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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 200612A: Fermi GBM detection
  2. Fermi GRB 200613A: Global MASTER-Net observations report
  3. GRB 200613A: Swift ToO observations
  4. GRB 200613A: Fermi-LAT detection
  5. GRB 200613A: Fermi GBM observation
  6. GRB 200612A: Swift/UVOT Upper Limits
  7. Baksan Neutrino Observatory Alert 200611.74: Global MASTER-Net observations report
  8. BALROG localization (Fermi Trigger 613719013 / GRB 200613229)
  9. GRB 200613A: Fermi GBM Final Real-time Localization
  10. GRB 200612A: Swift-BAT refined analysis
  11. GRB 200612A: Swift-XRT refined Analysis
  12. Konus-Wind observation of ultra-long GRB 200612A
  13. GRB 200612A: Enhanced Swift-XRT position
  14. GRB 200612A: Late Optical Maximum Deteted by MASTER
  15. GRB 200612A: BOOTES-3/YA optical upper limit
  16. Fermi trigger No 613630183: Global MASTER-Net observations report
  17. Swift GRB200612.19: Global MASTER-Net OT detection
  18. Swift GRB200612.19: Global MASTER-Net observations report
  19. GRB 200612A: Swift detection of a burst
  20. GRB 200609A: Insight-HXMT/HE detection
  21. GRB 200608A: Swift-BAT refined analysis
  22. Konus-Wind detection of GRB 200605A
  23. GRB 200605A: CALET Gamma-Ray Burst Monitor detection
  24. IceCube-200530A - SN2020lam classified as SN II without evidence of CSM interaction
  25. GRB 200609A: Fermi GBM Final Real-time Localization
  26. Swift GRB 200608A: Global MASTER-Net observations report
  27. GRB 200608A: BOOTES-3 and BOOTES-4 optical upper limit
  28. GRB 200608A: Swift detection of a burst
  29. GRB 200607B: AstroSat CZTI detection
  30. GRB 200522A: Further HST F125W Observations
  31. Fermi GRB 200607B: Global MASTER-Net observations report
  32. GRB 200607B: Fermi GBM Final Real-time Localization
  33. Fermi GRB 200607A: Global MASTER-Net observations report
  34. IPN triangulation of GRB 200605A (short)
  35. GRB 200607A: Fermi GBM Final Localization
  36. GRB 200607A: BALROG localization (Fermi Trigger 613212114 / GRB 200607362)
  37. GRB 200530A: Fermi GBM detection
  38. GRB 200530A: CALET Gamma-Ray Burst Monitor detection
  39. Correction to the GCN 27886: Previous bursts of 1RXS J1708-4009 (Swift trigger 975998)
  40. 1RXS J1708−4009: Swift-BAT refined analysis
  41. Fermi GRB 200605A: Global MASTER-Net observations report
  42. GRB 200605A: Fermi GBM Final Real-time Localization
  43. GRB 200530A: Fermi-LAT detection
  44. GRB 200604A: AstroSat CZTI detection
  45. Fermi trigger No 612988790: Global MASTER-Net observations report
  46. Fermi GRB 200604A: Global MASTER-Net observations report
  47. GRB 200604A: Fermi GBM Final Real-time Localization
  48. Swift detection of an SGR-like burst from 1RXS J1708−4009
  49. Baksan Neutrino Observatory Alert 200603.12: Global MASTER-Net observations report
  50. GRB 200529A: Swift/UVOT Upper Limits
  51. Konus-Wind observation of GRB200528A
  52. GRB 200601A: Insight-HXMT/HE detection
  53. IceCube-200530A: Upper limits from a search for additional neutrino events in IceCube
  54. Baksan Neutrino Observatory Alert 200601.42: Global MASTER-Net observations report
  55. Fermi-LAT Gamma-ray Observations of IceCube-200530A
  56. GRB 200529A: MITSuME Akeno optical upper limits
  57. Fermi GRB 200601A: Global MASTER-Net observations report
  58. GRB 200601A: Fermi GBM Final Real-time Localization
  59. IceCube-200530A: not observable by Fermi-GBM
  60. Fermi GRB 200531A: Global MASTER-Net observations report
  61. IceCube-200530A: No significant detection in HAWC
  62. IceCube-200530A: Candidate Counterparts from the Zwicky Transient Facility
  63. IceCube-200530A: No ANTARES neutrino counterpart
  64. GRB 200531A: Fermi GBM Final Real-time Localization
  65. IceCube Alert 200530.33: Global MASTER-Net observations report
  66. GRB 200529A: Swift-BAT refined analysis
  67. Konus-Wind observation of GRB 200524A
  68. IceCube-200530A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  69. IceCube-200530A - IceCube observation of a high-energy neutrino candidate event
  70. GRB 200530A: AstroSat CZTI detection
  71. GRB 200529A: Swift-XRT refined Analysis
  72. Fermi GRB 200530A: Global MASTER-Net observations report
  73. GRB 200530A: Fermi GBM Final Real-time Localization
  74. GRB 200528A: CAHA Upper Limit
  75. GRB 200529A: Fermi GBM Detection
  76. GRB 200529A: LCO Optical Afterglow Detection
  77. Fermi GRB 200529B: Global MASTER-Net observations report
  78. Fermi trigger No 612429771: Global MASTER-Net observations report
  79. GRB 200528A: CALET Gamma-Ray Burst Monitor detection
  80. GRB 200529B: Fermi GBM Final Real-time Localization
  81. GRB 200529A: BOOTES-2/TELMA early optical upper limit
  82. GRB 200528A: Swift-XRT refined Analysis
  83. GRB 200524A: SAO RAS optical observations
  84. GRB 200524A: Assy continued optical observations
  85. GRB 200528A: Assy optical upper limit
  86. GRB 200529A: Enhanced Swift-XRT position
  87. GRB 200529A: KAIT Optical Afterglow Confirmation
  88. GRB 200529A: NOT optical afterglow
  89. GRB 200529A: Swift detection of a burst
  90. GRB 200529A: Fermi GBM Final Real-time Localization
  91. Swift GRB200529.04: Global MASTER-Net observations report
  92. GRB 200528A: NOT optical upper limits
  93. GRB 200528A: Fermi GBM Observation
  94. GRB 200528A: Swift/UVOT Upper Limits
  95. GRB 200528A: Swift-BAT refined analysis
  96. GRB 200528A: 1.3m DFOT Optical Upper Limits
  97. GRB 200528A: Nanshan/NEXT optical upper limit
  98. GRB 200528A: Enhanced Swift-XRT position
  99. Swift GRB 200528A: Global MASTER-Net observations report
  100. GRB 200528A: MITSuME Akeno optical upper limits

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