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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"

39171 results found.

  1. GRB 250416B: Fermi GBM Final Real-time Localization
  2. GRB 250416A: Fermi GBM Final Real-time Localization
  3. SVOM/sb25041603: SVOM detection of an X-ray transient
  4. Fermi Gamma-ray Burst Monitor trigger 766474855/250416237 is not a GRB
  5. GRB 250413A: AstroSat CZTI detection
  6. EP250304a: ATCA radio observations
  7. GRB 250412A: AstroSat CZTI detection
  8. Fermi trigger No 766148493: Global MASTER-Net observations report
  9. Fermi trigger No 766173972: Global MASTER-Net observations report
  10. GRB 250411A: DDOTI Optical Observations
  11. Fermi GRB 250411A: Global MASTER-Net observations report
  12. GRB 250411A: Fermi GBM Final Real-time Localization
  13. GRB 250407A: Continued KAIT/Nickel optical observations
  14. GRB 250314A: e-MERLIN observations
  15. GRB 250407A: Mondy and AbAO Optical Observations
  16. GRB 250320B: cubesat Avion detection
  17. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  18. IPN triangulation of GRB 250407A
  19. EP250407a: Global MASTER-Net observations report
  20. GRB 250407A: LCO detection of a fading optical counterpart
  21. Fermi-LAT gamma-ray observations of IceCube-250406A
  22. EP250407a: Swift-XRT observations
  23. Konus-Wind detection of GRB 250407A
  24. GRB 250407A: SVOM/GRM observation of a bright long burst
  25. GRB 250407A: EP-WXT afterglow detection
  26. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  27. GRB 250407A: KAIT Optical Afterglow Candidate
  28. GRB 250407A: Fermi GBM Detection
  29. GRB 250407A: Swift-XRT afterglow detection
  30. Fermi GRB 250407A: Global MASTER-Net observations report
  31. GRB 250407A: Swift ToO observations
  32. GRB 250407A: SRG/ART-XC afterglow detection
  33. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  34. Konus-Wind detection of GRB 250406B (short/hard)
  35. IPN triangulation of GRB 250406B (short/hard)
  36. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  37. GRB 250407A: Fermi GBM Final Real-time Localization
  38. GRB 250406A: AstroSat CZTI detection
  39. IceCube Alert 250406.95: Global MASTER-Net observations report
  40. Fermi trigger No 765663719: Global MASTER-Net observations report
  41. Fermi GRB 250406A: Global MASTER-Net observations report
  42. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  43. GRB 250406A: Fermi GBM Final Real-time Localization
  44. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  45. Fermi trigger No 765619921: Global MASTER-Net observations report
  46. Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
  47. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  48. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  49. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  50. Konus-Wind detection of GRB 250404A / EP250404a
  51. GRB 250404A / EP250404a: Mondy optical observations
  52. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  53. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  54. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  55. GRB 250404A / EP250404a: NOT optical observations
  56. GRB 250331D: Swift-XRT afterglow detection
  57. GRB 250404B: AstroSat CZTI detection of a short burst
  58. GRB 250403A: AstroSat CZTI detection
  59. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  60. EP250404a: REM optical/NIR observations
  61. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  62. EP250404a: LCO optical counterpart detection
  63. Fermi GRB 250404A: Global MASTER-Net observations report
  64. EP250404a: Xinglong decaying optical counterpart
  65. GRB 250403A: Montarrenti Observatory optical detection
  66. GRB 250404A: Fermi GBM Detection
  67. EP250404a: Global MASTER-Net observations report
  68. GRB 250403A: KAIT optical observations
  69. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  70. EP250404a: Xinglong-2.16m spectroscopic redshift
  71. GRB 250403A: Fermi GBM observations
  72. GRB 250327B: VIRT Optical Upper Limit
  73. EP250404a: Mephisto multi-band optical detection
  74. GRB 250331C Swift-BAT refined analysis
  75. GRB 250331B Swift-BAT refined analysis
  76. GRB 250330A Swift-BAT refined analysis
  77. EP250404a: Nanshan/HMT optical counterpart detection
  78. EP250404a: Einstein Probe detection of an X-ray transient
  79. GRB 250404A: Fermi GBM Final Real-time Localization
  80. GRB 250402A: Mondy optical observations
  81. GRB 250403A: Swift/UVOT Detection
  82. GRB 250402A: Swift/UVOT Upper Limits
  83. GRB 250403A: SVOM/VT optical observation
  84. GRB 250403A: REM NIR afterglow detection
  85. GRB 250403A: LCO optical counterpart detection
  86. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  87. GRB 250403A: JinShan optical observations
  88. GRB 250402A: EP-FXT afterglow detection
  89. GRB 250403A: Optical counterpart detection by LCO.
  90. GRB 250403A: Swift-XRT observations
  91. GRB 250322A: 10 GHz VLA radio upper limits
  92. Fermi GRB 250403A: Global MASTER-Net observations report
  93. GRB 250403A: GOTO optical counterpart follow-up observations
  94. GRB 250402A: NUTTelA-TAO Early Optical Limits
  95. GRB 250403A: GMG Optical Observation
  96. GRB 250403A: 1.6m Mephisto multi-band optical detection
  97. GRB 250402A: Fermi GBM Observation
  98. GRB 250403A: SVOM/C-GFT optical observations
  99. GRB 250403A: GOTO detection of the optical afterglow
  100. GRB 250402A: Swift-XRT observations

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