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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"

19551 results found.

  1. The EP-WXT trigger 01709258652: Mondy optical observations
  2. EP260416a: Mondy optical observations
  3. GRB 260421B: 3.6m DOT optical observation
  4. EP260416a: ZTSh R band observations
  5. GRB 260421B: SVOM/GRM observation
  6. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  7. GOTO26djh/AT2026jpw: ATCA radio detection
  8. GRB 260421B: J-band upper limit with WINTER
  9. GRB 260421B: LCO optical counterpart detection
  10. GRB 260421A: AstroSat CZTI detection
  11. GRB 260421B: SVOM/VT optical observations
  12. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  13. GRB 260310A: Late-time Chandra X-ray Detection
  14. EP260416a: 1.3m DFOT optical observation
  15. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  16. GRB 260421B: LCO optical afterglow confirmation
  17. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  18. GRB 260421B: TRT optical counterpart detection
  19. GRB 260421B: SVOM detection of a long burst
  20. EP260321a: VLA radio follow-up
  21. GRB 260412A: LCOGT Optical Upper Limits
  22. EP260416a: Optical follow-up observations with Kinder
  23. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  24. GRB 260417A: SVOM/GRM observation
  25. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  26. EP260417a: GROWTH-India Telescope optical upper limit
  27. EP260417b: GROWTH-India Telescope optical upper limit
  28. EP260416a: Ondrejov D50 optical detection
  29. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  30. EP260416a: GMG Optical Observation
  31. EP260416a: LCO observations confirm end of flaring phase
  32. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  33. EP260417a: TRT optical counterpart detection
  34. EP260417a: Einstein Probe detection of an X-ray transient
  35. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  36. EP260417b: Einstein Probe detection of a fast X-ray transient
  37. EP260416a: KAIT optical upper limit
  38. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  39. EP260416a: WFST optical observations and rebrightening
  40. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  41. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  42. EP260416a: COLIBRÍ optical counterpart candidate
  43. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  44. EP260416a: Einstein Probe detection of an X-ray transient
  45. GOTO26djh/AT2026jpw : MASTER OT observation
  46. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  47. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  48. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  49. EP260321a: CMO SAI J,K observations
  50. GRB 260411B: Fermi-LAT detection
  51. GRB 260412A: SVOM detection of a long burst
  52. GRB 260411B: COLIBRÍ optical observations
  53. GRB260411B: 3.6m DOT optical observation
  54. GRB 260411A: SVOM/GRM observation
  55. GRB 260411B: SVOM/GRM observation of a long burst
  56. GRB 260411B: GOTO optical counterpart candidate
  57. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  58. GRB 260410A: COLIBRÍ optical upper limit
  59. EP-WXT01709259790: Optical Upper limits with kinder observations
  60. EP-WXT01709259790: Xinglong optical upper limit
  61. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  62. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  63. EP260409a: COLIBRÍ optical upper limits
  64. EP260409a: Einstein Probe detection of an X-ray transient
  65. EP260321a: VLA radio detection
  66. GRB 260402A: SVOM/ECLAIRs refined analysis
  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: Einstein Probe detection of a fast X-ray transient
  73. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  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. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  85. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  86. EP260324A / AT 2026hir: COLIBRÍ optical observations
  87. GRB 260402A: WINTER J-band upper limit
  88. GRB260402A: GROWTH-India Telescope optical upper limit
  89. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  90. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  91. GRB 260401A: SVOM/GRM observation
  92. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  93. GRB 260402A: Kilonova-Catcher optical upper limit
  94. GRB 260402A: MASTER optical observations
  95. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  96. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  97. GRB 260402A: SVOM detection of a burst
  98. EP260329b: Mondy and Assy-Turgen optical upper limits
  99. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  100. EP260321a :Xinglong optical observations

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