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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"

32509 results found.

  1. Fermi GRB 250411A: Global MASTER-Net observations report
  2. GRB 250407A: Continued KAIT/Nickel optical observations
  3. GRB 250314A: e-MERLIN observations
  4. GRB 250407A: Mondy and AbAO Optical Observations
  5. EP250227a: Further NOT optical observations
  6. GRB 250320B: cubesat Avion detection
  7. IceCube-250406A: Swift-XRT observations
  8. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  9. IPN triangulation of GRB 250407A
  10. EP250407a: Global MASTER-Net observations report
  11. GRB 250407A: LCO detection of a fading optical counterpart
  12. Fermi-LAT gamma-ray observations of IceCube-250406A
  13. EP250407a: Swift-XRT observations
  14. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  15. Konus-Wind detection of GRB 250407A
  16. GRB 250407A: SVOM/GRM observation of a bright long burst
  17. GRB 250407A: EP-WXT afterglow detection
  18. EP250407a: EP-WXT detection of a fast X-ray transient
  19. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  20. GRB 250407A: KAIT Optical Afterglow Candidate
  21. IceCube-250406A: No candidates from the Zwicky Transient Facility
  22. GRB 250407A: Fermi GBM Detection
  23. GRB 250407A: Swift-XRT afterglow detection
  24. Fermi GRB 250407A: Global MASTER-Net observations report
  25. GRB 250407A: Swift ToO observations
  26. GRB 250407A: SRG/ART-XC afterglow detection
  27. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  28. Konus-Wind detection of GRB 250406B (short/hard)
  29. IPN triangulation of GRB 250406B (short/hard)
  30. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  31. GRB 250406A: AstroSat CZTI detection
  32. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  33. Fermi GRB 250406A: Global MASTER-Net observations report
  34. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  35. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  36. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  37. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  38. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  39. Konus-Wind detection of GRB 250404A / EP250404a
  40. GRB 250404A / EP250404a: Mondy optical observations
  41. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  42. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  43. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  44. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  45. EP250402a: Optical upper limit with PD 1.3m observations
  46. GRB 250404A / EP250404a: NOT optical observations
  47. GRB 250403A: AstroSat CZTI detection
  48. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  49. EP250404a: REM optical/NIR observations
  50. EP250404a: Seimei/TriCCS optical counterpart detection
  51. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  52. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  53. EP250404a: LCO optical counterpart detection
  54. Fermi GRB 250404A: Global MASTER-Net observations report
  55. GRB 250403A: Montarrenti Observatory optical detection
  56. EP250404a: Global MASTER-Net observations report
  57. GRB 250403A: KAIT optical observations
  58. EP250404a: AKO Optical Afterglow Detection
  59. EP250404a: LAST detection of optical counterpart
  60. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  61. EP250404a: Xinglong-2.16m spectroscopic redshift
  62. GRB 250403A: Fermi GBM observations
  63. GRB 250327B: VIRT Optical Upper Limit
  64. EP250404a: Mephisto multi-band optical detection
  65. GRB 250331C Swift-BAT refined analysis
  66. GRB 250331B Swift-BAT refined analysis
  67. GRB 250330A Swift-BAT refined analysis
  68. EP250321A: J band upper limit by SYSU 80cm telescope
  69. EP250404a: BOOTES-4/JGT optical afterglow detection
  70. EP250404a: Nanshan/HMT optical counterpart detection
  71. EP250404a: Einstein Probe detection of an X-ray transient
  72. GRB 250402A: Mondy optical observations
  73. GRB 250403A: Swift/UVOT Detection
  74. GRB 250402A: Swift/UVOT Upper Limits
  75. EP250402a: Optical upper limit with Kinder observations
  76. GRB 250403A: SVOM/VT optical observation
  77. GRB 250403A: REM NIR afterglow detection
  78. GRB 250403A: LCO optical counterpart detection
  79. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  80. GRB 250403A: JinShan optical observations
  81. GRB 250402A: EP-FXT afterglow detection
  82. GRB 250403A: Optical counterpart detection by LCO.
  83. EP250402a: EP-FXT follow-up observations
  84. GRB 250403A: Swift-XRT observations
  85. GRB 250322A: 10 GHz VLA radio upper limits
  86. Fermi GRB 250403A: Global MASTER-Net observations report
  87. GRB 250403A: GOTO optical counterpart follow-up observations
  88. GRB 250402A: NUTTelA-TAO Early Optical Limits
  89. GRB 250403A: GMG Optical Observation
  90. GRB 250403A: 1.6m Mephisto multi-band optical detection
  91. GRB 250402A: Fermi GBM Observation
  92. GRB 250403A: SVOM/C-GFT optical observations
  93. GRB 250403A: GOTO detection of the optical afterglow
  94. GRB 250402A: Swift-XRT observations
  95. GRB 250403A : SVOM detection of a burst
  96. GRB 250225B: VLT host galaxy redshift z = 0.950
  97. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  98. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  99. GRB 250402A: REM optical/NIR upper limits
  100. GRB 250402A: LCO optical counterpart detection

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