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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').
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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"
body:"GRB"
submitter:"Judith Racusin"

24595 results found.

  1. GRB 250419A: SVOM/C-GFT optical observations
  2. GRB 250419A: Swift/UVOT Follow up
  3. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  4. GRB 250419A: LCO optical afterglow multi-band observations
  5. GRB 250419A: Mondy and AbAO Optical Observations
  6. GRB 250419A: AKO Optical Afterglow Detection
  7. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  8. GRB 250419A: Swift-XRT refined Analysis
  9. GRB 250419A: KAIT optical afterglow observations
  10. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  11. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  12. GRB 250419A: SVOM detection of a soft burst
  13. EP250416a: Swift/XRT counterpart fading
  14. EP20250416a: Swift/XRT counterpart detection
  15. IceCube-250416A: DDOTI Optical Observations
  16. EP250416a: Gemini South-GMOS optical counterpart
  17. SVOM/sb25041603 is not a GRB
  18. EP250416a: GSP optical upper limit
  19. EP250416a: Einstein Probe detection of an X-ray transient
  20. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  21. SVOM/sb25041603: SVOM detection of an X-ray transient
  22. IceCube 250414.324: DDOTI Optical Observations
  23. GRB 250413A: AstroSat CZTI detection
  24. EP250304a: ATCA radio observations
  25. EP250404a: Nanshan 0.43m Telescope optical observatios
  26. GRB 250411A: DDOTI Optical Observations
  27. Fermi GRB 250411A: Global MASTER-Net observations report
  28. GRB 250407A: Continued KAIT/Nickel optical observations
  29. GRB 250314A: e-MERLIN observations
  30. GRB 250407A: Mondy and AbAO Optical Observations
  31. EP250227a: Further NOT optical observations
  32. GRB 250320B: cubesat Avion detection
  33. IceCube-250406A: Swift-XRT observations
  34. GRB 250407A: LCO detection of a fading optical counterpart
  35. Fermi-LAT gamma-ray observations of IceCube-250406A
  36. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 250407A: SVOM/GRM observation of a bright long burst
  38. GRB 250407A: EP-WXT afterglow detection
  39. EP250407a: EP-WXT detection of a fast X-ray transient
  40. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  41. GRB 250407A: KAIT Optical Afterglow Candidate
  42. IceCube-250406A: No candidates from the Zwicky Transient Facility
  43. GRB 250407A: Fermi GBM Detection
  44. GRB 250407A: Swift-XRT afterglow detection
  45. GRB 250407A: SRG/ART-XC afterglow detection
  46. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  47. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  48. IPN triangulation of GRB 250406B (short/hard)
  49. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  50. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  51. IceCube 250406.951: DDOTI Optical Observations
  52. GRB 250406A: AstroSat CZTI detection
  53. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  54. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  55. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  56. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  57. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  58. Konus-Wind detection of GRB 250404A / EP250404a
  59. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  60. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  61. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  62. EP250402a: Optical upper limit with PD 1.3m observations
  63. GRB 250404A / EP250404a: NOT optical observations
  64. GRB 250331D: Swift-XRT afterglow detection
  65. GRB 250404B: AstroSat CZTI detection of a short burst
  66. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  67. EP250404a: REM optical/NIR observations
  68. EP250404a: Seimei/TriCCS optical counterpart detection
  69. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  70. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  71. EP250404a: LCO optical counterpart detection
  72. EP250404a: Xinglong decaying optical counterpart
  73. GRB 250403A: Montarrenti Observatory optical detection
  74. GRB 250404A: Fermi GBM Detection
  75. GRB 250403A: KAIT optical observations
  76. EP250404a: AKO Optical Afterglow Detection
  77. EP250404a: LAST detection of optical counterpart
  78. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  79. GRB 250403A: Fermi GBM observations
  80. GRB 250327B: VIRT Optical Upper Limit
  81. EP250404a: Mephisto multi-band optical detection
  82. GRB 250331C Swift-BAT refined analysis
  83. GRB 250331B Swift-BAT refined analysis
  84. GRB 250330A Swift-BAT refined analysis
  85. EP250321A: J band upper limit by SYSU 80cm telescope
  86. EP250404a: Nanshan/HMT optical counterpart detection
  87. EP250404a: Einstein Probe detection of an X-ray transient
  88. GRB 250403A: Swift/UVOT Detection
  89. GRB 250402A: Swift/UVOT Upper Limits
  90. EP250402a: Optical upper limit with Kinder observations
  91. GRB 250403A: REM NIR afterglow detection
  92. GRB 250403A: LCO optical counterpart detection
  93. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  94. GRB 250403A: JinShan optical observations
  95. GRB 250403A: Optical counterpart detection by LCO.
  96. EP250402a: EP-FXT follow-up observations
  97. GRB 250403A: Swift-XRT observations
  98. GRB 250322A: 10 GHz VLA radio upper limits
  99. GRB 250403A: GMG Optical Observation
  100. GRB 250403A: 1.6m Mephisto multi-band optical detection

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