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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"

28103 results found.

  1. sb25061207: EP-FXT follow-up observation and afterglow candidate
  2. GRB 250612B: Fermi GBM Observation
  3. EP250612a: SVOM/VT optical candidate
  4. GRB 250612C: Fermi GBM Observation
  5. sb25061218: SVOM detection of a X-ray transient
  6. sb25061207: Swift-XRT observations
  7. EP250612a/GRB 250612B: JinShan optical upper limit
  8. sb25061207: SVOM/VT optical counterpart
  9. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  10. GRB 250610B: Swift-XRT refined Analysis
  11. EP250610a: Upper limit from Fermi-GBM Observations
  12. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  13. EP250612a: Einstein Probe detection of an X-ray transient
  14. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  15. sb25061207: SVOM detection of a X-ray transient
  16. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  17. Fermi GBM Sub-Threshold Detection of GRB 250610B
  18. GRB 250610B: Swift/UVOT Detection
  19. EP250610A: Swift/UVOT Upper limits
  20. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  21. EP250610a: TNG NIR upper limit
  22. GRB 250610B: REM optical/NIR observations
  23. EP250610a: Liverpool Telescope optical upper limits
  24. GRB 250610B: additional Liverpool Telescope optical observations
  25. GRB 250610B: SVOM/GRM analysis
  26. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  27. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  28. GRB 250610B: Swift-XRT counterpart detection
  29. GRB 250610B: SVOM/VT optical counterpart
  30. GRB 250610B: OHP/T120 optical counterpart candidate
  31. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  32. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  33. GRB 250605A: Swift-BAT refined analysis
  34. EP250610a: SVOM/VT optical upper limit
  35. EP250610a: REM optical/NIR observations
  36. GRB 250609A: Fermi GBM Observation
  37. EP250610a: Swift-XRT counterpart detection
  38. EP250610a: COLIBRÍ optical upper limit
  39. EP250610a: Einstein Probe detection of an X-ray transient
  40. Fermi trigger No 771072240: Global MASTER-Net observations report
  41. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  42. GRB 250605A: Swift/UVOT Upper Limits
  43. GRB 250527C: CrAO Optical Upper Limit
  44. GRB 250607A: SVOM/GRM observation of a long burst
  45. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  46. GRB 250605A: Swift-XRT refined Analysis
  47. GRB 250605A: Enhanced Swift-XRT position
  48. GRB 250605A: Swift detection of a burst
  49. IPN triangulation of GRB 250404B
  50. IPN triangulation of GRB 250529A
  51. GRB 250601A: PRIME H band upper limit.
  52. GRB 250601A: PRIME J band upper limit.
  53. GRB 250601A: VLT/FORS2 Optical Observation
  54. GRB 250601A: Fermi GBM Observation
  55. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  56. GRB 250603A: Swift/UVOT Upper Limits
  57. GRB 250603A: Swift-XRT refined Analysis
  58. GRB 250603A: Enhanced Swift-XRT position
  59. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  60. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  61. GRB 250602A: Fermi GBM Observation
  62. GRB 250602A: DDOTI Optical Upper Limit
  63. GRB 250530C: Swift-BAT refined analysis
  64. GRB 250601A: Swift/XRT candidate afterglow
  65. GRB 250601A: Swift-XRT observations
  66. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  67. GRB 250601A: Fermi GBM Final Real-time Localization
  68. EP#01709177494: SVOM/VT optical observations
  69. EP#01709177494: Swift-XRT counterpart detection of known source
  70. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  71. GRB 250530C: Swift-XRT refined Analysis
  72. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  73. GRB 250530C: Enhanced Swift-XRT position
  74. GRB 250530C: Swift detection of a burst
  75. GRB 250530A: EP-FXT counterpart detection
  76. GRB 250530A: SVOM/VT optical upper limit
  77. GRB 250530A: Swift-XRT counterpart detection
  78. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  79. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  80. GRB 250530A: SVOM detection of a burst
  81. GRB 250527C: Swift/UVOT Upper Limits
  82. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  83. GRB 250527B: Swift-XRT observations
  84. GRB 250520A: Swift-BAT refined analysis
  85. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  86. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  87. GRB 250527B / MAXI J1450-527 : MAXI/GSC detection
  88. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  89. GRB 250314A: CIDER NB1008 upper limit
  90. EP250526a: COLIBRÍ optical upper limits
  91. EP250526a: Einstein Probe detection of a fast X-ray transient
  92. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  93. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  94. GRB 250523A: BALROG localization (Fermi Trigger 769703188 / GRB 250523602)
  95. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  96. EP#01709176612: Swift-XRT counterpart detection of flaring star
  97. GRB 250521D: DDOTI Optical Upper Limit
  98. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. GRB 250521D: LAST tentative optical counterpart candidate
  100. GRB 250521A: DDOTI Optical Upper Limit

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