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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"

32417 results found.

  1. GRB 250421A: Fermi GBM Final Real-time Localization
  2. GRB 250419A: Liverpool Telescope observations
  3. GRB 250419A: LCO optical observation
  4. GRB 250419A: JinShan optical observations
  5. GRB 250419A: SVOM/VT optical continuous observations
  6. GRB 250419A: SVOM/C-GFT optical observations
  7. GRB 250419A: Swift/UVOT Follow up
  8. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  9. GRB 250419A: LCO optical afterglow multi-band observations
  10. GRB 250419A: Mondy and AbAO Optical Observations
  11. GRB 250419A: Liverpool Telescope observations
  12. GRB 250419A: AKO Optical Afterglow Detection
  13. GRB 250419A: MASTER optical afterglow observation
  14. GRB 250407A: rest-frame energetics from Konus-Wind observation
  15. GRB 250419A: Swift-XRT localisation
  16. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  17. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  18. GRB 250419A: Swift-XRT refined Analysis
  19. GRB 250419A: GOTO optical counterpart detection
  20. GRB 250419A: KAIT optical afterglow observations
  21. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  22. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  23. GRB 250419A: SVOM detection of a soft burst
  24. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  25. Konus-Wind detection of GRB 250403A
  26. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  27. SVOM/sb25041603 is not a GRB
  28. Fermi Gamma-ray Burst Monitor trigger 766505186/250416588 (GRB 250416A) is not a GRB
  29. Fermi Gamma-ray Burst Monitor trigger 766511207/250416657 is not a GRB
  30. GRB 250416B: Fermi GBM Final Real-time Localization
  31. GRB 250416A: Fermi GBM Final Real-time Localization
  32. Fermi Gamma-ray Burst Monitor trigger 766474855/250416237 is not a GRB
  33. GRB 250413A: AstroSat CZTI detection
  34. EP250304a: ATCA radio observations
  35. GRB 250412A: AstroSat CZTI detection
  36. GRB 250411A: DDOTI Optical Observations
  37. Fermi GRB 250411A: Global MASTER-Net observations report
  38. GRB 250411A: Fermi GBM Final Real-time Localization
  39. GRB 250407A: Continued KAIT/Nickel optical observations
  40. GRB 250314A: e-MERLIN observations
  41. GRB 250407A: Mondy and AbAO Optical Observations
  42. GRB 250320B: cubesat Avion detection
  43. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  44. IPN triangulation of GRB 250407A
  45. GRB 250407A: LCO detection of a fading optical counterpart
  46. EP250407a: Swift-XRT observations
  47. Konus-Wind detection of GRB 250407A
  48. GRB 250407A: SVOM/GRM observation of a bright long burst
  49. GRB 250407A: EP-WXT afterglow detection
  50. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  51. GRB 250407A: KAIT Optical Afterglow Candidate
  52. GRB 250407A: Fermi GBM Detection
  53. GRB 250407A: Swift-XRT afterglow detection
  54. Fermi GRB 250407A: Global MASTER-Net observations report
  55. GRB 250407A: Swift ToO observations
  56. GRB 250407A: SRG/ART-XC afterglow detection
  57. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  58. Konus-Wind detection of GRB 250406B (short/hard)
  59. IPN triangulation of GRB 250406B (short/hard)
  60. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  61. GRB 250407A: Fermi GBM Final Real-time Localization
  62. GRB 250406A: AstroSat CZTI detection
  63. Fermi GRB 250406A: Global MASTER-Net observations report
  64. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  65. GRB 250406A: Fermi GBM Final Real-time Localization
  66. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  67. Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
  68. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  69. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  70. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  71. Konus-Wind detection of GRB 250404A / EP250404a
  72. GRB 250404A / EP250404a: Mondy optical observations
  73. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  74. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  75. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  76. GRB 250404A / EP250404a: NOT optical observations
  77. GRB 250331D: Swift-XRT afterglow detection
  78. GRB 250404B: AstroSat CZTI detection of a short burst
  79. GRB 250403A: AstroSat CZTI detection
  80. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  81. EP250404a: REM optical/NIR observations
  82. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  83. EP250404a: LCO optical counterpart detection
  84. Fermi GRB 250404A: Global MASTER-Net observations report
  85. GRB 250403A: Montarrenti Observatory optical detection
  86. GRB 250404A: Fermi GBM Detection
  87. GRB 250403A: KAIT optical observations
  88. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  89. EP250404a: Xinglong-2.16m spectroscopic redshift
  90. GRB 250403A: Fermi GBM observations
  91. GRB 250327B: VIRT Optical Upper Limit
  92. GRB 250331C Swift-BAT refined analysis
  93. GRB 250331B Swift-BAT refined analysis
  94. GRB 250330A Swift-BAT refined analysis
  95. EP250404a: Nanshan/HMT optical counterpart detection
  96. EP250404a: Einstein Probe detection of an X-ray transient
  97. GRB 250404A: Fermi GBM Final Real-time Localization
  98. GRB 250402A: Mondy optical observations
  99. GRB 250403A: Swift/UVOT Detection
  100. GRB 250402A: Swift/UVOT Upper Limits

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