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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"

32494 results found.

  1. Konus-Wind detection of GRB 250407A
  2. GRB 250407A: SVOM/GRM observation of a bright long burst
  3. GRB 250407A: EP-WXT afterglow detection
  4. EP250407a: EP-WXT detection of a fast X-ray transient
  5. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  6. GRB 250407A: KAIT Optical Afterglow Candidate
  7. IceCube-250406A: No candidates from the Zwicky Transient Facility
  8. GRB 250407A: Fermi GBM Detection
  9. GRB 250407A: Swift-XRT afterglow detection
  10. Fermi GRB 250407A: Global MASTER-Net observations report
  11. GRB 250407A: Swift ToO observations
  12. GRB 250407A: SRG/ART-XC afterglow detection
  13. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  14. Konus-Wind detection of GRB 250406B (short/hard)
  15. IPN triangulation of GRB 250406B (short/hard)
  16. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  17. GRB 250406A: AstroSat CZTI detection
  18. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  19. Fermi GRB 250406A: Global MASTER-Net observations report
  20. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  21. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  22. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  23. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  24. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  25. Konus-Wind detection of GRB 250404A / EP250404a
  26. GRB 250404A / EP250404a: Mondy optical observations
  27. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  28. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  29. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  30. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  31. EP250402a: Optical upper limit with PD 1.3m observations
  32. GRB 250404A / EP250404a: NOT optical observations
  33. GRB 250403A: AstroSat CZTI detection
  34. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  35. EP250404a: REM optical/NIR observations
  36. EP250404a: Seimei/TriCCS optical counterpart detection
  37. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  38. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  39. EP250404a: LCO optical counterpart detection
  40. Fermi GRB 250404A: Global MASTER-Net observations report
  41. GRB 250403A: Montarrenti Observatory optical detection
  42. EP250404a: Global MASTER-Net observations report
  43. GRB 250403A: KAIT optical observations
  44. EP250404a: AKO Optical Afterglow Detection
  45. EP250404a: LAST detection of optical counterpart
  46. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  47. EP250404a: Xinglong-2.16m spectroscopic redshift
  48. GRB 250403A: Fermi GBM observations
  49. GRB 250327B: VIRT Optical Upper Limit
  50. EP250404a: Mephisto multi-band optical detection
  51. GRB 250331C Swift-BAT refined analysis
  52. GRB 250331B Swift-BAT refined analysis
  53. GRB 250330A Swift-BAT refined analysis
  54. EP250321A: J band upper limit by SYSU 80cm telescope
  55. EP250404a: BOOTES-4/JGT optical afterglow detection
  56. EP250404a: Nanshan/HMT optical counterpart detection
  57. EP250404a: Einstein Probe detection of an X-ray transient
  58. GRB 250402A: Mondy optical observations
  59. GRB 250403A: Swift/UVOT Detection
  60. GRB 250402A: Swift/UVOT Upper Limits
  61. EP250402a: Optical upper limit with Kinder observations
  62. GRB 250403A: SVOM/VT optical observation
  63. GRB 250403A: REM NIR afterglow detection
  64. GRB 250403A: LCO optical counterpart detection
  65. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  66. GRB 250403A: JinShan optical observations
  67. GRB 250402A: EP-FXT afterglow detection
  68. GRB 250403A: Optical counterpart detection by LCO.
  69. EP250402a: EP-FXT follow-up observations
  70. GRB 250403A: Swift-XRT observations
  71. GRB 250322A: 10 GHz VLA radio upper limits
  72. Fermi GRB 250403A: Global MASTER-Net observations report
  73. GRB 250403A: GOTO optical counterpart follow-up observations
  74. GRB 250402A: NUTTelA-TAO Early Optical Limits
  75. GRB 250403A: GMG Optical Observation
  76. GRB 250403A: 1.6m Mephisto multi-band optical detection
  77. GRB 250402A: Fermi GBM Observation
  78. GRB 250403A: SVOM/C-GFT optical observations
  79. GRB 250403A: GOTO detection of the optical afterglow
  80. GRB 250402A: Swift-XRT observations
  81. GRB 250403A : SVOM detection of a burst
  82. GRB 250225B: VLT host galaxy redshift z = 0.950
  83. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  84. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  85. GRB 250402A: REM optical/NIR upper limits
  86. GRB 250402A: LCO optical counterpart detection
  87. GRB 250402A: refined SVOM/MXT data analysis
  88. GRB 250402A: SVOM/VT optical counterpart
  89. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  90. GRB 250314A: ALMA detection
  91. GRB 250329B: Swift/UVOT Upper Limit
  92. GRB 250329A: Swift/UVOT Upper Limit
  93. GRB 250327B: Swift/UVOT Detection
  94. GRB 250327A: Swift/UVOT Upper Limits
  95. GRB 250331E: SVOM/GRM observation
  96. GRB 250327B: Kilonova-Catcher Observations
  97. GRB250331D: AbAO optical observations
  98. GRB 250331D: Fermi GBM observation
  99. GRB 250331C: Swift/UVOT Upper Limits
  100. GRB 250331B: Swift/UVOT Upper Limits

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