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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"

32717 results found.

  1. EP250612a: Global MASTER-Net observations report
  2. GRB 250612C: Fermi GBM Observation
  3. sb25061207: Swift-XRT observations
  4. EP250612a/GRB 250612B: JinShan optical upper limit
  5. EP 250612a: AST3-3 Yaoan Optical Observation
  6. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  7. sb25061207: SVOM/VT optical counterpart
  8. EP250610a: Upper limit from Fermi-GBM Observations
  9. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  10. GRB 250610B: Liverpool Telescope continued monitoring
  11. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  12. EP250610a: continuous follow-up observations with EP-FXT
  13. GRB 250610B - SVOM/ECLAIRs refined analysis
  14. Fermi GBM Sub-Threshold Detection of GRB 250610B
  15. GRB 250610B: Swift/UVOT Detection
  16. EP250610A: Swift/UVOT Upper limits
  17. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  18. EP250610a: TNG NIR upper limit
  19. GRB 250610B: REM optical/NIR observations
  20. EP250610a: Liverpool Telescope optical upper limits
  21. GRB 250610B: SVOM/VT optical shallow decay
  22. GRB 250610B: additional Liverpool Telescope optical observations
  23. GRB 250610B: SVOM/GRM analysis
  24. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  25. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  26. GRB 250610B: Swift-XRT counterpart detection
  27. GRB 250610B: SVOM/VT optical counterpart
  28. GRB 250610B: LT detection of the optical counterpart
  29. GRB 250610B: OHP/T120 optical counterpart candidate
  30. GRB 250610B: GOTO optical upper limit
  31. EP250610a: Global MASTER-Net observations report
  32. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  33. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  34. GRB 250605A: Swift-BAT refined analysis
  35. EP250610a: SVOM/VT optical upper limit
  36. EP250610a: REM optical/NIR observations
  37. GRB 250609A: Fermi GBM Observation
  38. EP250610a: COLIBRÍ optical upper limit
  39. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  40. GRB 250605A: Swift/UVOT Upper Limits
  41. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  42. GRB 250527C: CrAO Optical Upper Limit
  43. GRB 250607A: SVOM/GRM observation of a long burst
  44. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  45. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  46. GRB 250605A: SVOM/VT optical upper limit
  47. Fermi GRB 250606A: Global MASTER-Net observations report
  48. GRB 250602A: GECAM detection
  49. GRB 250605A: LT optical observations
  50. Konus-Wind detection of GRB 250601A
  51. IPN triangulation of GRB 250404B
  52. IPN triangulation of GRB 250529A
  53. GRB 250601A: PRIME H band upper limit.
  54. GRB 250530A: SVOM/GRM analysis
  55. GRB 250601A: PRIME J band upper limit.
  56. GRB 250601A: VLT/FORS2 Optical Observation
  57. GRB 250601A: Fermi GBM Observation
  58. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  59. GRB 250603A: Swift/UVOT Upper Limits
  60. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  61. GRB 250602A: Fermi GBM Observation
  62. GRB 250602A: Fermi-LAT detection
  63. GRB 250602A: DDOTI Optical Upper Limit
  64. GRB 250530C: Swift-BAT refined analysis
  65. GRB 250521C: NOT spectroscopic observations exclude the afterglow candidate AT2025mgj
  66. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  67. GRB 250601A: Swift/XRT candidate afterglow
  68. GRB 250521C / AT2025mgj: Pan-STARRS multi-band and multi-epoch imaging and photometry
  69. Fermi GRB 250601A: Global MASTER-Net observations report
  70. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  71. GRB 250601A: Swift ToO observations
  72. GRB 250530A: VLT/HAWK-I NIR counterpart fading
  73. GRB 250521C/AT2025mgj: FTW optical and NIR observations
  74. EP#01709177494: SVOM/VT optical observations
  75. Fermi GRB 250531A: Global MASTER-Net observations report
  76. GRB 250530C: BOOTES-7 optical upper limit
  77. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  78. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  79. Swift GRB 250530C: Global MASTER-Net observations report
  80. GRB 250521C/AT2025mgj: NOT optical observations of the afterglow candidate
  81. GRB 250530A: EP-FXT counterpart detection
  82. GRB 250530A: SVOM/VT optical upper limit
  83. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  84. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  85. GRB 250527D: CALET Gamma-Ray Burst Monitor detection
  86. GRB 250527C: Swift/UVOT Upper Limits
  87. EP J1350.0-8622: EP-FXT follow-up observation
  88. EP-WXT trigger 01709177124: confirmation of a stellar flare by BOOTES-6
  89. GRB 250521C (short): Zwicky Transient Facility identification of a possible fast optical transient counterpart
  90. GRB 250520A: Swift-BAT refined analysis
  91. GRB 250527C: Swift ToO observations
  92. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  93. EP250526a: SVOM/VT optical upper limit
  94. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  95. GRB 250527B: Tiled Swift observations
  96. GRB 250520A: Gemini-South optical afterglow detection
  97. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  98. GRB 250314A: CIDER NB1008 upper limit
  99. EP250526a: COLIBRÍ optical upper limits
  100. EP250526a: Global MASTER-Net observations report

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