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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. Fermi trigger No 596690552: Global MASTER-Net observations report
  2. GRB 191129A: Fermi GBM Final Real-time Localization
  3. Baksan Neutrino Observatory Alert 191128.17: Global MASTER-Net observations report
  4. GRB 191125B: MASTER-VWFC synchronous observation
  5. IceCube-191122A: No significant detection in HAWC
  6. Baksan Neutrino Observatory Alert 191127.25: Global MASTER-Net observations report
  7. IceCube-191122A: Not observable by Fermi-GBM
  8. IceCube-191122A: Upper limits from a search for additional neutrino events in IceCube
  9. Fermi trigger No 596387570: Global MASTER-Net observations report
  10. GRB 191125B: Fermi GBM Final Real-time Localization
  11. GRB 191125A: Fermi GBM Final Real-time Localization
  12. Baksan Neutrino Observatory Alert 191124.13: Global MASTER-Net observations report
  13. Fermi-LAT Gamma-ray Observations of IceCube-191122A
  14. LIGO/Virgo S191124be: Global MASTER-Net observations report
  15. LIGO/Virgo S191124be: Retraction of GW compact binary merger candidate
  16. GRB 191123A: Swift/UVOT further analysis
  17. GRB 191123A: Swift-BAT refined analysis
  18. GRB 191123A: Swift-XRT refined Analysis
  19. GRB 191123A: Enhanced Swift-XRT position
  20. GRB 191123A: iTelescope optical upper limits
  21. GRB 191123A: Swift/UVOT detection
  22. IceCube-191122A: INTEGRAL was inactive at the time of the event
  23. IceCube-191122A: Global MASTER-Net observations report
  24. GRB 191123A: Swift detection of a burst with an optical counterpart
  25. GRB 191118A: Insight-HXMT/HE detection
  26. GRB 191122A: Swift/UVOT Upper Limits
  27. IceCube-191122A - IceCube observation of a high-energy neutrino candidate event
  28. GRB 191122A: Swift-BAT refined analysis
  29. GRB 191122A: Swift-XRT refined Analysis
  30. GRB 191122A: BOOTES-4/MET optical limit
  31. GRB 191122A: Enhanced Swift-XRT position
  32. GRB 191122A: CHES Optical Observations
  33. GRB 191122A: Prompt enhanced Swift-XRT position
  34. GRB 191122A: Swift detection of a burst
  35. GRB191116A: AstroSat CZTI detection of a short GRB
  36. IceCube-191119A: No significant detection in HAWC
  37. IceCube-191119A: No neutrino counterpart candidates in ANTARES search
  38. LIGO/Virgo S191120at: Retraction of GW compact binary merger candidate
  39. LIGO/Virgo S191120aj: Global MASTER-Net observations report
  40. LIGO/Virgo S191120aj: Retraction of GW compact binary merger candidate
  41. IceCube-191119A: Upper limits from a search for additional neutrino events in IceCube
  42. Fermi-LAT Gamma-ray Observations of IceCube-191119A
  43. IceCube-191119A: Upper limits from Fermi-GBM Observations
  44. IceCube-191119A - No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  45. IceCube-191119A - IceCube observation of a high-energy neutrino candidate event
