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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 S200105ae: AT2020pq, AT2020ps and AT2020pv 10.4m GTC spectroscopy
  2. LIGO/Virgo S200105ae: AT2020pp and AT2020py 10.4m GTC spectroscopy
  3. LIGO/Virgo S200105ae: AT2020oo 10.4m GTC spectroscopy
  4. IceCube-200109A: Swift-XRT and UVoT Follow-up Observations
  5. ANTARES 200108A: No detection by Swift-XRT
  6. IceCube-200109A: INTEGRAL was inactive at the time of the event
  7. IceCube-200109A: Upper limits from Fermi-GBM Observations
  8. IceCube-200109A: IceCube observation of a high-energy neutrino candidate event
  9. IceCube Alert 200109.99: Global MASTER-Net observations report
  10. IceCube Alert 200109.99: Global MASTER-Net observations report
  11. GRB 200107B: Swift/UVOT Observations
  12. GRB 200109A: Swift-BAT refined analysis
  13. Swift follow-up observations of IceCube-200107A: Identification of X-ray high state for 4FGL J0955.1+3551
  14. GRB 200109A: Swift/UVOT Upper Limits
  15. GRB 200109A: Fermi GBM observation
  16. LIGO/Virgo S200105ae: Updated Sky Localization and EM-Bright Probabilities
  17. LIGO/Virgo S200105ae : No significant candidates in TAROT - FRAM - GRANDMA observations.
  18. LIGO/Virgo S200105ae: Gaia Photometric Alerts transient candidate
  19. GRB 200107B: Swift-XRT refined Analysis
  20. Fermi-LAT ANTARES coincidence /ANTARES alert 200108.39: MASTER alert and inspect observation
  21. Fermi-LAT ANTARES coincidence: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  22. GRB 200109A: Swift-XRT refined Analysis
  23. GRB 200109A: Enhanced Swift-XRT position
  24. Fermi trigger No 600227156: Global MASTER-Net observations report
  25. Swift GRB200109.07: Global MASTER-Net observations report
  26. GRB 200109A: Swift detection of a burst
  27. GRB 200109A: Fermi GBM Final Real-time Localization
  28. Fermi-LAT ANTARES coincidence: Upper limits from Fermi-GBM Observations
  29. LIGO/Virgo S200105ae: GW data still under study
  30. Fermi-LAT ANTARES coincidence
  31. LIGO/Virgo S200105ae: Candidates from the Zwicky Transient Facility
  32. Swift GRB 200107B: Global MASTER-Net observations report
  33. GRB 200107B: Fermi GBM observation
  34. GRB 200107B: Swift-BAT refined analysis
  35. Fermi-LAT Gamma-ray Observations of IceCube-200107A
  36. IceCube-200107A: No significant detection in HAWC
  37. IceCube-200107A: No candidates from the Zwicky Transient Facility
  38. IceCube-200107A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  39. LIGO/Virgo S200108v: Retraction of GW compact binary merger candidate
  40. LIGO/Virgo S200105ae: Upper limits from CALET observations.
  41. GRB 200101A: CALET Gamma-Ray Burst Monitor detection
  42. LIGO/Virgo S200105ae: Upper Limits from the Zwicky Transient Facility
  43. GRB 200107B: Swift detection of a burst
  44. Swift GRB200107.81: Global MASTER-Net OT detection
  45. GRB 200107B: Fermi GBM Final Real-time Localization
  46. Swift GRB200107.81: Global MASTER-Net observations report
  47. LIGO/Virgo S200105ae: Further study ongoing for GW compact binary merger candidate
  48. IceCube-200107A: Upper limits from Fermi-GBM Observations
  49. IceCube-200107A: IceCube observation of a high-energy neutrino candidate event
  50. LIGO/Virgo 200105ae: No counterpart candidates in Fermi-LAT observations
  51. GRB 191228A: FRAM-ORM optical limit
  52. LIGO/Virgo S200105ae: AstroSat CZTI upper limits
  53. LIGO/Virgo S200105ae: Coverage and upper limits from MAXI/GSC observations
  54. LIGO/Virgo S200105ae: No counterpart candidates in HAWC observations
  55. LIGO/Virgo S200105ae: no counterpart candidates in the Swift/BAT observations
  56. LIGO/Virgo S200105ae: Upper limits from IceCube neutrino searches
  57. LIGO/Virgo S200105ae: not observable by AGILE-MCAL
  58. LIGO/Virgo S200105ae: Global MASTER-Net observations report
  59. LIGO/Virgo S200105ae: Upper limits from Fermi-GBM Observations
  60. LIGO/Virgo S200105ae: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  61. LIGO/Virgo S200105ae : no neutrino counterpart candidate in ANTARES search
  62. LIGO/Virgo S200105ae: We have issued GCN Notices to support automated processing
  63. S200106au and S200106av: Retraction of GW compact binary merger candidates
  64. LIGO/Virgo S200105ae: A subthreshold GW compact binary merger candidate
  65. Fermi trigger No 599954133: Global MASTER-Net observations report
  66. GRB 200105A: MAXI/GSC detection
  67. Konus-Wind observation of GRB200101A
  68. Fermi trigger No 599761015: Global MASTER-Net observations report
  69. IPN triangulation of GRB 200101A
  70. GRB 200103A: Fermi GBM Final Real-time Localization
  71. Fermi-LAT Gamma-ray Observations of IceCube-191231A
  72. GRB 200101A : AstroSat CZTI detection
  73. IceCube-191231A: Upper limits from a search for additional neutrino events in IceCube
  74. GRB 191228A: Early Optical Upper Limits from LCO
  75. IceCube Alert 200101.46: Global MASTER-Net observations report
  76. IceCube-191231A: No significant detection in HAWC
  77. GRB 200101A: Fermi GBM detection
  78. Fermi trigger No 599603971: Global MASTER-Net observations report
  79. GRB 200101A: BALROG localization (Fermi Trigger 599603971 / GRB 200101861)
  80. GRB 200101A: Fermi GBM Final Real-time Localization
  81. IceCube-191231A: No Neutrino Counterpart in ANTARES data
  82. IceCube-191231A: Upper limits from Fermi-GBM Observations
  83. IceCube-191231A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  84. IceCube-191231A: IceCube observation of a high-energy neutrino candidate event
  85. IceCube Alert 191231.46: Global MASTER-Net observations report
  86. GRB 191227A: Insight-HXMT/HE observation
  87. GRB 191227B: Insight-HXMT/HE observation
  88. GRB 191221B: CALET Gamma-Ray Burst Monitor detection
  89. GRB 191228A: Mondy optical upper limit
  90. Konus-Wind observation of GRB 191227A
  91. Konus-Wind observation of GRB 191227B
  92. IPN triangulation of GRB 191227B (short)
  93. GRB 191228A: Swift/UVOT Upper Limits
  94. GRB 191225A : AstroSat CZTI detection
  95. GRB 191228A: Swift-XRT refined Analysis
  96. GRB 191227A: Swift-BAT refined analysis
  97. GRB 191228A: Swift-BAT refined analysis
  98. GRB 191228A: Enhanced Swift-XRT position
  99. LIGO/Virgo S191216ap: Two candidate counterparts from UKIRT/WFCAM z-band observations
  100. GRB 191228A: ePESSTO+ NTT optical upper limit

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