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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"

18064 results found.

  1. EP#01709177494: SVOM/VT optical observations
  2. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  3. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  4. GRB 250530C: Enhanced Swift-XRT position
  5. GRB 250530C: Swift detection of a burst
  6. GRB 250530A: SVOM/VT optical upper limit
  7. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  8. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  9. GRB 250530A: SVOM detection of a burst
  10. GRB 250527C: Swift/UVOT Upper Limits
  11. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  12. GRB 250527B: Swift-XRT observations
  13. Fermi trigger No 770047117: Global MASTER-Net observations report
  14. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  15. GRB 250314A: CIDER NB1008 upper limit
  16. EP250526a: COLIBRÍ optical upper limits
  17. EP250526a: Einstein Probe detection of a fast X-ray transient
  18. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  19. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  20. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  21. GRB 250521D: DDOTI Optical Upper Limit
  22. The EP-WXT trigger 01709176612 is likely a flaring star
  23. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  24. GRB 250521D: LAST tentative optical counterpart candidate
  25. GRB 250520A: 10 GHz VLA radio source
  26. GRB 250521A: DDOTI Optical Upper Limit
  27. GRB 250520A: VLT/FORS2 Optical Observation
  28. GRB 250502A: Tautenburg observations
  29. GRB 250520A: Swift/UVOT Upper Limits
  30. Konus-Wind detection of GRB 250516B
  31. IPN triangulation of GRB 250516B
  32. GRB 250520A: J-band observations with WINTER
  33. GRB 250520A: Gemini-South optical observations
  34. GRB 250520A: REM optical/NIR early observations
  35. GRB 250520A:SVOM/VT optical candidate
  36. GRB 250520A: COLIBRÍ optical upper limit
  37. GRB 250520A: DDOTI Optical Upper Limit
  38. GRB 250520A: Enhanced Swift-XRT position
  39. GRB 250520A: Swift detection of a burst
  40. GRB 250516A: COLIBRÍ optical upper limit
  41. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  42. GRB 250515A: Swift-XRT observations
  43. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  44. GRB 250515A: 1.6m Mephisto optical detection
  45. GRB 250516A: Swift/UVOT Detection
  46. GRB 250516A: Enhanced Swift-XRT position
  47. GRB 250516A: Swift detection of a burst
  48. GRB 250424A: COLIBRÍ detection of the associated supernova
  49. GRB 250502A: TESS observations
  50. EP250512a/GRB 250512B: REM optical/NIR observations
  51. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  52. EP250511a: Gemini optical counterpart observation
  53. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  54. EP250511a: Mephisto optical upper limits
  55. GRB 250512B: SVOM detection of a burst
  56. EP250512a: Einstein Probe detection of an X-ray transient
  57. EP250511a: REM optical/NIR observations
  58. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  59. EP250511a: COLIBRÍ optical counterpart candidate
  60. EP250511a: Einstein Probe detection of an X-ray transient
  61. EP250508a: Gemini NIR upper limits
  62. GRB 250510A: Swift-XRT observations
  63. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  64. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  65. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. GRB 250507A: J-band observations with WINTER
  67. GRB 250509A: Enhanced Swift-XRT position
  68. GRB 250509A: Swift detection of a burst
  69. GRB 250506A: NOT optical upper limits
  70. EP250508a: Liverpool Telescope optical upper limits
  71. EP250508a: KAIT optical upper limit
  72. GRB 250507A: KAIT optical upper limit
  73. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  74. GRB 250505B: SVOM/GRM observation of a short burst
  75. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  76. EP250508a: REM optical/NIR observations
  77. GRB 250506A: Swift-XRT afterglow detection
  78. EP250508a: COLIBRÍ Optical Limit
  79. EP250508a: Einstein Probe detection of an X-ray transient
  80. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 250506A: Swift/UVOT Upper Limits
  82. GRB 250427B : SVOM detection of a burst through offline search
  83. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  84. GRB 250507A: REM optical/NIR observations
  85. GRB 250507A: SVOM/VT optical upper limit
  86. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  87. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  88. GRB 250507A: SVOM detection of a long burst
  89. GRB 250506A: Mephisto optical upper limits
  90. GRB 250502A: Bassano Bresciano Observatory upper limit
  91. GRB 250506A: Xinglong 2.16m optical upper limit
  92. GRB 250506A: REM optical/NIR upper limits
  93. GRB 250506A: TRT optical observations
  94. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  95. GRB 250504A: VLT/X-shooter upper limits
  96. GRB 250504A: REM optical/NIR observations
  97. GRB 250502A: REM optical/NIR observations
  98. GRB 250504A: MeerLICHT optical afterglow detection
  99. GRB 250504A: Enhanced Swift-XRT position
  100. GRB 250504A: Swift detection of a burst

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