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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"

31632 results found.

  1. GRB 250527C: Swift/UVOT Upper Limits
  2. EP J1350.0-8622: EP-FXT follow-up observation
  3. EP-WXT trigger 01709177124: confirmation of a stellar flare by BOOTES-6
  4. GRB 250521C (short): Zwicky Transient Facility identification of a possible fast optical transient counterpart
  5. GRB 250520A: Swift-BAT refined analysis
  6. GRB 250527C: Swift ToO observations
  7. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  8. EP250526a: SVOM/VT optical upper limit
  9. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  10. GRB 250527B: Tiled Swift observations
  11. GRB 250520A: Gemini-South optical afterglow detection
  12. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  13. GRB 250314A: CIDER NB1008 upper limit
  14. EP250526a: COLIBRÍ optical upper limits
  15. EP250526a: Global MASTER-Net observations report
  16. EP J1350.0-8622: BOOTES-6/DPRT optical upper limit
  17. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  18. GRB 250520A: 3 GHz MeerKAT Detection
  19. GRB 250520A: 10 GHz VLA Afterglow Confirmation
  20. Fermi GRB 250523A: Global MASTER-Net observations report
  21. EP-WXT trigger 01709176712: GOTO observations confirm stellar counterpart variability
  22. GRB 250521A: GRBAlpha detection
  23. GRB 250520A: GRBAlpha detection
  24. GRB 250521B: SVOM/VT optical upper limit
  25. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  26. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  27. Fermi GRB 250522B: Global MASTER-Net observations report
  28. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  29. GRB 250521D: SVOM/VT optical observations
  30. EP#01709176612: Swift-XRT counterpart detection of flaring star
  31. Fermi GRB 250521D: Global MASTER-Net observations report
  32. GRB 250521D: DDOTI Optical Upper Limit
  33. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  34. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  35. GRB 250521D: LAST tentative optical counterpart candidate
  36. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  37. GRB 250520A: 10 GHz VLA radio source
  38. GRB 250521B: Swift ToO observations
  39. GRB 250521A: DDOTI Optical Upper Limit
  40. Konus-Wind detection of GRB 250520A (short/hard)
  41. GRB 250520A: VLT/FORS2 Optical Observation
  42. GRB 250502A: Tautenburg observations
  43. GRB 250520A: Swift/UVOT Upper Limits
  44. Konus-Wind detection of GRB 250516B
  45. IPN triangulation of GRB 250516B
  46. GRB 250520A: J-band observations with WINTER
  47. GRB 250520A: Gemini-South optical observations
  48. GRB 250520A: REM optical/NIR early observations
  49. GRB 250520A：SVOM/VT optical candidate
  50. GRB 250520A: COLIBRÍ optical upper limit
  51. GRB 250520A: DDOTI Optical Upper Limit
  52. GRB 250520A: AstroSat CZTI detection of a short burst
  53. GRB 250516B: GRBAlpha detection
  54. GRB 250520A: SVOM/GRM observation
  55. GRB 250520A: GOTO optical upper limit
  56. GRB 250516B: Insight-HXMT detection
  57. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  58. GRB 250516A: Swift-BAT refined analysis
  59. GRB 250516A: COLIBRÍ optical upper limit
  60. Konus-Wind detection of GRB 250516A
  61. GRB 250516B: NuSTAR Detection of the Prompt Emission
  62. Fermi GRB 250516A: Global MASTER-Net observations report
  63. GRB 250515A: Swift-XRT observations
  64. GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
  65. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  66. Swift GRB 250516A: Global MASTER-Net observations report
  67. GRB 250515A: 1.6m Mephisto optical detection
  68. GRB 250516A: AstroSat CZTI detection
  69. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  70. GRB 250516A: Fermi GBM Observation
  71. GRB 250516A: Swift/UVOT Detection
  72. GRB 250515A: Swift ToO observations
  73. GRB 250512B / EP250512a: SVOM/GRM analysis
  74. GRB 250515A: GOTO candidate optical counterpart
  75. GRB 250424A: COLIBRÍ detection of the associated supernova
  76. Konus-Wind detection of GRB 250512B / EP250512a
  77. GRB 250502A: TESS observations
  78. GRB 250509A: Swift-BAT refined analysis
  79. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  80. Fermi GRB 250512A: Global MASTER-Net observations report
  81. Konus-Wind detection of GRB 250506A
  82. EP250512a/GRB 250512B: REM optical/NIR observations
  83. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  84. GRB 250507B: AstroSat CZTI detection
  85. EP250511a: Gemini optical counterpart observation
  86. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  87. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  88. EP250512a: Global MASTER-Net observations report
  89. EP250511a: FTW optical and NIR observations
  90. GRB 250512B/EP250512a: SVOM/VT optical fading
  91. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  92. EP250511a: Mephisto optical upper limits
  93. GRB 250506A: GRBAlpha detection
  94. GRB 250512B: SVOM detection of a burst
  95. EP250511a: REM optical/NIR observations
  96. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  97. EP250511a: SVOM/VT optical candidate comfirmation
  98. EP250511a: Global MASTER-Net observations report
  99. EP250511a: COLIBRÍ optical counterpart candidate
  100. EP250511a: BOOTES-5 optical upper limit

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