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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"

3106 results found.

  1. EP250416a: Global MASTER-Net observations report
  2. EP250404a: Nanshan 0.43m Telescope optical observatios
  3. Fermi trigger No 766173972: Global MASTER-Net observations report
  4. GRB 250407A: KAIT Optical Afterglow Candidate
  5. IceCube-250406A: No candidates from the Zwicky Transient Facility
  6. GRB 250407A: Swift-XRT afterglow detection
  7. Fermi GRB 250407A: Global MASTER-Net observations report
  8. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  9. Fermi GRB 250406A: Global MASTER-Net observations report
  10. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  11. Fermi GRB 250404A: Global MASTER-Net observations report
  12. EP250404a: Xinglong decaying optical counterpart
  13. GRB 250404A: Fermi GBM Detection
  14. EP250404a: AKO Optical Afterglow Detection
  15. GRB 250331B Swift-BAT refined analysis
  16. Fermi GRB 250331E: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  18. Fermi GRB 250330A: Global MASTER-Net observations report
  19. GRB 250330A: Prompt Swift-XRT position
  20. Swift GRB250330.26: Global MASTER-Net observations report
  21. GRB 250327B: ALMA detection
  22. GRB 250327B: VLA detection
  23. GRB 250329A: Fading optical counterpart detection by LCO.
  24. GRB 250327B: SVOM/VT optically bright counterpart
  25. GRB 250327B: SAO RAS optical candidate
  26. GRB 250327A: Fermi GBM observation
  27. GRB 250321C: Fermi GBM Final Real-time Localization
  28. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  29. FRB 20250316A: Upper limits for gamma-ray transient from Insight-HXMT/HE observations
  30. GRB 250317D: EIRSAT-1 GMOD Detection
  31. EP250315a: Einstein Probe detection of an X-ray transient
  32. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  33. Fermi trigger No 763581136: Global MASTER-Net observations report
  34. Fermi GRB 250313A: Global MASTER-Net observations report
  35. GRB 250313A: Fermi GBM Final Real-time Localization
  36. EP250302a: Chandra X-ray Detection
  37. Fermi trigger No 763509110: Global MASTER-Net observations report
  38. GRB 250311A: Swift-XRT observations
  39. EP250311a: Global MASTER-Net observations report
  40. GRB 250225B: Swift-BAT refined analysis
  41. GRB 250309B / AT2025dws: SAO RAS optical observations
  42. Fermi GRB 250309A: Global MASTER-Net observations report
  43. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  44. IceCube-250309A: No candidates from the Zwicky Transient Facility
  45. IceCube Alert 250309.32: Global MASTER-Net observations report
  46. Fermi trigger No 762963055: Global MASTER-Net observations report
  47. Fermi GRB 250305A: Global MASTER-Net observations report
  48. IPN triangulation of GRB 250222A
  49. EP250302a : GIT optical follow-up
  50. Fermi GRB 250302A: Global MASTER-Net observations report
  51. EP250302a: Nanshan/HMT optical counterpart detection
  52. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  53. EP250227a: Global MASTER-Net observations report
  54. EP250227a: Optical upper limits with Kinder observations
  55. GRB 250205A / EP250205A: further radio observations with the VLA
  56. Fermi GRB 250226A: Global MASTER-Net observations report
  57. Fermi GRB 250225A: Global MASTER-Net observations report
  58. The EP-WXT trigger 01709131882 is likely a flaring star
  59. EP250223a: LCO detection of the afterglow
  60. Konus-Wind detection of GRB 250217C (short)
  61. Fermi GRB 250217A: Global MASTER-Net observations report
  62. GRB 250217A: Fermi GBM Final Real-time Localization
  63. Fermi GRB 250216A: Global MASTER-Net observations report
  64. EP250215a: Global MASTER-Net observations report
  65. EP250207b: Xinglong optical upper limit
  66. EP250212a: Global MASTER-Net observations report
  67. Fermi trigger No 760945500: Global MASTER-Net observations report
  68. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  69. GRB 250212A: Fermi GBM Final Real-time Localization
  70. IceCube-250207A: One candidate from the Zwicky Transient Facility
  71. EP250207b: Global MASTER-Net observations report
  72. GRB 241128A: VIRT Optical Upper Limit
  73. EP250207b: a new X-ray transient detected by Einstein Probe
  74. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  75. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  76. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  77. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  78. IceCube-250203A: No transient candidates from the Zwicky Transient Facility
  79. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  80. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  81. IPN triangulation of GRB 250201A
  82. GRB 250202B: Fermi GBM Detection
  83. The EP-WXT trigger 01709131153 is not a real source
  84. GRB 250128B: VLA radio upper limit
  85. GRB 250129A: REM optical/NIR afterglow detection
  86. GRB 250129A: GOTO optical observations show brightening afterglow
  87. Fermi GRB 250128B: Global MASTER-Net observations report
  88. GRB 250129A: Swift detection of a burst with an optical counterpart
  89. GRB 250117A: Fermi GBM Observation
  90. Fermi GRB 250127B: Global MASTER-Net observations report
  91. IPN triangulation of GRB 250119C
  92. GECAM-A detection of a bright burst from SGR 1E1841-045
  93. EP250125a: Optical upper limit with Kinder observations
  94. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  95. IPN triangulation of a bright burst from SGR 1E1841-045
  96. GRB 250119B: Fermi GBM Observation
  97. GRB 250118A: Fermi GBM Final Real-time Localization
  98. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  99. Integral GRB250114.55: Global MASTER-Net observations report
  100. EP250108a / AT 2025kg: SAO RAS optical observations

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