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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 S190630ag: no counterpart candidate in the SVOM/GWAC observations
  2. GRB 190701A, Swift-BAT refined analysis
  3. GRB 190628B - AstroSat CZTI detection
  4. LIGO/Virgo S190701ah: KMTNet Observation
  5. LIGO/Virgo S190701ah: No transient candidates from CALET observations
  6. LIGO/Virgo S190701ah: Upper limits from Insight-HXMT/HE observations
  7. Fermi Gamma-ray Burst Monitor trigger 190626526/583245413 is not a GRB
  8. Fermi-LAT Gamma-ray Observations of IceCube-190629A
  9. LIGO/Virgo S190701ah: No counterpart candidates in the Swift/BAT Observations
  10. IPN triangulation of GRB 190630A (short)
  11. LIGO/Virgo S190701ah: Upper limits from AGILE-GRID observations
  12. LIGO/Virgo S190630ag: Upper limits from Insight-HXMT/HE observations
  13. LIGO/Virgo S190701ah: Upper limits from Fermi-GBM Observations
  14. GRB 190701A: Swift-XRT refined Analysis
  15. LIGO/Virgo S190630ag: Upper limits from CALET observations
  16. LIGO/Virgo S190701ah Global MASTER-Net observations report
  17. GRB 190630C: Swift-XRT refined Analysis
  18. LIGO/Virgo S190630ag: No counterpart candidates in KAIT observation
  19. LIGO/Virgo S190701ah: Coverage and upper limits from MAXI/GSC observations
  20. GRB 190701A: Swift/UVOT Upper Limits
  21. GRB190701A: No candidates/counterpart in optical follow-up from GROWTH-India Telescope
  22. LIGO/Virgo S190701ah: No counterpart candidates in AGILE-MCAL observations
  23. LIGO/Virgo S190701ah: No neutrino counterpart candidates in ANTARES search
  24. LIGO/Virgo S190701ah: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  25. LIGO/Virgo S190701ah: Identification of a GW compact binary merger candidate
  26. GRB 190630B: Tien Shan and Koshka Zeiss-1000 optical upper limits
  27. LIGO/Virgo S190701ah: Upper limits from IceCube neutrino searches
  28. GRB 190630C: ISON-Castelgrande optical upper limit
  29. GRB 190701A: COATLI Optical Observations
  30. GRB 190630C: Swift/UVOT Upper Limits
  31. GRB 190630C: KAIT Optical Upper Limit
  32. GRB 190630B: Swift/UVOT Upper Limits
  33. LIGO/Virgo S190630ag: No counterpart candidates in AGILE-GRID observations
  34. GRB 190630C: Swift-BAT refined analysis
  35. GRB 190701A: Enhanced Swift-XRT position
  36. GRB 190630C: AstroSat CZTI detection
  37. LIGO/Virgo S190630ag: No counterpart candidates in the Swift/BAT Observations
  38. GRB 190701A: MAXI/GSC detection
  39. GRB 190701B: a long GRB detected by IBAS
  40. GRB 190701A: Prompt enhanced Swift-XRT position
  41. GRB 190701A: Swift detection of a burst
  42. LIGO/Virgo S190630ag: No counterpart candidates in AGILE-MCAL observations
  43. LIGO/Virgo S190630ag: No counterpart candidates in Fermi-LAT observations
  44. GRB 190630B: KAIT Optical Afterglow Confirmation
  45. GRB 190630C: Enhanced Swift-XRT position
  46. Swift GRB190631. Global MASTER-Net observations report
  47. LIGO/Virgo S190630ag: Upper limits from Fermi-GBM Observations
  48. GRB 190630C: Swift detection of a burst
  49. LIGO/Virgo S190630ag: Coverage and upper limits from MAXI/GSC observations
  50. LIGO/Virgo S190630ag: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  51. LIGO/Virgo S190630ag: No neutrino counterpart candidates in ANTARES search
  52. LIGO/Virgo S190630ag: No counterpart candidates in HAWC observations
  53. LIGO/Virgo S190630ag: Identification of a GW compact binary merger candidate
  54. LIGO/Virgo S190630ag Global MASTER-Net observations report
  55. LIGO/Virgo S190630ag: Upper limits from IceCube neutrino searches
  56. GRB 190630B: Swift-XRT refined Analysis
  57. GRB 190630B, Swift-BAT refined analysis
  58. IceCube-190629A: Upper limits from Fermi-GBM Observations
  59. GRB 190627A: VLT/FORS2 spectroscopic redshift
  60. Fermi trigger No 583567803 Global MASTER-Net observations report
  61. GRB Swift Trigger 912102: KAIT Optical Afterglow Candidate
  62. Swift Trigger 912102: possible GRB 190630B
  63. GRB 190630A: Fermi GBM Final Real-time Localization
  64. GRB 190627A: Koshka Zeiss-1000 optical counterpart observations
  65. IceCube-190629A - IceCube observation of a high-energy neutrino candidate event
  66. Baksan Neutrino Observatory Alert 190629.56 Global MASTER-Net observations report
  67. IceCube Alert 190629.81 Global MASTER-Net observations report
  68. GRB 190627A : Xinglong 2.16m optical observation
  69. GRB 190627A: Swift-XRT refined Analysis
  70. GRB 190627A: GMG observation at the second epoch
  71. GRB 190627A: NOT optical observations
  72. GRB 190627A: Optical imaging by D50 from Ondrejov
  73. GRB 190627A: NIR imaging from Liverpool Telescope
  74. GRB 190627A: Optical imaging and spectroscopy from Calar Alto
  75. GRB 190627A: NUTTelA-TAO optical counterpart observations
  76. GRB 190627A: Swift-BAT refined analysis (short-soft burst)
  77. GRB 190610A: Further Swift-XRT observations
  78. GRB 190628A: Fermi GBM Final Real-time Localization
  79. GRB 190627A: GMG observation
  80. GRB 190627A: MASTER optical counterpart observation
  81. GRB190627A: VIRT Afterglow observation
  82. GRB 190627A: Montarrenti Observatory optical detection
  83. GRB 190627A: NUTTelA-TAO optical observations
  84. Fermi trigger No 583327924 Global MASTER-Net observations report
  85. GRB 190627A: Enhanced Swift-XRT position
  86. GRB 190627A: Swift/UVOT Detection
  87. GRB 190627A: Swift detection of a burst
  88. Fermi trigger No 583245413 Global MASTER-Net observations report
  89. Fermi trigger No 583245413 Global MASTER-Net observations report
  90. Fermi trigger No 583221986 Global MASTER-Net observations report
  91. GRB 190626B: Fermi GBM Final Real-time Localization
  92. GRB 190619B: AstroSat CZTI detection
  93. GRB 190626A: Fermi GBM Final Real-time Localization
  94. Fermi trigger No 583111521 Global MASTER-Net observations report
  95. Swift Trigger 911102 is likely not an astrophysical event
  96. IceCube-190619A: prompt emission upper limits from AstroSat-CZTI
  97. Swift GRB190624.86 Global MASTER-Net observations report
  98. Swift trigger 911102: D50 optical limit
  99. Swift Trigger 911102: a possible GRB
  100. GRB 190623A: Fermi GBM Final Real-time Localization

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