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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 201011A: Fermi GBM detection of a likely Long GRB in the direction of SGR 1830-0645
  2. Fermi trigger No 624139481: AGILE detection
  3. GRB 201012A: Fermi GBM Final Real-time Localization
  4. SGR 1830-0645: pre-discovery detection in Swift/BAT
  5. Fermi trigger No 624139481: Global MASTER-Net observations report
  6. SGR 1830-0645 / GRB 201010A: 1.5m OSN optical upper limit
  7. Fermi trigger No 624121589: Global MASTER-Net observations report
  8. SGR 1830-0645: Swift-BAT refined analysis
  9. GRB 201006A: Chandra upper limit on the X-ray afterglow
  10. SGR 1830-0645 / GRB 201010A: Kitab optical non-detection
  11. GRB 201010A: Enhanced Swift-XRT position
  12. Swift GRB201010.62: Global MASTER-Net observations report
  13. Swift detection of a new SGR 1830-0645 or a short GRB 201010A
  14. IceCube-200929A: JCMT/SCUBA2 observations
  15. IceCube-201007A: No significant detection in HAWC
  16. GRB 201008B: Fermi GBM Final Localization
  17. IceCube-201007A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 201009A: AstroSat CZTI detection
  19. GRB 201009A: AGILE detection of a burst
  20. GRB 201008A: Swift-XRT observations
  21. IceCube-200926A: Upper limits from Insight-HXMT Observations
  22. GRB 201008A: Swift ToO observations
  23. IceCube-201007A: Upper limits from Fermi-GBM Observations
  24. GRB 201008A: Swift/BAT-GUANO detection and possible arcminute localization
  25. Fermi-LAT Gamma-ray Observations of IceCube-201007A
  26. Fermi trigger No 623846261: Global MASTER-Net observations report
  27. Fermi trigger No 623873165: Global MASTER-Net observations report
  28. Swift-XRT observations of IceCube 201007A
  29. Baksan Neutrino Observatory Alert 201008.47: Global MASTER-Net observations report
  30. GRB 201008A: BALROG localization (Fermi Trigger 623846261 / GRB 201008443)
  31. IceCube-201007A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  32. IceCube-201007A - IceCube observation of a high-energy neutrino candidate track-like event
  33. IceCube Alert 201007.92: Global MASTER-Net observations report
  34. GRB 201006A: GROWTH-India Telescope optical upper limit
  35. GRB 201006A: Lowell Discovery Telescope upper limits
  36. GRB 201006A: MITSuME Akeno optical upper limits
  37. Fermi GRB 201007A: Global MASTER-Net observations report
  38. GRB 201007A: Fermi GBM Final Real-time Localization
  39. GRB 201006A: Swift-XRT refined Analysis
  40. GRB 201006A: Swift-BAT refined analysis
  41. Baksan Neutrino Observatory Alert 201006.88: Global MASTER-Net observations report
  42. GRB 201006A: Swift/UVOT Upper Limits
  43. GRB 201006A: Fermi GBM detection
  44. GRB 201006A is likely a short burst
  45. GRB 201006A: Enhanced Swift-XRT position
  46. INTEGRAL sub-threshold detection of GRB 201006A
  47. GRB 201006A: Swift detection of a burst
  48. Swift GRB201006.05: Global MASTER-Net observations report
  49. Fermi trigger No 623470566: Global MASTER-Net observations report
  50. GRB 201004A: Fermi GBM Final Localization
  51. Fermi trigger No 623493962: Global MASTER-Net observations report
  52. GRB 201001A: Swift/UVOT Upper Limits
  53. IceCube-200926A: No usable INTEGRAL data
  54. IceCube-200926B: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  55. IceCube-200929A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  56. IceCube-200926A: No candidate counterparts from the Zwicky Transient Facility
  57. GRB 201001A: TSHAO optical upper limit
  58. GRB 201001A: Xinglong-2.16m optical upper limit
  59. GRB 201001A: MITSuME Akeno optical upper limits
  60. IceCube-200926A: JCMT/SCUBA2 observations
  61. IceCube-200929A: No significant detection in HAWC
  62. GRB 201001A: Swift-BAT refined analysis
  63. GRB 201001A: Swift-XRT refined Analysis
  64. IceCube-200929A: Upper limits from a search for additional neutrino events in IceCube
  65. GRB 201001A: Fermi GBM observation
  66. Swift-XRT observations of IceCube 200929A
  67. GRB 201001A: Enhanced Swift-XRT position
  68. GRB 201001A: Swift detection of a burst
  69. GRB 201001A: Fermi GBM Final Real-time Localization
  70. Fermi-LAT Gamma-ray Observations of IceCube-200929A
  71. IceCube-200929A: Upper limits from Fermi-GBM Observations
  72. IceCube-200929A: No neutrino counterpart candidates in ANTARES search
  73. IceCube-200926B: No significant detection in HAWC
  74. GRB 200928B: Insight-HXMT/HE detection
  75. IceCube-200929A: IceCube observation of a high-energy neutrino candidate event
  76. IceCube-200926B: Upper limits from Fermi-GBM Observations
  77. IceCube-200926A: Upper limits from Fermi-GBM Observations
  78. IceCube Alert 200929.74: Global MASTER-Net observations report
  79. IceCube-200926A: No significant detection in HAWC
  80. Fermi GRB 200929A: Global MASTER-Net observations report
  81. GRB 200928B: AstroSat CZTI detection
  82. GRB 200929A: Fermi GBM Final Real-time Localization
  83. IceCube-200926B: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube-200926A: Upper limits from a search for additional neutrino events in IceCube
  85. GRB 200928B: BALROG localization (Fermi Trigger 622991684 / GRB 200928552)
  86. GRB 200928B: Fermi GBM Final Real-time Localization
  87. IceCube-200926A: No Candidate Counterparts from the Zwicky Transient Facility
  88. Fermi-LAT Gamma-ray Observations of IceCube-200926B
  89. GRB 200928A: Fermi GBM Final Localization
  90. IceCube-200926B: No neutrino counterpart candidates in ANTARES search
  91. IceCube Alert 200926.94: Global MASTER-Net observations report
  92. Swift-XRT observations of IceCube 200926A
  93. Konus-Wind detection of GRB 200920B
  94. Fermi-LAT Gamma-ray Observations of IceCube-200926A
  95. GRB 200925B: Swift-XRT refined analysis update
  96. GRB 200925B NUTTelA-TAO / BSTI Early Measurements (Preliminary)
  97. IceCube Alert 200926.33: Global MASTER-Net observations report
  98. IceCube-200926B: IceCube observation of a high-energy neutrino candidate event
  99. GRB 200925B: Swift-XRT refined Analysis
  100. GRB 200925B: Swift/UVOT Detection

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