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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"

12108 results found.

  1. Fermi GRB 250922B: Global MASTER-Net observations report
  2. Fermi trigger No 780156732: Global MASTER-Net observations report
  3. Konus-Wind detection of GRB 250920B
  4. Konus-Wind detection of GRB 250920A
  5. Konus-Wind detection of GRB 250911A
  6. GRB 250920B: Glowbug gamma-ray detection
  7. GRB 250916A: CrAO ZTSh R-band optical observations
  8. GRB 250920C: Swift-XRT refined Analysis
  9. GRB 250920B: Kitab-ISON optical upper limit
  10. GRB 250920C: GROWTH-India Telescope optical observations
  11. GRB 250920B: Fermi GBM Observation
  12. GRB 250920A: Fermi GBM Detection
  13. GRB 250920C: Fermi GBM Observation
  14. Swift GRB 250920C: Global MASTER-Net observations report
  15. GRB 250920B: FTW optical and NIR observations of the counterpart
  16. GRB 250920C: Optical counterpart detection by LCO
  17. GRB250920C: LCOGT Optical Detection
  18. GRB 250920B: Swift-XRT refined Analysis
  19. GRB 250920B: SVOM/C-GFT optical observations
  20. GRB 250920C: GOTO optical counterpart candidate
  21. Konus-Wind detection of GRB 250919A
  22. GRB 250920C: Fermi GBM Final Real-time Localization
  23. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  24. Swift GRB 250920B: Global MASTER-Net observations report
  25. GRB 250920A: AstroSat CZTI detection
  26. GRB 250920B: Fermi GBM Final Real-time Localization
  27. GRB 250920A: BALROG localization (Fermi Trigger 780029651 / GRB 250920121)
  28. GRB 250920A: Fermi GBM Final Localization
  29. GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
  30. GRB 250919A: Swift-XRT afterglow detection
  31. GRB 250919A: Fermi-LAT detection
  32. EP250919a: Einstein Probe detection of an X-ray transient
  33. GRB 250912A: SVOM/ECLAIRs refined analysis
  34. GRB 250916A: MAO/AZT-22 optical observations
  35. GRB 250916A: SAO RAS optical observations
  36. GRB 250917B: Fermi GBM Observation
  37. GRB 250916A: AstroSat CZTI detection of a bright long burst
  38. GRB 250910A: SVOM/ECLAIRs refined analysis
  39. Fermi GRB 250916A: Global MASTER-Net observations report
  40. SVOM/sb25091517: SVOM detection of an X-ray transient
  41. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  42. GRB 250912A: Swift-XRT observations
  43. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  44. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  45. EP250911a: Swift-XRT observations
  46. EP250910a: Global MASTER-Net observations report
  47. EP250911a: Einstein Probe detection of an X-ray transient
  48. GRB 250911A: Swift detection of a burst
  49. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  50. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  51. GRB 250909B: AstroSat CZTI detection of a long burst
  52. GRB 250909A: AstroSat CZTI detection
  53. GRB 250910A: SVOM detection of a faint burst
  54. EP#01709240653: Swift-XRT observations
  55. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  56. EP250908c: Global MASTER-Net observations report
  57. Fermi GRB 250909A: Global MASTER-Net observations report
  58. EP250908c: Einstein Probe detection of an X-ray transient
  59. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  60. GRB 250903A: Swift-XRT afterglow detection
  61. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  62. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  63. EP250905b: EP-FXT follow-up observation
  64. EP250905a: Liverpool Telescope observations
  65. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  66. EP250905b: Global MASTER-Net observations report
  67. EP250905b: EP-WXT detection of a fast X-ray transient
  68. EP250905a: FTW one optical and multiple NIR counterpart candidates
  69. GRB 250905A: Swift-XRT refined Analysis
  70. EP250905a: JinShan likely optical counterpart detection
  71. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  72. IceCube Alert 250905.84: Global MASTER-Net observations report
  73. EP250905a: Einstein Probe detection of an X-ray transient
  74. GRB 250903A: Swift/UVOT detection
  75. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  76. EP detected a brightening of LMXB 1ES 1735-26.9
  77. GRB 250905A: Swift detection of a burst
  78. Swift GRB250905.09: Global MASTER-Net observations report
  79. GRB 250903A: Swift-XRT observations
  80. EP250903a: Swift-XRT observations
  81. EP#01709201209: Swift-XRT observations
  82. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  83. GRB 250903A: EP-FXT counterpart detection
  84. EP250901a: Mondy, Assy and SAO RAS optical limits
  85. GRB 250902B: AstroSat CZTI detection
  86. GRB 250903A: SVOM detection of a burst
  87. EP250903a: Einstein Probe detection of an X-ray transient
  88. GRB 250902B: SVOM/GRM observation
  89. Fermi GRB 250902B: Global MASTER-Net observations report
  90. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  91. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  92. GRB 250901A: EP-FXT follow-up observation
  93. GRB 250901A: SVOM/VT optical afterglow with VHF data
  94. GRB 250901A: Swift-XRT afterglow detection
  95. EP250901a: Swift-XRT observations
  96. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  97. GRB 250901A: SVOM detection of a burst
  98. GRB 250830C: AstroSat CZTI detection of a long burst
  99. EP250901a: Einstein Probe detection of an X-ray transient
  100. EP250831a: EP-FXT follow-up observation

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