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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. IceCube-200620A: One Candidate Counterpart from the Zwicky Transient Facility
  2. Fermi-LAT Gamma-ray Observations of IceCube-200620A
  3. GRB 200613A: Continued CrAO optical observations
  4. IceCube-200620A: No ANTARES neutrino counterpart
  5. IceCube Alert 200620.13: Global MASTER-Net observations report
  6. GRB 200613A: CrAO optical observations
  7. GRB 200613A: R-band observations from HCT
  8. GRB 200613A: Further Liverpool Telescope observations
  9. IceCube-200620A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 200619C: Fermi GBM Final Real-time Localization
  11. Fermi GRB 200619B: Global MASTER-Net observations report
  12. GRB 200619B: AstroSat CZTI detection
  13. GRB 200619A: Fermi GBM observation
  14. Fermi trigger No 614239407: Global MASTER-Net observations report
  15. GRB 200619A: AGILE detection
  16. LIGO/Virgo MS200618aq: Retraction of a test binary neutron star candidate
  17. LIGO/Virgo MS200619bf: Retraction of a test binary neutron star candidate
  18. LIGO/Virgo MS200618bx: Retraction of a test binary neutron star candidate
  19. LIGO/Virgo MS200618bq: Retraction of a test binary neutron star candidate
  20. GRB 200619B: Fermi GBM Final Real-time Localization
  21. GRB 200619A: Insight-HXMT/HE detection
  22. Fermi trigger No 614226976: Global MASTER-Net observations report
  23. GRB 200613A: continued Kitab optical observations
  24. GRB 200613A: SAO RAS optical observations
  25. GRB 200617A: Insight-HXMT/HE detection
  26. IceCube-200530A - SN2020lls likely unrelated
  27. Swift/UVOT Observations of IceCube 200615A
  28. GRB 200613A: Mondy optical observations
  29. LIGO/Virgo MS200614ct: Identification of a test binary black hole candidate
  30. Fermi trigger No 614103490: Global MASTER-Net observations report
  31. Baksan Neutrino Observatory Alert 200617.47: Global MASTER-Net observations report
  32. GRB 200615B: CALET Gamma-Ray Burst Monitor detection
  33. Swift-XRT observations of IceCube 200615A
  34. IceCube-200615A: No significant detection in HAWC
  35. GRB 200613A: Jet-break from Xinglong-2.16m optical observations
  36. Fermi-LAT Gamma-ray Observations of IceCube-200615A
  37. IceCube-200614A: No significant detection in HAWC
  38. IceCube-200615A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 200616B: Fermi GBM Final Real-time Localization
  40. Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132
  41. LIGO/Virgo MS200615ce: Identification of a test binary black hole candidate
  42. GRB 200613A: CALET Gamma-Ray Burst Monitor detection
  43. LIGO/Virgo MS200614bz: Test Identification of a binary neutron star candidate
  44. GRB 200613A: MITSuME Akeno optical upper limits
  45. Fermi GRB 200616A: Global MASTER-Net observations report
  46. GRB 200615B: MAXI/GSC detection
  47. GRB 200616A: Fermi GBM Final Real-time Localization
  48. GRB 200613A: continued AbAO optical afterglow observations
  49. IceCube-200615A: Upper limits from Fermi-GBM Observations
  50. IceCube-200614A: Upper limits from a search for additional neutrino events in IceCube
  51. IceCube-200614A: not observable by Fermi-GBM
  52. IceCube-200615A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  53. IceCube Alert 200615.62: Global MASTER-Net observations report
  54. IceCube-200614A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  55. LIGO/Virgo MS200615h: Retraction of a test binary neutron star candidate
  56. IceCube-200615A: IceCube observation of a high-energy neutrino candidate event
  57. GRB 200613A: Continued Xinglong-2.16m optical observations
  58. Fermi GRB 200615A: Global MASTER-Net observations report
  59. GRB 200615A: Fermi GBM Final Real-time Localization
  60. Baksan Neutrino Observatory Alert 200614.34: Global MASTER-Net observations report
  61. IceCube Alert 200614.53: Global MASTER-Net observations report
  62. GRB 200613A: Swift/UVOT Detection
  63. GRB 200613A: Xinglong-2.16m optical observations
  64. Fermi GRB 200614A: Global MASTER-Net observations report
  65. IceCube-200614A - IceCube observation of a high-energy neutrino candidate track-like event
  66. GRB 200614A: Fermi GBM Final Real-time Localization
  67. GRB 200613A: Liverpool Telescope observations
  68. GRB 200613A: OAJ Afterglow: Error in Coordinates
  69. GRB 200613A: Kitab and AbAO optical afterglow observations, host galaxy candidate
  70. GRB 200613A: Swift-XRT afterglow detection
  71. GRB 200613A: Candidate afterglow from OAJ
  72. GRB 200612A: Fermi GBM detection
  73. Fermi GRB 200613A: Global MASTER-Net observations report
  74. GRB 200613A: Swift ToO observations
  75. GRB 200613A: Fermi-LAT detection
  76. GRB 200613A: Fermi GBM observation
  77. GRB 200612A: Swift/UVOT Upper Limits
  78. Baksan Neutrino Observatory Alert 200611.74: Global MASTER-Net observations report
  79. BALROG localization (Fermi Trigger 613719013 / GRB 200613229)
  80. GRB 200613A: Fermi GBM Final Real-time Localization
  81. GRB 200612A: Swift-BAT refined analysis
  82. GRB 200612A: Swift-XRT refined Analysis
  83. Konus-Wind observation of ultra-long GRB 200612A
  84. GRB 200612A: Enhanced Swift-XRT position
  85. GRB 200612A: Late Optical Maximum Deteted by MASTER
  86. GRB 200612A: BOOTES-3/YA optical upper limit
  87. Fermi trigger No 613630183: Global MASTER-Net observations report
  88. Swift GRB200612.19: Global MASTER-Net OT detection
  89. Swift GRB200612.19: Global MASTER-Net observations report
  90. GRB 200612A: Swift detection of a burst
  91. GRB 200609A: Insight-HXMT/HE detection
  92. GRB 200608A: Swift-BAT refined analysis
  93. Konus-Wind detection of GRB 200605A
  94. GRB 200605A: CALET Gamma-Ray Burst Monitor detection
  95. IceCube-200530A - SN2020lam classified as SN II without evidence of CSM interaction
  96. GRB 200609A: Fermi GBM Final Real-time Localization
  97. Swift GRB 200608A: Global MASTER-Net observations report
  98. GRB 200608A: BOOTES-3 and BOOTES-4 optical upper limit
  99. GRB 200608A: Swift detection of a burst
  100. GRB 200607B: AstroSat CZTI detection

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