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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"

19394 results found.

  1. EP250610a: SVOM/VT optical upper limit
  2. EP250610a: REM optical/NIR observations
  3. EP250610a: COLIBRÍ optical upper limit
  4. EP250610a: Einstein Probe detection of an X-ray transient
  5. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  6. GRB 250605A: Swift/UVOT Upper Limits
  7. The EP-WXT trigger 01709178283 is likely a flaring star
  8. GRB 250527C: CrAO Optical Upper Limit
  9. GRB 250607A: SVOM/GRM observation of a long burst
  10. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  11. GRB 250605A: Enhanced Swift-XRT position
  12. GRB 250605A: Swift detection of a burst
  13. IPN triangulation of GRB 250404B
  14. IPN triangulation of GRB 250529A
  15. GRB 250601A: PRIME H band upper limit.
  16. GRB 250601A: PRIME J band upper limit.
  17. GRB 250601A: VLT/FORS2 Optical Observation
  18. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  19. GRB 250603A: Swift/UVOT Upper Limits
  20. GRB 250603A: Enhanced Swift-XRT position
  21. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  22. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  23. GRB 250602A: DDOTI Optical Upper Limit
  24. EP#01709177494: SVOM/VT optical observations
  25. GRB 250530C: BOOTES-7 optical upper limit
  26. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  27. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  28. GRB 250530C: Enhanced Swift-XRT position
  29. GRB 250530C: Swift detection of a burst
  30. GRB 250530A: SVOM/VT optical upper limit
  31. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  32. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  33. GRB 250530A: SVOM detection of a burst
  34. GRB 250527C: Swift/UVOT Upper Limits
  35. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  36. GRB 250527B: Swift-XRT observations
  37. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  38. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  39. EP250526a: COLIBRÍ optical upper limits
  40. EP250526a: Einstein Probe detection of a fast X-ray transient
  41. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  42. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  43. GRB 250521A: GRBAlpha detection
  44. GRB 250520A: GRBAlpha detection
  45. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  46. GRB 250521D: DDOTI Optical Upper Limit
  47. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  48. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  49. GRB 250521D: LAST tentative optical counterpart candidate
  50. GRB 250521A: DDOTI Optical Upper Limit
  51. Konus-Wind detection of GRB 250520A (short/hard)
  52. GRB 250520A: VLT/FORS2 Optical Observation
  53. GRB 250502A: Tautenburg observations
  54. GRB 250520A: Swift/UVOT Upper Limits
  55. Konus-Wind detection of GRB 250516B
  56. IPN triangulation of GRB 250516B
  57. GRB 250520A: J-band observations with WINTER
  58. GRB 250520A: Gemini-South optical observations
  59. GRB 250520A: REM optical/NIR early observations
  60. GRB 250520A:SVOM/VT optical candidate
  61. GRB 250520A: COLIBRÍ optical upper limit
  62. GRB 250520A: DDOTI Optical Upper Limit
  63. GRB 250516B: GRBAlpha detection
  64. GRB 250520A: Enhanced Swift-XRT position
  65. GRB 250520A: Swift detection of a burst
  66. Swift GRB 250520A: Global MASTER-Net observations report
  67. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  68. GRB 250516A: COLIBRÍ optical upper limit
  69. GRB 250516B: NuSTAR Detection of the Prompt Emission
  70. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  71. GRB 250515A: Swift-XRT observations
  72. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  73. GRB 250515A: 1.6m Mephisto optical detection
  74. GRB 250516A: Swift/UVOT Detection
  75. GRB 250516B: GECAM-B detection of a bright long burst
  76. GRB 250516A: Enhanced Swift-XRT position
  77. GRB 250516A: Swift detection of a burst
  78. GRB 250515A: GOTO candidate optical counterpart
  79. GRB 250424A: COLIBRÍ detection of the associated supernova
  80. GRB 250502A: TESS observations
  81. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  82. Konus-Wind detection of GRB 250506A
  83. EP250512a/GRB 250512B: REM optical/NIR observations
  84. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  85. GRB 250507B: AstroSat CZTI detection
  86. EP250511a: Gemini optical counterpart observation
  87. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  88. EP250511a: Mephisto optical upper limits
  89. GRB 250507B: GRBAlpha detection
  90. GRB 250506A: GRBAlpha detection
  91. GRB 250512B: SVOM detection of a burst
  92. EP250512a: Einstein Probe detection of an X-ray transient
  93. EP250511a: REM optical/NIR observations
  94. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  95. EP250511a: COLIBRÍ optical counterpart candidate
  96. EP250511a: BOOTES-5 optical upper limit
  97. EP250511a: Einstein Probe detection of an X-ray transient
  98. EP250508a: Gemini NIR upper limits
  99. GRB 250510A: Swift-XRT observations
  100. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility

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