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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"

28253 results found.

  1. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  2. Fermi trigger No 798275385: Global MASTER-Net observations report
  3. EP260417a: GROWTH-India Telescope optical upper limit
  4. Fermi GRB 260417B: Global MASTER-Net observations report
  5. EP260417b: GROWTH-India Telescope optical upper limit
  6. EP260416a: Ondrejov D50 optical detection
  7. EP260417a: Global MASTER-Net observations report
  8. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  9. EP260416a: GMG Optical Observation
  10. Fermi GRB 260417A: Global MASTER-Net observations report
  11. EP260416a: LCO observations confirm end of flaring phase
  12. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  13. EP260417a: TRT optical counterpart detection
  14. EP260417a: Einstein Probe detection of an X-ray transient
  15. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  16. EP260417b: Einstein Probe detection of a fast X-ray transient
  17. EP260416a: KAIT optical upper limit
  18. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  19. EP260416a: WFST optical observations and rebrightening
  20. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  21. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  22. GRB 260415B: Glowbug gamma-ray detection
  23. GRB 260411B: Glowbug gamma-ray detection
  24. EP260416a: COLIBRÍ optical counterpart candidate
  25. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  26. EP260416a: Global MASTER-Net observations report
  27. EP260416a: Einstein Probe detection of an X-ray transient
  28. GOTO26djh/AT2026jpw : MASTER OT observation
  29. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  30. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  31. GRB 260415B: NuSTAR detection of long prompt emission
  32. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  33. Fermi trigger No 797912738: Global MASTER-Net observations report
  34. GRB 260414A: Glowbug gamma-ray detection
  35. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  36. EP260321a: CMO SAI J,K observations
  37. Fermi GRB 260413A: Global MASTER-Net observations report
  38. GRB 260410A: Glowbug gamma-ray detection of a short burst
  39. Fermi GRB 260412A: Global MASTER-Net observations report
  40. GRB 260412A: Fermi GBM Observation
  41. GRB 260411B: Fermi-LAT detection
  42. GRB 260411B: COLIBRÍ optical observations
  43. GRB 260410B: Fermi GBM Observation
  44. GRB260411B: 3.6m DOT optical observation
  45. GRB 260411A: SVOM/GRM observation
  46. GRB 260411B: SVOM/GRM observation of a long burst
  47. GRB 260409A: Insight-HXMT/HE detection
  48. GRB 260411B: Fermi GBM Detection
  49. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  50. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  51. GRB 260410A: COLIBRÍ optical upper limit
  52. EP-WXT01709259790: Optical Upper limits with kinder observations
  53. GRB 260410A: Fermi GBM Observation
  54. GRB 260410B: SVOM/GRM detection of a short faint burst
  55. EP-WXT01709259790: Xinglong optical upper limit
  56. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  57. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  58. EP260409a: COLIBRÍ optical upper limits
  59. EP260409a: Global MASTER-Net observations report
  60. EP260409a: Einstein Probe detection of an X-ray transient
  61. EP260321a: VLA radio detection
  62. GRB 260407A: Glowbug gamma-ray detection
  63. GRB 260402A: SVOM/ECLAIRs refined analysis
  64. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  65. EP260402a / GRB 260402A: Mephisto optical upper limits
  66. EP-WXT01709259586: Xinglong optical upper limit
  67. EP260403a: Mephisto optical upper limits
  68. EP260402a/GRB 260402A: Xinglong optical upper limit
  69. EP260405a: GMOS-N optical upper limits
  70. EP260405a: Global MASTER-Net observations report
  71. EP260405a: Einstein Probe detection of a fast X-ray transient
  72. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  73. Fermi trigger No 797039833: Global MASTER-Net observations report
  74. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  75. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  76. The EP-WXT trigger 01709259586 is likely a flaring star
  77. GRB 260330B: SVOM/VT further optical observation
  78. EP260403a: LCO optical observations of the counterpart
  79. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  80. EP260403a: LCO optical counterpart detection
  81. EP260403a: COLIBRÍ optical counterpart candidate
  82. GRB 260330B: SVOM/VT optical candidate
  83. EP260403a: Einstein Probe detection of an X-ray transient
  84. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  85. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  86. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  87. GRB 260402C: NuSTAR detection of prompt emission
  88. GRB 260402C: AstroSat CZTI detection of a long burst
  89. EP260324A / AT 2026hir: COLIBRÍ optical observations
  90. GRB 260402A: WINTER J-band upper limit
  91. GRB260402A: GROWTH-India Telescope optical upper limit
  92. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  93. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  94. GRB 260401A: SVOM/GRM observation
  95. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  96. GRB 260402A: Kilonova-Catcher optical upper limit
  97. GRB 260402A: MASTER optical observations
  98. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  100. GRB 260402A: SVOM detection of a burst

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