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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').
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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"

32714 results found.

  1. Fermi GRB 260130A: Global MASTER-Net observations report
  2. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  3. Fermi GRB 260129A: Global MASTER-Net observations report
  4. GRB 260128B: LCO optical upper limits
  5. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  6. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  7. IPN triangulation of GRB 260121A
  8. GRB 260127A: Swift-BAT refined analysis
  9. IPN triangulation of GRB 260127B (short)
  10. GRB 260127B: Swift-XRT observations
  11. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  12. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  13. EP260128a: NOT optical counterpart candidate
  14. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  15. EP260128a: Liverpool Telescope optical observations and possible counterpart
  16. EP260128a: LCO optical upper limits
  17. EP260126a: SVOM/VT optical upperlimit
  18. EP260128a: Global MASTER-Net observations report
  19. Fermi GRB 260127A: Global MASTER-Net observations report
  20. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  21. GRB 260127A: Fermi GBM Observation
  22. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  23. GRB 260127A: COLIBRÍ optical observations
  24. GRB 260127A: NOT optical observations
  25. GRB 260127B: Swift ToO observations
  26. EP260126a: Seimei/TriCCS optical upper limit
  27. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  28. GRB 260127B: GOTO candidate optical counterpart
  29. GRB 260127A: SVOM/C-GFT optical observations
  30. Fermi GRB 260127B: Global MASTER-Net observations report
  31. Swift GRB 260127A: Global MASTER-Net observations report
  32. GRB 260127A: LCO optical afterglow discovery
  33. GRB 260125A: Swift-XRT observations
  34. EP260126a: EP-FXT follow-up observation
  35. EP260126a: Optical upper limit with Kinder observations
  36. EP260126a: Liverpool Telescope optical upper limits
  37. EP260126a: Further NOT optical upper limits
  38. EP260126a: COLIBRÍ optical upper limits
  39. EP260126a: NOT optical observations
  40. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  41. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  42. Konus-Wind detection of GRB 260120B
  43. GRB 251222A: SVOM/ECLAIRs refined analysis
  44. GRB 260125A: Swift ToO observations
  45. GRB 260125A: GOTO candidate optical counterpart
  46. Fermi GRB 260125B: Global MASTER-Net observations report
  47. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  48. GRB 260114A: SVOM/VT optical upper limits
  49. GRB 260120A: AstroSat CZTI detection
  50. GRB 260122B: Swift-BAT refined analysis
  51. GRB 260120B: SVOM/GRM observation
  52. GRB 260120A: GECAM-B observation
  53. GRB 260120B: AstroSat CZTI detection
  54. GRB 260114A: Insight-HXMT/HE detection
  55. EP260119a: Assy AZT-20 optical observations
  56. EP260119a: Mondy and SAO RAS optical upper limits
  57. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  58. EP260119a: Xinglong optical upper limit
  59. Fermi GRB 260120C: Global MASTER-Net observations report
  60. GRB 260120B: Swift-BAT refined analysis
  61. EP260116a: COLIBRÍ further observations
  62. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  63. GRB 260120B: Fermi GBM Observation
  64. EP260105a: GTC/HiPERCAM optical observations
  65. GRB 260120B: Swift/UVOT Detection
  66. GRB 260120B: COLIBRÍ optical upper limits
  67. GRB 260120B: SVOM/C-GFT optical counterpart detection
  68. GRB 260101A: 239Alferov CubeSat detection
  69. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  70. EP260119A: Mondy I-Band Observations
  71. GRB 260114A: Swift/UVOT Upper Limits
  72. EP260119a: Liverpool Telescope optical follow-up observations
  73. GRB 251202A: further radio observations with the VLA
  74. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  75. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  76. EP260119a: KAIT optical observations
  77. EP260119a: SVOM/VT optical observation
  78. EP260119a: update of EP-FXT follow-up observation
  79. EP260119a: NOT optical observations
  80. EP260119a: SAO RAS optical observations
  81. EP260116a: COLIBRÍ detection of a fading optical source
  82. GRB 251208D: SVOM/ECLAIRs refined analysis
  83. GRB 251208D: SVOM/ECLAIRs refined analysis
  84. GRB 260117A: Swift-XRT afterglow detection
  85. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  86. EP260119a: Global MASTER-Net observations report
  87. GRB 260115A: AstroSat CZTI detection
  88. EP260119a: LCO optical observations
  89. GRB 260117A: ZTSh optical upper limit
  90. EP260119a: COLIBRÍ optical counterpart candidate
  91. EP260119a: preliminary result from the EP-FXT observation
  92. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  93. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  94. Swift trigger on the HMXB 1A 1118-61
  95. GRB 260117A: SVOM/VT optical candidate
  96. GRB 260117A: SVOM/C-GFT upper limit
  97. GRB 260117A: Swift ToO observations
  98. EP 260116a: COLIBRÍ optical upper limit
  99. GRB 260115A: GECAM-B observation
  100. FRB 20251229A: COLIBRÍ further inspection of the updated localization

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