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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"

36154 results found.

  1. SVOM/sb25042207: GOTO optical upper limits
  2. GRB 250421A: AstroSat CZTI detection
  3. GRB250419A: VLA radio detection
  4. GRB 250419A: Mephisto Multi-band Optical Detection
  5. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  6. GRB 250419A: Optical Observations via Virtual Telescope Project
  7. GRB 250419A: Mondy Continued Optical Observations
  8. Fermi GRB 250421A: Global MASTER-Net observations report
  9. GRB 250421B: AstroSat CZTI detection of a bright long burst
  10. GRB 250421A: Fermi GBM Final Real-time Localization
  11. GRB 250419A: Liverpool Telescope observations
  12. GRB 250419A: LCO optical observation
  13. GRB 250419A: JinShan optical observations
  14. GRB 250419A: SVOM/VT optical continuous observations
  15. GRB 250419A: SVOM/C-GFT optical observations
  16. GRB 250419A: Swift/UVOT Follow up
  17. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  18. GRB 250419A: LCO optical afterglow multi-band observations
  19. GRB 250419A: Mondy and AbAO Optical Observations
  20. GRB 250419A: Liverpool Telescope observations
  21. GRB 250419A: AKO Optical Afterglow Detection
  22. GRB 250419A: MASTER optical afterglow observation
  23. GRB 250407A: rest-frame energetics from Konus-Wind observation
  24. GRB 250419A: Swift-XRT localisation
  25. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  26. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  27. GRB 250419A: Swift-XRT refined Analysis
  28. GRB 250419A: GOTO optical counterpart detection
  29. GRB 250419A: KAIT optical afterglow observations
  30. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  31. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  32. GRB 250419A: SVOM detection of a soft burst
  33. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  34. Konus-Wind detection of GRB 250403A
  35. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  36. SVOM/sb25041603 is not a GRB
  37. Fermi Gamma-ray Burst Monitor trigger 766505186/250416588 (GRB 250416A) is not a GRB
  38. Fermi Gamma-ray Burst Monitor trigger 766511207/250416657 is not a GRB
  39. GRB 250416B: Fermi GBM Final Real-time Localization
  40. GRB 250416A: Fermi GBM Final Real-time Localization
  41. Fermi Gamma-ray Burst Monitor trigger 766474855/250416237 is not a GRB
  42. GRB 250413A: AstroSat CZTI detection
  43. EP250304a: ATCA radio observations
  44. GRB 250412A: AstroSat CZTI detection
  45. GRB 250411A: DDOTI Optical Observations
  46. Fermi GRB 250411A: Global MASTER-Net observations report
  47. GRB 250411A: Fermi GBM Final Real-time Localization
  48. GRB 250407A: Continued KAIT/Nickel optical observations
  49. GRB 250314A: e-MERLIN observations
  50. GRB 250407A: Mondy and AbAO Optical Observations
  51. GRB 250320B: cubesat Avion detection
  52. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  53. IPN triangulation of GRB 250407A
  54. GRB 250407A: LCO detection of a fading optical counterpart
  55. EP250407a: Swift-XRT observations
  56. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  57. Konus-Wind detection of GRB 250407A
  58. GRB 250407A: SVOM/GRM observation of a bright long burst
  59. GRB 250407A: EP-WXT afterglow detection
  60. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  61. GRB 250407A: KAIT Optical Afterglow Candidate
  62. GRB 250407A: Fermi GBM Detection
  63. GRB 250407A: Swift-XRT afterglow detection
  64. Fermi GRB 250407A: Global MASTER-Net observations report
  65. GRB 250407A: Swift ToO observations
  66. GRB 250407A: SRG/ART-XC afterglow detection
  67. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  68. Konus-Wind detection of GRB 250406B (short/hard)
  69. IPN triangulation of GRB 250406B (short/hard)
  70. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  71. GRB 250407A: Fermi GBM Final Real-time Localization
  72. GRB 250406A: AstroSat CZTI detection
  73. Fermi GRB 250406A: Global MASTER-Net observations report
  74. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  75. GRB 250406A: Fermi GBM Final Real-time Localization
  76. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  77. Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
  78. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  79. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  80. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  81. Konus-Wind detection of GRB 250404A / EP250404a
  82. GRB 250404A / EP250404a: Mondy optical observations
  83. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  84. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  85. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  86. GRB 250404A / EP250404a: NOT optical observations
  87. GRB 250331D: Swift-XRT afterglow detection
  88. GRB 250404B: AstroSat CZTI detection of a short burst
  89. GRB 250403A: AstroSat CZTI detection
  90. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  91. EP250404a: REM optical/NIR observations
  92. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  93. EP250404a: LCO optical counterpart detection
  94. Fermi GRB 250404A: Global MASTER-Net observations report
  95. GRB 250403A: Montarrenti Observatory optical detection
  96. GRB 250404A: Fermi GBM Detection
  97. GRB 250403A: KAIT optical observations
  98. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  99. EP250404a: Xinglong-2.16m spectroscopic redshift
  100. GRB 250403A: Fermi GBM observations

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