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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"

28704 results found.

  1. EP250227a: Further NOT optical observations
  2. GRB 250320B: cubesat Avion detection
  3. IceCube-250406A: Swift-XRT observations
  4. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  5. IPN triangulation of GRB 250407A
  6. EP250407a: Global MASTER-Net observations report
  7. GRB 250407A: LCO detection of a fading optical counterpart
  8. Fermi-LAT gamma-ray observations of IceCube-250406A
  9. EP250407a: Swift-XRT observations
  10. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  11. Konus-Wind detection of GRB 250407A
  12. GRB 250407A: SVOM/GRM observation of a bright long burst
  13. GRB 250407A: EP-WXT afterglow detection
  14. EP250407a: EP-WXT detection of a fast X-ray transient
  15. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  16. GRB 250407A: KAIT Optical Afterglow Candidate
  17. IceCube-250406A: No candidates from the Zwicky Transient Facility
  18. GRB 250407A: Fermi GBM Detection
  19. GRB 250407A: Swift-XRT afterglow detection
  20. Fermi GRB 250407A: Global MASTER-Net observations report
  21. GRB 250407A: Swift ToO observations
  22. GRB 250407A: SRG/ART-XC afterglow detection
  23. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  24. Konus-Wind detection of GRB 250406B (short/hard)
  25. IPN triangulation of GRB 250406B (short/hard)
  26. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  27. GRB 250406A: AstroSat CZTI detection
  28. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  29. Fermi GRB 250406A: Global MASTER-Net observations report
  30. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  31. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  32. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  33. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  34. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  35. Konus-Wind detection of GRB 250404A / EP250404a
  36. GRB 250404A / EP250404a: Mondy optical observations
  37. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  38. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  39. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  40. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  41. EP250402a: Optical upper limit with PD 1.3m observations
  42. GRB 250404A / EP250404a: NOT optical observations
  43. GRB 250403A: AstroSat CZTI detection
  44. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  45. EP250404a: REM optical/NIR observations
  46. EP250404a: Seimei/TriCCS optical counterpart detection
  47. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  48. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  49. EP250404a: LCO optical counterpart detection
  50. Fermi GRB 250404A: Global MASTER-Net observations report
  51. GRB 250403A: Montarrenti Observatory optical detection
  52. EP250404a: Global MASTER-Net observations report
  53. GRB 250403A: KAIT optical observations
  54. EP250404a: AKO Optical Afterglow Detection
  55. EP250404a: LAST detection of optical counterpart
  56. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  57. EP250404a: Xinglong-2.16m spectroscopic redshift
  58. GRB 250403A: Fermi GBM observations
  59. GRB 250327B: VIRT Optical Upper Limit
  60. EP250404a: Mephisto multi-band optical detection
  61. GRB 250331C Swift-BAT refined analysis
  62. GRB 250331B Swift-BAT refined analysis
  63. GRB 250330A Swift-BAT refined analysis
  64. EP250321A: J band upper limit by SYSU 80cm telescope
  65. EP250404a: BOOTES-4/JGT optical afterglow detection
  66. EP250404a: Nanshan/HMT optical counterpart detection
  67. EP250404a: Einstein Probe detection of an X-ray transient
  68. GRB 250402A: Mondy optical observations
  69. GRB 250403A: Swift/UVOT Detection
  70. GRB 250402A: Swift/UVOT Upper Limits
  71. EP250402a: Optical upper limit with Kinder observations
  72. GRB 250403A: SVOM/VT optical observation
  73. GRB 250403A: REM NIR afterglow detection
  74. GRB 250403A: LCO optical counterpart detection
  75. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  76. GRB 250403A: JinShan optical observations
  77. GRB 250402A: EP-FXT afterglow detection
  78. GRB 250403A: Optical counterpart detection by LCO.
  79. EP250402a: EP-FXT follow-up observations
  80. GRB 250403A: Swift-XRT observations
  81. GRB 250322A: 10 GHz VLA radio upper limits
  82. Fermi GRB 250403A: Global MASTER-Net observations report
  83. GRB 250403A: GOTO optical counterpart follow-up observations
  84. GRB 250402A: NUTTelA-TAO Early Optical Limits
  85. GRB 250403A: GMG Optical Observation
  86. GRB 250403A: 1.6m Mephisto multi-band optical detection
  87. GRB 250402A: Fermi GBM Observation
  88. GRB 250403A: SVOM/C-GFT optical observations
  89. GRB 250403A: GOTO detection of the optical afterglow
  90. GRB 250402A: Swift-XRT observations
  91. GRB 250403A : SVOM detection of a burst
  92. GRB 250225B: VLT host galaxy redshift z = 0.950
  93. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  94. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  95. GRB 250402A: REM optical/NIR upper limits
  96. GRB 250402A: LCO optical counterpart detection
  97. GRB 250402A: refined SVOM/MXT data analysis
  98. GRB 250402A: SVOM/VT optical counterpart
  99. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  100. GRB 250314A: ALMA detection

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