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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"

28056 results found.

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

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