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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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').
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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"

28051 results found.

  1. EP250428b: Einstein Probe detection of a fast X-ray transient
  2. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  3. EP250427a: Lesedi optical counterpart detection
  4. EP250427A: COLIBRÍ Continuing Optical Observations
  5. GRB250427A/EP250427a GIT optical afterglow detection:
  6. EP250427a: LT optical counterpart detection
  7. GRB 250427A: Swift-XRT refined Analysis
  8. EP250427a / GRB 250427A: LCO optical counterpart detection
  9. EP250427a: REM optical/NIR afterglow detection
  10. GRB 250424A: LCO optical observation
  11. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  12. EP250427A: COLIBRÍ Optical Detection
  13. EP250427a: TRT optical counterpart detection
  14. EP250427a: Einstein Probe detection of a fast X-ray transient
  15. GRB 250424A: Swift-BAT refined analysis
  16. GRB 250424A: SVOM/GRM observation of a long burst
  17. GRB 250424A: PRIME near-infrared detection
  18. GRB 250424A: WINTER J-band detection
  19. GRB 250424A: EIRSAT-1 GMOD Detection
  20. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  21. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  22. GRB 250419A: Mondy Optical Observations
  23. GRB 250424A: Swift/UVOT Detection
  24. Fermi-LAT gamma-ray observations of IceCube-250421A
  25. GRB 250424A: Skynet Optical Observations
  26. GRB 250424A: Kilonova-Catcher optical afterglow detection
  27. GRB 250330B: GRBAlpha detection
  28. GRB 250424A: Swift-XRT refined Analysis
  29. GRB 250424A: Enhanced Swift-XRT position
  30. GRB 250424A: AstroSat CZTI detection of a bright long burst
  31. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  32. GRB 250424A: BlackGEM optical afterglow detection
  33. GRB 250424A: DDOTI Afterglow Detection
  34. GRB 250424A: REM optical/NIR afterglow detection
  35. GRB 250424A: Swift detection of a burst with an optical counterpart
  36. Swift GRB 250424A: Global MASTER-Net OT detection
  37. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  38. EP250421a: Nickel optical upper limit
  39. EP250421a: Upper limits from Fermi-GBM Observations
  40. SVOM/sb25042207: SVOM detection of an X-ray transient
  41. IceCube-250421A: DDOTI Detection of the LAST Candidate
  42. GRB 250419A: Mephisto Multi-band Optical Detection
  43. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  44. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  45. EP250421a: NOT optical observations
  46. GRB 250419A: Optical Observations via Virtual Telescope Project
  47. EP250421a: REM optical upper limit
  48. EP250421A: COLIBRÍ Optical Upper Limit
  49. GRB 250419A: Mondy Continued Optical Observations
  50. GRB 250421B: AstroSat CZTI detection of a bright long burst
  51. EP250421a: Einstein Probe detection of an X-ray transient
  52. EP250421a: Mephisto optical counterpart confirmation
  53. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  54. EP250421a: JinShan likely optical counterpart
  55. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  56. GRB 250419A: LCO optical observation
  57. GRB 250419A: JinShan optical observations
  58. GRB 250419A: SVOM/C-GFT optical observations
  59. GRB 250419A: Swift/UVOT Follow up
  60. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  61. GRB 250419A: LCO optical afterglow multi-band observations
  62. GRB 250419A: Mondy and AbAO Optical Observations
  63. GRB 250419A: AKO Optical Afterglow Detection
  64. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  65. GRB 250419A: Swift-XRT refined Analysis
  66. GRB 250419A: KAIT optical afterglow observations
  67. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  68. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  69. GRB 250419A: SVOM detection of a soft burst
  70. EP250416a: Swift/XRT counterpart fading
  71. EP20250416a: Swift/XRT counterpart detection
  72. IceCube-250416A: DDOTI Optical Observations
  73. EP250416a: Gemini South-GMOS optical counterpart
  74. SVOM/sb25041603 is not a GRB
  75. EP250416a: GSP optical upper limit
  76. EP250416a: Einstein Probe detection of an X-ray transient
  77. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  78. SVOM/sb25041603: SVOM detection of an X-ray transient
  79. IceCube 250414.324: DDOTI Optical Observations
  80. GRB 250413A: AstroSat CZTI detection
  81. EP250304a: ATCA radio observations
  82. EP250404a: Nanshan 0.43m Telescope optical observatios
  83. GRB 250411A: DDOTI Optical Observations
  84. Fermi GRB 250411A: Global MASTER-Net observations report
  85. GRB 250407A: Continued KAIT/Nickel optical observations
  86. GRB 250314A: e-MERLIN observations
  87. GRB 250407A: Mondy and AbAO Optical Observations
  88. EP250227a: Further NOT optical observations
  89. GRB 250320B: cubesat Avion detection
  90. IceCube-250406A: Swift-XRT observations
  91. GRB 250407A: LCO detection of a fading optical counterpart
  92. Fermi-LAT gamma-ray observations of IceCube-250406A
  93. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 250407A: SVOM/GRM observation of a bright long burst
  95. GRB 250407A: EP-WXT afterglow detection
  96. EP250407a: EP-WXT detection of a fast X-ray transient
  97. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  98. GRB 250407A: KAIT Optical Afterglow Candidate
  99. IceCube-250406A: No candidates from the Zwicky Transient Facility
  100. GRB 250407A: Fermi GBM Detection

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