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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').
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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"

20498 results found.

  1. EP260416a: Mondy optical observations
  2. GRB 260421B: SVOM/ECLAIRs refined analysis
  3. GRB 260421B: 3.6m DOT optical observation
  4. EP260416a: ZTSh R band observations
  5. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  6. GRB 260421B: SVOM/GRM observation
  7. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  8. GOTO26djh/AT2026jpw: ATCA radio detection
  9. GRB 260421B: J-band upper limit with WINTER
  10. GRB 260421B: LCO optical counterpart detection
  11. GRB 260412A: SVOM/ECLAIRs refined analysis
  12. GRB 260421B: SVOM/VT optical observations
  13. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  14. GRB 260310A: Late-time Chandra X-ray Detection
  15. EP260416a: 1.3m DFOT optical observation
  16. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  17. GRB 260421B: LCO optical afterglow confirmation
  18. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  19. GRB 260421B: TRT optical counterpart detection
  20. GRB 260421B: SVOM detection of a long burst
  21. EP260321a: VLA radio follow-up
  22. GRB 260412A: LCOGT Optical Upper Limits
  23. EP260416a: Optical follow-up observations with Kinder
  24. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  25. GRB 260417A: SVOM/GRM observation
  26. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  27. EP260417a: GROWTH-India Telescope optical upper limit
  28. EP260417b: GROWTH-India Telescope optical upper limit
  29. EP260416a: Ondrejov D50 optical detection
  30. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  31. EP260416a: GMG Optical Observation
  32. EP260416a: LCO observations confirm end of flaring phase
  33. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  34. EP260417a: TRT optical counterpart detection
  35. EP260417a: Einstein Probe detection of an X-ray transient
  36. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  37. EP260417b: Einstein Probe detection of a fast X-ray transient
  38. EP260416a: KAIT optical upper limit
  39. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  40. EP260416a: WFST optical observations and rebrightening
  41. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  42. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  43. EP260416a: COLIBRÍ optical counterpart candidate
  44. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  45. EP260416a: Einstein Probe detection of an X-ray transient
  46. GOTO26djh/AT2026jpw : MASTER OT observation
  47. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  48. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  49. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  50. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  51. EP260321a: CMO SAI J,K observations
  52. GRB 260412A: Insight-HXMT/HE detection
  53. GRB 260412A: GECAM-B observation of a long burst
  54. GRB 260411B: Fermi-LAT detection
  55. GRB 260411B: COLIBRÍ optical observations
  56. GRB260411B: 3.6m DOT optical observation
  57. GRB 260411A: SVOM/GRM observation
  58. GRB 260411B: SVOM/GRM observation of a long burst
  59. GRB 260411B: Fermi GBM Detection
  60. GRB 260411B: GOTO optical counterpart candidate
  61. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  62. GRB 260410A: COLIBRÍ optical upper limit
  63. EP-WXT01709259790: Optical Upper limits with kinder observations
  64. EP-WXT01709259790: Xinglong optical upper limit
  65. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  66. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  67. EP260409a: COLIBRÍ optical upper limits
  68. EP260409a: Einstein Probe detection of an X-ray transient
  69. EP260321a: VLA radio detection
  70. GRB 260402A: SVOM/ECLAIRs refined analysis
  71. EP260402a / GRB 260402A: Mephisto optical upper limits
  72. EP-WXT01709259586: Xinglong optical upper limit
  73. EP260403a: Mephisto optical upper limits
  74. EP260402a/GRB 260402A: Xinglong optical upper limit
  75. GRID detection of GRB 260401A
  76. EP260405a: GMOS-N optical upper limits
  77. EP260405a: Einstein Probe detection of a fast X-ray transient
  78. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  79. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  80. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  81. GRB 260330B: SVOM/VT further optical observation
  82. GRB 260330B: SVOM/ECLAIRs refined analysis
  83. EP260403a: LCO optical observations of the counterpart
  84. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  85. EP260403a: LCO optical counterpart detection
  86. EP260403a: COLIBRÍ optical counterpart candidate
  87. GRB 260330B: SVOM/VT optical candidate
  88. EP260403a: Einstein Probe detection of an X-ray transient
  89. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  90. GRB 260403A: AstroSat CZTI detection
  91. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  92. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  93. GRB 260402C: AstroSat CZTI detection of a long burst
  94. EP260324A / AT 2026hir: COLIBRÍ optical observations
  95. GRB 260402A: WINTER J-band upper limit
  96. GRB260402A: GROWTH-India Telescope optical upper limit
  97. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  98. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  99. GRB 260401A: SVOM/GRM observation
  100. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient

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