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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').
Advanced Search

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"

16218 results found.

  1. GRB 250419A: Mephisto Multi-band Optical Detection
  2. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  3. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  4. EP250421a: NOT optical observations
  5. GRB 250419A: Optical Observations via Virtual Telescope Project
  6. EP250421a: REM optical upper limit
  7. EP250421A: COLIBRÍ Optical Upper Limit
  8. GRB 250419A: Mondy Continued Optical Observations
  9. Fermi GRB 250421A: Global MASTER-Net observations report
  10. EP250421a: Einstein Probe detection of an X-ray transient
  11. EP250421a: Mephisto optical counterpart confirmation
  12. EP250421a: JinShan likely optical counterpart
  13. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  14. GRB 250419A: LCO optical observation
  15. GRB 250419A: JinShan optical observations
  16. GRB 250419A: SVOM/C-GFT optical observations
  17. GRB 250419A: Swift/UVOT Follow up
  18. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  19. GRB 250419A: LCO optical afterglow multi-band observations
  20. GRB 250419A: Mondy and AbAO Optical Observations
  21. GRB 250419A: AKO Optical Afterglow Detection
  22. GRB 250419A: KAIT optical afterglow observations
  23. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  24. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  25. GRB 250419A: SVOM detection of a soft burst
  26. EP250416a: refined EP-WXT and EP-FXT analysis
  27. EP20250416a: Swift/XRT counterpart detection
  28. IceCube-250416A: DDOTI Optical Observations
  29. EP250416a: Gemini South-GMOS optical counterpart
  30. SVOM/sb25041603 is not a GRB
  31. EP250416a: Einstein Probe detection of an X-ray transient
  32. IceCube-250416A: Global MASTER-Net observations report
  33. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  34. IceCube 250414.324: DDOTI Optical Observations
  35. EP250304a: ATCA radio observations
  36. EP250404a: Nanshan 0.43m Telescope optical observatios
  37. GRB 250411A: DDOTI Optical Observations
  38. GRB 250314A: e-MERLIN observations
  39. GRB 250407A: Mondy and AbAO Optical Observations
  40. EP250227a: Further NOT optical observations
  41. IceCube-250406A: Swift-XRT observations
  42. GRB 250407A: LCO detection of a fading optical counterpart
  43. GRB 250407A: SVOM/GRM observation of a bright long burst
  44. GRB 250407A: EP-WXT afterglow detection
  45. EP250407a: EP-WXT detection of a fast X-ray transient
  46. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  47. GRB 250407A: KAIT Optical Afterglow Candidate
  48. IceCube-250406A: No candidates from the Zwicky Transient Facility
  49. GRB 250407A: Swift-XRT afterglow detection
  50. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  51. IPN triangulation of GRB 250406B (short/hard)
  52. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  53. IceCube 250406.951: DDOTI Optical Observations
  54. IceCube Alert 250406.95: Global MASTER-Net observations report
  55. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  56. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  57. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  58. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  59. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  60. Konus-Wind detection of GRB 250404A / EP250404a
  61. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  62. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  63. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  64. EP250402a: Optical upper limit with PD 1.3m observations
  65. GRB 250404A / EP250404a: NOT optical observations
  66. GRB 250331D: Swift-XRT afterglow detection
  67. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  68. EP250404a: REM optical/NIR observations
  69. EP250404a: Seimei/TriCCS optical counterpart detection
  70. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  71. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  72. EP250404a: LCO optical counterpart detection
  73. EP250404a: Xinglong decaying optical counterpart
  74. GRB 250403A: Montarrenti Observatory optical detection
  75. GRB 250403A: KAIT optical observations
  76. EP250404a: AKO Optical Afterglow Detection
  77. EP250404a: LAST detection of optical counterpart
  78. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  79. GRB 250327B: VIRT Optical Upper Limit
  80. EP250404a: Mephisto multi-band optical detection
  81. EP250321A: J band upper limit by SYSU 80cm telescope
  82. EP250404a: Nanshan/HMT optical counterpart detection
  83. EP250404a: Einstein Probe detection of an X-ray transient
  84. GRB 250403A: Swift/UVOT Detection
  85. GRB 250402A: Swift/UVOT Upper Limits
  86. EP250402a: Optical upper limit with Kinder observations
  87. GRB 250403A: REM NIR afterglow detection
  88. GRB 250403A: LCO optical counterpart detection
  89. GRB 250403A: JinShan optical observations
  90. GRB 250402A: EP-FXT afterglow detection
  91. GRB 250403A: Optical counterpart detection by LCO.
  92. EP250402a: EP-FXT follow-up observations
  93. GRB 250403A: GMG Optical Observation
  94. GRB 250403A: 1.6m Mephisto multi-band optical detection
  95. GRB 250403A: SVOM/C-GFT optical observations
  96. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  97. GRB 250402A: REM optical/NIR upper limits
  98. GRB 250402A: LCO optical counterpart detection
  99. The EP-WXT trigger 01709133862 is a flaring star
  100. EP250402a: Einstein Probe detection of a fast X-ray transient

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