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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"

19571 results found.

  1. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  2. GRB 250603A: Swift/UVOT Upper Limits
  3. GRB 250603A: Enhanced Swift-XRT position
  4. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  5. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  6. GRB 250602A: DDOTI Optical Upper Limit
  7. GRB 250601A: Swift ToO observations
  8. EP#01709177494: SVOM/VT optical observations
  9. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  10. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  11. GRB 250530C: Enhanced Swift-XRT position
  12. GRB 250530C: Swift detection of a burst
  13. GRB 250521C/AT2025mgj: NOT optical observations of the afterglow candidate
  14. GRB 250530A: SVOM/VT optical upper limit
  15. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  16. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  17. GRB 250530A: SVOM detection of a burst
  18. GRB 250527C: Swift/UVOT Upper Limits
  19. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  20. GRB 250527B: Swift-XRT observations
  21. GRB 250527C: Swift ToO observations
  22. GRB 250527B: Tiled Swift observations
  23. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  24. EP250526a: COLIBRÍ optical upper limits
  25. EP250526a: Einstein Probe detection of a fast X-ray transient
  26. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  27. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  28. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  29. GRB 250521D: DDOTI Optical Upper Limit
  30. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  31. GRB 250521D: LAST tentative optical counterpart candidate
  32. GRB 250521B: Swift ToO observations
  33. GRB 250521A: DDOTI Optical Upper Limit
  34. GRB 250521B: SVOM detection of a burst through offline search
  35. GRB 250520A: VLT/FORS2 Optical Observation
  36. GRB 250502A: Tautenburg observations
  37. GRB 250520A: Swift/UVOT Upper Limits
  38. IPN triangulation of GRB 250516B
  39. GRB 250520A: J-band observations with WINTER
  40. GRB 250520A: Gemini-South optical observations
  41. GRB 250520A: REM optical/NIR early observations
  42. GRB 250520A:SVOM/VT optical candidate
  43. GRB 250520A: COLIBRÍ optical upper limit
  44. GRB 250520A: DDOTI Optical Upper Limit
  45. GRB 250520A: Enhanced Swift-XRT position
  46. GRB 250520A: Swift detection of a burst
  47. GRB 250516A: COLIBRÍ optical upper limit
  48. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  49. GRB 250515A: Swift-XRT observations
  50. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  51. GRB 250515A: 1.6m Mephisto optical detection
  52. GRB 250516A: AstroSat CZTI detection
  53. GRB 250516A: Swift/UVOT Detection
  54. GRB 250515A: Swift ToO observations
  55. GRB 250516A: Enhanced Swift-XRT position
  56. GRB 250516A: Swift detection of a burst
  57. GRB 250424A: COLIBRÍ detection of the associated supernova
  58. Konus-Wind detection of GRB 250512B / EP250512a
  59. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  60. EP250512a/GRB 250512B: REM optical/NIR observations
  61. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  62. GRB 250507B: AstroSat CZTI detection
  63. EP250511a: Gemini optical counterpart observation
  64. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  65. EP250511a: Mephisto optical upper limits
  66. GRB 250512B: SVOM detection of a burst
  67. EP250512a: Einstein Probe detection of an X-ray transient
  68. EP250511a: REM optical/NIR observations
  69. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  70. EP250511a: COLIBRÍ optical counterpart candidate
  71. EP250511a: Einstein Probe detection of an X-ray transient
  72. EP250508a: Gemini NIR upper limits
  73. GRB 250510A: Swift-XRT observations
  74. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  75. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  76. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  77. GRB 250507A: J-band observations with WINTER
  78. GRB 250509A: Enhanced Swift-XRT position
  79. GRB 250509A: Swift detection of a burst
  80. GRB 250506A: NOT optical upper limits
  81. EP250508a: Liverpool Telescope optical upper limits
  82. EP250508a: KAIT optical upper limit
  83. GRB 250507A: KAIT optical upper limit
  84. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  85. GRB 250505B: SVOM/GRM observation of a short burst
  86. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  87. EP250508a: REM optical/NIR observations
  88. GRB 250506A: Swift-XRT afterglow detection
  89. EP250508a: COLIBRÍ Optical Limit
  90. EP250508a: Einstein Probe detection of an X-ray transient
  91. GRB 250506A: Swift/UVOT Upper Limits
  92. GRB 250427B : SVOM detection of a burst through offline search
  93. GRB 250430A / EP250430a: AstroSat CZTI detection
  94. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  95. GRB 250507A: REM optical/NIR observations
  96. GRB 250507A: SVOM/VT optical upper limit
  97. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  98. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  99. GRB 250507A: SVOM detection of a long burst
  100. GRB 250506A: Mephisto optical upper limits

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