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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').
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"

24772 results found.

  1. GRB 250430A: Bassano Bresciano Observatory upper limit
  2. GRB 250430A : MITSuME Akeno optical upper limits
  3. SVOM/sb25043004: EP-FXT observations
  4. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  5. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  6. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  7. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 250430A: AKO Optical Afterglow Detection
  9. GRB 250430A: Kanata optical upper limit
  10. EP 250427A: Optical counterpart detection by LCO.
  11. GRB 250430A: Swift detection of a burst with optical counterpart
  12. EP250427a/GRB250427A: HCT optical follow-up
  13. SVOM/sb25043004: SVOM detection of a X-ray transient
  14. EP250428b: GROWTH-India telescope optical upper limit
  15. EP250428b: SAO RAS optical upper limit
  16. EP250428b: LAST optical upper limit
  17. GRB 250427A: Swift/UVOT Detection
  18. EP250428b: Global MASTER-Net observations report
  19. EP250428b: Einstein Probe detection of a fast X-ray transient
  20. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  21. EP250427a: Lesedi optical counterpart detection
  22. EP250427A: COLIBRÍ Continuing Optical Observations
  23. GRB250427A/EP250427a GIT optical afterglow detection:
  24. EP250427a: LT optical counterpart detection
  25. GRB 250427A: Swift-XRT refined Analysis
  26. EP250427a / GRB 250427A: LCO optical counterpart detection
  27. EP250427a: REM optical/NIR afterglow detection
  28. GRB 250424A: LCO optical observation
  29. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  30. EP250427A: COLIBRÍ Optical Detection
  31. EP250427a: TRT optical counterpart detection
  32. EP250427a: Einstein Probe detection of a fast X-ray transient
  33. GRB 250424A: Swift-BAT refined analysis
  34. GRB 250424A: SVOM/GRM observation of a long burst
  35. GRB 250424A: PRIME near-infrared detection
  36. GRB 250424A: WINTER J-band detection
  37. GRB 250424A: EIRSAT-1 GMOD Detection
  38. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  39. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  40. GRB 250419A: Mondy Optical Observations
  41. GRB 250424A: Swift/UVOT Detection
  42. Fermi-LAT gamma-ray observations of IceCube-250421A
  43. GRB 250424A: Skynet Optical Observations
  44. GRB 250424A: Kilonova-Catcher optical afterglow detection
  45. GRB 250330B: GRBAlpha detection
  46. GRB 250424A: Swift-XRT refined Analysis
  47. GRB 250424A: Enhanced Swift-XRT position
  48. GRB 250424A: AstroSat CZTI detection of a bright long burst
  49. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  50. GRB 250424A: BlackGEM optical afterglow detection
  51. GRB 250424A: DDOTI Afterglow Detection
  52. GRB 250424A: REM optical/NIR afterglow detection
  53. GRB 250424A: Swift detection of a burst with an optical counterpart
  54. Swift GRB 250424A: Global MASTER-Net OT detection
  55. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  56. EP250421a: Nickel optical upper limit
  57. EP250421a: Upper limits from Fermi-GBM Observations
  58. SVOM/sb25042207: SVOM detection of an X-ray transient
  59. IceCube-250421A: DDOTI Detection of the LAST Candidate
  60. GRB 250419A: Mephisto Multi-band Optical Detection
  61. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  62. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  63. EP250421a: NOT optical observations
  64. GRB 250419A: Optical Observations via Virtual Telescope Project
  65. EP250421a: REM optical upper limit
  66. EP250421A: COLIBRÍ Optical Upper Limit
  67. GRB 250419A: Mondy Continued Optical Observations
  68. GRB 250421B: AstroSat CZTI detection of a bright long burst
  69. EP250421a: Einstein Probe detection of an X-ray transient
  70. EP250421a: Mephisto optical counterpart confirmation
  71. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  72. EP250421a: JinShan likely optical counterpart
  73. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  74. GRB 250419A: LCO optical observation
  75. GRB 250419A: JinShan optical observations
  76. GRB 250419A: SVOM/C-GFT optical observations
  77. GRB 250419A: Swift/UVOT Follow up
  78. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  79. GRB 250419A: LCO optical afterglow multi-band observations
  80. GRB 250419A: Mondy and AbAO Optical Observations
  81. GRB 250419A: AKO Optical Afterglow Detection
  82. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  83. GRB 250419A: Swift-XRT refined Analysis
  84. GRB 250419A: KAIT optical afterglow observations
  85. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  86. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  87. GRB 250419A: SVOM detection of a soft burst
  88. EP250416a: Swift/XRT counterpart fading
  89. EP20250416a: Swift/XRT counterpart detection
  90. IceCube-250416A: DDOTI Optical Observations
  91. EP250416a: Gemini South-GMOS optical counterpart
  92. SVOM/sb25041603 is not a GRB
  93. EP250416a: GSP optical upper limit
  94. EP250416a: Einstein Probe detection of an X-ray transient
  95. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  96. SVOM/sb25041603: SVOM detection of an X-ray transient
  97. IceCube 250414.324: DDOTI Optical Observations
  98. GRB 250413A: AstroSat CZTI detection
  99. EP250304a: ATCA radio observations
  100. EP250404a: Nanshan 0.43m Telescope optical observatios

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