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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"

28091 results found.

  1. EP250612a/GRB 250612B: JinShan optical upper limit
  2. sb25061207: SVOM/VT optical counterpart
  3. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  4. GRB 250610B: Swift-XRT refined Analysis
  5. EP250610a: Upper limit from Fermi-GBM Observations
  6. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  7. EP250612a: Einstein Probe detection of an X-ray transient
  8. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  9. sb25061207: SVOM detection of a X-ray transient
  10. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  11. Fermi GBM Sub-Threshold Detection of GRB 250610B
  12. GRB 250610B: Swift/UVOT Detection
  13. EP250610A: Swift/UVOT Upper limits
  14. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  15. EP250610a: TNG NIR upper limit
  16. GRB 250610B: REM optical/NIR observations
  17. EP250610a: Liverpool Telescope optical upper limits
  18. GRB 250610B: additional Liverpool Telescope optical observations
  19. GRB 250610B: SVOM/GRM analysis
  20. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  21. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  22. GRB 250610B: Swift-XRT counterpart detection
  23. GRB 250610B: SVOM/VT optical counterpart
  24. GRB 250610B: OHP/T120 optical counterpart candidate
  25. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  26. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  27. GRB 250605A: Swift-BAT refined analysis
  28. EP250610a: SVOM/VT optical upper limit
  29. EP250610a: REM optical/NIR observations
  30. GRB 250609A: Fermi GBM Observation
  31. EP250610a: Swift-XRT counterpart detection
  32. EP250610a: COLIBRÍ optical upper limit
  33. EP250610a: Einstein Probe detection of an X-ray transient
  34. Fermi trigger No 771072240: Global MASTER-Net observations report
  35. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  36. GRB 250605A: Swift/UVOT Upper Limits
  37. GRB 250527C: CrAO Optical Upper Limit
  38. GRB 250607A: SVOM/GRM observation of a long burst
  39. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  40. GRB 250605A: Swift-XRT refined Analysis
  41. GRB 250605A: Enhanced Swift-XRT position
  42. GRB 250605A: Swift detection of a burst
  43. IPN triangulation of GRB 250404B
  44. IPN triangulation of GRB 250529A
  45. GRB 250601A: PRIME H band upper limit.
  46. GRB 250601A: PRIME J band upper limit.
  47. GRB 250601A: VLT/FORS2 Optical Observation
  48. GRB 250601A: Fermi GBM Observation
  49. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  50. GRB 250603A: Swift/UVOT Upper Limits
  51. GRB 250603A: Swift-XRT refined Analysis
  52. GRB 250603A: Enhanced Swift-XRT position
  53. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  54. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  55. GRB 250602A: Fermi GBM Observation
  56. GRB 250602A: DDOTI Optical Upper Limit
  57. GRB 250530C: Swift-BAT refined analysis
  58. GRB 250601A: Swift/XRT candidate afterglow
  59. GRB 250601A: Swift-XRT observations
  60. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  61. GRB 250601A: Fermi GBM Final Real-time Localization
  62. EP#01709177494: SVOM/VT optical observations
  63. EP#01709177494: Swift-XRT counterpart detection of known source
  64. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  65. GRB 250530C: Swift-XRT refined Analysis
  66. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  67. GRB 250530C: Enhanced Swift-XRT position
  68. GRB 250530C: Swift detection of a burst
  69. GRB 250530A: EP-FXT counterpart detection
  70. GRB 250530A: SVOM/VT optical upper limit
  71. GRB 250530A: Swift-XRT counterpart detection
  72. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  73. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  74. GRB 250530A: SVOM detection of a burst
  75. GRB 250527C: Swift/UVOT Upper Limits
  76. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  77. GRB 250527B: Swift-XRT observations
  78. GRB 250520A: Swift-BAT refined analysis
  79. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  80. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  81. GRB 250527B / MAXI J1450-527 : MAXI/GSC detection
  82. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  83. GRB 250314A: CIDER NB1008 upper limit
  84. EP250526a: COLIBRÍ optical upper limits
  85. EP250526a: Einstein Probe detection of a fast X-ray transient
  86. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  87. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  88. GRB 250523A: BALROG localization (Fermi Trigger 769703188 / GRB 250523602)
  89. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  90. EP#01709176612: Swift-XRT counterpart detection of flaring star
  91. GRB 250521D: DDOTI Optical Upper Limit
  92. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. GRB 250521D: LAST tentative optical counterpart candidate
  94. GRB 250521A: DDOTI Optical Upper Limit
  95. GRB 250520A: VLT/FORS2 Optical Observation
  96. GRB 250502A: Tautenburg observations
  97. GRB 250520A: Swift/UVOT Upper Limits
  98. IPN triangulation of GRB 250516B
  99. GRB 250520A: J-band observations with WINTER
  100. GRB 250520A: Gemini-South optical observations

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