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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 201012A: Fermi GBM Final Real-time Localization
  2. SGR 1830-0645: pre-discovery detection in Swift/BAT
  3. Fermi trigger No 624139481: Global MASTER-Net observations report
  4. SGR 1830-0645 / GRB 201010A: 1.5m OSN optical upper limit
  5. Fermi trigger No 624121589: Global MASTER-Net observations report
  6. SGR 1830-0645: Swift-BAT refined analysis
  7. GRB 201006A: Chandra upper limit on the X-ray afterglow
  8. SGR 1830-0645 / GRB 201010A: Kitab optical non-detection
  9. GRB 201010A: Enhanced Swift-XRT position
  10. Swift GRB201010.62: Global MASTER-Net observations report
  11. Swift detection of a new SGR 1830-0645 or a short GRB 201010A
  12. IceCube-200929A: JCMT/SCUBA2 observations
  13. IceCube-201007A: No significant detection in HAWC
  14. GRB 201008B: Fermi GBM Final Localization
  15. IceCube-201007A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 201009A: AstroSat CZTI detection
  17. GRB 201009A: AGILE detection of a burst
  18. GRB 201008A: Swift-XRT observations
  19. IceCube-200926A: Upper limits from Insight-HXMT Observations
  20. GRB 201008A: Swift ToO observations
  21. IceCube-201007A: Upper limits from Fermi-GBM Observations
  22. GRB 201008A: Swift/BAT-GUANO detection and possible arcminute localization
  23. Fermi-LAT Gamma-ray Observations of IceCube-201007A
  24. Fermi trigger No 623846261: Global MASTER-Net observations report
  25. Fermi trigger No 623873165: Global MASTER-Net observations report
  26. Swift-XRT observations of IceCube 201007A
  27. Baksan Neutrino Observatory Alert 201008.47: Global MASTER-Net observations report
  28. GRB 201008A: BALROG localization (Fermi Trigger 623846261 / GRB 201008443)
  29. IceCube-201007A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  30. IceCube-201007A - IceCube observation of a high-energy neutrino candidate track-like event
  31. IceCube Alert 201007.92: Global MASTER-Net observations report
  32. GRB 201006A: GROWTH-India Telescope optical upper limit
  33. GRB 201006A: Lowell Discovery Telescope upper limits
  34. GRB 201006A: MITSuME Akeno optical upper limits
  35. Fermi GRB 201007A: Global MASTER-Net observations report
  36. GRB 201007A: Fermi GBM Final Real-time Localization
  37. GRB 201006A: Swift-XRT refined Analysis
  38. GRB 201006A: Swift-BAT refined analysis
  39. Baksan Neutrino Observatory Alert 201006.88: Global MASTER-Net observations report
  40. GRB 201006A: Swift/UVOT Upper Limits
  41. GRB 201006A: Fermi GBM detection
  42. GRB 201006A is likely a short burst
  43. GRB 201006A: Enhanced Swift-XRT position
  44. INTEGRAL sub-threshold detection of GRB 201006A
  45. GRB 201006A: Swift detection of a burst
  46. Swift GRB201006.05: Global MASTER-Net observations report
  47. Fermi trigger No 623470566: Global MASTER-Net observations report
  48. GRB 201004A: Fermi GBM Final Localization
  49. Fermi trigger No 623493962: Global MASTER-Net observations report
  50. GRB 201001A: Swift/UVOT Upper Limits
  51. IceCube-200926A: No usable INTEGRAL data
  52. IceCube-200926B: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  53. IceCube-200929A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  54. IceCube-200926A: No candidate counterparts from the Zwicky Transient Facility
  55. GRB 201001A: TSHAO optical upper limit
  56. GRB 201001A: Xinglong-2.16m optical upper limit
  57. GRB 201001A: MITSuME Akeno optical upper limits
  58. IceCube-200926A: JCMT/SCUBA2 observations
  59. IceCube-200929A: No significant detection in HAWC
  60. GRB 201001A: Swift-BAT refined analysis
  61. GRB 201001A: Swift-XRT refined Analysis
  62. IceCube-200929A: Upper limits from a search for additional neutrino events in IceCube
  63. GRB 201001A: Fermi GBM observation
  64. Swift-XRT observations of IceCube 200929A
  65. GRB 201001A: Enhanced Swift-XRT position
  66. GRB 201001A: Swift detection of a burst
  67. GRB 201001A: Fermi GBM Final Real-time Localization
  68. Fermi-LAT Gamma-ray Observations of IceCube-200929A
  69. IceCube-200929A: Upper limits from Fermi-GBM Observations
  70. IceCube-200929A: No neutrino counterpart candidates in ANTARES search
  71. IceCube-200926B: No significant detection in HAWC
  72. GRB 200928B: Insight-HXMT/HE detection
  73. IceCube-200929A: IceCube observation of a high-energy neutrino candidate event
  74. IceCube-200926B: Upper limits from Fermi-GBM Observations
  75. IceCube-200926A: Upper limits from Fermi-GBM Observations
  76. IceCube Alert 200929.74: Global MASTER-Net observations report
  77. IceCube-200926A: No significant detection in HAWC
  78. Fermi GRB 200929A: Global MASTER-Net observations report
  79. GRB 200928B: AstroSat CZTI detection
  80. GRB 200929A: Fermi GBM Final Real-time Localization
  81. IceCube-200926B: Upper limits from a search for additional neutrino events in IceCube
  82. IceCube-200926A: Upper limits from a search for additional neutrino events in IceCube
  83. GRB 200928B: BALROG localization (Fermi Trigger 622991684 / GRB 200928552)
  84. GRB 200928B: Fermi GBM Final Real-time Localization
  85. IceCube-200926A: No Candidate Counterparts from the Zwicky Transient Facility
  86. Fermi-LAT Gamma-ray Observations of IceCube-200926B
  87. GRB 200928A: Fermi GBM Final Localization
  88. IceCube-200926B: No neutrino counterpart candidates in ANTARES search
  89. IceCube Alert 200926.94: Global MASTER-Net observations report
  90. Swift-XRT observations of IceCube 200926A
  91. Konus-Wind detection of GRB 200920B
  92. Fermi-LAT Gamma-ray Observations of IceCube-200926A
  93. GRB 200925B: Swift-XRT refined analysis update
  94. GRB 200925B NUTTelA-TAO / BSTI Early Measurements (Preliminary)
  95. IceCube Alert 200926.33: Global MASTER-Net observations report
  96. IceCube-200926B: IceCube observation of a high-energy neutrino candidate event
  97. GRB 200925B: Swift-XRT refined Analysis
  98. GRB 200925B: Swift/UVOT Detection
  99. GRB 200925B: Swift-BAT refined analysis
  100. GRB 200922A: Chilescope optical observations

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