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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"

26309 results found.

  1. GRB 260429A: cubesat Avion detection
  2. GRB 260616A: Fermi-LAT detection
  3. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  4. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  5. GRB 260614A: AstroSat CZTI detection
  6. EP260616a: EP-WXT detection of a fast X-ray transient
  7. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  8. GRB 260616B: Fermi GBM Detection
  9. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  10. GRB 260614B: SVOM/ECLAIRs refined analysis
  11. GRB 260614B: GECAM-B observation
  12. GRB 260610B: SVOM/GRM observation
  13. GRB 260614B: SVOM/VT optical afterglow confirmation
  14. GRB 260614B: Fermi GBM Observation
  15. GRB 260614A: GECAM-B observation
  16. GRB 260614B: SVOM/VT optical candidate from VHF data
  17. GRB 260614B: SVOM detection of a burst
  18. GRB 260611B: SVOM/GRM detection
  19. GRB 260603C: AstroSat CZTI detection
  20. GRB 260610B: further Liverpool Telescope optical observations
  21. GRB 260610B: Fermi GBM Observation
  22. GRB 260610B / AT2026owq: GRANDMA optical observations
  23. GRB 260610B / AT2026owq: further SAO RAS optical observations
  24. EP260605a: COLIBRÍ optical upper limits
  25. GRB 260610b: Liverpool Telescope optical observations
  26. IceCube-260610A: No candidates from the Zwicky Transient Facility
  27. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  28. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  29. GRB 260610B / AT2026owq: SVOM/VT optical observations
  30. GRB 260610B / AT2026owq: SAO RAS optical observations
  31. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  32. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  33. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  34. GRB 260610B / AT2026owq: Early ATLAS observations
  35. GRB 260610B: TRT optical observation
  36. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  37. EP260610b: COLIBRÍ optical observations
  38. GRB 260610B: DDOTI optical observations
  39. EP260610b: MAO/AZT-22 optical observations
  40. GRB 260610B: GOTO optical counterpart candidate
  41. EP260610b: NOT optical observation
  42. EP260610b: SVOM/VT optical confirmation with blue color
  43. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  44. GRB 260515A: SOAR optical observations
  45. EP260610b: Gemini North optical counterpart candidate
  46. EP260610a: SVOM/VT optical upper limits
  47. EP260610b: Einstein Probe detection of an X-ray transient
  48. Konus-Wind detection of GRB 260601A
  49. IPN triangulation of GRB 260601A (short/hard)
  50. EP260610a: COLIBRÍ optical upper limits
  51. EP260610a: Einstein Probe detection of a fast X-ray transient
  52. Konus-Wind detection of GRB 260604C
  53. GRB 260608A: Fermi GRB Observation
  54. GRB 260604C: AstroSat CZTI detection
  55. IPN triangulation of GRB 260601B / EP260601a
  56. GRB 260604C: SVOM/ECLAIRs refined analysis
  57. GRB 260608A: SVOM/ECLAIRs refined analysis
  58. Konus-Wind detection of GRB 260607B
  59. GRB 260607B: GECAM-B observation
  60. GRB 260604C: further SAO RAS optical observations
  61. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  62. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  63. GRB 260604C: SVOM/C-GFT upper limit
  64. GRB 260607B: AstroSat CZTI detection
  65. GRB 260608A: SVOM detection of a burst
  66. EP260605a: EP-FXT follow-up observation
  67. GRB 260607A: TRT optical observations
  68. GRB 260604C: GRANDMA further observations
  69. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  70. GRB 260604A: SVOM/GRM detection
  71. GRB 260607B: Fermi GBM Observation
  72. GRB 260607B: Fermi-LAT detection
  73. GRB 260607B: Fermi GBM Final Localization Correction
  74. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  75. GRB 260604C: GECAM-B observation
  76. GRB 260604C: 6 GHz VLA observations
  77. GRB 260604C: SAO RAS optical observations
  78. GRB 260604C: GRANDMA observations
  79. GRB 260604B: SVOM/GRM detection
  80. GRB 260605A: Insight-HXMT/HE detection
  81. GRB260603A: SVOM/ECLAIRs refined analysis
  82. EP260605a: Einstein Probe detection of a fast X-ray transient
  83. EP260603a: COLIBRÍ optical upper limit
  84. GRB 260604A: Glowbug gamma-ray detection
  85. GRB 260604C: LCO optical upper limit
  86. EP260602d: EP-FXT follow-up observation
  87. EP260602c: EP-FXT follow-up observation
  88. GRB 260601B / EP260601a: AstroSat CZTI detection
  89. GRB 260527A/EP260527a: 6 GHz VLA observations
  90. GRB 260604C: GOTO detections of the optical afterglow
  91. GRB 260604C: Kilonova-Catcher optical afterglow detection
  92. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  93. GRB 260604C: Jinshan optical observations
  94. GRB 260604C: Fermi GBM Observation
  95. EP260602d: J-band upper limit with WINTER
  96. EP260602b: J-band upper limit with WINTER
  97. GRB 260604C: LAST detection of optical counterpart candidate
  98. SVOM GRB260604.85: Global MASTER-Net observations report
  99. GRB 260604C: SVOM detection of a long burst
  100. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger

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