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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"

24598 results found.

  1. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  2. GRB 250419A: LCO optical observation
  3. GRB 250419A: JinShan optical observations
  4. GRB 250419A: SVOM/C-GFT optical observations
  5. GRB 250419A: Swift/UVOT Follow up
  6. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  7. GRB 250419A: LCO optical afterglow multi-band observations
  8. GRB 250419A: Mondy and AbAO Optical Observations
  9. GRB 250419A: AKO Optical Afterglow Detection
  10. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  11. GRB 250419A: Swift-XRT refined Analysis
  12. GRB 250419A: KAIT optical afterglow observations
  13. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  14. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  15. GRB 250419A: SVOM detection of a soft burst
  16. EP250416a: Swift/XRT counterpart fading
  17. EP20250416a: Swift/XRT counterpart detection
  18. IceCube-250416A: DDOTI Optical Observations
  19. EP250416a: Gemini South-GMOS optical counterpart
  20. SVOM/sb25041603 is not a GRB
  21. EP250416a: GSP optical upper limit
  22. EP250416a: Einstein Probe detection of an X-ray transient
  23. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  24. SVOM/sb25041603: SVOM detection of an X-ray transient
  25. IceCube 250414.324: DDOTI Optical Observations
  26. GRB 250413A: AstroSat CZTI detection
  27. EP250304a: ATCA radio observations
  28. EP250404a: Nanshan 0.43m Telescope optical observatios
  29. GRB 250411A: DDOTI Optical Observations
  30. Fermi GRB 250411A: Global MASTER-Net observations report
  31. GRB 250407A: Continued KAIT/Nickel optical observations
  32. GRB 250314A: e-MERLIN observations
  33. GRB 250407A: Mondy and AbAO Optical Observations
  34. EP250227a: Further NOT optical observations
  35. GRB 250320B: cubesat Avion detection
  36. IceCube-250406A: Swift-XRT observations
  37. GRB 250407A: LCO detection of a fading optical counterpart
  38. Fermi-LAT gamma-ray observations of IceCube-250406A
  39. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  40. GRB 250407A: SVOM/GRM observation of a bright long burst
  41. GRB 250407A: EP-WXT afterglow detection
  42. EP250407a: EP-WXT detection of a fast X-ray transient
  43. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  44. GRB 250407A: KAIT Optical Afterglow Candidate
  45. IceCube-250406A: No candidates from the Zwicky Transient Facility
  46. GRB 250407A: Fermi GBM Detection
  47. GRB 250407A: Swift-XRT afterglow detection
  48. GRB 250407A: SRG/ART-XC afterglow detection
  49. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  50. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  51. IPN triangulation of GRB 250406B (short/hard)
  52. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  53. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  54. IceCube 250406.951: DDOTI Optical Observations
  55. GRB 250406A: AstroSat CZTI detection
  56. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  57. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  58. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  59. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  60. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  61. Konus-Wind detection of GRB 250404A / EP250404a
  62. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  63. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  64. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  65. EP250402a: Optical upper limit with PD 1.3m observations
  66. GRB 250404A / EP250404a: NOT optical observations
  67. GRB 250331D: Swift-XRT afterglow detection
  68. GRB 250404B: AstroSat CZTI detection of a short burst
  69. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  70. EP250404a: REM optical/NIR observations
  71. EP250404a: Seimei/TriCCS optical counterpart detection
  72. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  73. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  74. EP250404a: LCO optical counterpart detection
  75. EP250404a: Xinglong decaying optical counterpart
  76. GRB 250403A: Montarrenti Observatory optical detection
  77. GRB 250404A: Fermi GBM Detection
  78. GRB 250403A: KAIT optical observations
  79. EP250404a: AKO Optical Afterglow Detection
  80. EP250404a: LAST detection of optical counterpart
  81. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  82. GRB 250403A: Fermi GBM observations
  83. GRB 250327B: VIRT Optical Upper Limit
  84. EP250404a: Mephisto multi-band optical detection
  85. GRB 250331C Swift-BAT refined analysis
  86. GRB 250331B Swift-BAT refined analysis
  87. GRB 250330A Swift-BAT refined analysis
  88. EP250321A: J band upper limit by SYSU 80cm telescope
  89. EP250404a: Nanshan/HMT optical counterpart detection
  90. EP250404a: Einstein Probe detection of an X-ray transient
  91. GRB 250403A: Swift/UVOT Detection
  92. GRB 250402A: Swift/UVOT Upper Limits
  93. EP250402a: Optical upper limit with Kinder observations
  94. GRB 250403A: REM NIR afterglow detection
  95. GRB 250403A: LCO optical counterpart detection
  96. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  97. GRB 250403A: JinShan optical observations
  98. GRB 250403A: Optical counterpart detection by LCO.
  99. EP250402a: EP-FXT follow-up observations
  100. GRB 250403A: Swift-XRT observations

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