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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"

28291 results found.

  1. GRB 250502A: Swift-XRT afterglow detection
  2. GRB 250502A: NOT optical observations
  3. GRB 250502B: AstroSat CZTI detection
  4. GRB 250502A: AKO Optical Afterglow Detection
  5. GRB 250502A: LCO optical counterpart detection
  6. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  7. GRB 250407A: VZLUSAT-2 detection
  8. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  9. GRB 250502B: DDOTI Optical Observations
  10. GRB 250430A: Swift-XRT refined Analysis
  11. GRB 250502A: Early optical counterpart detection by LCO.
  12. GRB 250430A: Swift/UVOT Detection
  13. GRB 250502A: TRT optical afterglow confirmation
  14. GRB 250430A: Enhanced Swift-XRT position
  15. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  16. GRB 250502A: SVOM detection of a burst
  17. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  18. GRB 250430A: KAIT optical observations
  19. GRB 250430A / EP250430a: J-band upper limits with WINTER
  20. GRB 250430A: NUTTelA-TAO Early Measurements
  21. GRB 250430A: DDOTI Optical Observations
  22. GRB 250430A: Leavitt Observatory optical upper limit
  23. GRB 250430A: Bassano Bresciano Observatory upper limit
  24. GRB 250430A : MITSuME Akeno optical upper limits
  25. SVOM/sb25043004: EP-FXT observations
  26. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  27. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  28. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  29. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 250430A: AKO Optical Afterglow Detection
  31. GRB 250430A: Kanata optical upper limit
  32. EP 250427A: Optical counterpart detection by LCO.
  33. GRB 250430A: Swift detection of a burst with optical counterpart
  34. EP250427a/GRB250427A: HCT optical follow-up
  35. SVOM/sb25043004: SVOM detection of a X-ray transient
  36. EP250428b: GROWTH-India telescope optical upper limit
  37. EP250428b: SAO RAS optical upper limit
  38. EP250428b: LAST optical upper limit
  39. GRB 250427A: Swift/UVOT Detection
  40. EP250428b: Global MASTER-Net observations report
  41. EP250428b: Einstein Probe detection of a fast X-ray transient
  42. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  43. EP250427a: Lesedi optical counterpart detection
  44. EP250427A: COLIBRÍ Continuing Optical Observations
  45. GRB250427A/EP250427a GIT optical afterglow detection:
  46. EP250427a: LT optical counterpart detection
  47. GRB 250427A: Swift-XRT refined Analysis
  48. EP250427a / GRB 250427A: LCO optical counterpart detection
  49. EP250427a: REM optical/NIR afterglow detection
  50. GRB 250424A: LCO optical observation
  51. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  52. EP250427A: COLIBRÍ Optical Detection
  53. EP250427a: TRT optical counterpart detection
  54. EP250427a: Einstein Probe detection of a fast X-ray transient
  55. GRB 250424A: Swift-BAT refined analysis
  56. GRB 250424A: SVOM/GRM observation of a long burst
  57. GRB 250424A: PRIME near-infrared detection
  58. GRB 250424A: WINTER J-band detection
  59. GRB 250424A: EIRSAT-1 GMOD Detection
  60. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  61. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  62. GRB 250419A: Mondy Optical Observations
  63. GRB 250424A: Swift/UVOT Detection
  64. Fermi-LAT gamma-ray observations of IceCube-250421A
  65. GRB 250424A: Skynet Optical Observations
  66. GRB 250424A: Kilonova-Catcher optical afterglow detection
  67. GRB 250330B: GRBAlpha detection
  68. GRB 250424A: Swift-XRT refined Analysis
  69. GRB 250424A: Enhanced Swift-XRT position
  70. GRB 250424A: AstroSat CZTI detection of a bright long burst
  71. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  72. GRB 250424A: BlackGEM optical afterglow detection
  73. GRB 250424A: DDOTI Afterglow Detection
  74. GRB 250424A: REM optical/NIR afterglow detection
  75. GRB 250424A: Swift detection of a burst with an optical counterpart
  76. Swift GRB 250424A: Global MASTER-Net OT detection
  77. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  78. EP250421a: Nickel optical upper limit
  79. EP250421a: Upper limits from Fermi-GBM Observations
  80. SVOM/sb25042207: SVOM detection of an X-ray transient
  81. IceCube-250421A: DDOTI Detection of the LAST Candidate
  82. GRB 250419A: Mephisto Multi-band Optical Detection
  83. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  84. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  85. EP250421a: NOT optical observations
  86. GRB 250419A: Optical Observations via Virtual Telescope Project
  87. EP250421a: REM optical upper limit
  88. EP250421A: COLIBRÍ Optical Upper Limit
  89. GRB 250419A: Mondy Continued Optical Observations
  90. GRB 250421B: AstroSat CZTI detection of a bright long burst
  91. EP250421a: Einstein Probe detection of an X-ray transient
  92. EP250421a: Mephisto optical counterpart confirmation
  93. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  94. EP250421a: JinShan likely optical counterpart
  95. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  96. GRB 250419A: LCO optical observation
  97. GRB 250419A: JinShan optical observations
  98. GRB 250419A: SVOM/C-GFT optical observations
  99. GRB 250419A: Swift/UVOT Follow up
  100. GRB 250416C / EP250416a: SVOM/GRM observation of a burst

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