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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').
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"

5386 results found.

  1. Fermi GRB 260512A: Global MASTER-Net observations report
  2. GRB 260511B: further SAO RAS optical observations
  3. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  4. GRB 260511B: LCO optical counterpart detection
  5. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  6. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  7. GRB 260511B: SVOM detection of a burst
  8. GRB 260510C: EP-FXT follow-up observation
  9. Fermi GRB 260511A: Global MASTER-Net observations report
  10. GRB 260510C: MAXI/GSC detection
  11. SVOM GRB 260509A: MASTER-OAFA optical observation
  12. Fermi GRB 260510A: Global MASTER-Net observations report
  13. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  14. GRB 260509A: SVOM detection of a burst
  15. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  17. IPN triangulation of GRB 260428A
  18. SVOM GRB 260504B: MASTER-OAFA optical observations
  19. Fermi GRB 260504A: Global MASTER-Net observations report
  20. EP260430a: LCO optical upper limits
  21. EP260430a: Global MASTER-Net observations report
  22. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  23. Fermi trigger No 798737427: Global MASTER-Net observations report
  24. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  25. Fermi GRB 260421C: Global MASTER-Net observations report
  26. Fermi GRB 260421B: Global MASTER-Net observations report
  27. Fermi GRB 260421A: Global MASTER-Net observations report
  28. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  29. EP260417a: Global MASTER-Net observations report
  30. Fermi GRB 260417A: Global MASTER-Net observations report
  31. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  32. EP260416a: COLIBRÍ optical counterpart candidate
  33. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  34. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  35. Fermi trigger No 797912738: Global MASTER-Net observations report
  36. GRB 260410A: Glowbug gamma-ray detection of a short burst
  37. GRB 260410A: Insight-HXMT/HE detection
  38. Konus-Wind detection of GRB 260410A (short/hard)
  39. EP260321a: SVOM/VT optical observations and color changes around peak
  40. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  41. GRB 260410A: COLIBRÍ optical upper limit
  42. GRB 260410A: Fermi GBM Observation
  43. GRB 260410A: Fermi-LAT detection
  44. GRB 260410A: Fermi GBM Final Real-time Localization
  45. EP260409a: COLIBRÍ optical upper limits
  46. EP260403a: Mephisto optical upper limits
  47. EP260321a: Upper limits from VLA radio observations
  48. EP260405a: Global MASTER-Net observations report
  49. Fermi trigger No 797039833: Global MASTER-Net observations report
  50. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  51. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  52. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  53. GRB 260330B: SVOM/ECLAIRs refined analysis
  54. EP260403a: LCO optical observations of the counterpart
  55. EP260403a: LCO optical counterpart detection
  56. GRB 260330B: SVOM/VT optical candidate
  57. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  58. GRB 260403A: AstroSat CZTI detection
  59. EP260324A / AT 2026hir: COLIBRÍ optical observations
  60. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  61. EP260329b: Mondy and Assy-Turgen optical upper limits
  62. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  63. EP260321a :Xinglong optical observations
  64. EP260327a: Xinglong optical upper limit
  65. EP260329b: GOTO detection of optical counterpart
  66. GRB 260330B: SVOM/VT optical upper limits
  67. GRB 260321A: SVOM/ECLAIRs refined analysis
  68. EP260329b: J-band upper limits with WINTER
  69. EP260329a: J-band upper limit with WINTER
  70. GRB 260330A: Glowbug gamma-ray detection
  71. GRB 260310A: VLA Multi-frequency Radio Observations
  72. Fermi GBM Sub-Threshold Detection of GRB 260330B
  73. GRB 260330B: LCO optical upper limits
  74. GRB 260330B: SVOM detection of a burst
  75. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  76. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  77. EP260329a: COLIBRÍ optical upper limit
  78. EP260329a: EP-FXT follow up observation
  79. GRB 260330A: Fermi GBM Final Real-time Localization
  80. EP260329b: Global MASTER-Net observations report
  81. Fermi trigger No 796485221: Global MASTER-Net observations report
  82. GRB 260327A: Insight-HXMT/HE detection
  83. EP 260329b: COLIBRÍ optical observations
  84. EP260329a: Optical upper limit with Kinder observations
  85. EP260329b: LCO optical observations of the counterpart
  86. GRB 260326A: Insight-HXMT/HE detection
  87. EP260329b: Einstein Probe detection of an X-ray transient
  88. EP260329a: Einstein Probe detection of an X-ray transient
  89. EP-WXT trigger 01709259209: TRT optical counterpart detection
  90. GRID detection of GRB 260326A
  91. GRB 260310A: Gemini-North Spectral Confirmation of Supernova Features
  92. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  93. EP260327a: SVOM/VT optical upper limits
  94. EP260327a: WINTER J-band upper limit
  95. EP260327a: COLIBRÍ optical upper limits
  96. GRB 260327A: AstroSat CZTI detection of a long burst
  97. EP260327a: Gemini-North optical upper limits
  98. EP260324a: GROWTH-India Telescope optical observation
  99. EP260327a: Global MASTER-Net observations report
  100. EP260327a: Einstein Probe detection of an X-ray transient

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