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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"

19879 results found.

  1. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  2. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  3. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  4. AT2026nik: EP-FXT X-ray counterpart
  5. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  6. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  7. IPN triangulation of a bright burst from SGR 1E1841-045
  8. EP260321a: Chandra X-ray Non-detection
  9. Swift BAT trigger 1500295: A solar flare
  10. Swift BAT trigger 1500287: A solar flare
  11. Swift BAT trigger 1500148: A solar flare
  12. Retraction of GCN 43965: GRB is actually solar flare
  13. GRB 260312A: Swift detection of a burst
  14. GRB 260208A: radio detection with the VLA
  15. IPN triangulation of GRB 260212A
  16. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  17. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  18. GRB 260208A: Swift UVOT detection
  19. GRB 260208A: LCO detection of the optical counterpart
  20. GRB 260208B: refined analysis of the EP-FXT observation
  21. GRB 260204A: Swift-XRT afterglow detection
  22. GRB 260208A: Fermi GBM Observation
  23. GRB 260208B: Swift-XRT observations
  24. GRB 260204A: Swift/UVOT Upper Limits
  25. GRB 260208B: EP-FXT observation
  26. GRB 260208B: SVOM/VT optical candidate
  27. GRB 260208A: SVOM/VT optical observation
  28. GRB 260208A: Swift-XRT observations
  29. GRB 260208B: Swift ToO observations
  30. GRB 260208B: Fermi-LAT detection
  31. GRB 260208A: Fermi-LAT detection
  32. GRB 260208A: Swift ToO observations
  33. GRB 260206A: Swift-XRT observations
  34. GRB 260206A: Tiled Swift observations
  35. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  36. GRB 260204A: Swift-XRT observations
  37. GRB 260204A: SVOM/VT optical candidate
  38. GRB 251230A: MeerLICHT afterglow detection
  39. GRB 260127A: GECAM-B observation
  40. GRB 260127B: AstroSat CZTI detection
  41. IPN triangulation of GRB 260121A
  42. GRB 260127A: Swift-BAT refined analysis
  43. GRB 260127B: Swift-XRT observations
  44. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  45. GRB 260127A: Fermi GBM Observation
  46. GRB 260127A: COLIBRÍ optical observations
  47. GRB 260127B: Swift ToO observations
  48. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  49. GRB 260127A: Swift-XRT refined Analysis
  50. GRB 260127A: SVOM/C-GFT optical observations
  51. GRB 260127A: Enhanced Swift-XRT position
  52. GRB 260127A: Prompt enhanced Swift-XRT position
  53. Swift GRB 260127A: Global MASTER-Net observations report
  54. GRB 260127A: Swift detection of a burst
  55. GRB 260125A: Swift-XRT observations
  56. Konus-Wind detection of GRB 260120B
  57. GRB 260125A: Swift ToO observations
  58. GRB 260114A: SVOM/VT optical upper limits
  59. GRB 260122B: Swift-BAT refined analysis
  60. GRB 260120B: SVOM/GRM observation
  61. GRB 260120B: AstroSat CZTI detection
  62. GRB 260114A: Insight-HXMT/HE detection
  63. GRB 260122B: Swift detection of a burst
  64. Swift GRB260122.97: Global MASTER-Net observations report
  65. GRB 260120B: Swift-BAT refined analysis
  66. GRB 260120B: Swift-XRT refined Analysis
  67. GRB 260120B: Fermi GBM Observation
  68. GRB 260120B: Swift/UVOT Detection
  69. GRB 260120B: COLIBRÍ optical upper limits
  70. GRB 260120B: Enhanced Swift-XRT position
  71. GRB 260120B: SVOM/C-GFT optical counterpart detection
  72. GRB 260101A: 239Alferov CubeSat detection
  73. GRB 260120B: Swift detection of a burst
  74. Swift GRB260120B: Global MASTER-Net observations report
  75. GRB 260114A: Swift/UVOT Upper Limits
  76. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  77. GRB 260117A: Swift-XRT afterglow detection
  78. GRB 260117A: ZTSh optical upper limit
  79. Swift GRB260118.48: Global MASTER-Net observations report
  80. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  81. Swift trigger on the HMXB 1A 1118-61
  82. GRB 260117A: SVOM/VT optical candidate
  83. GRB 260117A: SVOM/C-GFT upper limit
  84. GRB 260117A: Swift-XRT observations
  85. GRB 260117A: Swift ToO observations
  86. Swift triggered on the HMXB 1A 1118-61
  87. GRB 260114A: VLT/MUSE spectroscopic observations
  88. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  89. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  90. GRB260114A: STEP/T80S optical limits
  91. GRB 251222A: radio detection with the VLA
  92. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  93. Konus-Wind detection of GRB 260114A
  94. GRB 260114A: Swift-XRT refined Analysis
  95. GRB 260114A: 6 GHz VLA observations
  96. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  97. GRB 260114A : MITSuME Akeno optical upper limits
  98. GRB 260114A: COLIBRÍ optical upper limits
  99. GRB 260114A: TNG NIR upper limit
  100. GRB 260114A: NOT optical observations

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