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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"

32723 results found.

  1. EP-WXT trigger 01709260303: KAIT optical observations
  2. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  3. GRB 260417A: SVOM/GRM observation
  4. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  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. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  10. EP260417a: Global MASTER-Net observations report
  11. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  12. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  13. EP260416a: GMG Optical Observation
  14. Fermi GRB 260417A: Global MASTER-Net observations report
  15. Konus-Wind detection of GRB 260411B
  16. GRB 260417A: AstroSat CZTI detection
  17. IPN triangulation of GRB 260411B
  18. EP260416a: LCO observations confirm end of flaring phase
  19. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  20. EP260417a: TRT optical counterpart detection
  21. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  22. EP-WXT trigger 01709259586: KAIT optical observations
  23. EP260416a: KAIT optical upper limit
  24. GRB 260414A: Insight-HXMT/HE detection
  25. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  26. EP260416a: WFST optical observations and rebrightening
  27. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  28. EP260416a: SVOM/VT optical observation
  29. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  30. GRB 260415B: Glowbug gamma-ray detection
  31. GRB 260411B: Glowbug gamma-ray detection
  32. GRB 260415A: Insight-HXMT/HE detection
  33. EP260416a: COLIBRÍ optical counterpart candidate
  34. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  35. EP260416a: Global MASTER-Net observations report
  36. GOTO26djh/AT2026jpw : MASTER OT observation
  37. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  38. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  39. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  40. GRB 260415B: NuSTAR detection of long prompt emission
  41. GRB 260414A: Glowbug gamma-ray detection
  42. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  43. EP260321a: CMO SAI J,K observations
  44. GRB 260412A: Insight-HXMT/HE detection
  45. Fermi GRB 260413A: Global MASTER-Net observations report
  46. GRB 260410A: Glowbug gamma-ray detection of a short burst
  47. GRB 260410B: Insight-HXMT/HE detection
  48. GRB 260410A: Insight-HXMT/HE detection
  49. Konus-Wind detection of GRB 260410A (short/hard)
  50. GRB 260411B: GECAM-B observation of a long burst
  51. EP260321a: SVOM/VT optical observations and color changes around peak
  52. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  53. GRB 260412A: GECAM-B observation of a long burst
  54. Fermi GRB 260412A: Global MASTER-Net observations report
  55. GRB 260412A: Fermi GBM Observation
  56. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  57. GRB 260411B: Fermi-LAT detection
  58. GRB 260412A: SVOM detection of a long burst
  59. GRB 260411B: COLIBRÍ optical observations
  60. GRB 260410B: Fermi GBM Observation
  61. GRB 260411B: Ondrejov D50 optical afterglow detection
  62. GRB260411B: 3.6m DOT optical observation
  63. GRB 260411A: SVOM/GRM observation
  64. GRB 260411B: SVOM/GRM observation of a long burst
  65. GRB 260409A: Insight-HXMT/HE detection
  66. GRB 260411B: Fermi GBM Detection
  67. GRB 260411B: GOTO optical counterpart candidate
  68. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  69. GRB 260410A: COLIBRÍ optical upper limit
  70. EP-WXT01709259790: Optical Upper limits with kinder observations
  71. GRB 260410A: Fermi GBM Observation
  72. GRB 260410B: SVOM/GRM detection of a short faint burst
  73. GRB 260410A: Fermi-LAT detection
  74. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  75. EP260321a: Chandra X-ray Non-detection
  76. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  77. GRB 260407A: GECAM-A detection
  78. GRB 260407A: Insight-HXMT/HE detection
  79. EP260409a: SVOM/VT optical upper limits
  80. EP260409a: COLIBRÍ optical upper limits
  81. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  82. EP260409a: Global MASTER-Net observations report
  83. EP260321a: VLA radio detection
  84. GRB 260407A: Glowbug gamma-ray detection
  85. GRB 260402A: SVOM/ECLAIRs refined analysis
  86. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  87. GRB 260310A / AT2026fgk: X-ray rebrightening
  88. EP260402a / GRB 260402A: Mephisto optical upper limits
  89. EP-WXT01709259586: Xinglong optical upper limit
  90. EP260403a: Mephisto optical upper limits
  91. EP260402a/GRB 260402A: Xinglong optical upper limit
  92. EP260321a: Upper limits from VLA radio observations
  93. GRID detection of GRB 260401A
  94. EP260321a: uGMRT observations
  95. EP260405a: GMOS-N optical upper limits
  96. EP260405a: SVOM/VT optical upper limits
  97. EP260405a: Global MASTER-Net observations report
  98. EP260405a: Einstein Probe detection of a fast X-ray transient
  99. GRB 260403A: GECAM-B observation of a long burst
  100. EP260324A / AT 2026hir: COLIBRÍ further optical observations

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