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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 190627A: Discovery Channel Telescope late time observations
  2. LIGO/Virgo IceCube-190704A: No counterpart candidates in INTEGRAL SPI- ACS and IBIS prompt observation
  3. IceCube-190704A: not observable by Fermi-GBM
  4. Trigger 913042: Swift triggered on noise peak
  5. IceCube Alert 190704.78 Global MASTER-Net observations report
  6. IceCube-190704A - IceCube observation of a high-energy neutrino candidate event
  7. Baksan Neutrino Observatory Alert 190703.21 Global MASTER-Net observations report
  8. Konus-Wind observation of GRB 190701B
  9. GRB 190530A: Observation of the afterglow by NOEMA
  10. LIGO/Virgo S190630ag: Gaia Photometric Alerts transient candidate
  11. Baksan Neutrino Observatory Alert 190703.56 Global MASTER-Net observations report
  12. Fermi trigger No 583854113 Global MASTER-Net observations report
  13. LIGO/Virgo S190630ag: no counterpart candidate in the SVOM/GWAC observations
  14. GRB 190701A, Swift-BAT refined analysis
  15. GRB 190628B - AstroSat CZTI detection
  16. LIGO/Virgo S190701ah: KMTNet Observation
  17. LIGO/Virgo S190701ah: No transient candidates from CALET observations
  18. LIGO/Virgo S190701ah: Upper limits from Insight-HXMT/HE observations
  19. Fermi Gamma-ray Burst Monitor trigger 190626526/583245413 is not a GRB
  20. Fermi-LAT Gamma-ray Observations of IceCube-190629A
  21. LIGO/Virgo S190701ah: No counterpart candidates in the Swift/BAT Observations
  22. IPN triangulation of GRB 190630A (short)
  23. LIGO/Virgo S190701ah: Upper limits from AGILE-GRID observations
  24. LIGO/Virgo S190630ag: Upper limits from Insight-HXMT/HE observations
  25. LIGO/Virgo S190701ah: Upper limits from Fermi-GBM Observations
  26. GRB 190701A: Swift-XRT refined Analysis
  27. LIGO/Virgo S190630ag: Upper limits from CALET observations
  28. LIGO/Virgo S190701ah Global MASTER-Net observations report
  29. GRB 190630C: Swift-XRT refined Analysis
  30. LIGO/Virgo S190630ag: No counterpart candidates in KAIT observation
  31. LIGO/Virgo S190701ah: Coverage and upper limits from MAXI/GSC observations
  32. GRB 190701A: Swift/UVOT Upper Limits
  33. GRB190701A: No candidates/counterpart in optical follow-up from GROWTH-India Telescope
  34. LIGO/Virgo S190701ah: No counterpart candidates in AGILE-MCAL observations
  35. LIGO/Virgo S190701ah: No neutrino counterpart candidates in ANTARES search
  36. LIGO/Virgo S190701ah: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  37. LIGO/Virgo S190701ah: Identification of a GW compact binary merger candidate
  38. GRB 190630B: Tien Shan and Koshka Zeiss-1000 optical upper limits
  39. LIGO/Virgo S190701ah: Upper limits from IceCube neutrino searches
  40. GRB 190630C: ISON-Castelgrande optical upper limit
  41. GRB 190701A: COATLI Optical Observations
  42. GRB 190630C: Swift/UVOT Upper Limits
  43. GRB 190630C: KAIT Optical Upper Limit
  44. GRB 190630B: Swift/UVOT Upper Limits
  45. LIGO/Virgo S190630ag: No counterpart candidates in AGILE-GRID observations
  46. GRB 190630C: Swift-BAT refined analysis
  47. GRB 190701A: Enhanced Swift-XRT position
  48. GRB 190630C: AstroSat CZTI detection
  49. LIGO/Virgo S190630ag: No counterpart candidates in the Swift/BAT Observations
  50. GRB 190701A: MAXI/GSC detection
  51. GRB 190701B: a long GRB detected by IBAS
  52. GRB 190701A: Prompt enhanced Swift-XRT position
  53. GRB 190701A: Swift detection of a burst
  54. LIGO/Virgo S190630ag: No counterpart candidates in AGILE-MCAL observations
  55. LIGO/Virgo S190630ag: No counterpart candidates in Fermi-LAT observations
  56. GRB 190630B: KAIT Optical Afterglow Confirmation
  57. GRB 190630C: Enhanced Swift-XRT position
  58. Swift GRB190631. Global MASTER-Net observations report
  59. LIGO/Virgo S190630ag: Upper limits from Fermi-GBM Observations
  60. GRB 190630C: Swift detection of a burst
  61. LIGO/Virgo S190630ag: Coverage and upper limits from MAXI/GSC observations
  62. LIGO/Virgo S190630ag: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  63. LIGO/Virgo S190630ag: No neutrino counterpart candidates in ANTARES search
  64. LIGO/Virgo S190630ag: No counterpart candidates in HAWC observations
  65. LIGO/Virgo S190630ag: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo S190630ag Global MASTER-Net observations report
  67. LIGO/Virgo S190630ag: Upper limits from IceCube neutrino searches
  68. GRB 190630B: Swift-XRT refined Analysis
  69. GRB 190630B, Swift-BAT refined analysis
  70. IceCube-190629A: Upper limits from Fermi-GBM Observations
  71. GRB 190627A: VLT/FORS2 spectroscopic redshift
  72. Fermi trigger No 583567803 Global MASTER-Net observations report
  73. GRB Swift Trigger 912102: KAIT Optical Afterglow Candidate
  74. Swift Trigger 912102: possible GRB 190630B
  75. GRB 190630A: Fermi GBM Final Real-time Localization
  76. GRB 190627A: Koshka Zeiss-1000 optical counterpart observations
  77. IceCube-190629A - IceCube observation of a high-energy neutrino candidate event
  78. Baksan Neutrino Observatory Alert 190629.56 Global MASTER-Net observations report
  79. IceCube Alert 190629.81 Global MASTER-Net observations report
  80. GRB 190627A : Xinglong 2.16m optical observation
  81. GRB 190627A: Swift-XRT refined Analysis
  82. GRB 190627A: GMG observation at the second epoch
  83. GRB 190627A: NOT optical observations
  84. GRB 190627A: Optical imaging by D50 from Ondrejov
  85. GRB 190627A: NIR imaging from Liverpool Telescope
  86. GRB 190627A: Optical imaging and spectroscopy from Calar Alto
  87. GRB 190627A: NUTTelA-TAO optical counterpart observations
  88. GRB 190627A: Swift-BAT refined analysis (short-soft burst)
  89. GRB 190610A: Further Swift-XRT observations
  90. GRB 190628A: Fermi GBM Final Real-time Localization
  91. GRB 190627A: GMG observation
  92. GRB 190627A: MASTER optical counterpart observation
  93. GRB190627A: VIRT Afterglow observation
  94. GRB 190627A: Montarrenti Observatory optical detection
  95. GRB 190627A: NUTTelA-TAO optical observations
  96. Fermi trigger No 583327924 Global MASTER-Net observations report
  97. GRB 190627A: Enhanced Swift-XRT position
  98. GRB 190627A: Swift/UVOT Detection
  99. GRB 190627A: Swift detection of a burst
  100. Fermi trigger No 583245413 Global MASTER-Net observations report

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