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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"

21458 results found.

  1. GRB 231028A: Fermi GBM Detection
  2. Swift GRB 231028A: Global MASTER-Net observations report
  3. GRB 231028A: Swift detection of a burst
  4. GRB 231025A: Fermi GBM Observation
  5. GRB 231025A: Swift/BAT-GUANO detection of a likely short burst
  6. GRB 231018A: Swift/BAT-GUANO detection of a long burst outside the coded FOV
  7. LIGO/Virgo/KAGRA S231020bw: Upper limits from Swift/BAT-GUANO
  8. GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
  9. GRB 231017A: 1.3m DFOT Optical upper limit
  10. GRB 231018A: Glowbug gamma-ray detection
  11. IPN triangulation of GRB 231018A
  12. GRB 231017A: Swift/UVOT Upper Limit
  13. GRB 230911C: ATCA detection of possible radio counterpart
  14. GRB 231017A: GOTO optical upper limits
  15. GRB 231017A: JinShan optical upper limit
  16. GRB 231017A: Las Cumbres optical upper limit
  17. GRB 231017A: LCOGT Optical Upper Limits
  18. GRB231017A: GROWTH-India upper limits on the optical afterglow
  19. GRB 231017A: Fermi GBM Detection
  20. GRB 231017A: Swift-XRT observations
  21. GRB 231017A: Swift ToO observations
  22. GRB 231017A: Swift/BAT-GUANO candidate arcminute localization of a burst
  23. LIGO/Virgo/KAGRA S231014r: Upper limits from Swift/BAT-GUANO
  24. LIGO/Virgo/KAGRA S231005j: Upper limits from Swift/BAT-GUANO
  25. LIGO/Virgo/KAGRA S231001aq: Upper limits from Swift/BAT-GUANO
  26. LIGO/Virgo/KAGRA S230930al: Upper limits from Swift/BAT-GUANO
  27. LIGO/Virgo/KAGRA S230928cb: Upper limits from Swift/BAT-GUANO
  28. NuEm-230927A: Swift-XRT follow-up
  29. Swift Triggers 1192745 and 1192747 are not astrophysical events
  30. Swift Triggers 1192740, 1192742 and 1192743 are not astrophysical events
  31. Swift Triggers 1192735 and 1192737 are not astrophysical events
  32. Konus-Wind detection of GRB 230919A
  33. LIGO/Virgo/KAGRA S230924an: Upper limits from Swift/BAT-GUANO
  34. LIGO/Virgo/KAGRA S230920al: Upper limits from Swift/BAT-GUANO
  35. LIGO/Virgo/KAGRA S230919bj: Upper limits from Swift/BAT-GUANO
  36. LIGO/Virgo/KAGRA S230917af: GRAWITA wide-field observations
  37. LIGO/Virgo/KAGRA S230917af: Zwicky Transient Facility observations
  38. IPN triangulation of GRB 230919A (short)
  39. GRB 230919A: Fermi GBM Observation
  40. GRB 230919A: Swift/BAT-GUANO detection of a possibly short burst outside the coded FOV
  41. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  42. GRB 230915A: Fermi GBM observation
  43. Swift Triggers 1192480, 1192481, 1192482 and 1192483 are not astrophysical events
  44. GRB 230911A: Fermi GBM Observation
  45. Swift GRB230916.18: Global MASTER-Net observations report
  46. GRB 230915A: Swift/BAT-GUANO detection of a burst
  47. LIGO/Virgo/KAGRA S230914ak: Upper limits from Swift/BAT-GUANO
  48. Swift GRB230916.19: Global MASTER-Net observations report
  49. Swift GRB230916.18: Global MASTER-Net observations report
  50. Swift Triggers 1192234, 1192235 and 1192236 are not astrophysical events
  51. Swift GRB230916.13: Global MASTER-Net observations report
  52. Swift GRB230916.12: Global MASTER-Net observations report
  53. Swift GRB230916.11: Global MASTER-Net observations report
  54. Swift Trigger 1192233 is not a GRB
  55. GRB 230911A: Swift-XRT afterglow detection
  56. GRB 230913A: CALET Gamma-Ray Burst Monitor detection
  57. Swift Trigger 1192088 is not an astrophysical event
  58. GRB 230913A: Glowbug gamma-ray detection
  59. Swift Trigger 1191994 is not an astrophysical event
  60. Swift GRB230913.70: Global MASTER-Net observations report
  61. GRB 230913A: Fermi GBM Observation
  62. Swift Trigger 1191904 is not a GRB
  63. Swift GRB230913.70: Global MASTER-Net observations report
  64. Swift Trigger 1191903 is not an astrophysical event
  65. GRB 230911A: Swift ToO observations
  66. GRB 230913A: Swift/BAT-GUANO arcminute localization of a burst
  67. GRB 230908A: CALET Gamma-Ray Burst Monitor detection
  68. GRB 230911C: Swift-XRT refined Analysis
  69. GRB 230911C: Swift-BAT refined analysis
  70. GRB230911C: BOOTES-6/DPRT optical upper limit
  71. GRB 230906A: Chandra detection of the X-ray afterglow
  72. Swift GRB 230911C: Global MASTER-Net observations report
  73. IPN triangulation of GRB 230911D (long)
  74. GRB 230911D: Fermi-LAT detection
  75. GRB230911C: LCOGT Optical Upper Limits
  76. GRB 230911C: Swift/UVOT Upper Limits
  77. GRB 230911C: GOTO optical upper limits
  78. GRB 230908A: Swift/BAT-GUANO detection of a long burst outside the coded FOV
  79. GRB 230911C: Enhanced Swift-XRT position
  80. GRB 230911C: Swift detection of a burst
  81. GRB 230906A: BlackGEM upper limits
  82. GRB 230903A: TESS observations of optical emission
  83. GRB 230906A: Swift/UVOT Upper Limits
  84. GRID detection of GRB 230827A
  85. GRB 230906A: Swift-XRT observations
  86. IPN triangulation of GRB 230906A (short)
  87. GRB 230906A: Swift ToO observations
  88. Swift Attitude Control Affecting Some UVOT Images
  89. GRB 230812B: Chandra late-time detection of the X-ray afterglow
  90. GRB 230903A: Swift-XRT refined Analysis
  91. GRB 230903A: Enhanced Swift-XRT position
  92. GRB 230903A: VLT/X-shooter optical observations
  93. GRB 230903A: Swift-BAT refined analysis
  94. GRB 230903A: Fermi GBM detection
  95. GRB 230903A: LCOGT Optical Upper Limits
  96. GRB 230903A: Swift detection of a burst
  97. Swift GRB230903.72: Global MASTER-Net observations report
  98. GRB 230827A: Glowbug gamma-ray detection
  99. GRB 230826A: Glowbug gamma-ray detection
  100. GRB 230827B: Swift-XRT afterglow detection

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