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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"

20410 results found.

  1. GRB 260428A: AstroSat CZTI detection
  2. EP260416a: Mondy and Terskol optical upper limits
  3. GRB 260424B: COLIBRÍ optical upper limit
  4. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  5. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  6. GRB 260401A: cubesat Avion detection
  7. EP260321a: Upper limits from ATCA radio observations
  8. GRB 260421B: Kilonova-Catcher optical afterglow detection
  9. EP260416a: Mondy optical observations
  10. GRB 260421B: SVOM/ECLAIRs refined analysis
  11. GRB 260421B: 3.6m DOT optical observation
  12. EP260416a: ZTSh R band observations
  13. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  14. GRB 260421B: SVOM/GRM observation
  15. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  16. GOTO26djh/AT2026jpw: ATCA radio detection
  17. GRB 260421B: J-band upper limit with WINTER
  18. GRB 260421B: LCO optical counterpart detection
  19. GRB 260412A: SVOM/ECLAIRs refined analysis
  20. GRB 260421B: SVOM/VT optical observations
  21. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  22. GRB 260310A: Late-time Chandra X-ray Detection
  23. EP260416a: 1.3m DFOT optical observation
  24. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  25. GRB 260421B: LCO optical afterglow confirmation
  26. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  27. GRB 260421B: TRT optical counterpart detection
  28. GRB 260421B: SVOM detection of a long burst
  29. EP260321a: VLA radio follow-up
  30. GRB 260412A: LCOGT Optical Upper Limits
  31. EP260416a: Optical follow-up observations with Kinder
  32. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  33. GRB 260417A: SVOM/GRM observation
  34. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  35. EP260417a: GROWTH-India Telescope optical upper limit
  36. EP260417b: GROWTH-India Telescope optical upper limit
  37. EP260416a: Ondrejov D50 optical detection
  38. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  39. EP260416a: GMG Optical Observation
  40. EP260416a: LCO observations confirm end of flaring phase
  41. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  42. EP260417a: TRT optical counterpart detection
  43. EP260417a: Einstein Probe detection of an X-ray transient
  44. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  45. EP260417b: Einstein Probe detection of a fast X-ray transient
  46. EP260416a: KAIT optical upper limit
  47. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  48. EP260416a: WFST optical observations and rebrightening
  49. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  50. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  51. EP260416a: COLIBRÍ optical counterpart candidate
  52. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  53. EP260416a: Einstein Probe detection of an X-ray transient
  54. GOTO26djh/AT2026jpw : MASTER OT observation
  55. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  56. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  57. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  58. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  59. EP260321a: CMO SAI J,K observations
  60. GRB 260412A: Insight-HXMT/HE detection
  61. GRB 260412A: GECAM-B observation of a long burst
  62. GRB 260411B: Fermi-LAT detection
  63. GRB 260411B: COLIBRÍ optical observations
  64. GRB260411B: 3.6m DOT optical observation
  65. GRB 260411A: SVOM/GRM observation
  66. GRB 260411B: SVOM/GRM observation of a long burst
  67. GRB 260411B: Fermi GBM Detection
  68. GRB 260411B: GOTO optical counterpart candidate
  69. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  70. GRB 260410A: COLIBRÍ optical upper limit
  71. EP-WXT01709259790: Optical Upper limits with kinder observations
  72. EP-WXT01709259790: Xinglong optical upper limit
  73. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  74. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  75. EP260409a: COLIBRÍ optical upper limits
  76. EP260409a: Einstein Probe detection of an X-ray transient
  77. EP260321a: VLA radio detection
  78. GRB 260402A: SVOM/ECLAIRs refined analysis
  79. EP260402a / GRB 260402A: Mephisto optical upper limits
  80. EP-WXT01709259586: Xinglong optical upper limit
  81. EP260403a: Mephisto optical upper limits
  82. EP260402a/GRB 260402A: Xinglong optical upper limit
  83. GRID detection of GRB 260401A
  84. EP260405a: GMOS-N optical upper limits
  85. EP260405a: Einstein Probe detection of a fast X-ray transient
  86. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  87. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  88. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  89. GRB 260330B: SVOM/VT further optical observation
  90. GRB 260330B: SVOM/ECLAIRs refined analysis
  91. EP260403a: LCO optical observations of the counterpart
  92. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  93. EP260403a: LCO optical counterpart detection
  94. EP260403a: COLIBRÍ optical counterpart candidate
  95. GRB 260330B: SVOM/VT optical candidate
  96. EP260403a: Einstein Probe detection of an X-ray transient
  97. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  98. GRB 260403A: AstroSat CZTI detection
  99. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  100. EP260402a/GRB 260402A: Jinshan near-infrared upper limit

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