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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"

28285 results found.

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

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