  46. GRB 191118A: BALROG localization (Fermi Trigger 595807926 / GRB 191118925)
  47. GRB 191118A: Fermi GBM Final Real-time Localization
  48. GRB 191117B: Fermi GBM Final Real-time Localization
  49. LIGO/Virgo S191117j: Retraction of GW compact binary merger candidate
  50. GRB 191117A: Fermi GBM Final Real-time Localization
  51. Swift Trigger 937114 is not an astrophysical source
  52. Swift GRB191115A: Global MASTER-Net observations report
  53. LIGO/Virgo S191110af: Retraction of GW unmodeled transient candidate
  54. LIGO/Virgo S191110af: Upper limits from KM3NeT MeV neutrino search.
  55. LIGO/Virgo S191110af: Upper limits from Konus-Wind observations
  56. GRB 191111A: Insight-HXMT/HE detection
  57. GRB 191027A: CALET Gamma-Ray Burst Monitor detection
  58. LIGO/Virgo S191105e: Updated Sky Localization
  59. Announcing the GW Treasure Map
  60. LIGO/Virgo S191110af: Potential pulsar counterparts
  61. Konus-Wind observation of the recent SGR 1935+2154 activity
  62. GRB 191113A: Fermi GBM Final Real-time Localization
  63. GRB 191031D: CALET Gamma-Ray Burst Monitor detection
  64. GRB 191112A: Fermi GBM Final Real-time Localization
  65. LIGO/Virgo S191110af: Swift XRT observations, no secure afterglow found
  66. LIGO/Virgo S191110af: Upper limits from CALET observations.
  67. LIGO/Virgo S191109d: Not observable by CALET
  68. LIGO/Virgo S191110af: Upper limits from IceCube MeV neutrino searches
  69. LIGO/Virgo S191110af: no counterpart candidates in the Swift/BAT observations
  70. GRB 191111B: BALROG localization (Fermi Trigger 595170435 / GRB 191111547)
  71. LIGO/Virgo S191110af: No counterpart candidates in INTEGRAL SPI-ACS, and IBIS prompt observation
  72. GRB 191111B: Fermi GBM Final Real-time Localization
  73. LIGO/Virgo S191110af: No neutrino counterpart candidate in ANTARES search
  74. LIGO/Virgo S191110af: No counterpart candidates in Fermi-LAT observations
  75. LIGO/Virgo S191110af: upper limits from AGILE/MCAL observations
  76. LIGO/Virgo S191110af: Evryscope observation report, no counterpart candidates
  77. GRB 191111A: Fermi GBM Final Real-time Localization
  78. LIGO/Virgo S191110af: No counterpart candidates in INTEGRAL SPI-ACS, prompt observation
  79. LIGO/Virgo S191110af: Upper limits from Fermi-GBM Observations
  80. LIGO/Virgo S191110af: Coverage and upper limits from MAXI/GSC observations
  81. LIGO/Virgo S191110af: Identification of a GW unmodeled transient candidate
  82. LIGO/Virgo S191110af: Upper limits from IceCube neutrino searches
  83. LIGO/Virgo S191110af: Global MASTER-Net observations report
  84. LIGO/Virgo S191109d: No significant candidates in FRAM-TAROT-GRANDMA observations
  85. LIGO/Virgo S191110x: Retraction of GW compact binary merger candidate
  86. LIGO/Virgo S191110x: Global MASTER-Net observations report
  87. LIGO/Virgo S191109d: No counterpart candidates in Fermi-LAT observations
  88. LIGO/Virgo S191105e: No significant candidates in FRAM-TAROT-GRANDMA observations
  89. GRB 191110A: Fermi GBM Final Real-time Localization
  90. LIGO/Virgo S191105e: Upper limits from Insight-HXMT/HE observations
  91. LIGO/Virgo S191109d: AstroSat CZTI upper limits
  92. LIGO/Virgo S191109d: no counterpart candidates in the Swift/BAT observations
  93. LIGO/Virgo S191109d : no neutrino counterpart candidate in ANTARES search
  94. LIGO/Virgo S191109d: Global MASTER-Net observations report
  95. LIGO/Virgo S191109d: upper limits from AGILE-GRID observations mailed-by:
  96. LIGO/Virgo S191109d: No counterpart candidates in INTEGRAL SPI-ACS,prompt observation
  97. LIGO/Virgo S191109d: upper limits from AGILE/MCAL observations
  98. LIGO/Virgo S191109d: Upper limits from Fermi-GBM Observations
  99. LIGO/Virgo S191109d: Coverage and upper limits from MAXI/GSC observations
  100. LIGO/Virgo S191109d: Upper limits from IceCube neutrino searches

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