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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. LIGO/Virgo S191204r: Coverage and upper limits from MAXI/GSC observations
  2. IceCube-191204A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  3. LIGO/Virgo S191204r: upper limits from AGILE-GRID observations
  4. LIGO/Virgo S191204r: upper limits from AGILE-MCAL observations
  5. LIGO/Virgo S191204r : no neutrino counterpart candidate in ANTARES search
  6. LIGO/Virgo S191204r: Upper limits from IceCube neutrino searches
  7. LIGO/Virgo S191204r: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo S191204r: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  9. LIGO/Virgo S191204r: Global MASTER-Net observations report
  10. GRB 191130A: Swift ToO observations
  11. GRB 191202A: Fermi-LAT detection
  12. GRB 191202A: Fermi GBM observation
  13. Fermi trigger No 597049044: Global MASTER-Net observations report
  14. GRB 191130A, a long burst detected in Swift-BAT ground analysis
  15. GRB 191202A: AstroSat CZTI detection
  16. GRB 191203A: Fermi GBM Final Real-time Localization
  17. GRB 191004A: correction to reported GROND upper limits
  18. GRB 191202A: Fermi GBM Final Real-time Localization
  19. GRB 191201A: AstroSat CZTI detection
  20. LIGO/Virgo S191129u: No transient candidates in CALET observations
  21. Fermi trigger No 596786686: Global MASTER-Net observations report
  22. Fermi trigger No 596808579: Global MASTER-Net observations report
  23. Fermi GBM trigger 596808579/191130507 is not a GRB
  24. LIGO/Virgo S191129u: Upper limits from Insight-HXMT/HE observations
  25. GRB 191129A: AstroSat CZTI detection
  26. LIGO/Virgo S191129u: No counterpart candidates in Fermi-LAT observations
  27. LIGO/Virgo S191129u: not observable by Fermi-GBM
  28. LIGO/Virgo S191129u: Swift/BAT in SAA
  29. LIGO/Virgo S191129u: no INTEGRAL data available
  30. LIGO/Virgo S191129u: No counterpart candidates in HAWC observations
  31. LIGO/Virgo S191129u: Coverage and upper limits from MAXI/GSC observations
  32. LIGO/Virgo S191129u: upper limits from AGILE/GRID observations
  33. LIGO/Virgo S191129u : no neutrino counterpart candidate in ANTARES search
  34. LIGO/Virgo S191129u: upper limits from AGILE/MCAL observations
  35. LIGO/Virgo S191129u: Upper limits from IceCube neutrino searches
  36. LIGO/Virgo S191129u: Global MASTER-Net observations report
  37. LIGO/Virgo S191129u: Identification of a GW compact binary merger candidate
  38. Fermi trigger No 596690552: Global MASTER-Net observations report
  39. GRB 191129A: Fermi GBM Final Real-time Localization
  40. Baksan Neutrino Observatory Alert 191128.17: Global MASTER-Net observations report
  41. GRB 191125B: MASTER-VWFC synchronous observation
  42. IceCube-191122A: No significant detection in HAWC
  43. Baksan Neutrino Observatory Alert 191127.25: Global MASTER-Net observations report
  44. IceCube-191122A: Not observable by Fermi-GBM
  45. IceCube-191122A: Upper limits from a search for additional neutrino events in IceCube
  46. Fermi trigger No 596387570: Global MASTER-Net observations report
  47. GRB 191125B: Fermi GBM Final Real-time Localization
  48. GRB 191125A: Fermi GBM Final Real-time Localization
  49. Baksan Neutrino Observatory Alert 191124.13: Global MASTER-Net observations report
  50. Fermi-LAT Gamma-ray Observations of IceCube-191122A
  51. LIGO/Virgo S191124be: Global MASTER-Net observations report
  52. LIGO/Virgo S191124be: Retraction of GW compact binary merger candidate
  53. GRB 191123A: Swift/UVOT further analysis
  54. GRB 191123A: Swift-BAT refined analysis
  55. GRB 191123A: Swift-XRT refined Analysis
  56. GRB 191123A: Enhanced Swift-XRT position
  57. GRB 191123A: iTelescope optical upper limits
  58. GRB 191123A: Swift/UVOT detection
  59. IceCube-191122A: INTEGRAL was inactive at the time of the event
  60. IceCube-191122A: Global MASTER-Net observations report
  61. GRB 191123A: Swift detection of a burst with an optical counterpart
  62. GRB 191118A: Insight-HXMT/HE detection
  63. GRB 191122A: Swift/UVOT Upper Limits
  64. IceCube-191122A - IceCube observation of a high-energy neutrino candidate event
  65. GRB 191122A: Swift-BAT refined analysis
  66. GRB 191122A: Swift-XRT refined Analysis
  67. GRB 191122A: BOOTES-4/MET optical limit
  68. GRB 191122A: Enhanced Swift-XRT position
  69. GRB 191122A: CHES Optical Observations
  70. GRB 191122A: Prompt enhanced Swift-XRT position
  71. GRB 191122A: Swift detection of a burst
  72. GRB191116A: AstroSat CZTI detection of a short GRB
  73. IceCube-191119A: No significant detection in HAWC
  74. IceCube-191119A: No neutrino counterpart candidates in ANTARES search
  75. LIGO/Virgo S191120at: Retraction of GW compact binary merger candidate
  76. LIGO/Virgo S191120aj: Global MASTER-Net observations report
  77. LIGO/Virgo S191120aj: Retraction of GW compact binary merger candidate
  78. IceCube-191119A: Upper limits from a search for additional neutrino events in IceCube
  79. Fermi-LAT Gamma-ray Observations of IceCube-191119A
  80. IceCube-191119A: Upper limits from Fermi-GBM Observations
  81. IceCube-191119A - No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  82. IceCube-191119A - IceCube observation of a high-energy neutrino candidate event
  83. GRB 191118A: BALROG localization (Fermi Trigger 595807926 / GRB 191118925)
  84. GRB 191118A: Fermi GBM Final Real-time Localization
  85. GRB 191117B: Fermi GBM Final Real-time Localization
  86. LIGO/Virgo S191117j: Retraction of GW compact binary merger candidate
  87. GRB 191117A: Fermi GBM Final Real-time Localization
  88. Swift Trigger 937114 is not an astrophysical source
  89. Swift GRB191115A: Global MASTER-Net observations report
  90. LIGO/Virgo S191110af: Retraction of GW unmodeled transient candidate
  91. LIGO/Virgo S191110af: Upper limits from KM3NeT MeV neutrino search.
  92. LIGO/Virgo S191110af: Upper limits from Konus-Wind observations
  93. GRB 191111A: Insight-HXMT/HE detection
  94. GRB 191027A: CALET Gamma-Ray Burst Monitor detection
  95. LIGO/Virgo S191105e: Updated Sky Localization
  96. Announcing the GW Treasure Map
  97. LIGO/Virgo S191110af: Potential pulsar counterparts
  98. Konus-Wind observation of the recent SGR 1935+2154 activity
  99. GRB 191113A: Fermi GBM Final Real-time Localization
  100. GRB 191031D: CALET Gamma-Ray Burst Monitor detection

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