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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 200101A: CALET Gamma-Ray Burst Monitor detection
  2. LIGO/Virgo S200105ae: Upper Limits from the Zwicky Transient Facility
  3. GRB 200107B: Swift detection of a burst
  4. Swift GRB200107.81: Global MASTER-Net OT detection
  5. GRB 200107B: Fermi GBM Final Real-time Localization
  6. Swift GRB200107.81: Global MASTER-Net observations report
  7. LIGO/Virgo S200105ae: Further study ongoing for GW compact binary merger candidate
  8. IceCube-200107A: Upper limits from Fermi-GBM Observations
  9. IceCube-200107A: IceCube observation of a high-energy neutrino candidate event
  10. LIGO/Virgo 200105ae: No counterpart candidates in Fermi-LAT observations
  11. GRB 191228A: FRAM-ORM optical limit
  12. LIGO/Virgo S200105ae: AstroSat CZTI upper limits
  13. LIGO/Virgo S200105ae: Coverage and upper limits from MAXI/GSC observations
  14. LIGO/Virgo S200105ae: No counterpart candidates in HAWC observations
  15. LIGO/Virgo S200105ae: no counterpart candidates in the Swift/BAT observations
  16. LIGO/Virgo S200105ae: Upper limits from IceCube neutrino searches
  17. LIGO/Virgo S200105ae: not observable by AGILE-MCAL
  18. LIGO/Virgo S200105ae: Global MASTER-Net observations report
  19. LIGO/Virgo S200105ae: Upper limits from Fermi-GBM Observations
  20. LIGO/Virgo S200105ae: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  21. LIGO/Virgo S200105ae : no neutrino counterpart candidate in ANTARES search
  22. LIGO/Virgo S200105ae: We have issued GCN Notices to support automated processing
  23. S200106au and S200106av: Retraction of GW compact binary merger candidates
  24. LIGO/Virgo S200105ae: A subthreshold GW compact binary merger candidate
  25. Fermi trigger No 599954133: Global MASTER-Net observations report
  26. GRB 200105A: MAXI/GSC detection
  27. Konus-Wind observation of GRB200101A
  28. Fermi trigger No 599761015: Global MASTER-Net observations report
  29. IPN triangulation of GRB 200101A
  30. GRB 200103A: Fermi GBM Final Real-time Localization
  31. Fermi-LAT Gamma-ray Observations of IceCube-191231A
  32. GRB 200101A : AstroSat CZTI detection
  33. IceCube-191231A: Upper limits from a search for additional neutrino events in IceCube
  34. GRB 191228A: Early Optical Upper Limits from LCO
  35. IceCube Alert 200101.46: Global MASTER-Net observations report
  36. IceCube-191231A: No significant detection in HAWC
  37. GRB 200101A: Fermi GBM detection
  38. Fermi trigger No 599603971: Global MASTER-Net observations report
  39. GRB 200101A: BALROG localization (Fermi Trigger 599603971 / GRB 200101861)
  40. GRB 200101A: Fermi GBM Final Real-time Localization
  41. IceCube-191231A: No Neutrino Counterpart in ANTARES data
  42. IceCube-191231A: Upper limits from Fermi-GBM Observations
  43. IceCube-191231A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  44. IceCube-191231A: IceCube observation of a high-energy neutrino candidate event
  45. IceCube Alert 191231.46: Global MASTER-Net observations report
  46. GRB 191227A: Insight-HXMT/HE observation
  47. GRB 191227B: Insight-HXMT/HE observation
  48. GRB 191221B: CALET Gamma-Ray Burst Monitor detection
  49. GRB 191228A: Mondy optical upper limit
  50. Konus-Wind observation of GRB 191227A
  51. Konus-Wind observation of GRB 191227B
  52. IPN triangulation of GRB 191227B (short)
  53. GRB 191228A: Swift/UVOT Upper Limits
  54. GRB 191225A : AstroSat CZTI detection
  55. GRB 191228A: Swift-XRT refined Analysis
  56. GRB 191227A: Swift-BAT refined analysis
  57. GRB 191228A: Swift-BAT refined analysis
  58. GRB 191228A: Enhanced Swift-XRT position
  59. LIGO/Virgo S191216ap: Two candidate counterparts from UKIRT/WFCAM z-band observations
  60. GRB 191228A: ePESSTO+ NTT optical upper limit
  61. GRB 191228A: UKIRT NIR upper limit
  62. LIGO/Virgo S191222n: No transient candidates in CALET observations
  63. GRB 191228A: Swift detection of a burst
  64. Swift GRB191228.00: Global MASTER-Net observations report
  65. GRB 191227A: Fermi GBM detection
  66. GRB 191227A: Marginal detection by Fermi-LAT
  67. GRB 191227A: MITSuME Akeno optical upper limits
  68. Swift GRB191227A: Global MASTER-Net OT detection
  69. GRB 191227A: Swift detection of a burst
  70. Swift GRB191227.07: Global MASTER-Net observations report
  71. GRB 191227A: Fermi GBM Final Real-time Localization
  72. Swift Trigger 946234: further Swift analysis
  73. LIGO/Virgo S191213g: AT2019wxt 10.4m GTC further spectroscopy
  74. Swift GRB191226.25: Global MASTER-Net observations report
  75. Swift Triggers 946256 and 946257 are not a GRB
  76. Swift GRB191226.02: Global MASTER-Net observations report
  77. Swift Trigger 946234 is probably not a GRB
  78. Swift trigger 946234/GRB 191226.02 : MASTER obervation
  79. LIGO/Virgo S191225aq: Retraction of GW compact binary merger candidate
  80. LIGO/Virgo S191225aq: Global MASTER-Net observations report
  81. GRB 191225B: BALROG localization (Fermi Trigger 598988276 / GRB 191225735)
  82. Fermi trigger No 598988276: Global MASTER-Net observations report
  83. GRB 191225B: Fermi GBM Final Real-time Localization
  84. GRB 191221B: ATCA detection of the radio afterglow
  85. GRB 191225A: Fermi GBM Final Real-time Localization
  86. LIGO/Virgo S191205ah: MASTER OT detection
  87. LIGO/Virgo S191213g: Pan-STARRS monitoring shows PS19hgw (AT2019wxt) to be fading quickly
  88. Konus-Wind observation of GRB 191221B
  89. LIGO/Virgo S191222n : No significant candidates in FRAM-TAROT-GRANDMA observations
  90. GRB 191221B: Swift/UVOT Detection
  91. GRB 191221B: Insight-HXMT/HE detection
  92. LIGO/Virgo S191222n: Updated Sky Localization
  93. LIGO/Virgo S191222n: no counterpart candidate in SVOM/GWAC observations
  94. LIGO/Virgo S191216ap: Updated Source Classification
  95. LIGO/Virgo S191216ap: Upper limits from Insight-HXMT/HE observations
  96. GRB 191220.59: AstroSat CZTI detection
  97. GRB 191221B: AstroSat CZTI detection
  98. GRB 191221B: iTelescope T17 detection
  99. GRB 191221B: iTelescope optical observations
  100. GRB 191221B: ALMA detection

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