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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 200617A: Insight-HXMT/HE detection
  2. IceCube-200530A - SN2020lls likely unrelated
  3. Swift/UVOT Observations of IceCube 200615A
  4. GRB 200613A: Mondy optical observations
  5. LIGO/Virgo MS200614ct: Identification of a test binary black hole candidate
  6. Fermi trigger No 614103490: Global MASTER-Net observations report
  7. Baksan Neutrino Observatory Alert 200617.47: Global MASTER-Net observations report
  8. GRB 200615B: CALET Gamma-Ray Burst Monitor detection
  9. Swift-XRT observations of IceCube 200615A
  10. IceCube-200615A: No significant detection in HAWC
  11. GRB 200613A: Jet-break from Xinglong-2.16m optical observations
  12. Fermi-LAT Gamma-ray Observations of IceCube-200615A
  13. IceCube-200614A: No significant detection in HAWC
  14. IceCube-200615A: Upper limits from a search for additional neutrino events in IceCube
  15. GRB 200616B: Fermi GBM Final Real-time Localization
  16. Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132
  17. LIGO/Virgo MS200615ce: Identification of a test binary black hole candidate
  18. GRB 200613A: CALET Gamma-Ray Burst Monitor detection
  19. LIGO/Virgo MS200614bz: Test Identification of a binary neutron star candidate
  20. GRB 200613A: MITSuME Akeno optical upper limits
  21. Fermi GRB 200616A: Global MASTER-Net observations report
  22. GRB 200615B: MAXI/GSC detection
  23. GRB 200616A: Fermi GBM Final Real-time Localization
  24. GRB 200613A: continued AbAO optical afterglow observations
  25. IceCube-200615A: Upper limits from Fermi-GBM Observations
  26. IceCube-200614A: Upper limits from a search for additional neutrino events in IceCube
  27. IceCube-200614A: not observable by Fermi-GBM
  28. IceCube-200615A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  29. IceCube Alert 200615.62: Global MASTER-Net observations report
  30. IceCube-200614A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  31. LIGO/Virgo MS200615h: Retraction of a test binary neutron star candidate
  32. IceCube-200615A: IceCube observation of a high-energy neutrino candidate event
  33. GRB 200613A: Continued Xinglong-2.16m optical observations
  34. Fermi GRB 200615A: Global MASTER-Net observations report
  35. GRB 200615A: Fermi GBM Final Real-time Localization
  36. Baksan Neutrino Observatory Alert 200614.34: Global MASTER-Net observations report
  37. IceCube Alert 200614.53: Global MASTER-Net observations report
  38. GRB 200613A: Swift/UVOT Detection
  39. GRB 200613A: Xinglong-2.16m optical observations
  40. Fermi GRB 200614A: Global MASTER-Net observations report
  41. IceCube-200614A - IceCube observation of a high-energy neutrino candidate track-like event
  42. GRB 200614A: Fermi GBM Final Real-time Localization
  43. GRB 200613A: Liverpool Telescope observations
  44. GRB 200613A: OAJ Afterglow: Error in Coordinates
  45. GRB 200613A: Kitab and AbAO optical afterglow observations, host galaxy candidate
  46. GRB 200613A: Swift-XRT afterglow detection
  47. GRB 200613A: Candidate afterglow from OAJ
  48. GRB 200612A: Fermi GBM detection
  49. Fermi GRB 200613A: Global MASTER-Net observations report
  50. GRB 200613A: Swift ToO observations
  51. GRB 200613A: Fermi-LAT detection
  52. GRB 200613A: Fermi GBM observation
  53. GRB 200612A: Swift/UVOT Upper Limits
  54. Baksan Neutrino Observatory Alert 200611.74: Global MASTER-Net observations report
  55. BALROG localization (Fermi Trigger 613719013 / GRB 200613229)
  56. GRB 200613A: Fermi GBM Final Real-time Localization
  57. GRB 200612A: Swift-BAT refined analysis
  58. GRB 200612A: Swift-XRT refined Analysis
  59. Konus-Wind observation of ultra-long GRB 200612A
  60. GRB 200612A: Enhanced Swift-XRT position
  61. GRB 200612A: Late Optical Maximum Deteted by MASTER
  62. GRB 200612A: BOOTES-3/YA optical upper limit
  63. Fermi trigger No 613630183: Global MASTER-Net observations report
  64. Swift GRB200612.19: Global MASTER-Net OT detection
  65. Swift GRB200612.19: Global MASTER-Net observations report
  66. GRB 200612A: Swift detection of a burst
  67. GRB 200609A: Insight-HXMT/HE detection
  68. GRB 200608A: Swift-BAT refined analysis
  69. Konus-Wind detection of GRB 200605A
  70. GRB 200605A: CALET Gamma-Ray Burst Monitor detection
  71. IceCube-200530A - SN2020lam classified as SN II without evidence of CSM interaction
  72. GRB 200609A: Fermi GBM Final Real-time Localization
  73. Swift GRB 200608A: Global MASTER-Net observations report
  74. GRB 200608A: BOOTES-3 and BOOTES-4 optical upper limit
  75. GRB 200608A: Swift detection of a burst
  76. GRB 200607B: AstroSat CZTI detection
  77. GRB 200522A: Further HST F125W Observations
  78. Fermi GRB 200607B: Global MASTER-Net observations report
  79. GRB 200607B: Fermi GBM Final Real-time Localization
  80. Fermi GRB 200607A: Global MASTER-Net observations report
  81. IPN triangulation of GRB 200605A (short)
  82. GRB 200607A: Fermi GBM Final Localization
  83. GRB 200607A: BALROG localization (Fermi Trigger 613212114 / GRB 200607362)
  84. GRB 200530A: Fermi GBM detection
  85. GRB 200530A: CALET Gamma-Ray Burst Monitor detection
  86. Correction to the GCN 27886: Previous bursts of 1RXS J1708-4009 (Swift trigger 975998)
  87. 1RXS J1708−4009: Swift-BAT refined analysis
  88. Fermi GRB 200605A: Global MASTER-Net observations report
  89. GRB 200605A: Fermi GBM Final Real-time Localization
  90. GRB 200530A: Fermi-LAT detection
  91. GRB 200604A: AstroSat CZTI detection
  92. Fermi trigger No 612988790: Global MASTER-Net observations report
  93. Fermi GRB 200604A: Global MASTER-Net observations report
  94. GRB 200604A: Fermi GBM Final Real-time Localization
  95. Swift detection of an SGR-like burst from 1RXS J1708−4009
  96. Baksan Neutrino Observatory Alert 200603.12: Global MASTER-Net observations report
  97. GRB 200529A: Swift/UVOT Upper Limits
  98. Konus-Wind observation of GRB200528A
  99. GRB 200601A: Insight-HXMT/HE detection
  100. IceCube-200530A: Upper limits from a search for additional neutrino events in IceCube

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