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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"

28091 results found.

  1. GRB 250419A: AKO Optical Afterglow Detection
  2. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  3. GRB 250419A: Swift-XRT refined Analysis
  4. GRB 250419A: KAIT optical afterglow observations
  5. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  6. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  7. GRB 250419A: SVOM detection of a soft burst
  8. EP250416a: Swift/XRT counterpart fading
  9. EP20250416a: Swift/XRT counterpart detection
  10. IceCube-250416A: DDOTI Optical Observations
  11. EP250416a: Gemini South-GMOS optical counterpart
  12. SVOM/sb25041603 is not a GRB
  13. EP250416a: GSP optical upper limit
  14. EP250416a: Einstein Probe detection of an X-ray transient
  15. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  16. SVOM/sb25041603: SVOM detection of an X-ray transient
  17. IceCube 250414.324: DDOTI Optical Observations
  18. GRB 250413A: AstroSat CZTI detection
  19. EP250304a: ATCA radio observations
  20. EP250404a: Nanshan 0.43m Telescope optical observatios
  21. GRB 250411A: DDOTI Optical Observations
  22. Fermi GRB 250411A: Global MASTER-Net observations report
  23. GRB 250407A: Continued KAIT/Nickel optical observations
  24. GRB 250314A: e-MERLIN observations
  25. GRB 250407A: Mondy and AbAO Optical Observations
  26. EP250227a: Further NOT optical observations
  27. GRB 250320B: cubesat Avion detection
  28. IceCube-250406A: Swift-XRT observations
  29. GRB 250407A: LCO detection of a fading optical counterpart
  30. Fermi-LAT gamma-ray observations of IceCube-250406A
  31. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 250407A: SVOM/GRM observation of a bright long burst
  33. GRB 250407A: EP-WXT afterglow detection
  34. EP250407a: EP-WXT detection of a fast X-ray transient
  35. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  36. GRB 250407A: KAIT Optical Afterglow Candidate
  37. IceCube-250406A: No candidates from the Zwicky Transient Facility
  38. GRB 250407A: Fermi GBM Detection
  39. GRB 250407A: Swift-XRT afterglow detection
  40. GRB 250407A: SRG/ART-XC afterglow detection
  41. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  42. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  43. IPN triangulation of GRB 250406B (short/hard)
  44. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  45. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  46. IceCube 250406.951: DDOTI Optical Observations
  47. GRB 250406A: AstroSat CZTI detection
  48. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  49. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  50. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  51. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  52. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  53. Konus-Wind detection of GRB 250404A / EP250404a
  54. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  55. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  56. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  57. EP250402a: Optical upper limit with PD 1.3m observations
  58. GRB 250404A / EP250404a: NOT optical observations
  59. GRB 250331D: Swift-XRT afterglow detection
  60. GRB 250404B: AstroSat CZTI detection of a short burst
  61. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  62. EP250404a: REM optical/NIR observations
  63. EP250404a: Seimei/TriCCS optical counterpart detection
  64. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  65. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  66. EP250404a: LCO optical counterpart detection
  67. EP250404a: Xinglong decaying optical counterpart
  68. GRB 250403A: Montarrenti Observatory optical detection
  69. GRB 250404A: Fermi GBM Detection
  70. GRB 250403A: KAIT optical observations
  71. EP250404a: AKO Optical Afterglow Detection
  72. EP250404a: LAST detection of optical counterpart
  73. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  74. GRB 250403A: Fermi GBM observations
  75. GRB 250327B: VIRT Optical Upper Limit
  76. EP250404a: Mephisto multi-band optical detection
  77. GRB 250331C Swift-BAT refined analysis
  78. GRB 250331B Swift-BAT refined analysis
  79. GRB 250330A Swift-BAT refined analysis
  80. EP250321A: J band upper limit by SYSU 80cm telescope
  81. EP250404a: Nanshan/HMT optical counterpart detection
  82. EP250404a: Einstein Probe detection of an X-ray transient
  83. GRB 250403A: Swift/UVOT Detection
  84. GRB 250402A: Swift/UVOT Upper Limits
  85. EP250402a: Optical upper limit with Kinder observations
  86. GRB 250403A: REM NIR afterglow detection
  87. GRB 250403A: LCO optical counterpart detection
  88. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  89. GRB 250403A: JinShan optical observations
  90. GRB 250403A: Optical counterpart detection by LCO.
  91. EP250402a: EP-FXT follow-up observations
  92. GRB 250403A: Swift-XRT observations
  93. GRB 250322A: 10 GHz VLA radio upper limits
  94. GRB 250403A: GMG Optical Observation
  95. GRB 250403A: 1.6m Mephisto multi-band optical detection
  96. GRB 250402A: Fermi GBM Observation
  97. GRB 250403A: SVOM/C-GFT optical observations
  98. GRB 250402A: Swift-XRT observations
  99. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  100. GRB 250402A: REM optical/NIR upper limits

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