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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"

3820 results found.

  1. Fermi GRB 250510C: Global MASTER-Net observations report
  2. Fermi GRB 250510B: Global MASTER-Net observations report
  3. GRB 250509A: Fermi GBM Final Real-time Localization
  4. GRB 250506A: NOT optical upper limits
  5. GRB 250506A: Swift XRT observations and possible counterpart detection
  6. GRB 250506A: TRT optical observations
  7. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  8. GRB 250504A: MeerLICHT optical afterglow detection
  9. Fermi GRB 250504A: Global MASTER-Net observations report
  10. Swift GRB250504.98: Global MASTER-Net observations report
  11. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  12. GRB 250430A: Leavitt Observatory optical upper limit
  13. GRB 250430A : MITSuME Akeno optical upper limits
  14. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  15. GRB 250430A: AKO Optical Afterglow Detection
  16. Swift GRB250430.73: Global MASTER-Net observations report
  17. EP250427a/GRB250427A: HCT optical follow-up
  18. EP250428b: SVOM/VT upper limit
  19. EP250428b: SAO RAS optical upper limit
  20. EP250428b: LAST optical upper limit
  21. IceCube-250429A - IceCube observation of a high-energy neutrino candidate track-like event
  22. EP250428b: Global MASTER-Net observations report
  23. EP250427a/GRB 250427A: FTW optical and NIR observations of the counterpart
  24. EP250427a: TRT optical counterpart detection
  25. EP 250427a: BOOTES-7 optical afterglow candidate
  26. GRB 250424A: SVOM/VT optical observation
  27. GRB 250419A: Mondy Optical Observations
  28. GRB 250424A: Swift/UVOT Detection
  29. GRB 250424A: Swift detection of a burst with an optical counterpart
  30. GRB250419A: VLA radio detection
  31. GRB 250419A: Mephisto Multi-band Optical Detection
  32. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  33. GRB 250419A: Optical Observations via Virtual Telescope Project
  34. IceCube Alert 250421.71: Global MASTER-Net observations report
  35. EP250421a: JinShan likely optical counterpart
  36. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  37. GRB 250419A: Swift/UVOT Follow up
  38. GRB 250419A: AKO Optical Afterglow Detection
  39. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  40. GRB 250419A: SVOM detection of a soft burst
  41. GRB 250412A: AstroSat CZTI detection
  42. EP250404a: Nanshan 0.43m Telescope optical observatios
  43. Fermi trigger No 766148493: Global MASTER-Net observations report
  44. Fermi trigger No 766173972: Global MASTER-Net observations report
  45. Fermi GRB 250407A: Global MASTER-Net observations report
  46. Fermi GRB 250406A: Global MASTER-Net observations report
  47. GRB 250402A: Mondy optical observations
  48. EP250402a: Einstein Probe detection of a fast X-ray transient
  49. Fermi GRB 250331E: Global MASTER-Net observations report
  50. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  51. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  52. SVOM/sb25033102: SVOM detection of an X-ray transient
  53. GRB 250328A: 1.6m Mephisto optical observations
  54. GRB 250327B: ALMA detection
  55. GRB 250327B: VLA detection
  56. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  57. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  58. GRB250329A: REM optical afterglow detection
  59. GRB 250329A: Swift-XRT afterglow detection
  60. GRB 250329A: Fading optical counterpart detection by LCO.
  61. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  62. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  63. GRB 250329A: SVOM/VT optical counterpart confirmation
  64. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  65. GRB 250327B: further optical observations by LCOGT
  66. GRB 250327B: SVOM/VT optically bright counterpart
  67. GRB 250327B: SAO RAS optical candidate
  68. IPN triangulation of GRB 250322B
  69. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  70. FRB 250316A: DDOTI Continued Optical Observations
  71. GRB 250322A: MASTER optical observation
  72. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  73. EP250321a: SVOM/VT optical observation
  74. GRB 250320B: AstroSat CZTI detection
  75. Fermi GRB 250320B: Global MASTER-Net observations report
  76. GRB 250321A: GOTO optical upper limits
  77. GRB 250319B: Fermi GBM Final Localization
  78. Fermi trigger No 763933627: Global MASTER-Net observations report
  79. GRB 250316A: Swift/UVOT Upper Limits
  80. GRB 250317A: Fermi GBM Final Real-time Localization
  81. Fermi GRB 250313A: Global MASTER-Net observations report
  82. EP250311a/GRB 250311A: EP-FXT follow-up observation
  83. Fermi GRB 250312B: Global MASTER-Net observations report
  84. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  85. GRB 250309B / AT2025dws: SAO RAS optical observations
  86. IceCube Alert 250309.32: Global MASTER-Net observations report
  87. EP250304A: Upper limits from Fermi-GBM Observations
  88. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  89. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  90. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  91. EP250302a: Mondy Continued Optical Observations
  92. Fermi GRB 250302A: Global MASTER-Net observations report
  93. Fermi GRB 250225A: Global MASTER-Net observations report
  94. GRB 250225B: Swift detection of a burst
  95. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  96. EP250223a: REM NIR upper limit
  97. GRB 250223B: Fermi GBM Final Localization
  98. Fermi trigger No 762020305: Global MASTER-Net observations report
  99. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  100. GRB 250221A: continued Mondy optical observations, brightening afterglow

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