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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"

32509 results found.

  1. GRB 250521B: SVOM/VT optical upper limit
  2. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  3. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  4. Fermi GRB 250522B: Global MASTER-Net observations report
  5. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  6. GRB 250521D: SVOM/VT optical observations
  7. EP#01709176612: Swift-XRT counterpart detection of flaring star
  8. Fermi GRB 250521D: Global MASTER-Net observations report
  9. GRB 250521D: DDOTI Optical Upper Limit
  10. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  11. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  12. GRB 250521D: LAST tentative optical counterpart candidate
  13. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  14. GRB 250520A: 10 GHz VLA radio source
  15. GRB 250521B: Swift ToO observations
  16. GRB 250521A: DDOTI Optical Upper Limit
  17. Konus-Wind detection of GRB 250520A (short/hard)
  18. GRB 250520A: VLT/FORS2 Optical Observation
  19. GRB 250502A: Tautenburg observations
  20. GRB 250520A: Swift/UVOT Upper Limits
  21. Konus-Wind detection of GRB 250516B
  22. IPN triangulation of GRB 250516B
  23. GRB 250520A: J-band observations with WINTER
  24. GRB 250520A: Gemini-South optical observations
  25. GRB 250520A: REM optical/NIR early observations
  26. GRB 250520A:SVOM/VT optical candidate
  27. GRB 250520A: COLIBRÍ optical upper limit
  28. GRB 250520A: DDOTI Optical Upper Limit
  29. GRB 250520A: AstroSat CZTI detection of a short burst
  30. GRB 250516B: GRBAlpha detection
  31. GRB 250520A: SVOM/GRM observation
  32. GRB 250520A: GOTO optical upper limit
  33. GRB 250516B: Insight-HXMT detection
  34. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  35. GRB 250516A: Swift-BAT refined analysis
  36. GRB 250516A: COLIBRÍ optical upper limit
  37. Konus-Wind detection of GRB 250516A
  38. GRB 250516B: NuSTAR Detection of the Prompt Emission
  39. Fermi GRB 250516A: Global MASTER-Net observations report
  40. GRB 250515A: Swift-XRT observations
  41. GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
  42. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  43. Swift GRB 250516A: Global MASTER-Net observations report
  44. GRB 250515A: 1.6m Mephisto optical detection
  45. GRB 250516A: AstroSat CZTI detection
  46. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  47. GRB 250516A: Fermi GBM Observation
  48. GRB 250516A: Swift/UVOT Detection
  49. GRB 250515A: Swift ToO observations
  50. GRB 250512B / EP250512a: SVOM/GRM analysis
  51. GRB 250515A: GOTO candidate optical counterpart
  52. GRB 250424A: COLIBRÍ detection of the associated supernova
  53. Konus-Wind detection of GRB 250512B / EP250512a
  54. GRB 250502A: TESS observations
  55. GRB 250509A: Swift-BAT refined analysis
  56. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  57. Fermi GRB 250512A: Global MASTER-Net observations report
  58. Konus-Wind detection of GRB 250506A
  59. EP250512a/GRB 250512B: REM optical/NIR observations
  60. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  61. GRB 250507B: AstroSat CZTI detection
  62. EP250511a: Gemini optical counterpart observation
  63. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  64. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  65. EP250512a: Global MASTER-Net observations report
  66. EP250511a: FTW optical and NIR observations
  67. GRB 250512B/EP250512a: SVOM/VT optical fading
  68. GRB 250512B/EP250512a:SVOM/VT bright optical counterpart
  69. EP250511a: Mephisto optical upper limits
  70. GRB 250506A: GRBAlpha detection
  71. GRB 250512B: SVOM detection of a burst
  72. EP250511a: REM optical/NIR observations
  73. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  74. EP250511a: SVOM/VT optical candidate comfirmation
  75. EP250511a: Global MASTER-Net observations report
  76. EP250511a: COLIBRÍ optical counterpart candidate
  77. EP250511a: BOOTES-5 optical upper limit
  78. EP250508a: Gemini NIR upper limits
  79. GRB 250510B: Fermi GBM Observation
  80. Fermi GRB 250510C: Global MASTER-Net observations report
  81. Fermi GRB 250510B: Global MASTER-Net observations report
  82. GRB 250510A: Swift-XRT observations
  83. GRB 250509A: Fermi GBM Observation
  84. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  85. GRB 250510A: follow-up observation with EP-FXT
  86. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  87. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  88. GRB 250507A: J-band observations with WINTER (duplicate submission)
  89. GRB 250507A: J-band observations with WINTER
  90. EP250508a: SVOM/VT optical candidate fading
  91. Fermi GRB 250509A: Global MASTER-Net observations report
  92. Swift GRB 250509A: Global MASTER-Net observations report
  93. GRB 250506A: NOT optical upper limits
  94. EP250508a: Liverpool Telescope optical upper limits
  95. EP250508a: follow-up observation with EP-FXT
  96. EP250508a: SVOM/VT optical candidate
  97. EP250508a: KAIT optical upper limit
  98. GRB 250507A: KAIT optical upper limit
  99. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  100. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.

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