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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"

28039 results found.

  1. EP260417b: Einstein Probe detection of a fast X-ray transient
  2. EP260416a: KAIT optical upper limit
  3. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  4. EP260416a: WFST optical observations and rebrightening
  5. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  6. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  7. GRB 260415B: Glowbug gamma-ray detection
  8. GRB 260411B: Glowbug gamma-ray detection
  9. EP260416a: COLIBRÍ optical counterpart candidate
  10. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  11. EP260416a: Global MASTER-Net observations report
  12. EP260416a: Einstein Probe detection of an X-ray transient
  13. GOTO26djh/AT2026jpw : MASTER OT observation
  14. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  15. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  16. GRB 260415B: NuSTAR detection of long prompt emission
  17. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  18. Fermi trigger No 797912738: Global MASTER-Net observations report
  19. GRB 260414A: Glowbug gamma-ray detection
  20. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  21. EP260321a: CMO SAI J,K observations
  22. Fermi GRB 260413A: Global MASTER-Net observations report
  23. GRB 260410A: Glowbug gamma-ray detection of a short burst
  24. Fermi GRB 260412A: Global MASTER-Net observations report
  25. GRB 260412A: Fermi GBM Observation
  26. GRB 260411B: Fermi-LAT detection
  27. GRB 260411B: COLIBRÍ optical observations
  28. GRB 260410B: Fermi GBM Observation
  29. GRB260411B: 3.6m DOT optical observation
  30. GRB 260411A: SVOM/GRM observation
  31. GRB 260411B: SVOM/GRM observation of a long burst
  32. GRB 260409A: Insight-HXMT/HE detection
  33. GRB 260411B: Fermi GBM Detection
  34. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  35. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  36. GRB 260410A: COLIBRÍ optical upper limit
  37. EP-WXT01709259790: Optical Upper limits with kinder observations
  38. GRB 260410A: Fermi GBM Observation
  39. GRB 260410B: SVOM/GRM detection of a short faint burst
  40. EP-WXT01709259790: Xinglong optical upper limit
  41. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  42. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  43. EP260409a: COLIBRÍ optical upper limits
  44. EP260409a: Global MASTER-Net observations report
  45. EP260409a: Einstein Probe detection of an X-ray transient
  46. EP260321a: VLA radio detection
  47. GRB 260407A: Glowbug gamma-ray detection
  48. GRB 260402A: SVOM/ECLAIRs refined analysis
  49. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  50. EP260402a / GRB 260402A: Mephisto optical upper limits
  51. EP-WXT01709259586: Xinglong optical upper limit
  52. EP260403a: Mephisto optical upper limits
  53. EP260402a/GRB 260402A: Xinglong optical upper limit
  54. EP260405a: GMOS-N optical upper limits
  55. EP260405a: Global MASTER-Net observations report
  56. EP260405a: Einstein Probe detection of a fast X-ray transient
  57. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  58. Fermi trigger No 797039833: Global MASTER-Net observations report
  59. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  60. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  61. The EP-WXT trigger 01709259586 is likely a flaring star
  62. GRB 260330B: SVOM/VT further optical observation
  63. EP260403a: LCO optical observations of the counterpart
  64. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  65. EP260403a: LCO optical counterpart detection
  66. EP260403a: COLIBRÍ optical counterpart candidate
  67. GRB 260330B: SVOM/VT optical candidate
  68. EP260403a: Einstein Probe detection of an X-ray transient
  69. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  70. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  71. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  72. GRB 260402C: NuSTAR detection of prompt emission
  73. GRB 260402C: AstroSat CZTI detection of a long burst
  74. EP260324A / AT 2026hir: COLIBRÍ optical observations
  75. GRB 260402A: WINTER J-band upper limit
  76. GRB260402A: GROWTH-India Telescope optical upper limit
  77. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  78. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  79. GRB 260401A: SVOM/GRM observation
  80. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  81. GRB 260402A: Kilonova-Catcher optical upper limit
  82. GRB 260402A: MASTER optical observations
  83. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  84. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  85. GRB 260402A: SVOM detection of a burst
  86. Fermi GRB 260401A: Global MASTER-Net observations report
  87. GRB 260401A: Fermi GBM Observation
  88. GRB 260401A: NuSTAR detection of prompt emission
  89. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  90. GRB 260401A: MAXI/GSC detection
  91. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  92. GRB 260401A: Fermi GBM Final Real-time Localization
  93. EP260329b: Mondy and Assy-Turgen optical upper limits
  94. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  95. EP260321a :Xinglong optical observations
  96. EP260327a: Xinglong optical upper limit
  97. GRB 260330B: SVOM/VT optical upper limits
  98. Konus-Wind detection of GRB 260320A
  99. GRB 260321A: SVOM/ECLAIRs refined analysis
  100. EP260329b: J-band upper limits with WINTER

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