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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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

36155 results found.

  1. GRB 260207B: Fermi GBM Final Real-time Localization
  2. GRB 260207A: Fermi GBM Final Localization
  3. EP260131a: VLA detection
  4. GRB 260206A: Tiled Swift observations
  5. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  6. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  7. GRB 260204A: Swift-XRT observations
  8. GRB 260204A: LCO optical afterglow detection
  9. GRB 260204A: SVOM/VT optical candidate
  10. GRB 260204A : MASTER Global robotic net optical observations
  11. Fermi GBM Sub-Threshold Detection of GRB 260204A
  12. GRB 260204A: GOTO optical upper limit
  13. GRB 260204A: LCO optical upper limits
  14. GRB 260204B: Fermi GBM Final Real-time Localization
  15. GRB 260204A: SVOM detection of a burst
  16. GRB 260121A: 239Alferov CubeSat detection
  17. Konus-Wind detection of GRB 260121A
  18. GRB 260131A/B: OHP/T193 optical observations
  19. GRB 260131A: KAIT optical observations
  20. GRB 251230A: MeerLICHT afterglow detection
  21. GRB 260131A: FTW optical and NIR observations
  22. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  23. GRID detection of GRB 260131A/B
  24. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  25. GRB 260130A: Insight-HXMT/HE detection
  26. GRB 260130A: GECAM-B observation of a short burst
  27. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  28. GRB 260131A/B: EP/FXT X-ray afterglow detection
  29. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  30. GRB 260127B: Insight-HXMT/HE detection
  31. GRB 260127B: GECAM-B observation of a short burst
  32. GRB 260127A: GECAM-B observation
  33. GRB 260131A: NOT spectroscopic redshift z = 1.434
  34. Konus-Wind detection of GRB 260128A / EP260128a
  35. GRB 260131A: Insight-HXMT/HE detection
  36. Konus-Wind detection of GRB 260131A/B
  37. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  38. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  39. GRB 260131A/B: Fermi GBM Observation
  40. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  41. GRB 260131B: MAXI/GSC detection
  42. GRB 260131A: Fermi GBM Final Real-time Localization
  43. GRB 260127B: AstroSat CZTI detection
  44. GRB 260130A: Fermi GBM Detection
  45. GRB 260127B: Fermi GBM Detection
  46. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  47. Fermi GRB 260130A: Global MASTER-Net observations report
  48. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  49. GRB 260130A: Fermi GBM Final Real-time Localization
  50. Fermi GRB 260129A: Global MASTER-Net observations report
  51. GRB 260128B: LCO optical upper limits
  52. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  53. IPN triangulation of GRB 260121A
  54. GRB 260127A: Swift-BAT refined analysis
  55. GRB 260129B: Fermi GBM Final Localization
  56. GRB 260128B: SVOM detection of a burst through offline search
  57. GRB 260129A: Fermi GBM Final Localization
  58. IPN triangulation of GRB 260127B (short)
  59. GRB 260127B: Swift-XRT observations
  60. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  61. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  62. Fermi GRB 260127A: Global MASTER-Net observations report
  63. GRB 260127A: Fermi GBM Observation
  64. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  65. GRB 260127A: COLIBRÍ optical observations
  66. GRB 260127A: NOT optical observations
  67. GRB 260127B: Swift ToO observations
  68. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  69. GRB 260127A: Swift-XRT refined Analysis
  70. GRB 260127B: GOTO candidate optical counterpart
  71. GRB 260127A: SVOM/C-GFT optical observations
  72. GRB 260127A: Enhanced Swift-XRT position
  73. Fermi GRB 260127B: Global MASTER-Net observations report
  74. GRB 260127B: Fermi GBM Final Real-time Localization
  75. GRB 260127A: Prompt enhanced Swift-XRT position
  76. Swift GRB 260127A: Global MASTER-Net observations report
  77. GRB 260127A: LCO optical afterglow discovery
  78. GRB 260127A: Swift detection of a burst
  79. GRB 260127A: Fermi GBM Final Real-time Localization
  80. GRB 260125A: Swift-XRT observations
  81. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  82. Konus-Wind detection of GRB 260120B
  83. GRB 251222A: SVOM/ECLAIRs refined analysis
  84. GRB 260125A: Swift ToO observations
  85. GRB 260125A: GOTO candidate optical counterpart
  86. Fermi GRB 260125B: Global MASTER-Net observations report
  87. GRB 260125B: Fermi GBM Final Real-time Localization
  88. GRB 260125A: Fermi GBM Final Real-time Localization
  89. GRB 260114A: SVOM/VT optical upper limits
  90. GRB 260120A: AstroSat CZTI detection
  91. GRB 260122B: Swift-BAT refined analysis
  92. GRB 260120B: SVOM/GRM observation
  93. GRB 260120A: GECAM-B observation
  94. GRB 260120B: AstroSat CZTI detection
  95. GRB 260114A: Insight-HXMT/HE detection
  96. GRB 260122B: Swift detection of a burst
  97. EP260119a: Assy AZT-20 optical observations
  98. EP260119a: Mondy and SAO RAS optical upper limits
  99. GRB 260122A: Fermi GBM Final Real-time Localization
  100. Fermi GRB 260120C: Global MASTER-Net observations report

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