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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"

27784 results found.

  1. GRB 231017A: Las Cumbres optical upper limit
  2. GRB 231015A: Glowbug gamma-ray detection
  3. GRB 231017A: LCOGT Optical Upper Limits
  4. GRB231017A: GROWTH-India upper limits on the optical afterglow
  5. GRB 231015A: AstroSat CZTI detection
  6. GRB 231018A: Fermi GBM Detection
  7. GRB 231017A: Fermi GBM Detection
  8. GRB 231017A: Swift-XRT observations
  9. GRB 231018A: Fermi GBM Final Real-time Localization
  10. GRB 231017A: Swift ToO observations
  11. GRB 231017A: Swift/BAT-GUANO candidate arcminute localization of a burst
  12. GRB231017A: Fermi GBM Final Localization
  13. LIGO/Virgo/KAGRA S231014r: Upper limits from Swift/BAT-GUANO
  14. (correction) Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field
  15. Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field.
  16. IceCube-231014A - IceCube observation of a high-energy neutrino candidate track-like event
  17. GRB 231012A: Fermi GBM Final Real-time Localization
  18. GRB 231012A: Fermi GBM Final Real-time Localization
  19. GRB 231004A: Glowbug gamma-ray detection
  20. LIGO/Virgo/KAGRA S231005j: Upper limits from Swift/BAT-GUANO
  21. IceCube-231004A: No significant detection in HAWC
  22. GRB 231004A: CALET Gamma-Ray Burst Monitor detection
  23. IceCube-231004A - IceCube observation of a high-energy neutrino candidate track-like event
  24. GRB 231004A: Fermi GBM Final Real-time Localization
  25. GRB 231003A: Fermi GBM Final Real-time Localization
  26. LIGO/Virgo/KAGRA S231001aq: Upper limits from Swift/BAT-GUANO
  27. LIGO/Virgo/KAGRA S230930al: Upper limits from Swift/BAT-GUANO
  28. LIGO/Virgo/KAGRA S230928cb: Upper limits from Swift/BAT-GUANO
  29. GRB 230827B: 10.4m GTC spectroscopic redshift
  30. GRB 230930A: Fermi GBM Final Real-time Localization
  31. NuEm-230927A: Swift-XRT follow-up
  32. Swift Triggers 1192745 and 1192747 are not astrophysical events
  33. Swift Triggers 1192740, 1192742 and 1192743 are not astrophysical events
  34. Swift Triggers 1192735 and 1192737 are not astrophysical events
  35. Konus-Wind detection of GRB 230919A
  36. LIGO/Virgo/KAGRA S230924an: Upper limits from Swift/BAT-GUANO
  37. LIGO/Virgo/KAGRA S230920al: Upper limits from Swift/BAT-GUANO
  38. LIGO/Virgo/KAGRA S230919bj: Upper limits from Swift/BAT-GUANO
  39. LIGO/Virgo/KAGRA S230917af: GRAWITA wide-field observations
  40. LIGO/Virgo/KAGRA S230917af: Zwicky Transient Facility observations
  41. GRB 230921A: Fermi GBM Final Real-time Localization
  42. IPN triangulation of GRB 230919A (short)
  43. GRB 230919A: Fermi GBM Observation
  44. GRB 230919A: Swift/BAT-GUANO detection of a possibly short burst outside the coded FOV
  45. GRB 230919A: AstroSat CZTI detection
  46. GRB 230918B: GOTO detection of a fast-rising transient in the GBM localisation region
  47. GRB 230919A: Fermi GBM Final Real-time Localization
  48. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  49. Detection of self-absorbed radio emission from GRB 230812B with the JVLA + uGMRT
  50. GRB 230918B: Fermi GBM Final Real-time Localization
  51. GRB 230918A (short): Glowbug gamma-ray detection
  52. GRB 230916B: Glowbug gamma-ray detection
  53. ZTF and SEDM Observations of the Candidate Optical Afterglow AT 2023sva
  54. GRB 230915A: Fermi GBM observation
  55. LIGO/Virgo/KAGRA S230918aq: Retraction of GW compact binary merger candidate
  56. GRB 230918A: Fermi GBM Final Real-time Localization
  57. GRB 230917A: AstroSat CZTI detection
  58. Swift Triggers 1192480, 1192481, 1192482 and 1192483 are not astrophysical events
  59. GRB 230915B: Glowbug gamma-ray detection
  60. GRB 230911A: Fermi GBM Observation
  61. Swift GRB230916.18: Global MASTER-Net observations report
  62. LIGO/Virgo/KAGRA S230904n: Correction of the coordinates of the ZTF candidate counterpart
  63. GRB 230915A: Swift/BAT-GUANO detection of a burst
  64. LIGO/Virgo/KAGRA S230914ak: Upper limits from Swift/BAT-GUANO
  65. GRB 230911D: GRBAlpha detection
  66. Swift GRB230916.19: Global MASTER-Net observations report
  67. Swift GRB230916.18: Global MASTER-Net observations report
  68. Swift Triggers 1192234, 1192235 and 1192236 are not astrophysical events
  69. Swift GRB230916.13: Global MASTER-Net observations report
  70. Swift GRB230916.12: Global MASTER-Net observations report
  71. Swift GRB230916.11: Global MASTER-Net observations report
  72. Swift Trigger 1192233 is not a GRB
  73. GRB 230911A: Swift-XRT afterglow detection
  74. GRB 230913A: CALET Gamma-Ray Burst Monitor detection
  75. Swift Trigger 1192088 is not an astrophysical event
  76. GRB 230913A: Glowbug gamma-ray detection
  77. IceCube-230914A - IceCube observation of a high-energy neutrino candidate track-like event
  78. Swift Trigger 1191994 is not an astrophysical event
  79. Swift GRB230913.70: Global MASTER-Net observations report
  80. GRB 230913A: Fermi GBM Observation
  81. LIGO/Virgo/KAGRA S230904n: One ZTF candidate counterpart to coincident neutrino event
  82. Swift Trigger 1191904 is not a GRB
  83. Swift GRB230913.70: Global MASTER-Net observations report
  84. Swift Trigger 1191903 is not an astrophysical event
  85. GRB 230911A: Swift ToO observations
  86. GRB 230913A: Swift/BAT-GUANO arcminute localization of a burst
  87. GRB 230913A: Fermi GBM Final Real-time Localization
  88. GRB 230908A: CALET Gamma-Ray Burst Monitor detection
  89. GRB 230911D: NuSTAR Detection of Prompt Emission
  90. GRB 230911B: AstroSat CZTI detection
  91. GRB 230911C: Swift-XRT refined Analysis
  92. GRB 230911C: Swift-BAT refined analysis
  93. GRB230911C: BOOTES-6/DPRT optical upper limit
  94. GRB 230906A: Chandra detection of the X-ray afterglow
  95. Swift GRB 230911C: Global MASTER-Net observations report
  96. IPN triangulation of GRB 230911D (long)
  97. GRB 230911D: Fermi-LAT detection
  98. GRB230911C: LCOGT Optical Upper Limits
  99. GRB 230911C: Swift/UVOT Upper Limits
  100. GRB 230911B: GRBAlpha and VZLUSAT-2 joint detection

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