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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"

24794 results found.

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

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