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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 S190706ai: Upper limits from IceCube neutrino searches
  2. IceCube-190704A - HAWC follow-up
  3. GRB 190706B: Enhanced Swift-XRT position
  4. GRB 190706B: Prompt enhanced Swift-XRT position
  5. GRB 190706B: Swift detection of a burst
  6. GRB 190706A: MAXI/GSC detection
  7. Fermi trigger No 584007338 Global MASTER-Net observations report
  8. IceCube-190704A: Upper limits from Insight-HXMT/HE observations
  9. Fermi-LAT Gamma-ray Observations of IceCube-190704A and detection of the new gamma-ray source 1WHSP J104516.2+275133
  10. IceCube-190704A: Upper limits from a search for additional neutrino events in IceCube
  11. LIGO/Virgo S190701ah: Updated sky localization
  12. GRB 190627A: Discovery Channel Telescope late time observations
  13. LIGO/Virgo IceCube-190704A: No counterpart candidates in INTEGRAL SPI- ACS and IBIS prompt observation
  14. IceCube-190704A: not observable by Fermi-GBM
  15. Trigger 913042: Swift triggered on noise peak
  16. IceCube Alert 190704.78 Global MASTER-Net observations report
  17. IceCube-190704A - IceCube observation of a high-energy neutrino candidate event
  18. Baksan Neutrino Observatory Alert 190703.21 Global MASTER-Net observations report
  19. Konus-Wind observation of GRB 190701B
  20. GRB 190530A: Observation of the afterglow by NOEMA
  21. LIGO/Virgo S190630ag: Gaia Photometric Alerts transient candidate
  22. Baksan Neutrino Observatory Alert 190703.56 Global MASTER-Net observations report
  23. Fermi trigger No 583854113 Global MASTER-Net observations report
  24. LIGO/Virgo S190630ag: no counterpart candidate in the SVOM/GWAC observations
  25. GRB 190701A, Swift-BAT refined analysis
  26. GRB 190628B - AstroSat CZTI detection
  27. LIGO/Virgo S190701ah: KMTNet Observation
  28. LIGO/Virgo S190701ah: No transient candidates from CALET observations
  29. LIGO/Virgo S190701ah: Upper limits from Insight-HXMT/HE observations
  30. Fermi Gamma-ray Burst Monitor trigger 190626526/583245413 is not a GRB
  31. Fermi-LAT Gamma-ray Observations of IceCube-190629A
  32. LIGO/Virgo S190701ah: No counterpart candidates in the Swift/BAT Observations
  33. IPN triangulation of GRB 190630A (short)
  34. LIGO/Virgo S190701ah: Upper limits from AGILE-GRID observations
  35. LIGO/Virgo S190630ag: Upper limits from Insight-HXMT/HE observations
  36. LIGO/Virgo S190701ah: Upper limits from Fermi-GBM Observations
  37. GRB 190701A: Swift-XRT refined Analysis
  38. LIGO/Virgo S190630ag: Upper limits from CALET observations
  39. LIGO/Virgo S190701ah Global MASTER-Net observations report
  40. GRB 190630C: Swift-XRT refined Analysis
  41. LIGO/Virgo S190630ag: No counterpart candidates in KAIT observation
  42. LIGO/Virgo S190701ah: Coverage and upper limits from MAXI/GSC observations
  43. GRB 190701A: Swift/UVOT Upper Limits
  44. GRB190701A: No candidates/counterpart in optical follow-up from GROWTH-India Telescope
  45. LIGO/Virgo S190701ah: No counterpart candidates in AGILE-MCAL observations
  46. LIGO/Virgo S190701ah: No neutrino counterpart candidates in ANTARES search
  47. LIGO/Virgo S190701ah: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  48. LIGO/Virgo S190701ah: Identification of a GW compact binary merger candidate
  49. GRB 190630B: Tien Shan and Koshka Zeiss-1000 optical upper limits
  50. LIGO/Virgo S190701ah: Upper limits from IceCube neutrino searches
  51. GRB 190630C: ISON-Castelgrande optical upper limit
  52. GRB 190701A: COATLI Optical Observations
  53. GRB 190630C: Swift/UVOT Upper Limits
  54. GRB 190630C: KAIT Optical Upper Limit
  55. GRB 190630B: Swift/UVOT Upper Limits
  56. LIGO/Virgo S190630ag: No counterpart candidates in AGILE-GRID observations
  57. GRB 190630C: Swift-BAT refined analysis
  58. GRB 190701A: Enhanced Swift-XRT position
  59. GRB 190630C: AstroSat CZTI detection
  60. LIGO/Virgo S190630ag: No counterpart candidates in the Swift/BAT Observations
  61. GRB 190701A: MAXI/GSC detection
  62. GRB 190701B: a long GRB detected by IBAS
  63. GRB 190701A: Prompt enhanced Swift-XRT position
  64. GRB 190701A: Swift detection of a burst
  65. LIGO/Virgo S190630ag: No counterpart candidates in AGILE-MCAL observations
  66. LIGO/Virgo S190630ag: No counterpart candidates in Fermi-LAT observations
  67. GRB 190630B: KAIT Optical Afterglow Confirmation
  68. GRB 190630C: Enhanced Swift-XRT position
  69. Swift GRB190631. Global MASTER-Net observations report
  70. LIGO/Virgo S190630ag: Upper limits from Fermi-GBM Observations
  71. GRB 190630C: Swift detection of a burst
  72. LIGO/Virgo S190630ag: Coverage and upper limits from MAXI/GSC observations
  73. LIGO/Virgo S190630ag: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  74. LIGO/Virgo S190630ag: No neutrino counterpart candidates in ANTARES search
  75. LIGO/Virgo S190630ag: No counterpart candidates in HAWC observations
  76. LIGO/Virgo S190630ag: Identification of a GW compact binary merger candidate
  77. LIGO/Virgo S190630ag Global MASTER-Net observations report
  78. LIGO/Virgo S190630ag: Upper limits from IceCube neutrino searches
  79. GRB 190630B: Swift-XRT refined Analysis
  80. GRB 190630B, Swift-BAT refined analysis
  81. IceCube-190629A: Upper limits from Fermi-GBM Observations
  82. GRB 190627A: VLT/FORS2 spectroscopic redshift
  83. Fermi trigger No 583567803 Global MASTER-Net observations report
  84. GRB Swift Trigger 912102: KAIT Optical Afterglow Candidate
  85. Swift Trigger 912102: possible GRB 190630B
  86. GRB 190630A: Fermi GBM Final Real-time Localization
  87. GRB 190627A: Koshka Zeiss-1000 optical counterpart observations
  88. IceCube-190629A - IceCube observation of a high-energy neutrino candidate event
  89. Baksan Neutrino Observatory Alert 190629.56 Global MASTER-Net observations report
  90. IceCube Alert 190629.81 Global MASTER-Net observations report
  91. GRB 190627A : Xinglong 2.16m optical observation
  92. GRB 190627A: Swift-XRT refined Analysis
  93. GRB 190627A: GMG observation at the second epoch
  94. GRB 190627A: NOT optical observations
  95. GRB 190627A: Optical imaging by D50 from Ondrejov
  96. GRB 190627A: NIR imaging from Liverpool Telescope
  97. GRB 190627A: Optical imaging and spectroscopy from Calar Alto
  98. GRB 190627A: NUTTelA-TAO optical counterpart observations
  99. GRB 190627A: Swift-BAT refined analysis (short-soft burst)
  100. GRB 190610A: Further Swift-XRT observations

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