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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 S190814bv: KMTNet observation
  2. LIGO/Virgo S190814bv: No counterpart candidates in the Swift/BAT Observations
  3. LIGO/Virgo S190814bv: MeerLICHT coverage second preliminary skymap
  4. LIGO/Virgo S190814bv Global MASTER-Net optical observations
  5. LIGO/Virgo S190814bv : No counterpart candidate in TAROT-GRANDMA observations
  6. LIGO/Virgo S190814bv: no candidates from GOTO imaging observations
  7. LIGO/Virgo S190814bv: Candidates found in initial DESGW search
  8. LIGO/Virgo S190814bv: Upper limits from AGILE-GRID observations
  9. IPN triangulation of GRB 190813A (short)
  10. LIGO/Virgo S190814bv: Update on Sky-Localization and Source-Classification
  11. LIGO/Virgo S190814bv: no candidates from WHT imaging of candidate galaxies
  12. LIGO/Virgo S190814bv: GRAWITA TNG imaging of selected galaxies
  13. LIGO/Virgo S190814bv : no neutrino counterpart candidate in ANTARES search
  14. LIGO/Virgo S190814bv: Coverage and upper limits from MAXI/GSC observations
  15. LIGO/Virgo S190814bv: Liverpool Telescope imaging of selected galaxies
  16. LIGO/Virgo S190814bv: No counterpart candidates in AGILE-MCAL observations
  17. LIGO/Virgo S190814bv: Upper limits from Fermi-GBM Observations
  18. LIGO/Virgo S190814bv: Nordic Optical Telescope imaging of selected galaxies
  19. LIGO/Virgo S190814bv: Identification of a GW compact binary merger candidate
  20. LIGO/Virgo S190814bv: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  21. LIGO/Virgo S190814bv Global MASTER-Net observations report
  22. LIGO/Virgo S190814bv: Upper limits from IceCube neutrino searches
  23. LIGO/Virgo S190814bv: CLU/NED Galaxies in the 50% Localization Volume
  24. GRB 190814A: Fermi GBM Final Real-time Localization
  25. Fermi trigger No 587392154 Global MASTER-Net observations report
  26. GRB 190813A: Fermi GBM Final Real-time Localization
  27. IPN triangulation of GRB 190805B
  28. HAWC-190806A: Upper limits from Insight-HXMT/HE observations
  29. FRB 190806: MASTER optical observation
  30. Konus-Wind observation of GRB 190810A
  31. IPN triangulation of GRB 190810A (short)
  32. Fermi trigger No 587084236 Global MASTER-Net observations report
  33. GRB 190810A: Fermi GBM Final Real-time Localization
  34. HAWC-190806A: upper limits from INTEGRAL SPI-ACS and IBIS prompt observation
  35. HAWC-190806A: Upper limits from Fermi-GBM Observations
  36. HAWC-190806A: Swift-XRT observations
  37. HAWC Burst Alert 1008846_957: Konus-Wind observations
  38. GRB 190726A: Insight-HXMT/HE detection
  39. Correction to Swift GCN 25303
  40. Trigger_11505: Tiled Swift observations
  41. LIGO/Virgo S190728q: New optical candidates from the DESGW program
  42. LIGO/Virgo S190808ae: Retraction of GW compact binary merger candidate
  43. LIGO/Virgo S190808ae: Coverage and upper limits from MAXI/GSC observations
  44. LIGO/Virgo S190808ae: CLU/NED Galaxies in the 50% Localization Volume
  45. LIGO/Virgo S190808ae: No counterpart candidates in HAWC observations
  46. LIGO/Virgo S190808ae: One Coincident Neutrino Candidate from IceCube Search
  47. LIGO/Virgo S190808ae: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo S190808ae Global MASTER-Net observations report
  49. GRB 190808B: BALROG localization (Fermi Trigger 586980202 / GRB 190808752)
  50. Fermi trigger No 586980202 Global MASTER-Net observations report
  51. GRB 190808B: Fermi GBM Final Real-time Localization
  52. HAWC Burst Alert 1008846_957: IceCube Neutrino Search
  53. GRB 190808A: Fermi GBM Final Real-time Localization
  54. GRB 190804A: AstroSat CZTI detection
  55. Fermi trigger No 586896678 Global MASTER-Net observations report
  56. GRB 190805B: AstroSat CZTI detection
  57. GRB 190804B: Swift-XRT afterglow detection
  58. Konus-Wind observation of GRB 190805B
  59. Alert from the HAWC Burst Monitor
  60. HAWC Alert 190806.56 Global MASTER-Net observations report
  61. Fermi trigger No 586788607 Global MASTER-Net observations report
  62. Fermi trigger No 586800758 Global MASTER-Net observations report
  63. GRB 190806A: Fermi GBM Final Real-time Localization
  64. GRB 190805B: Swift-XRT observations
  65. Fermi trigger No 586676451 Global MASTER-Net observations report
  66. GRB 190805B: Fermi GBM detection
  67. LIGO/Virgo S190728q: AT2019lvw 10.4m GTC spectroscopy
  68. GRB 190805B: Tiled Swift observations
  69. Konus-Wind observation of GRB 190731A
  70. GRB 190804B: Swift-XRT observations
  71. GRB 190805B: BALROG localization (Fermi Trigger 586673165 / GRB 190805199)
  72. GRB 190805B: MAXI/GSC detection
  73. GRB 190805B: Fermi GBM Final Real-time Localization
  74. GRB 190805A: Fermi GBM Final Real-time Localization
  75. Fermi trigger No 586638042 Global MASTER-Net observations report
  76. MAXI GRB190804.33 Global MASTER-Net observations report
  77. Fermi trigger No 586600841 Global MASTER-Net observations report
  78. GRB 190804C: BALROG localization (Fermi Trigger 586638042 / GRB 190804792)
  79. GRB 190804C: Fermi GBM Final Real-time Localization
  80. GRB 190804B: Tiled Swift observations
  81. GRB 190804B: MAXI/GSC detection
  82. LIGO/Virgo S190728q: AT2019lzc 10.4m GTC spectroscopy
  83. Fermi trigger No 586574612 Global MASTER-Net observations report
  84. GRB 190804A: Fermi GBM Final Real-time Localization
  85. GRB 190731A: AstroSat CZTI detection
  86. GRB 190731A: Swift/UVOT Upper Limits
  87. GRB 190731A: no OT detected by MASTER
  88. IceCube 190730A: No counterpart candidates or blazar activity in GOTO observations
  89. GRB 190720B: AstroSat CZTI detection
  90. LIGO/Virgo S190728q: AT2019lzt 10.4m GTC spectroscopy
  91. GRB 190719C: VLT/X-shooter spectroscopic redshift of the host galaxy
  92. GRB 190731A: Swift-XRT afterglow detection
  93. IPN Triangulation of GRB 190731A
  94. LIGO/Virgo S190727h: Updated sky localization
  95. GRB 190731A: Fermi GBM detection
  96. GRB 190726B: AstroSat CZTI detection
  97. GRB 190731A: CALET Gamma-Ray Burst Monitor detection
  98. GRB 190731A: Swift ToO observations
  99. GRB190731A: Fermi-LAT detection
  100. Fermi trigger No 586305505 Global MASTER-Net observations report

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