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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"

19488 results found.

  1. SVOM/sb25042207: XRT observations
  2. SVOM/sb25042207: GOTO optical upper limits
  3. GRB 250421A: AstroSat CZTI detection
  4. SVOM/sb25042207: SVOM detection of an X-ray transient
  5. IceCube-250421A: DDOTI Detection of the LAST Candidate
  6. GRB 250419A: Mephisto Multi-band Optical Detection
  7. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  8. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  9. EP250421a: NOT optical observations
  10. GRB 250419A: Optical Observations via Virtual Telescope Project
  11. EP250421a: REM optical upper limit
  12. EP250421A: COLIBRÍ Optical Upper Limit
  13. GRB 250419A: Mondy Continued Optical Observations
  14. EP250421a: Einstein Probe detection of an X-ray transient
  15. EP250421a: Mephisto optical counterpart confirmation
  16. EP250421a: JinShan likely optical counterpart
  17. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  18. GRB 250419A: LCO optical observation
  19. GRB 250419A: JinShan optical observations
  20. GRB 250419A: SVOM/C-GFT optical observations
  21. GRB 250419A: Swift/UVOT Follow up
  22. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  23. GRB 250419A: LCO optical afterglow multi-band observations
  24. GRB 250419A: Mondy and AbAO Optical Observations
  25. GRB 250419A: AKO Optical Afterglow Detection
  26. GRB 250419A: KAIT optical afterglow observations
  27. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  28. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  29. GRB 250419A: SVOM detection of a soft burst
  30. EP20250416a: Swift/XRT counterpart detection
  31. IceCube-250416A: DDOTI Optical Observations
  32. EP250416a: Gemini South-GMOS optical counterpart
  33. SVOM/sb25041603 is not a GRB
  34. EP250416a: Einstein Probe detection of an X-ray transient
  35. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  36. SVOM/sb25041603: SVOM detection of an X-ray transient
  37. IceCube 250414.324: DDOTI Optical Observations
  38. EP250404a: Nanshan 0.43m Telescope optical observatios
  39. GRB 250411A: DDOTI Optical Observations
  40. GRB 250314A: e-MERLIN observations
  41. GRB 250407A: Mondy and AbAO Optical Observations
  42. EP250227a: Further NOT optical observations
  43. GRB 250320B: cubesat Avion detection
  44. IceCube-250406A: Swift-XRT observations
  45. EP250407a: Global MASTER-Net observations report
  46. GRB 250407A: LCO detection of a fading optical counterpart
  47. GRB 250407A: SVOM/GRM observation of a bright long burst
  48. GRB 250407A: EP-WXT afterglow detection
  49. EP250407a: EP-WXT detection of a fast X-ray transient
  50. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  51. GRB 250407A: KAIT Optical Afterglow Candidate
  52. IceCube-250406A: No candidates from the Zwicky Transient Facility
  53. GRB 250407A: Swift-XRT afterglow detection
  54. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  55. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  56. Konus-Wind detection of GRB 250406B (short/hard)
  57. IPN triangulation of GRB 250406B (short/hard)
  58. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  59. IceCube 250406.951: DDOTI Optical Observations
  60. GRB 250406A: AstroSat CZTI detection
  61. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  62. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  63. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  64. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  65. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  66. Konus-Wind detection of GRB 250404A / EP250404a
  67. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  68. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  69. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  70. EP250402a: Optical upper limit with PD 1.3m observations
  71. GRB 250404A / EP250404a: NOT optical observations
  72. GRB 250331D: Swift-XRT afterglow detection
  73. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  74. EP250404a: REM optical/NIR observations
  75. EP250404a: Seimei/TriCCS optical counterpart detection
  76. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  77. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  78. EP250404a: LCO optical counterpart detection
  79. EP250404a: Xinglong decaying optical counterpart
  80. GRB 250403A: Montarrenti Observatory optical detection
  81. GRB 250403A: KAIT optical observations
  82. EP250404a: AKO Optical Afterglow Detection
  83. EP250404a: LAST detection of optical counterpart
  84. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  85. GRB 250327B: VIRT Optical Upper Limit
  86. EP250404a: Mephisto multi-band optical detection
  87. EP250321A: J band upper limit by SYSU 80cm telescope
  88. EP250404a: Nanshan/HMT optical counterpart detection
  89. EP250404a: Einstein Probe detection of an X-ray transient
  90. GRB 250403A: Swift/UVOT Detection
  91. GRB 250402A: Swift/UVOT Upper Limits
  92. EP250402a: Optical upper limit with Kinder observations
  93. GRB 250403A: REM NIR afterglow detection
  94. GRB 250403A: LCO optical counterpart detection
  95. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  96. GRB 250403A: JinShan optical observations
  97. GRB 250403A: Optical counterpart detection by LCO.
  98. GRB 250402A: NUTTelA-TAO Early Optical Limits
  99. GRB 250403A: GMG Optical Observation
  100. GRB 250403A: 1.6m Mephisto multi-band optical detection

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