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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"

28048 results found.

  1. EP260417a: Global MASTER-Net observations report
  2. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  3. EP260416a: GMG Optical Observation
  4. Fermi GRB 260417A: Global MASTER-Net observations report
  5. EP260416a: LCO observations confirm end of flaring phase
  6. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  7. EP260417a: TRT optical counterpart detection
  8. EP260417a: Einstein Probe detection of an X-ray transient
  9. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  10. EP260417b: Einstein Probe detection of a fast X-ray transient
  11. EP260416a: KAIT optical upper limit
  12. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  13. EP260416a: WFST optical observations and rebrightening
  14. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  15. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  16. GRB 260415B: Glowbug gamma-ray detection
  17. GRB 260411B: Glowbug gamma-ray detection
  18. EP260416a: COLIBRÍ optical counterpart candidate
  19. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  20. EP260416a: Global MASTER-Net observations report
  21. EP260416a: Einstein Probe detection of an X-ray transient
  22. GOTO26djh/AT2026jpw : MASTER OT observation
  23. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  24. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  25. GRB 260415B: NuSTAR detection of long prompt emission
  26. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  27. Fermi trigger No 797912738: Global MASTER-Net observations report
  28. GRB 260414A: Glowbug gamma-ray detection
  29. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  30. EP260321a: CMO SAI J,K observations
  31. Fermi GRB 260413A: Global MASTER-Net observations report
  32. GRB 260410A: Glowbug gamma-ray detection of a short burst
  33. Fermi GRB 260412A: Global MASTER-Net observations report
  34. GRB 260412A: Fermi GBM Observation
  35. GRB 260411B: Fermi-LAT detection
  36. GRB 260411B: COLIBRÍ optical observations
  37. GRB 260410B: Fermi GBM Observation
  38. GRB260411B: 3.6m DOT optical observation
  39. GRB 260411A: SVOM/GRM observation
  40. GRB 260411B: SVOM/GRM observation of a long burst
  41. GRB 260409A: Insight-HXMT/HE detection
  42. GRB 260411B: Fermi GBM Detection
  43. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  44. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  45. GRB 260410A: COLIBRÍ optical upper limit
  46. EP-WXT01709259790: Optical Upper limits with kinder observations
  47. GRB 260410A: Fermi GBM Observation
  48. GRB 260410B: SVOM/GRM detection of a short faint burst
  49. EP-WXT01709259790: Xinglong optical upper limit
  50. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  51. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  52. EP260409a: COLIBRÍ optical upper limits
  53. EP260409a: Global MASTER-Net observations report
  54. EP260409a: Einstein Probe detection of an X-ray transient
  55. EP260321a: VLA radio detection
  56. GRB 260407A: Glowbug gamma-ray detection
  57. GRB 260402A: SVOM/ECLAIRs refined analysis
  58. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  59. EP260402a / GRB 260402A: Mephisto optical upper limits
  60. EP-WXT01709259586: Xinglong optical upper limit
  61. EP260403a: Mephisto optical upper limits
  62. EP260402a/GRB 260402A: Xinglong optical upper limit
  63. EP260405a: GMOS-N optical upper limits
  64. EP260405a: Global MASTER-Net observations report
  65. EP260405a: Einstein Probe detection of a fast X-ray transient
  66. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  67. Fermi trigger No 797039833: Global MASTER-Net observations report
  68. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  69. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  70. The EP-WXT trigger 01709259586 is likely a flaring star
  71. GRB 260330B: SVOM/VT further optical observation
  72. EP260403a: LCO optical observations of the counterpart
  73. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  74. EP260403a: LCO optical counterpart detection
  75. EP260403a: COLIBRÍ optical counterpart candidate
  76. GRB 260330B: SVOM/VT optical candidate
  77. EP260403a: Einstein Probe detection of an X-ray transient
  78. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  79. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  80. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  81. GRB 260402C: NuSTAR detection of prompt emission
  82. GRB 260402C: AstroSat CZTI detection of a long burst
  83. EP260324A / AT 2026hir: COLIBRÍ optical observations
  84. GRB 260402A: WINTER J-band upper limit
  85. GRB260402A: GROWTH-India Telescope optical upper limit
  86. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  87. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  88. GRB 260401A: SVOM/GRM observation
  89. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  90. GRB 260402A: Kilonova-Catcher optical upper limit
  91. GRB 260402A: MASTER optical observations
  92. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  94. GRB 260402A: SVOM detection of a burst
  95. Fermi GRB 260401A: Global MASTER-Net observations report
  96. GRB 260401A: Fermi GBM Observation
  97. GRB 260401A: NuSTAR detection of prompt emission
  98. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 260401A: MAXI/GSC detection
  100. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)

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