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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

23558 results found.

  1. GRB 250320B: cubesat Avion detection
  2. IceCube-250406A: Swift-XRT observations
  3. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  4. IPN triangulation of GRB 250407A
  5. GRB 250407A: LCO detection of a fading optical counterpart
  6. EP250407a: Swift-XRT observations
  7. GRB 250407A: SVOM/GRM observation of a bright long burst
  8. GRB 250407A: EP-WXT afterglow detection
  9. EP250407a: EP-WXT detection of a fast X-ray transient
  10. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  11. GRB 250407A: KAIT Optical Afterglow Candidate
  12. IceCube-250406A: No candidates from the Zwicky Transient Facility
  13. GRB 250407A: Swift-XRT afterglow detection
  14. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  15. IPN triangulation of GRB 250406B (short/hard)
  16. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  17. IceCube 250406.951: DDOTI Optical Observations
  18. Fermi trigger No 765663719: Global MASTER-Net observations report
  19. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  20. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  21. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  22. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  23. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  24. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  25. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  26. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  27. EP250402a: Optical upper limit with PD 1.3m observations
  28. GRB 250404A / EP250404a: NOT optical observations
  29. GRB 250331D: Swift-XRT afterglow detection
  30. GRB 250403A: AstroSat CZTI detection
  31. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  32. EP250404a: REM optical/NIR observations
  33. EP250404a: Seimei/TriCCS optical counterpart detection
  34. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  35. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  36. EP250404a: LCO optical counterpart detection
  37. EP250404a: Xinglong decaying optical counterpart
  38. GRB 250403A: Montarrenti Observatory optical detection
  39. GRB 250403A: KAIT optical observations
  40. EP250404a: AKO Optical Afterglow Detection
  41. EP250404a: LAST detection of optical counterpart
  42. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  43. GRB 250327B: VIRT Optical Upper Limit
  44. EP250404a: Mephisto multi-band optical detection
  45. EP250321A: J band upper limit by SYSU 80cm telescope
  46. EP250404a: Nanshan/HMT optical counterpart detection
  47. EP250404a: Einstein Probe detection of an X-ray transient
  48. GRB 250403A: Swift/UVOT Detection
  49. GRB 250402A: Swift/UVOT Upper Limits
  50. EP250402a: Optical upper limit with Kinder observations
  51. GRB 250403A: REM NIR afterglow detection
  52. GRB 250403A: LCO optical counterpart detection
  53. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  54. GRB 250403A: JinShan optical observations
  55. GRB 250403A: Optical counterpart detection by LCO.
  56. GRB 250322A: 10 GHz VLA radio upper limits
  57. GRB 250403A: GMG Optical Observation
  58. GRB 250403A: 1.6m Mephisto multi-band optical detection
  59. GRB 250403A: SVOM/C-GFT optical observations
  60. GRB 250403A: Fermi GBM Final Real-time Localization
  61. GRB 250225B: VLT host galaxy redshift z = 0.950
  62. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  63. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  64. GRB 250402A: REM optical/NIR upper limits
  65. GRB 250402A: LCO optical counterpart detection
  66. EP250402a: Einstein Probe detection of a fast X-ray transient
  67. GRB 250402A: SVOM/VT optical counterpart
  68. GRB 250402A: SVOM detection of a burst
  69. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  70. GRB 250329B: Swift/UVOT Upper Limit
  71. GRB 250329A: Swift/UVOT Upper Limit
  72. GRB 250327B: Swift/UVOT Detection
  73. GRB 250327A: Swift/UVOT Upper Limits
  74. GRB 250331E: SVOM/GRM observation
  75. GRB 250327B: Kilonova-Catcher Observations
  76. GRB250331D: AbAO optical observations
  77. GRB 250331C: Swift/UVOT Upper Limits
  78. GRB 250331B: Swift/UVOT Upper Limits
  79. GRB 250328A: AbAO AS-32 Optical Observations
  80. GRB 250219A: NOT candidate host galaxy detection
  81. GRB 250331D: Swift-XRT observations
  82. GRB 250322B possible detection by the AstroSat Satellite
  83. GRB 250330B: SVOM/GRM observation of a short burst
  84. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  85. GRB 250331C: Enhanced Swift-XRT position
  86. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  87. GRB 250331B: Enhanced Swift-XRT position
  88. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  89. GRB 250330A: VLT/FORS2 Afterglow Detection
  90. GRB20250327B: 45th Parallel Observatory upper limit
  91. GRB 250328A: Swift/UVOT Detection
  92. GRB 250328A: Swift-XRT refined Analysis
  93. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  94. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  95. GRB 250331C: Swift detection of a burst
  96. GRB 250331B: Swift detection of a burst
  97. GRB 250330A: SVOM/VT optical upper limit
  98. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  99. GRB 250330A: Swift/UVOT Upper Limits
  100. GRB 250330A: Swift-XRT afterglow detection

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