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

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