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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 S190602aq: No counterpart candidates in Fermi-LAT observations
  2. LIGO/Virgo S190602aq: No counterpart candidates in the Swift/BAT Observations
  3. LIGO/Virgo S190602aq: Upper limits from Fermi-GBM Observations
  4. LIGO/Virgo S190602aq: Upper limits from AGILE-GRID observations
  5. LIGO/Virgo S190602aq: No counterpart candidate in AGILE-MCAL observations
  6. LIGO/Virgo S190602aq Global MASTER-Net observations report
  7. LIGO/Virgo S190602aq: Coverage and upper limits from MAXI/GSC observations
  8. LIGO/Virgo S190602aq: No neutrino counterpart candidates in ANTARES search
  9. LIGO/Virgo S190602aq: No counterpart candidates in HAWC observations
  10. LIGO/Virgo S190602aq: Identification of a GW compact binary merger candidate
  11. LIGO/Virgo S190602aq: Upper limits from IceCube neutrino searches
  12. Konus-Wind observation of extremely bright GRB 190530A
  13. GRB 190530A: Insight-HXMT/HE detection
  14. GRB 190531B: Insight-HXMT/HE detection
  15. GRB 190530A: Mondy and AbAO optical observations
  16. GRB 190531B: VLT optical upper limit
  17. Fermi trigger No 581068049 Global MASTER-Net observations report
  18. GRB 190530A: Konkoly optical observations of the afterglow
  19. GRB 190530A: SAO RAS optical observations
  20. GRB 190531B: MASTER optical observation
  21. GRB 190531B: Swift-XRT afterglow detection
  22. GRB 190531B: Fermi GBM observations
  23. Fermi Fermi trigger No 581002688 Global MASTER-Net observations report
  24. GRB 190530A: Swift/UVOT Detection
  25. GRB 190531B: Swift ToO observations
  26. GRB 190531B: Fermi-LAT detection
  27. GRB 190530A: Steep afterglow decay found by OSN
  28. GRB 190531B: name correction re. GCN 24696
  29. GRB 190530A: AbAO optical observations
  30. GRB 190530A: Xinglong 2.16m optical observation
  31. Fermi Trigger 581026217 / GRB 190531840 / GRB190531A: BALROG localization
  32. GRB 190531B: Fermi GBM Final Real-time Localization
  33. GRB 190530A: AstroSat CZTI detection
  34. GRB 190530A: optical afterglow detection by 5 MASTER telescopes
  35. GRB 190530A: Fermi GBM observation
  36. GRB 190531A: Fermi GBM Final Real-time Localization
  37. GRB 190530A: COATLI Optical Detection of the Fading Afterglow
  38. GRB 190530A: Swift-XRT afterglow detection
  39. GRB 190530A: GWAC-F30 optical detection
  40. GRB 190530A: OAJ optical detection
  41. GRB 190530A: NOT photometry and spectroscopy
  42. Fermi GRB190530.43 Global MASTER-Net observations report
  43. GRB 190530A: Bright afterglow confirmed by OSN
  44. GRB 190530A: AGILE/GRID analysis
  45. LIGO/Virgo S190503bf: Gaia Photometric Alerts transient candidate
  46. GRB 190530A: Swift ToO observations
  47. GRB 190530A: MASTER OT detection
  48. GRB 190530A: Fermi-LAT detection
  49. GRB 190530A: AGILE-MCAL detection
  50. Fermi Trigger 580904353 / GRB 190530430 / GRB190530A: BALROG localization
  51. GRB 190530A: Fermi GBM Final Real-time Localization
  52. IceCube-190504A: Kanata optical/NIR follow-up observations
  53. IceCube 41485283_132628.amon retraction
  54. LIGO/Virgo S190425z: No counterpart candidate in Zadko-GRANDMA observations.
  55. LIGO/Virgo S190521r : Gaia Photometric Alerts transient candidate
  56. LIGO/Virgo S190518bb: AstroSat CZTI upper limits
  57. LIGO/Virgo S190521g: AstroSat CZTI upper limits
  58. LIGO/Virgo S190517h: AstroSat CZTI upper limits
  59. LIGO/Virgo S190519bj: AstroSat CZTI upper limits
  60. GRB 190525A: AstroSat CZTI detection
  61. LIGO/Virgo S190521r: CNEOST follow-up observations
  62. GRB 190525A: Insight-HXMT/HE detection
  63. Fermi GRB190525.67 Global MASTER-Net observations report
  64. Fermi GRB190525.03 Global MASTER-Net observations report
  65. GRB 190525A: Fermi GBM Final Real-time Localization
  66. LIGO/Virgo S190521r: Kanata optical/NIR follow-up observations of the CNEOST Transient
  67. LIGO/Virgo S190521r: No optical counterpart from SVOM/GWAC-F30 observations.
  68. LIGO/Virgo S190521r: No optical counterpart from SVOM/GWAC observations.
  69. LIGO/Virgo S190521g: No optical counterpart from SVOM/GWAC-F30 observations.
  70. LIGO/Virgo S190521g: No optical counterpart from SVOM/GWAC observations.
  71. LIGO/Virgo S190524q: Retraction of GW compact binary merger candidate
  72. LIGO/Virgo S190524q Global MASTER-Net observations report
  73. LIGO/Virgo S190517h: Gaia Photometric Alerts transient candidate
  74. LIGO/Virgo S190521r: No candidate counterparts from ATLAS observations of the skymap
  75. Konus-Wind observation of GRB 190519A
  76. LIGO/Virgo S190521g: Upper limits from Insight-HXMT/HE observations
  77. LIGO/Virgo S190521r: RATIR Optical and NIR Observations of the CNEOST Transient
  78. LIGO/Virgo S190521r: No transient candidates from CALET observations
  79. LIGO/Virgo S190521g: Upper limits from CALET observations
  80. LIGO/Virgo S190521r: One optical transient from CNEOST
  81. LIGO/Virgo S190521g: Swift/BAT Counterpart Search
  82. LIGO/Virgo S190521r: Swift/BAT Counterpart Search
  83. LIGO/Virgo S190521g: No Counterparts in DDOTI/OAN Optical Observations
  84. LIGO/Virgo S190521r: Coverage and upper limits from Fermi-LAT observations
  85. LIGO/Virgo S190521r: Upper limits from Fermi-GBM observations
  86. LIGO/Virgo S190521g : Upper limits from Fermi-GBM observations
  87. LIGO/Virgo S190521g: Updated sky localization
  88. LIGO/Virgo S190521g: No candidate counterpart in Fermi-LAT observations
  89. LIGO/Virgo S190521r: Upper limits from AGILE-GRID observations
  90. LIGO/Virgo S190521r Global MASTER-Net observations report
  91. LIGO/Virgo S190521r: No counterpart candidate in AGILE-MCAL observations
  92. LIGO/Virgo S190521r: Coverage and upper limits from MAXI/GSC observations
  93. LIGO/Virgo S190521r: No neutrino counterpart candidates in ANTARES search
  94. LIGO/Virgo S190521r: IceCube Neutrino Search
  95. LIGO/Virgo S190521r: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo S190517h : No counterpart candidate in TAROT-GRANDMA observations.
  97. LIGO/Virgo S190521r: No counterpart candidates in HAWC observations
  98. LIGO/Virgo S190521r: No counterpart candidates in INTEGRAL SPI/ACS prompt observation
  99. LIGO/Virgo S190521g: No neutrino counterpart candidates in ANTARES search
  100. LIGO/Virgo S190519bj: Fermi-LAT search for a high-energy gamma-ray counterpart

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