRB 260130A: Fermi GBM Final Real-time Localization
  77. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  78. GRB 260129B: Fermi GBM Final Localization
  79. GRB 260128B: SVOM detection of a burst through offline search
  80. GRB 260129A: Fermi GBM Final Localization
  81. IPN triangulation of GRB 260127B (short)
  82. GRB 260127B: Swift-XRT observations
  83. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  84. EP260128a: NOT optical counterpart candidate
  85. EP260128a: Liverpool Telescope optical observations and possible counterpart
  86. EP260126a: SVOM/VT optical upperlimit
  87. EP260128a: Einstein Probe detection of an X-ray transient
  88. GRB 260127A: Fermi GBM Observation
  89. GRB 260127B: Swift ToO observations
  90. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  91. GRB 260127A: Swift-XRT refined Analysis
  92. GRB 260127A: SVOM/C-GFT optical observations
  93. GRB 260127A: Enhanced Swift-XRT position
  94. GRB 260127B: Fermi GBM Final Real-time Localization
  95. GRB 260127A: Prompt enhanced Swift-XRT position
  96. GRB 260127A: LCO optical afterglow discovery
  97. GRB 260127A: Swift detection of a burst
  98. GRB 260127A: Fermi GBM Final Real-time Localization
  99. GRB 260125A: Swift-XRT observations
  100. EP260126a: EP-FXT follow-up observation

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