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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"
  1. GRB 181203A: Swift detection of a burst
  2. GRB 181201A: Further COATLI Optical Monitoring
  3. GRB 181201A: Insight-HXMT/HE detection
  4. GRB 181202A: Global MASTER-Net optical observations
  5. GRB 181202A: Swift-BAT refined analysis
  6. GRB 181201A: VLT/FORS2 tentative spectroscopic redshift
  7. GRB 181202A: Swift-XRT refined Analysis
  8. GRB 181201A: GROND detection of the afterglow and redshift upper limit of z < 3
  9. GRB 181201A: optical observations in Chilescope observatory
  10. GRB 181201A: Global MASTER-Net prompt optical descovery and afterglow observations
  11. GRB 181202A: Enhanced Swift-XRT position
  12. GRB 181202A: Swift detection of a burst with an optical counterpart
  13. GRB 181201A: COATLI Optical Detection
  14. GRB 181201A: Fermi-LAT detection
  15. GRB 181201A: Zeiss-1000/CrAO optical observations
  16. GRB 181201A: NOT optical observations
  17. GRB 181201A: optical observations in SAAO
  18. GRB 181201A MASTER-Net OT continued observation
  19. GRB 181201A: iTelescope optical afterglow detection
  20. GRB 181201A: Swift-XRT afterglow detection
  21. GRB 181201A: Swift ToO observations
  22. GRB 181201A: Swift-XRT afterglow
  23. GRB 181201A: likely Swift/XRT afterglow
  24. GRB 181201A MASTER-Net OT detection
  25. GRB 181201A: a long GRB detected by INTEGRAL
  26. GRB 181119A: CALET Gamma-Ray Burst Monitor detection
  27. GRB 181123B: ATCA 5/9 GHz rapid-response radio observation
  28. Short-duration GRB 181121.4: MASTER-Tavrida possible OT detection near the PGC galaxy during large Fermi error box inspection
  29. GRB 181127A : a long GRB detected by INTEGRAL
  30. GRB 181126A: Swift-BAT refined analysis
  31. GRB 181126A: No Ks-band afterglow detection with Keck I
  32. GRB 181123B: Keck further near-infrared imaging
  33. GRB 181126A: Swift/UVOT Upper Limits
  34. GRB 181126A: Swift-XRT refined Analysis
  35. GRB 181126A deep Gemini imaging
  36. GRB 181126A: Fermi GBM observation
  37. Konus-Wind observation of GRB 181121A
  38. GRB 181126A: Enhanced Swift-XRT position
  39. GRB 181126A: Prompt enhanced Swift-XRT position
  40. GRB 181126A: Swift detection of a burst
  41. GRB 181123B: Insight-HXMT/HE detection
  42. GRB 181125A: Fermi GBM observation
  43. GRB 181125A: Swift-BAT refined analysis
  44. IPN Triangulation of GRB 181121A (short)
  45. GRB 181125A: Swift detection of a burst
  46. GRB 181121A: AstroSat CZTI detection
  47. Swift J1858.6-0814/GRB 181123A: Swift/BAT location correction to GCN 23442
  48. Swift trigger 873178: GRB 181123A is Swift J1858.6-0814
  49. GRB 181123B: Global MASTER Net optical inspection
  50. GRB 181123B: Swift-BAT lag analysis and search for extended emission
  51. GRB 181123A, Swift-BAT refined analysis
  52. GRB 181123B: Keck near-infrared imaging
  53. GRB 181123B: Gemini-North optical detection
  54. GRB 181119A: AstroSat CZTI detection
  55. GRB 181123B: Swift/UVOT Upper Limits
  56. GRB 181020A: AstroSat CZTI detection
  57. GRB 181123B: Swift-XRT refined Analysis
  58. GRB 181123B: Enhanced Swift-XRT position
  59. GRB 181123B: Prompt enhanced Swift-XRT position
  60. GRB 181123B: Swift detection of a short burst
  61. GRB 181123A: Swift detection of a burst
  62. GRB 181119A: Insight-HXMT/HE detection
  63. GRB 181121A: AGILE/MCAL detection of a burst
  64. GRB 181120A: Fermi GBM observation
  65. GRB 181120A: Fermi-LAT detection
  66. Swift Trigger 872470: further Swift analysis
  67. Swift Trigger 872470 is probably not a GRB
  68. Konus-Wind observation of GRB 181110A
  69. GRB 181110A: optical observations in Chilescope observatory
  70. GROND observations of GRB181110A
  71. GRB 181110A: VLT/X-shooter redshift
  72. GRB 181110A, Swift-BAT refined analysis
  73. GRB 181110A: Swift/UVOT Detection
  74. GRB 181110A: Swift-XRT refined Analysis
  75. GRB 181110A: Enhanced Swift-XRT position
  76. GRB 181110A: optical observations from iTelescope SSO
  77. GRB 181110A: MITSuME Akeno optical observation
  78. GRB 181110A: Kanata 1.5m optical observation
  79. GRB 181110A: Swift detection of a burst with an optical counterpart
  80. Swift Trigger 871103 is not an astrophysical event
  81. Fermi GRB 181105.31: Global MASTER Net optical observations
  82. GRB 181103A: AbAO optical upper limit
  83. GRB 181028A: Insight-HXMT/HE detection
  84. GRB 181103A: MITSuME Okayama optical upper limits
  85. GRB 181103A: Swift/UVOT Detection
  86. GRB 181103A: Nanshan-1m optical upper limit
  87. GRB 181103A: Swift-BAT refined analysis
  88. GRB 181103A: Swift-XRT refined Analysis
  89. GRB 181103A: Enhanced Swift-XRT position
  90. GRB 181103A: Swift detection of a burst
  91. FACT follow-up of IceCube20181023A
  92. GRB 181030A: Swift/UVOT Detection
  93. GRB 181028A: CALET Gamma-Ray Burst Monitor detection
  94. IceCube-181031A retraction
  95. GRB 181030A, Swift-BAT refined analysis
  96. GRB 181030A: RATIR Optical and NIR Observations
  97. GRB 181026A: AstroSat CZTI detection
  98. GRB 181030A: Swift-XRT refined Analysis
  99. Konus-Wind observation of GRB 181028A
  100. GRB 181030A: MASTER Net OT detection

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