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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. BALROG localization (Fermi Trigger 613719013 / GRB 200613229)
  2. GRB 200613A: Fermi GBM Final Real-time Localization
  3. GRB 200612A: Swift-BAT refined analysis
  4. GRB 200612A: Swift-XRT refined Analysis
  5. Konus-Wind observation of ultra-long GRB 200612A
  6. GRB 200612A: Enhanced Swift-XRT position
  7. GRB 200612A: Late Optical Maximum Deteted by MASTER
  8. GRB 200612A: BOOTES-3/YA optical upper limit
  9. Fermi trigger No 613630183: Global MASTER-Net observations report
  10. Swift GRB200612.19: Global MASTER-Net OT detection
  11. Swift GRB200612.19: Global MASTER-Net observations report
  12. GRB 200612A: Swift detection of a burst
  13. GRB 200609A: Insight-HXMT/HE detection
  14. GRB 200608A: Swift-BAT refined analysis
  15. Konus-Wind detection of GRB 200605A
  16. GRB 200605A: CALET Gamma-Ray Burst Monitor detection
  17. IceCube-200530A - SN2020lam classified as SN II without evidence of CSM interaction
  18. GRB 200609A: Fermi GBM Final Real-time Localization
  19. Swift GRB 200608A: Global MASTER-Net observations report
  20. GRB 200608A: BOOTES-3 and BOOTES-4 optical upper limit
  21. GRB 200608A: Swift detection of a burst
  22. GRB 200607B: AstroSat CZTI detection
  23. GRB 200522A: Further HST F125W Observations
  24. Fermi GRB 200607B: Global MASTER-Net observations report
  25. GRB 200607B: Fermi GBM Final Real-time Localization
  26. Fermi GRB 200607A: Global MASTER-Net observations report
  27. IPN triangulation of GRB 200605A (short)
  28. GRB 200607A: Fermi GBM Final Localization
  29. GRB 200607A: BALROG localization (Fermi Trigger 613212114 / GRB 200607362)
  30. GRB 200530A: Fermi GBM detection
  31. GRB 200530A: CALET Gamma-Ray Burst Monitor detection
  32. Correction to the GCN 27886: Previous bursts of 1RXS J1708-4009 (Swift trigger 975998)
  33. 1RXS J1708−4009: Swift-BAT refined analysis
  34. Fermi GRB 200605A: Global MASTER-Net observations report
  35. GRB 200605A: Fermi GBM Final Real-time Localization
  36. GRB 200530A: Fermi-LAT detection
  37. GRB 200604A: AstroSat CZTI detection
  38. Fermi trigger No 612988790: Global MASTER-Net observations report
  39. Fermi GRB 200604A: Global MASTER-Net observations report
  40. GRB 200604A: Fermi GBM Final Real-time Localization
  41. Swift detection of an SGR-like burst from 1RXS J1708−4009
  42. Baksan Neutrino Observatory Alert 200603.12: Global MASTER-Net observations report
  43. GRB 200529A: Swift/UVOT Upper Limits
  44. Konus-Wind observation of GRB200528A
  45. GRB 200601A: Insight-HXMT/HE detection
  46. IceCube-200530A: Upper limits from a search for additional neutrino events in IceCube
  47. Baksan Neutrino Observatory Alert 200601.42: Global MASTER-Net observations report
  48. Fermi-LAT Gamma-ray Observations of IceCube-200530A
  49. GRB 200529A: MITSuME Akeno optical upper limits
  50. Fermi GRB 200601A: Global MASTER-Net observations report
  51. GRB 200601A: Fermi GBM Final Real-time Localization
  52. IceCube-200530A: not observable by Fermi-GBM
  53. Fermi GRB 200531A: Global MASTER-Net observations report
  54. IceCube-200530A: No significant detection in HAWC
  55. IceCube-200530A: Candidate Counterparts from the Zwicky Transient Facility
  56. IceCube-200530A: No ANTARES neutrino counterpart
  57. GRB 200531A: Fermi GBM Final Real-time Localization
  58. IceCube Alert 200530.33: Global MASTER-Net observations report
  59. GRB 200529A: Swift-BAT refined analysis
  60. Konus-Wind observation of GRB 200524A
  61. IceCube-200530A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  62. IceCube-200530A - IceCube observation of a high-energy neutrino candidate event
  63. GRB 200530A: AstroSat CZTI detection
  64. GRB 200529A: Swift-XRT refined Analysis
  65. Fermi GRB 200530A: Global MASTER-Net observations report
  66. GRB 200530A: Fermi GBM Final Real-time Localization
  67. GRB 200528A: CAHA Upper Limit
  68. GRB 200529A: Fermi GBM Detection
  69. GRB 200529A: LCO Optical Afterglow Detection
  70. Fermi GRB 200529B: Global MASTER-Net observations report
  71. Fermi trigger No 612429771: Global MASTER-Net observations report
  72. GRB 200528A: CALET Gamma-Ray Burst Monitor detection
  73. GRB 200529B: Fermi GBM Final Real-time Localization
  74. GRB 200529A: BOOTES-2/TELMA early optical upper limit
  75. GRB 200528A: Swift-XRT refined Analysis
  76. GRB 200524A: SAO RAS optical observations
  77. GRB 200524A: Assy continued optical observations
  78. GRB 200528A: Assy optical upper limit
  79. GRB 200529A: Enhanced Swift-XRT position
  80. GRB 200529A: KAIT Optical Afterglow Confirmation
  81. GRB 200529A: NOT optical afterglow
  82. GRB 200529A: Swift detection of a burst
  83. GRB 200529A: Fermi GBM Final Real-time Localization
  84. Swift GRB200529.04: Global MASTER-Net observations report
  85. GRB 200528A: NOT optical upper limits
  86. GRB 200528A: Fermi GBM Observation
  87. GRB 200528A: Swift/UVOT Upper Limits
  88. GRB 200528A: Swift-BAT refined analysis
  89. GRB 200528A: 1.3m DFOT Optical Upper Limits
  90. GRB 200528A: Nanshan/NEXT optical upper limit
  91. GRB 200528A: Enhanced Swift-XRT position
  92. Swift GRB 200528A: Global MASTER-Net observations report
  93. GRB 200528A: MITSuME Akeno optical upper limits
  94. GRB 200528A: Potential host galaxy in PanSTARRS, SDSS and WISE
  95. GRB 200528A: Swift detection of a burst
  96. GRB 200528A: Fermi GBM Final Real-time Localization
  97. GRB 200524A: Assy optical observations
  98. Baksan Neutrino Observatory Alert 200526.85: Global MASTER-Net observations report
  99. IceCube-200523A: Upper limits from a search for additional neutrino events in IceCube
  100. GRB 200522A: HST F125W new point source detection

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