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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"

27924 results found.

  1. GRB 250502a: Liverpool Telescope optical follow-up
  2. GRB 250502B: AstroSat CZTI detection
  3. GRB 250502A: AKO Optical Afterglow Detection
  4. GRB 250502A: LCO optical counterpart detection
  5. GRB 250502A: Swift ToO observations
  6. GRB 250502C: Fermi GBM Final Localization
  7. GRB 250407A: VZLUSAT-2 detection
  8. GRB 250430A: Swift-XRT refined Analysis
  9. GRB 250502A: Early optical counterpart detection by LCO.
  10. GRB 250430A: Swift/UVOT Detection
  11. GRB 250430A: Enhanced Swift-XRT position
  12. GRB 250430A: Optical Observations via Virtual Telescope Project, Italy
  13. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  14. GRB 250502B: Fermi GBM Final Real-time Localization
  15. GRB 250502A: SVOM detection of a burst
  16. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  17. EP250428b: Pan-STARRS follow-up, upper limit on the optical counterpart, and possible host galaxy.
  18. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  19. GRB 250430A: DDOTI Optical Observations
  20. GRB 250430A: Leavitt Observatory optical upper limit
  21. GRB 250430A: Bassano Bresciano Observatory upper limit
  22. GRB 250430A : MITSuME Akeno optical upper limits
  23. GRB 250430A / EP250430a: VLT/X-shooter spectroscopic redshift z = 0.767
  24. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  25. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  26. GRB 250430A: AKO Optical Afterglow Detection
  27. EP 250427A: Optical counterpart detection by LCO.
  28. GRB 250430A: Swift detection of a burst with optical counterpart
  29. Swift GRB250430.73: Global MASTER-Net observations report
  30. SVOM/sb25043004: SVOM detection of a X-ray transient
  31. EP250428b: refined analysis of the EP-FXT follow-up observation
  32. IceCube-250429A - IceCube observation of a high-energy neutrino candidate track-like event
  33. GRB 250427A: Swift/UVOT Detection
  34. EP250428b: Einstein Probe detection of a fast X-ray transient
  35. EP250427a: EP-FXT follow-up observations
  36. EP250427a: Lesedi optical counterpart detection
  37. GRB250427A/EP250427a GIT optical afterglow detection:
  38. EP250427a: LT optical counterpart detection
  39. GRB 250427A: Swift-XRT refined Analysis
  40. EP250427a / GRB 250427A: LCO optical counterpart detection
  41. EP250427a / GRB 250427A: VLT/X-shooter redshift confirmation z = 1.520
  42. EP250427a: REM optical/NIR afterglow detection
  43. GRB 250424A: LCO optical observation
  44. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  45. EP250427A: COLIBRÍ Optical Detection
  46. EP250427a: TRT optical counterpart detection
  47. EP 250427a: BOOTES-7 optical afterglow candidate
  48. EP250427a: Einstein Probe detection of a fast X-ray transient
  49. GRB 250424A: Swift-BAT refined analysis
  50. IceCube-250426A - IceCube observation of a high-energy neutrino candidate track-like event
  51. GRB 250424A: SVOM/GRM observation of a long burst
  52. GRB 250424A: PRIME near-infrared detection
  53. GRB 250424A: WINTER J-band detection
  54. GRB 250424A: EIRSAT-1 GMOD Detection
  55. GRB 250424A: Swift/UVOT Detection
  56. Konus-Wind detection of GRB 250424A
  57. GRB 250424A: Skynet Optical Observations
  58. GRB 250424A: Kilonova-Catcher optical afterglow detection
  59. GRB 250419a: Continued Liverpool Telescope observations
  60. GRB 250407A: GRBAlpha detection
  61. GRB 250404A / EP250404a: GRBAlpha detection
  62. GRB 250330B: GRBAlpha detection
  63. GRB 250424A: Swift-XRT refined Analysis
  64. GRB 250424A: Enhanced Swift-XRT position
  65. GRB 250424A: AstroSat CZTI detection of a bright long burst
  66. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  67. GRB 250424A: BlackGEM optical afterglow detection
  68. GRB 250424A: VLT/X-shooter spectroscopic redshift z = 0.310
  69. GRB 250424A: likely host galaxy
  70. GRB 250424A: DDOTI Afterglow Detection
  71. GRB 250424A: REM optical/NIR afterglow detection
  72. GRB 250424A: Swift detection of a burst with an optical counterpart
  73. Swift GRB 250424A: Global MASTER-Net observations report
  74. Swift GRB 250424A: Global MASTER-Net OT detection
  75. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  76. SVOM/sb25042207: XRT observations
  77. SVOM/sb25042207: BOOTES-2 early optical upper limit
  78. GRB 250421A: AstroSat CZTI detection
  79. SVOM/sb25042207: SVOM detection of an X-ray transient
  80. GRB250419A: VLA radio detection
  81. IceCube-250421A: DDOTI Detection of the LAST Candidate
  82. GRB 250419A: Mephisto Multi-band Optical Detection
  83. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  84. EP250421a: NOT optical observations
  85. GRB 250419A: Optical Observations via Virtual Telescope Project
  86. EP250421a: Swift/XRT counterpart detection
  87. GRB 250421B: AstroSat CZTI detection of a bright long burst
  88. EP250421a: Einstein Probe detection of an X-ray transient
  89. EP250421a: Mephisto optical counterpart confirmation
  90. IceCube-250421A - IceCube observation of a high-energy neutrino candidate track-like event
  91. GRB 250421A: Fermi GBM Final Real-time Localization
  92. GRB 250419A: Liverpool Telescope observations
  93. GRB 250419A: Swift/UVOT Follow up
  94. GRB 250419A: LCO optical afterglow multi-band observations
  95. GRB 250419A: Mondy and AbAO Optical Observations
  96. GRB 250419A: AKO Optical Afterglow Detection
  97. GRB 250419A: Swift-XRT localisation
  98. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  99. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  100. GRB 250419A: Swift-XRT refined Analysis

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