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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"

39307 results found.

  1. GRB 260208B: SVOM/GRM observation of a bright burst
  2. GRB 260208B: Fermi GBM Detection
  3. LAT GRB 260208B: Global MASTER-Net observations report
  4. GRB 260208B: Fermi-LAT detection
  5. GRB 260208C: Fermi GBM Final Real-time Localization
  6. GRB 260208A: Fermi-LAT detection
  7. GRB 260207B: GECAM-B observation
  8. GRB 260208A: Swift ToO observations
  9. GRB 260208A: Fermi GBM Classification Correction
  10. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  11. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  12. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  13. GRB 260208B: Fermi GBM Final Real-time Localization
  14. Fermi GRB 260208A: Global MASTER-Net observations report
  15. Fermi Gamma-ray Burst Monitor trigger 792220053/260208214 is not a GRB
  16. GRB 260208A: Fermi GBM Final Real-time Localization
  17. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  18. GRB 260207A : MASTER optical counterpart discovery
  19. GRB 260131A/B: Mondy and Terskol optical observations
  20. Fermi GRB 260207B: Global MASTER-Net observations report
  21. GRB 260206A: Swift-XRT observations
  22. GRB 260207B: Fermi GBM Final Real-time Localization
  23. GRB 260207A: Fermi GBM Final Localization
  24. Fermi trigger No 792135758: Global MASTER-Net observations report
  25. EP260131a: VLA detection
  26. GRB 260206A: Tiled Swift observations
  27. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  28. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  29. GRB 260204A: Swift-XRT observations
  30. GRB 260204A: LCO optical afterglow detection
  31. GRB 260204A: SVOM/VT optical candidate
  32. GRB 260204A : MASTER Global robotic net optical observations
  33. Fermi GBM Sub-Threshold Detection of GRB 260204A
  34. GRB 260204A: GOTO optical upper limit
  35. GRB 260204A: LCO optical upper limits
  36. GRB 260204B: Fermi GBM Final Real-time Localization
  37. GRB 260204A: SVOM detection of a burst
  38. GRB 260121A: 239Alferov CubeSat detection
  39. Konus-Wind detection of GRB 260121A
  40. GRB 260131A/B: OHP/T193 optical observations
  41. GRB 260131A: KAIT optical observations
  42. GRB 251230A: MeerLICHT afterglow detection
  43. GRB 260131A: FTW optical and NIR observations
  44. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  45. GRID detection of GRB 260131A/B
  46. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  47. GRB 260130A: Insight-HXMT/HE detection
  48. GRB 260130A: GECAM-B observation of a short burst
  49. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  50. GRB 260131A/B: EP/FXT X-ray afterglow detection
  51. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  52. GRB 260127B: Insight-HXMT/HE detection
  53. GRB 260127B: GECAM-B observation of a short burst
  54. GRB 260127A: GECAM-B observation
  55. GRB 260131A: NOT spectroscopic redshift z = 1.434
  56. EP260131a: COLIBRÍ further observations
  57. Konus-Wind detection of GRB 260128A / EP260128a
  58. GRB 260131A: Insight-HXMT/HE detection
  59. Konus-Wind detection of GRB 260131A/B
  60. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  61. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  62. GRB 260131A/B: Fermi GBM Observation
  63. EP260131a: COLIBRÍ observations of slow optical fading
  64. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  65. GRB 260131B: MAXI/GSC detection
  66. GRB 260131A: Fermi GBM Final Real-time Localization
  67. EP260131a: COLIBRÍ optical observations of the counterpart
  68. GRB 260127B: AstroSat CZTI detection
  69. GRB 260130A: Fermi GBM Detection
  70. GRB 260127B: Fermi GBM Detection
  71. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  72. Fermi GRB 260130A: Global MASTER-Net observations report
  73. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  74. GRB 260130A: Fermi GBM Final Real-time Localization
  75. Fermi GRB 260129A: Global MASTER-Net observations report
  76. GRB 260128B: LCO optical upper limits
  77. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  78. IPN triangulation of GRB 260121A
  79. GRB 260127A: Swift-BAT refined analysis
  80. GRB 260129B: Fermi GBM Final Localization
  81. GRB 260128B: SVOM detection of a burst through offline search
  82. GRB 260129A: Fermi GBM Final Localization
  83. IPN triangulation of GRB 260127B (short)
  84. GRB 260127B: Swift-XRT observations
  85. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  86. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  87. EP260128a: LCO optical upper limits
  88. EP260128a: Global MASTER-Net observations report
  89. Fermi GRB 260127A: Global MASTER-Net observations report
  90. GRB 260127A: Fermi GBM Observation
  91. GRB 260127A: COLIBRÍ optical observations
  92. GRB 260127A: NOT optical observations
  93. GRB 260127B: Swift ToO observations
  94. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  95. GRB 260127A: Swift-XRT refined Analysis
  96. GRB 260127B: GOTO candidate optical counterpart
  97. GRB 260127A: SVOM/C-GFT optical observations
  98. GRB 260127A: Enhanced Swift-XRT position
  99. Fermi GRB 260127B: Global MASTER-Net observations report
  100. GRB 260127B: Fermi GBM Final Real-time Localization

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