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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

27777 results found.

  1. GRB 231017A: Swift-XRT observations
  2. GRB 231018A: Fermi GBM Final Real-time Localization
  3. GRB 231017A: Swift ToO observations
  4. GRB 231017A: Swift/BAT-GUANO candidate arcminute localization of a burst
  5. GRB231017A: Fermi GBM Final Localization
  6. LIGO/Virgo/KAGRA S231014r: Upper limits from Swift/BAT-GUANO
  7. (correction) Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field
  8. Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field.
  9. IceCube-231014A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 231012A: Fermi GBM Final Real-time Localization
  11. GRB 231012A: Fermi GBM Final Real-time Localization
  12. GRB 231004A: Glowbug gamma-ray detection
  13. LIGO/Virgo/KAGRA S231005j: Upper limits from Swift/BAT-GUANO
  14. IceCube-231004A: No significant detection in HAWC
  15. GRB 231004A: CALET Gamma-Ray Burst Monitor detection
  16. IceCube-231004A - IceCube observation of a high-energy neutrino candidate track-like event
  17. GRB 231004A: Fermi GBM Final Real-time Localization
  18. GRB 231003A: Fermi GBM Final Real-time Localization
  19. LIGO/Virgo/KAGRA S231001aq: Upper limits from Swift/BAT-GUANO
  20. LIGO/Virgo/KAGRA S230930al: Upper limits from Swift/BAT-GUANO
  21. LIGO/Virgo/KAGRA S230928cb: Upper limits from Swift/BAT-GUANO
  22. GRB 230827B: 10.4m GTC spectroscopic redshift
  23. GRB 230930A: Fermi GBM Final Real-time Localization
  24. NuEm-230927A: Swift-XRT follow-up
  25. Swift Triggers 1192745 and 1192747 are not astrophysical events
  26. Swift Triggers 1192740, 1192742 and 1192743 are not astrophysical events
  27. Swift Triggers 1192735 and 1192737 are not astrophysical events
  28. Konus-Wind detection of GRB 230919A
  29. LIGO/Virgo/KAGRA S230924an: Upper limits from Swift/BAT-GUANO
  30. LIGO/Virgo/KAGRA S230920al: Upper limits from Swift/BAT-GUANO
  31. LIGO/Virgo/KAGRA S230919bj: Upper limits from Swift/BAT-GUANO
  32. LIGO/Virgo/KAGRA S230917af: GRAWITA wide-field observations
  33. LIGO/Virgo/KAGRA S230917af: Zwicky Transient Facility observations
  34. GRB 230921A: Fermi GBM Final Real-time Localization
  35. IPN triangulation of GRB 230919A (short)
  36. GRB 230919A: Fermi GBM Observation
  37. GRB 230919A: Swift/BAT-GUANO detection of a possibly short burst outside the coded FOV
  38. GRB 230919A: AstroSat CZTI detection
  39. GRB 230918B: GOTO detection of a fast-rising transient in the GBM localisation region
  40. GRB 230919A: Fermi GBM Final Real-time Localization
  41. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  42. Detection of self-absorbed radio emission from GRB 230812B with the JVLA + uGMRT
  43. GRB 230918B: Fermi GBM Final Real-time Localization
  44. GRB 230918A (short): Glowbug gamma-ray detection
  45. GRB 230916B: Glowbug gamma-ray detection
  46. ZTF and SEDM Observations of the Candidate Optical Afterglow AT 2023sva
  47. GRB 230915A: Fermi GBM observation
  48. LIGO/Virgo/KAGRA S230918aq: Retraction of GW compact binary merger candidate
  49. GRB 230918A: Fermi GBM Final Real-time Localization
  50. GRB 230917A: AstroSat CZTI detection
  51. Swift Triggers 1192480, 1192481, 1192482 and 1192483 are not astrophysical events
  52. GRB 230915B: Glowbug gamma-ray detection
  53. GRB 230911A: Fermi GBM Observation
  54. Swift GRB230916.18: Global MASTER-Net observations report
  55. LIGO/Virgo/KAGRA S230904n: Correction of the coordinates of the ZTF candidate counterpart
  56. GRB 230915A: Swift/BAT-GUANO detection of a burst
  57. LIGO/Virgo/KAGRA S230914ak: Upper limits from Swift/BAT-GUANO
  58. GRB 230911D: GRBAlpha detection
  59. Swift GRB230916.19: Global MASTER-Net observations report
  60. Swift GRB230916.18: Global MASTER-Net observations report
  61. Swift Triggers 1192234, 1192235 and 1192236 are not astrophysical events
  62. Swift GRB230916.13: Global MASTER-Net observations report
  63. Swift GRB230916.12: Global MASTER-Net observations report
  64. Swift GRB230916.11: Global MASTER-Net observations report
  65. Swift Trigger 1192233 is not a GRB
  66. GRB 230911A: Swift-XRT afterglow detection
  67. GRB 230913A: CALET Gamma-Ray Burst Monitor detection
  68. Swift Trigger 1192088 is not an astrophysical event
  69. GRB 230913A: Glowbug gamma-ray detection
  70. IceCube-230914A - IceCube observation of a high-energy neutrino candidate track-like event
  71. Swift Trigger 1191994 is not an astrophysical event
  72. Swift GRB230913.70: Global MASTER-Net observations report
  73. GRB 230913A: Fermi GBM Observation
  74. LIGO/Virgo/KAGRA S230904n: One ZTF candidate counterpart to coincident neutrino event
  75. Swift Trigger 1191904 is not a GRB
  76. Swift GRB230913.70: Global MASTER-Net observations report
  77. Swift Trigger 1191903 is not an astrophysical event
  78. GRB 230911A: Swift ToO observations
  79. GRB 230913A: Swift/BAT-GUANO arcminute localization of a burst
  80. GRB 230913A: Fermi GBM Final Real-time Localization
  81. GRB 230908A: CALET Gamma-Ray Burst Monitor detection
  82. GRB 230911D: NuSTAR Detection of Prompt Emission
  83. GRB 230911B: AstroSat CZTI detection
  84. GRB 230911C: Swift-XRT refined Analysis
  85. GRB 230911C: Swift-BAT refined analysis
  86. GRB230911C: BOOTES-6/DPRT optical upper limit
  87. GRB 230906A: Chandra detection of the X-ray afterglow
  88. Swift GRB 230911C: Global MASTER-Net observations report
  89. IPN triangulation of GRB 230911D (long)
  90. GRB 230911D: Fermi-LAT detection
  91. GRB230911C: LCOGT Optical Upper Limits
  92. GRB 230911C: Swift/UVOT Upper Limits
  93. GRB 230911B: GRBAlpha and VZLUSAT-2 joint detection
  94. GRB 230908A: Swift/BAT-GUANO detection of a long burst outside the coded FOV
  95. GRB 230911B: correction to the KW GCN 34659
  96. Konus-Wind detection of GRB 230811D
  97. GRB 230911C: Enhanced Swift-XRT position
  98. GRB 230911D: Fermi GBM Final Localization
  99. GRB 230911C: Swift detection of a burst
  100. GRB 230911B: Fermi GBM Final Real-time Localization

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