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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"

28282 results found.

  1. GRB 250502A: Early optical counterpart detection by LCO.
  2. GRB 250430A: Swift/UVOT Detection
  3. GRB 250502A: TRT optical afterglow confirmation
  4. GRB 250430A: Enhanced Swift-XRT position
  5. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  6. GRB 250502A: SVOM detection of a burst
  7. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  8. GRB 250430A: KAIT optical observations
  9. GRB 250430A / EP250430a: J-band upper limits with WINTER
  10. GRB 250430A: NUTTelA-TAO Early Measurements
  11. GRB 250430A: DDOTI Optical Observations
  12. GRB 250430A: Leavitt Observatory optical upper limit
  13. GRB 250430A: Bassano Bresciano Observatory upper limit
  14. GRB 250430A : MITSuME Akeno optical upper limits
  15. SVOM/sb25043004: EP-FXT observations
  16. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  17. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  18. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  19. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  20. GRB 250430A: AKO Optical Afterglow Detection
  21. GRB 250430A: Kanata optical upper limit
  22. EP 250427A: Optical counterpart detection by LCO.
  23. GRB 250430A: Swift detection of a burst with optical counterpart
  24. EP250427a/GRB250427A: HCT optical follow-up
  25. SVOM/sb25043004: SVOM detection of a X-ray transient
  26. EP250428b: GROWTH-India telescope optical upper limit
  27. EP250428b: SAO RAS optical upper limit
  28. EP250428b: LAST optical upper limit
  29. GRB 250427A: Swift/UVOT Detection
  30. EP250428b: Global MASTER-Net observations report
  31. EP250428b: Einstein Probe detection of a fast X-ray transient
  32. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  33. EP250427a: Lesedi optical counterpart detection
  34. EP250427A: COLIBRÍ Continuing Optical Observations
  35. GRB250427A/EP250427a GIT optical afterglow detection:
  36. EP250427a: LT optical counterpart detection
  37. GRB 250427A: Swift-XRT refined Analysis
  38. EP250427a / GRB 250427A: LCO optical counterpart detection
  39. EP250427a: REM optical/NIR afterglow detection
  40. GRB 250424A: LCO optical observation
  41. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  42. EP250427A: COLIBRÍ Optical Detection
  43. EP250427a: TRT optical counterpart detection
  44. EP250427a: Einstein Probe detection of a fast X-ray transient
  45. GRB 250424A: Swift-BAT refined analysis
  46. GRB 250424A: SVOM/GRM observation of a long burst
  47. GRB 250424A: PRIME near-infrared detection
  48. GRB 250424A: WINTER J-band detection
  49. GRB 250424A: EIRSAT-1 GMOD Detection
  50. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  51. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  52. GRB 250419A: Mondy Optical Observations
  53. GRB 250424A: Swift/UVOT Detection
  54. Fermi-LAT gamma-ray observations of IceCube-250421A
  55. GRB 250424A: Skynet Optical Observations
  56. GRB 250424A: Kilonova-Catcher optical afterglow detection
  57. GRB 250330B: GRBAlpha detection
  58. GRB 250424A: Swift-XRT refined Analysis
  59. GRB 250424A: Enhanced Swift-XRT position
  60. GRB 250424A: AstroSat CZTI detection of a bright long burst
  61. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  62. GRB 250424A: BlackGEM optical afterglow detection
  63. GRB 250424A: DDOTI Afterglow Detection
  64. GRB 250424A: REM optical/NIR afterglow detection
  65. GRB 250424A: Swift detection of a burst with an optical counterpart
  66. Swift GRB 250424A: Global MASTER-Net OT detection
  67. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  68. EP250421a: Nickel optical upper limit
  69. EP250421a: Upper limits from Fermi-GBM Observations
  70. SVOM/sb25042207: SVOM detection of an X-ray transient
  71. IceCube-250421A: DDOTI Detection of the LAST Candidate
  72. GRB 250419A: Mephisto Multi-band Optical Detection
  73. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  74. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  75. EP250421a: NOT optical observations
  76. GRB 250419A: Optical Observations via Virtual Telescope Project
  77. EP250421a: REM optical upper limit
  78. EP250421A: COLIBRÍ Optical Upper Limit
  79. GRB 250419A: Mondy Continued Optical Observations
  80. GRB 250421B: AstroSat CZTI detection of a bright long burst
  81. EP250421a: Einstein Probe detection of an X-ray transient
  82. EP250421a: Mephisto optical counterpart confirmation
  83. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  84. EP250421a: JinShan likely optical counterpart
  85. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  86. GRB 250419A: LCO optical observation
  87. GRB 250419A: JinShan optical observations
  88. GRB 250419A: SVOM/C-GFT optical observations
  89. GRB 250419A: Swift/UVOT Follow up
  90. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  91. GRB 250419A: LCO optical afterglow multi-band observations
  92. GRB 250419A: Mondy and AbAO Optical Observations
  93. GRB 250419A: AKO Optical Afterglow Detection
  94. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  95. GRB 250419A: Swift-XRT refined Analysis
  96. GRB 250419A: KAIT optical afterglow observations
  97. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  98. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  99. GRB 250419A: SVOM detection of a soft burst
  100. EP250416a: Swift/XRT counterpart fading

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