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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"

24869 results found.

  1. GRB 250430A : MITSuME Akeno optical upper limits
  2. SVOM/sb25043004: EP-FXT observations
  3. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  4. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  5. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  6. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 250430A: AKO Optical Afterglow Detection
  8. GRB 250430A: Kanata optical upper limit
  9. EP 250427A: Optical counterpart detection by LCO.
  10. GRB 250430A: Swift detection of a burst with optical counterpart
  11. EP250427a/GRB250427A: HCT optical follow-up
  12. SVOM/sb25043004: SVOM detection of a X-ray transient
  13. EP250428b: GROWTH-India telescope optical upper limit
  14. EP250428b: SAO RAS optical upper limit
  15. EP250428b: LAST optical upper limit
  16. GRB 250427A: Swift/UVOT Detection
  17. EP250428b: Global MASTER-Net observations report
  18. EP250428b: Einstein Probe detection of a fast X-ray transient
  19. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  20. EP250427a: Lesedi optical counterpart detection
  21. EP250427A: COLIBRÍ Continuing Optical Observations
  22. GRB250427A/EP250427a GIT optical afterglow detection:
  23. EP250427a: LT optical counterpart detection
  24. GRB 250427A: Swift-XRT refined Analysis
  25. EP250427a / GRB 250427A: LCO optical counterpart detection
  26. EP250427a: REM optical/NIR afterglow detection
  27. GRB 250424A: LCO optical observation
  28. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  29. EP250427A: COLIBRÍ Optical Detection
  30. EP250427a: TRT optical counterpart detection
  31. EP250427a: Einstein Probe detection of a fast X-ray transient
  32. GRB 250424A: Swift-BAT refined analysis
  33. GRB 250424A: SVOM/GRM observation of a long burst
  34. GRB 250424A: PRIME near-infrared detection
  35. GRB 250424A: WINTER J-band detection
  36. GRB 250424A: EIRSAT-1 GMOD Detection
  37. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  38. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 250419A: Mondy Optical Observations
  40. GRB 250424A: Swift/UVOT Detection
  41. Fermi-LAT gamma-ray observations of IceCube-250421A
  42. GRB 250424A: Skynet Optical Observations
  43. GRB 250424A: Kilonova-Catcher optical afterglow detection
  44. GRB 250330B: GRBAlpha detection
  45. GRB 250424A: Swift-XRT refined Analysis
  46. GRB 250424A: Enhanced Swift-XRT position
  47. GRB 250424A: AstroSat CZTI detection of a bright long burst
  48. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  49. GRB 250424A: BlackGEM optical afterglow detection
  50. GRB 250424A: DDOTI Afterglow Detection
  51. GRB 250424A: REM optical/NIR afterglow detection
  52. GRB 250424A: Swift detection of a burst with an optical counterpart
  53. Swift GRB 250424A: Global MASTER-Net OT detection
  54. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  55. EP250421a: Nickel optical upper limit
  56. EP250421a: Upper limits from Fermi-GBM Observations
  57. SVOM/sb25042207: SVOM detection of an X-ray transient
  58. IceCube-250421A: DDOTI Detection of the LAST Candidate
  59. GRB 250419A: Mephisto Multi-band Optical Detection
  60. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  61. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  62. EP250421a: NOT optical observations
  63. GRB 250419A: Optical Observations via Virtual Telescope Project
  64. EP250421a: REM optical upper limit
  65. EP250421A: COLIBRÍ Optical Upper Limit
  66. GRB 250419A: Mondy Continued Optical Observations
  67. GRB 250421B: AstroSat CZTI detection of a bright long burst
  68. EP250421a: Einstein Probe detection of an X-ray transient
  69. EP250421a: Mephisto optical counterpart confirmation
  70. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  71. EP250421a: JinShan likely optical counterpart
  72. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  73. GRB 250419A: LCO optical observation
  74. GRB 250419A: JinShan optical observations
  75. GRB 250419A: SVOM/C-GFT optical observations
  76. GRB 250419A: Swift/UVOT Follow up
  77. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  78. GRB 250419A: LCO optical afterglow multi-band observations
  79. GRB 250419A: Mondy and AbAO Optical Observations
  80. GRB 250419A: AKO Optical Afterglow Detection
  81. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  82. GRB 250419A: Swift-XRT refined Analysis
  83. GRB 250419A: KAIT optical afterglow observations
  84. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  85. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  86. GRB 250419A: SVOM detection of a soft burst
  87. EP250416a: Swift/XRT counterpart fading
  88. EP20250416a: Swift/XRT counterpart detection
  89. IceCube-250416A: DDOTI Optical Observations
  90. EP250416a: Gemini South-GMOS optical counterpart
  91. SVOM/sb25041603 is not a GRB
  92. EP250416a: GSP optical upper limit
  93. EP250416a: Einstein Probe detection of an X-ray transient
  94. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  95. SVOM/sb25041603: SVOM detection of an X-ray transient
  96. IceCube 250414.324: DDOTI Optical Observations
  97. GRB 250413A: AstroSat CZTI detection
  98. EP250304a: ATCA radio observations
  99. EP250404a: Nanshan 0.43m Telescope optical observatios
  100. GRB 250411A: DDOTI Optical Observations

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