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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.

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

19309 results found.

  1. EP260405a: SVOM/VT optical upper limits
  2. EP260405a: Global MASTER-Net observations report
  3. EP260405a: Einstein Probe detection of a fast X-ray transient
  4. The EP-WXT trigger 01709259621 is likely a flaring star
  5. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  6. The EP-WXT trigger 01709259615 is likely a flaring star
  7. Fermi trigger No 797039833: Global MASTER-Net observations report
  8. GRB 260403A: GECAM-B observation of a long burst
  9. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  10. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  11. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  12. The EP-WXT trigger 01709259586 is likely a flaring star
  13. GRB 260330B: SVOM/VT further optical observation
  14. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  15. GRB 260330B: SVOM/ECLAIRs refined analysis
  16. EP260403a: LCO optical observations of the counterpart
  17. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  18. EP260403a: LCO optical counterpart detection
  19. EP260403a: COLIBRÍ optical counterpart candidate
  20. GRB 260330B: SVOM/VT optical candidate
  21. EP260403a: Einstein Probe detection of an X-ray transient
  22. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  23. GRB 260403A: AstroSat CZTI detection
  24. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  25. GRB 260402B: GECAM-B observation
  26. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  27. GRB 260402C: NuSTAR detection of prompt emission
  28. GRB 260402C: AstroSat CZTI detection of a long burst
  29. EP260324A / AT 2026hir: COLIBRÍ optical observations
  30. GRB 260403A: Fermi GBM Final Real-time Localization
  31. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  32. GRB 260402B: Fermi GBM Final Real-time Localization
  33. GRB 260402A: WINTER J-band upper limit
  34. GRB260402A: GROWTH-India Telescope optical upper limit
  35. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  36. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  37. GRB 260401A: SVOM/GRM observation
  38. GRB 260401A: GECAM-B observation
  39. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  40. GRB 260402A: MASTER optical observations
  41. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  42. GRB 260402A: SVOM detection of a burst
  43. Fermi GRB 260401A: Global MASTER-Net observations report
  44. GRB 260401A: Fermi GBM Observation
  45. GRB 260401A: NuSTAR detection of prompt emission
  46. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  47. GRB 260401A: MAXI/GSC detection
  48. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  49. GRB 260401A: Fermi GBM Final Real-time Localization
  50. EP260329b: Mondy and Assy-Turgen optical upper limits
  51. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  52. EP260321a :Xinglong optical observations
  53. EP260327a: Xinglong optical upper limit
  54. EP260329b: GOTO detection of optical counterpart
  55. GRB 260330B: SVOM/VT optical upper limits
  56. Konus-Wind detection of GRB 260320A
  57. GRB 260321A: SVOM/ECLAIRs refined analysis
  58. EP260329b: J-band upper limits with WINTER
  59. EP260329a: J-band upper limit with WINTER
  60. GRB 260330A: Glowbug gamma-ray detection
  61. GRB 260310A: VLA Multi-frequency Radio Observations
  62. Fermi GBM Sub-Threshold Detection of GRB 260330B
  63. GRB 260330B: LCO optical upper limits
  64. GRB 260330B: SVOM detection of a burst
  65. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  66. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  67. EP260329a: COLIBRÍ optical upper limit
  68. EP260329a: EP-FXT follow up observation
  69. GRB 260330A: Fermi GBM Final Real-time Localization
  70. EP260329b: Global MASTER-Net observations report
  71. Fermi trigger No 796485221: Global MASTER-Net observations report
  72. GRB 260327A: Insight-HXMT/HE detection
  73. EP260329b: Optical follow-up with Kinder observations
  74. EP 260329b: COLIBRÍ optical observations
  75. EP260329a: Optical upper limit with Kinder observations
  76. EP260329b: LCO optical observations of the counterpart
  77. GRB 260326A: Insight-HXMT/HE detection
  78. EP260329b: Einstein Probe detection of an X-ray transient
  79. EP260329a: Einstein Probe detection of an X-ray transient
  80. EP-WXT trigger 01709259209: TRT optical counterpart detection
  81. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  82. GRID detection of GRB 260326A
  83. GRB 260310A: Gemini-North Spectral Confirmation of Supernova Features
  84. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  85. EP260327a: SVOM/VT optical upper limits
  86. SMA Detection of GRB 260310A / AT 2026fgk
  87. EP260327a: WINTER J-band upper limit
  88. EP260327a: COLIBRÍ optical upper limits
  89. GRB 260327A: AstroSat CZTI detection of a long burst
  90. EP260327a: Gemini-North optical upper limits
  91. EP260324a: GROWTH-India Telescope optical observation
  92. EP260327a: Global MASTER-Net observations report
  93. EP260327a: Einstein Probe detection of an X-ray transient
  94. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  95. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  96. The EP-WXT trigger 01709259173 is likely a flaring star
  97. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  98. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  99. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  100. GRB 260326A: Fermi GBM Detection

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