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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').
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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"
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submitter:"Judith Racusin"

21907 results found.

  1. GRB 250424A: WINTER J-band detection
  2. GRB 250419A: Mondy Optical Observations
  3. GRB 250424A: Swift/UVOT Detection
  4. Konus-Wind detection of GRB 250424A
  5. GRB 250424A: Skynet Optical Observations
  6. GRB 250424A: Kilonova-Catcher optical afterglow detection
  7. GRB 250407A: GRBAlpha detection
  8. GRB 250404A / EP250404a: GRBAlpha detection
  9. GRB 250330B: GRBAlpha detection
  10. GRB 250419A: SVOM/ECLAIRs refined analysis
  11. GRB 250424A: Enhanced Swift-XRT position
  12. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  13. GRB 250424A: BlackGEM optical afterglow detection
  14. GRB 250424A: DDOTI Afterglow Detection
  15. GRB 250424A: REM optical/NIR afterglow detection
  16. GRB 250424A: Swift detection of a burst with an optical counterpart
  17. Swift GRB 250424A: Global MASTER-Net OT detection
  18. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  19. EP250421a: Nickel optical upper limit
  20. SVOM/sb25042207: XRT observations
  21. SVOM/sb25042207: GOTO optical upper limits
  22. GRB 250421A: AstroSat CZTI detection
  23. SVOM/sb25042207: SVOM detection of an X-ray transient
  24. IceCube-250421A: DDOTI Detection of the LAST Candidate
  25. GRB 250419A: Mephisto Multi-band Optical Detection
  26. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  27. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  28. EP250421a: NOT optical observations
  29. GRB 250419A: Optical Observations via Virtual Telescope Project
  30. EP250421a: REM optical upper limit
  31. EP250421A: COLIBRÍ Optical Upper Limit
  32. GRB 250419A: Mondy Continued Optical Observations
  33. EP250421a: Einstein Probe detection of an X-ray transient
  34. EP250421a: Mephisto optical counterpart confirmation
  35. EP250421a: JinShan likely optical counterpart
  36. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  37. GRB 250419A: LCO optical observation
  38. GRB 250419A: JinShan optical observations
  39. GRB 250419A: SVOM/C-GFT optical observations
  40. GRB 250419A: Swift/UVOT Follow up
  41. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  42. GRB 250419A: LCO optical afterglow multi-band observations
  43. GRB 250419A: Mondy and AbAO Optical Observations
  44. GRB 250419A: AKO Optical Afterglow Detection
  45. GRB 250419A: KAIT optical afterglow observations
  46. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  47. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  48. GRB 250419A: SVOM detection of a soft burst
  49. EP20250416a: Swift/XRT counterpart detection
  50. IceCube-250416A: DDOTI Optical Observations
  51. EP250416a: Gemini South-GMOS optical counterpart
  52. SVOM/sb25041603 is not a GRB
  53. EP250416a: Einstein Probe detection of an X-ray transient
  54. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  55. SVOM/sb25041603: SVOM detection of an X-ray transient
  56. IceCube 250414.324: DDOTI Optical Observations
  57. EP250404a: Nanshan 0.43m Telescope optical observatios
  58. GRB 250411A: DDOTI Optical Observations
  59. GRB 250314A: e-MERLIN observations
  60. GRB 250407A: Mondy and AbAO Optical Observations
  61. EP250227a: Further NOT optical observations
  62. GRB 250320B: cubesat Avion detection
  63. IceCube-250406A: Swift-XRT observations
  64. EP250407a: Global MASTER-Net observations report
  65. GRB 250407A: LCO detection of a fading optical counterpart
  66. GRB 250407A: SVOM/GRM observation of a bright long burst
  67. GRB 250407A: EP-WXT afterglow detection
  68. EP250407a: EP-WXT detection of a fast X-ray transient
  69. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  70. GRB 250407A: KAIT Optical Afterglow Candidate
  71. IceCube-250406A: No candidates from the Zwicky Transient Facility
  72. GRB 250407A: Swift-XRT afterglow detection
  73. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  74. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  75. Konus-Wind detection of GRB 250406B (short/hard)
  76. IPN triangulation of GRB 250406B (short/hard)
  77. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  78. IceCube 250406.951: DDOTI Optical Observations
  79. GRB 250406A: AstroSat CZTI detection
  80. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  81. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  82. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  83. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  84. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  85. Konus-Wind detection of GRB 250404A / EP250404a
  86. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  87. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  88. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  89. EP250402a: Optical upper limit with PD 1.3m observations
  90. GRB 250404A / EP250404a: NOT optical observations
  91. GRB 250331D: Swift-XRT afterglow detection
  92. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  93. EP250404a: REM optical/NIR observations
  94. EP250404a: Seimei/TriCCS optical counterpart detection
  95. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  96. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  97. EP250404a: LCO optical counterpart detection
  98. EP250404a: Xinglong decaying optical counterpart
  99. GRB 250403A: Montarrenti Observatory optical detection
  100. GRB 250403A: KAIT optical observations

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