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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 201026A: FRAM-ORM optical detection limit
  2. GRB 201020A: 1.3m DFOT, optical upper limits
  3. GRB 201027A: Swift detection of a burst
  4. Swift GRB201027.05: Global MASTER-Net observations report
  5. GRB 201026A: NanShan/NEXT-0.6m optical upper limit
  6. GRB 201026A: NOT optical upper limits
  7. GRB 201026A: Swift detection of a burst
  8. Swift GRB201026.94: Global MASTER-Net observations report
  9. GRB 201024A: 1.3m DFOT optical observations
  10. GRB 201020B: 1.3m DFOT continued optical follow-up observations
  11. GRB201024A: correction to GCN28777 - there was no rebrightening
  12. GRB 201024A: MITSuME Akeno optical upper limits
  13. GRB 201024A: Swift-BAT refined analysis
  14. GRB201024A: rebrightening after initial steep decline
  15. GRB 201020B: HCT and GIT continued optical follow-up observations
  16. GRB 201024A: Swift-XRT refined Analysis
  17. GRB 201024A: Swift/UVOT Detection
  18. GRB 201020B: follow-up observations with Savelli Telescope
  19. GRB 201020B: 1.3m DFOT optical observations
  20. GRB 201024A: VIRT optical observations
  21. GRB 201024A: Enhanced Swift-XRT position
  22. GRB 201020B: follow-up observations at Konkoly
  23. GRB 201020B: continued Mondy optical observations
  24. GRB 200901A: FRAM-Auger optical limit
  25. GRB 201024A: FRAM-ORM afterglow detection
  26. GRB 201020B: Redshift from GTC/OSIRIS
  27. GRB 201024A: Redshift from GTC/OSIRIS
  28. GRB 201024A: BOOTES-2/TELMA early optical observation and 1.5m OSN follow-up
  29. GRB 201024A: MASTER correction to GCN 28760
  30. GRB 201024A: Swift detection of a burst with an optical afterglow
  31. Swift GRB201024A: Global MASTER-Net OT detection
  32. Swift GRB201024.12: Global MASTER-Net observations report
  33. IceCube-201021A: No significant detection in HAWC
  34. IceCube-201021A: One candidate counterpart from the Zwicky Transient Facility
  35. IceCube-201021A: Optical counterpart of WISEA J172314.13+142101.5
  36. GRB 201021C: Swift-BAT refined analysis
  37. GRB 201021C: Swift-XRT refined Analysis
  38. GRB 201020B: GROWTH-India Telescope optical observations
  39. Baksan Neutrino Observatory Alert 201022.66: Global MASTER-Net observations report
  40. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  41. GRB 201020B: Konkoly Obs. optical detection
  42. Swift-XRT observations of IceCube 201021A (2)
  43. GRB 201021C: Fermi GBM detection
  44. GRB 201020A: GROWTH-India Telescope late-time optical upper limit
  45. IceCube-201021A: Upper limits from a search for additional neutrino events in IceCube
  46. GRB 201021C: Swift/UVOT Detection
  47. Konus-Wind detection of GRB 201020A
  48. GRB 201020B: Swift/UVOT Detection
  49. GRB 201020A: Swift/UVOT Observations
  50. GRB 201014A: 2.0m HCT upper limit
  51. GRB 201020B: Swift-XRT afterglow detection
  52. GRB 201021C: VLT/X-shooter redshift
  53. IceCube-201021A: No neutrino counterpart candidates in ANTARES search
  54. GRB 201020A: VIRT optical observations
  55. GRB 201021C: Enhanced Swift-XRT position
  56. IceCube-201021A: Upper limits from Fermi-GBM Observations
  57. HAWC-201019A: not observable by Fermi-GBM
  58. GRB 201021C: MASTER optical synchronously observation
  59. IceCube-201021A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  60. Swift GRB201021.85: Global MASTER-Net observations report
  61. GRB 201021C: Swift detection of a burst with an optical counterpart
  62. HAWC-201019A: No Neutrino Counterpart detected with ANTARES
  63. MAXI GRB201021.68: Global MASTER-Net observations report
  64. GRB200826A: GMOS-N detection of a supernova bump
  65. GRB 201021B MAXI/GSC detection
  66. GRB 201020B: Mondy optical observations
  67. Swift-XRT observations of IceCube 201021A
  68. Konus-Wind detection of GRB 201020B
  69. IceCube Alert 201021.28: Global MASTER-Net observations report
  70. GRB 201015A: SAO RAS optical observations
  71. GRB 201020B: Swift ToO observations
  72. GRB 201020B: Nanshan/NEXT optical afterglow confirmation
  73. GRB 201020B: MASTER bright optical afterglow detection
  74. GRB 201020A: Redshift from GTC/OSIRIS
  75. GRB 201020B: Fermi-LAT detection
  76. IceCube-201021A: IceCube observation of a high-energy neutrino candidate event
  77. GRB 201020B: AGILE detection
  78. GRB 201020A: DOAO optical afterglow observations
  79. GRB 201021A: Fermi GBM Final Real-time Localization
  80. GRB 201020A: GROWTH-India Telescope optical observations
  81. GRB 201020B: Fermi GBM detection
  82. Alert from the HAWC Burst Monitor HAWC-201019A
  83. GRB 201020A: CrAO/ZTSH optical observations
  84. GRB 201020A: Swift-XRT refined Analysis
  85. GRB 201020A: Fermi GBM observation
  86. GRB 201020A: Swift-BAT refined analysis
  87. Fermi GRB 201020B: Global MASTER-Net observations report
  88. GRB 201020A: Assy optical observations
  89. GRB 201020B: Fermi GBM Final Real-time Localization
  90. GRB 201020A: Nanshan/NEXT optical observations
  91. Swift GRB 201020A: Global MASTER-Net observations report
  92. GRB 201014A: SAO RAS optical observations
  93. GRB 201020A: Enhanced Swift-XRT position
  94. GRB 201020A: MITSuME Akeno optical observation
  95. GRB 201020A: Swift detection of a burst with an optical counterpart.
  96. GRB 201019B: AstroSat CZTI detection
  97. GRB 201016A: Insight-HXMT/HE detection
  98. GRB 201017A iTelescope observation
  99. GRB 201017A: SAO RAS optical observations
  100. GRB 201017A: GROWTH-India optical upper limit

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