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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"

4571 results found.

  1. EP250512a: Global MASTER-Net observations report
  2. Fermi GRB 250510C: Global MASTER-Net observations report
  3. GRB 250510C: Fermi GBM Final Real-time Localization
  4. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  5. GRB 250509A: Swift-XRT refined Analysis
  6. EP250508a: Liverpool Telescope optical upper limits
  7. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  8. EP250508a: Global MASTER-Net observations report
  9. GRB 250504A: Swift-XRT refined Analysis
  10. Fermi GRB 250502B: Global MASTER-Net observations report
  11. GRB 250430A: SVOM/VT optical observations
  12. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  13. Fermi trigger No 767623859: Global MASTER-Net observations report
  14. EP250428b: SAO RAS optical upper limit
  15. GRB 250424A: LCO optical observation
  16. EP250427a: TRT optical counterpart detection
  17. GRB 250424A: WINTER J-band detection
  18. GRB 250424A: EIRSAT-1 GMOD Detection
  19. GRB 250424A: SVOM/VT optical observation
  20. GRB 250424A: Swift-XRT refined Analysis
  21. GRB 250424A: AstroSat CZTI detection of a bright long burst
  22. GRB 250424A: BlackGEM optical afterglow detection
  23. GRB 250424A: DDOTI Afterglow Detection
  24. GRB 250424A: REM optical/NIR afterglow detection
  25. Swift GRB250424A: Global MASTER-Net observations report
  26. Swift GRB250424A: Global MASTER-Net OT detection
  27. SVOM/sb25042207: BOOTES-2 early optical upper limit
  28. EP250421a: Swift/XRT counterpart detection
  29. Fermi GRB 250421A: Global MASTER-Net observations report
  30. IceCube Alert 250421.71: Global MASTER-Net observations report
  31. EP250421a: JinShan likely optical counterpart
  32. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  33. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  34. IceCube-250416A: DDOTI Optical Observations
  35. EP250404a: Nanshan 0.43m Telescope optical observatios
  36. Fermi trigger No 766148493: Global MASTER-Net observations report
  37. Fermi trigger No 766173972: Global MASTER-Net observations report
  38. Fermi GRB 250411A: Global MASTER-Net observations report
  39. IPN triangulation of GRB 250407A
  40. Fermi GRB 250407A: Global MASTER-Net observations report
  41. IceCube 250406.951: DDOTI Optical Observations
  42. IceCube Alert 250406.95: Global MASTER-Net observations report
  43. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  44. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  45. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  46. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  47. Fermi GRB 250404A: Global MASTER-Net observations report
  48. EP250404a: Xinglong decaying optical counterpart
  49. GRB 250403A: Montarrenti Observatory optical detection
  50. EP250404a: Global MASTER-Net observations report
  51. EP250404a: Nanshan/HMT optical counterpart detection
  52. GRB 250403A: Swift/UVOT Detection
  53. EP250402a: Optical upper limit with Kinder observations
  54. GRB 250403A: Swift-XRT observations
  55. GRB 250403A: GOTO optical counterpart follow-up observations
  56. GRB 250403A: GMG Optical Observation
  57. GRB 250331C: Swift-XRT refined Analysis
  58. GRB 250331B: Swift-XRT refined Analysis
  59. GRB 250331B: Swift-XRT refined Analysis
  60. Fermi GRB 250331E: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  62. GRB 250331B: Swift detection of a burst
  63. GRB 250331A: MAXI/GSC detection
  64. GRB 250330A: Swift-XRT afterglow detection
  65. IceCube Alert 250330.35: Global MASTER-Net observations report
  66. GRB 250327B: CrAO and SAO RAS Optical Observations
  67. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  68. GRB 250327A: Swift-XRT refined Analysis
  69. GRB 250327B: GOTO optical counterpart detection
  70. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  71. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  72. GRB 250322A: Swift-XRT refined Analysis
  73. GRB 250322A: AstroSat CZTI detection of a short burst
  74. FRB 250316A: DDOTI Continued Optical Observations
  75. EP250321a: Liverpool Telescope optical follow-up
  76. GRB 250312A: GECAM-A detection
  77. GRB 250321A: Swift-BAT refined analysis
  78. GRB 250321A: Swift-XRT refined Analysis
  79. GRB 250317B: NOT optical observations suggest an optical plateau phase
  80. Fermi GRB 250316A: Global MASTER-Net observations report
  81. GRB 250313.89 / Fermi trigger 763594063: bright OT AT 2025ehi detection
  82. Fermi GRB 250313A: Global MASTER-Net observations report
  83. GRB 250312A: Swift-XRT refined Analysis
  84. GRB 250312A: Swift detection of a burst
  85. GRB 230509B: 1.3m DFOT Optical observations
  86. IPN triangulation of GRB 250308A (short)
  87. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  88. GRB 250309B: Swift-XRT refined Analysis
  89. IceCube Alert 250309.32: Global MASTER-Net observations report
  90. Fermi GRB 250307A: Global MASTER-Net observations report
  91. Fermi trigger No 762963055: Global MASTER-Net observations report
  92. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  93. Konus-Wind detection of GRB 250222A
  94. IPN triangulation of GRB 250222A
  95. EP250302a: Global MASTER-Net observations report
  96. Fermi GRB 250302A: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  98. EP250228a: Optical observations with Kinder and Swift/UVOT
  99. GRB 250225B: VLT/HAWKI near-infrared observations
  100. EP250223a: J band upper limit by SYSU 80cm telescope

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