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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

21931 results found.

  1. Fermi GRB 250606A: Global MASTER-Net observations report
  2. Fermi trigger No 770867684: Global MASTER-Net observations report
  3. GRB 250605A: LT optical observations
  4. Swift GRB250605.79: Global MASTER-Net observations report
  5. GRB 250601A: PRIME H band upper limit.
  6. GRB 250530A: SVOM/GRM analysis
  7. GRB 250601A: PRIME J band upper limit.
  8. GRB 250601A: VLT/FORS2 Optical Observation
  9. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  10. GRB 250603A: Swift/UVOT Upper Limits
  11. Fermi trigger No 770638414: Global MASTER-Net observations report
  12. Swift GRB250603.05: Global MASTER-Net observations report
  13. GRB 250602A: DDOTI Optical Upper Limit
  14. GRB 250521C: NOT spectroscopic observations exclude the afterglow candidate AT2025mgj
  15. GRB 250601A: Swift/XRT candidate afterglow
  16. GRB 250521C / AT2025mgj: Pan-STARRS multi-band and multi-epoch imaging and photometry
  17. GRB 250601A: Swift-XRT observations
  18. Fermi GRB 250601A: Global MASTER-Net observations report
  19. Fermi trigger No 770470765: Global MASTER-Net observations report
  20. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  21. GRB 250601A: Swift ToO observations
  22. GRB 250521C/AT2025mgj: FTW optical and NIR observations
  23. EP#01709177494: SVOM/VT optical observations
  24. Fermi GRB 250531A: Global MASTER-Net observations report
  25. EP#01709177494: Swift-XRT counterpart detection of known source
  26. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  27. Swift GRB 250530C: Global MASTER-Net observations report
  28. GRB 250521C/AT2025mgj: NOT optical observations of the afterglow candidate
  29. GRB 250530A: SVOM/VT optical upper limit
  30. GRB 250530A: Swift-XRT counterpart detection
  31. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  32. GRB 250527C: Swift/UVOT Upper Limits
  33. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  34. GRB 250527B: Swift-XRT observations
  35. GRB 250521C (short): Zwicky Transient Facility identification of a possible fast optical transient counterpart
  36. GRB 250527C: Swift ToO observations
  37. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  38. EP250526a: SVOM/VT optical upper limit
  39. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  40. GRB 250527B: Tiled Swift observations
  41. GRB 250520A: Gemini-South optical afterglow detection
  42. Fermi trigger No 770058372: Global MASTER-Net observations report
  43. Fermi trigger No 770047117: Global MASTER-Net observations report
  44. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  45. GRB 250314A: CIDER NB1008 upper limit
  46. EP250526a: Global MASTER-Net observations report
  47. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  48. GRB 250520A: 3 GHz MeerKAT Detection
  49. GRB 250520A: 10 GHz VLA Afterglow Confirmation
  50. Fermi GRB 250523A: Global MASTER-Net observations report
  51. Fermi trigger No 769611916: Global MASTER-Net observations report
  52. EP-WXT trigger 01709176712: GOTO observations confirm stellar counterpart variability
  53. GRB 250521B: SVOM/VT optical upper limit
  54. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  55. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  56. Fermi GRB 250522B: Global MASTER-Net observations report
  57. GRB 250521D: SVOM/VT optical observations
  58. EP#01709176612: Swift-XRT counterpart detection of flaring star
  59. Fermi GRB 250521D: Global MASTER-Net observations report
  60. Fermi trigger No 769533898: Global MASTER-Net observations report
  61. Fermi trigger No 769499303: Global MASTER-Net observations report
  62. GRB 250521D: DDOTI Optical Upper Limit
  63. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  64. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  65. GRB 250521D: LAST tentative optical counterpart candidate
  66. GRB 250520A: 10 GHz VLA radio source
  67. GRB 250521B: Swift ToO observations
  68. GRB 250521A: DDOTI Optical Upper Limit
  69. GRB 250520A: VLT/FORS2 Optical Observation
  70. GRB 250502A: Tautenburg observations
  71. GRB 250520A: Swift/UVOT Upper Limits
  72. GRB 250520A: J-band observations with WINTER
  73. GRB 250520A: Gemini-South optical observations
  74. GRB 250520A: REM optical/NIR early observations
  75. GRB 250520A: COLIBRÍ optical upper limit
  76. GRB 250520A: DDOTI Optical Upper Limit
  77. GRB 250520A: GOTO optical upper limit
  78. Swift GRB 250520A: Global MASTER-Net observations report
  79. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  80. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  81. Fermi GRB 250516A: Global MASTER-Net observations report
  82. GRB 250515A: Swift-XRT observations
  83. GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
  84. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  85. Swift GRB 250516A: Global MASTER-Net observations report
  86. GRB 250515A: 1.6m Mephisto optical detection
  87. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  88. GRB 250516A: Swift/UVOT Detection
  89. GRB 250515A: Swift ToO observations
  90. GRB 250515A: GOTO candidate optical counterpart
  91. MAXI GRB250515.65: Global MASTER-Net observations report
  92. GRB 250424A: COLIBRÍ detection of the associated supernova
  93. GRB 250502A: TESS observations
  94. Fermi trigger No 768922089: Global MASTER-Net observations report
  95. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  96. Fermi GRB 250512A: Global MASTER-Net observations report
  97. EP250512a/GRB 250512B: REM optical/NIR observations
  98. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  99. EP250511a: Gemini optical counterpart observation
  100. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations

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