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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').
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"

19386 results found.

  1. GRB 250607A: SVOM/GRM observation of a long burst
  2. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  3. GRB 250605A: Enhanced Swift-XRT position
  4. GRB 250605A: Swift detection of a burst
  5. IPN triangulation of GRB 250404B
  6. IPN triangulation of GRB 250529A
  7. GRB 250601A: PRIME H band upper limit.
  8. GRB 250601A: PRIME J band upper limit.
  9. GRB 250601A: VLT/FORS2 Optical Observation
  10. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  11. GRB 250603A: Swift/UVOT Upper Limits
  12. GRB 250603A: Enhanced Swift-XRT position
  13. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  14. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  15. GRB 250602A: DDOTI Optical Upper Limit
  16. EP#01709177494: SVOM/VT optical observations
  17. GRB 250530C: BOOTES-7 optical upper limit
  18. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  19. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  20. GRB 250530C: Enhanced Swift-XRT position
  21. GRB 250530C: Swift detection of a burst
  22. GRB 250530A: SVOM/VT optical upper limit
  23. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  24. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  25. GRB 250530A: SVOM detection of a burst
  26. GRB 250527C: Swift/UVOT Upper Limits
  27. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  28. GRB 250527B: Swift-XRT observations
  29. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  30. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  31. EP250526a: COLIBRÍ optical upper limits
  32. EP250526a: Einstein Probe detection of a fast X-ray transient
  33. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  34. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  35. GRB 250521A: GRBAlpha detection
  36. GRB 250520A: GRBAlpha detection
  37. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  38. GRB 250521D: DDOTI Optical Upper Limit
  39. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  40. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  41. GRB 250521D: LAST tentative optical counterpart candidate
  42. GRB 250521A: DDOTI Optical Upper Limit
  43. Konus-Wind detection of GRB 250520A (short/hard)
  44. GRB 250520A: VLT/FORS2 Optical Observation
  45. GRB 250502A: Tautenburg observations
  46. GRB 250520A: Swift/UVOT Upper Limits
  47. Konus-Wind detection of GRB 250516B
  48. IPN triangulation of GRB 250516B
  49. GRB 250520A: J-band observations with WINTER
  50. GRB 250520A: Gemini-South optical observations
  51. GRB 250520A: REM optical/NIR early observations
  52. GRB 250520A:SVOM/VT optical candidate
  53. GRB 250520A: COLIBRÍ optical upper limit
  54. GRB 250520A: DDOTI Optical Upper Limit
  55. GRB 250516B: GRBAlpha detection
  56. GRB 250520A: Enhanced Swift-XRT position
  57. GRB 250520A: Swift detection of a burst
  58. Swift GRB 250520A: Global MASTER-Net observations report
  59. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  60. GRB 250516A: COLIBRÍ optical upper limit
  61. GRB 250516B: NuSTAR Detection of the Prompt Emission
  62. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  63. GRB 250515A: Swift-XRT observations
  64. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  65. GRB 250515A: 1.6m Mephisto optical detection
  66. GRB 250516A: Swift/UVOT Detection
  67. GRB 250516B: GECAM-B detection of a bright long burst
  68. GRB 250516A: Enhanced Swift-XRT position
  69. GRB 250516A: Swift detection of a burst
  70. GRB 250515A: GOTO candidate optical counterpart
  71. GRB 250424A: COLIBRÍ detection of the associated supernova
  72. GRB 250502A: TESS observations
  73. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  74. Konus-Wind detection of GRB 250506A
  75. EP250512a/GRB 250512B: REM optical/NIR observations
  76. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  77. GRB 250507B: AstroSat CZTI detection
  78. EP250511a: Gemini optical counterpart observation
  79. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  80. EP250511a: Mephisto optical upper limits
  81. GRB 250507B: GRBAlpha detection
  82. GRB 250506A: GRBAlpha detection
  83. GRB 250512B: SVOM detection of a burst
  84. EP250512a: Einstein Probe detection of an X-ray transient
  85. EP250511a: REM optical/NIR observations
  86. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  87. EP250511a: COLIBRÍ optical counterpart candidate
  88. EP250511a: BOOTES-5 optical upper limit
  89. EP250511a: Einstein Probe detection of an X-ray transient
  90. EP250508a: Gemini NIR upper limits
  91. GRB 250510A: Swift-XRT observations
  92. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  93. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  94. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  95. GRB 250507A: J-band observations with WINTER
  96. GRB 250509A: Enhanced Swift-XRT position
  97. GRB 250509A: Swift detection of a burst
  98. GRB 250506A: NOT optical upper limits
  99. EP250508a: Liverpool Telescope optical upper limits
  100. EP250508a: KAIT optical upper limit

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