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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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 201209A: AstroSat CZTI detection
  2. GRB 201207A: AGILE detection
  3. GRB 201209A: Enhanced Swift-XRT position
  4. IceCube-201130A: Optical and NIR Imaging Follow-up by Kanata Telescope
  5. GRB 201209A: KAIT Optical Upper Limit
  6. GRB 201209A: FRAM-Auger optical limit
  7. GRB 201209A: Swift detection of a burst
  8. Swift GRB201209.24: Global MASTER-Net observations report
  9. GRB 201208A: Fermi-LAT detection
  10. GRB 201208A: Swift ToO observations
  11. GRB 201208A: AstroSat CZTI detection
  12. GRB 201207A: AstroSat CZTI detection
  13. Fermi GRB 201208A: Global MASTER-Net observations report
  14. GRB 201208A: Fermi GBM Final Real-time Localization
  15. Fermi GRB 201207A: Global MASTER-Net observations report
  16. GRB 201207A: Fermi GBM Final Real-time Localization
  17. GRB 201203A: Swift-BAT refined analysis
  18. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  19. GRB 201203A: GROWTH-India Telescope optical upper limit.
  20. GRB 201203A: MITSuME Okayama optical upper limits
  21. Swift GRB 201203A: Global MASTER-Net observations report
  22. GRB 201203A: Swift-XRT afterglow detection
  23. IceCube-201130A: No Candidate Counterparts from the Zwicky Transient Facility
  24. GRB 201203A: KAIT Optical Upper Limit
  25. GRB 201203A: DDOTI Observations
  26. GRB 201203A: FRAM-Auger optical limit
  27. GRB 201203A: Swift detection of a burst
  28. IceCube-201130A: No significant detection in HAWC
  29. IceCube-201130A: Upper limits from a search for additional neutrino events in IceCube
  30. IceCube-201130A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  31. GRB201130A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 628407054)
  32. GRB 201128B: Swift-XRT observations
  33. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  34. Fermi-LAT Gamma-ray Observations of IceCube-201130A
  35. IceCube-201130A: Not observable by Fermi-GBM
  36. GRB 201201A: DDOTI Observations
  37. Fermi GRB 201201A: Global MASTER-Net observations report
  38. GRB 201128B: Swift ToO observations
  39. Swift-XRT observations of IceCube 201130A
  40. GRB 201201A: Fermi GBM Final Real-time Localization
  41. GRB 201128B: Swift/BAT-GUANO detection and arcminute localization
  42. GRB 201128A: Swift/UVOT Upper Limits
  43. IceCube-201130A: IceCube observation of a high-energy neutrino candidate event
  44. IceCube Alert 201130.85: Global MASTER-Net observations report
  45. GRB 201130A: DDOTI Observations
  46. Fermi GRB 201130A: Global MASTER-Net observations report
  47. GRB 201130A: Fermi GBM Final Real-time Localization
  48. Baksan Neutrino Observatory Alert 201128.90: Global MASTER-Net observations report
  49. GRB 201128A: Swift-BAT refined analysis
  50. GRB 201128A: Swift-XRT refined Analysis
  51. Fermi trigger No 628278856: Global MASTER-Net observations report
  52. GRB 201128A: Enhanced Swift-XRT position
  53. GRB 201128A: DDOTI Observations
  54. GRB 201128A: Swift detection of a burst
  55. Fermi trigger No 628140709: DDOTI/OAN optical observations report
  56. Fermi trigger No 628140709: Global MASTER-Net observations report
  57. IceCube-201114A: Updated photometry for three DECam candidate optical counterparts
  58. GRB 201121A: Insight-HXMT/HE detection
  59. AMON IC_HAWC NuEm-201124A: No Neutrino Counterpart detected with ANTARES
  60. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
  61. IceCube Alert 201124.34: Global MASTER-Net observations report
  62. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-201124A
  63. GRB 200826A: TNG and LBT constraints on a supernova bump
  64. GRB 201122A: Insight-HXMT/HE detection
  65. IceCube-201114A: DECam observations and candidate optical counterpart
  66. IceCube-201120A: Upper limits from a search for additional neutrino events in IceCube
  67. GRB 201015A L-band observations with e-MERLIN
  68. INTEGRAL Weak #8831 and #8832: AROMA-N Optical Observation
  69. Fermi-LAT Gamma-ray Observations of IceCube-201120A
  70. IceCube-201120A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  71. Fermi trigger No 627645769: Global MASTER-Net observations report
  72. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  73. GRB 201015A radio afterglow with e-MERLIN
  74. Fermi GRB 201121A: Global MASTER-Net observations report
  75. GRB 201121B: Fermi GBM Final Real-time Localization
  76. GRB 201121A: BALROG localization (Fermi Trigger 627614994 / GRB 201121062)
  77. GRB 201121A: Fermi GBM Final Real-time Localization
  78. Fermi GRB 201120B: Global MASTER-Net observations report
  79. GRB 201120B: Fermi GBM Final Localization
  80. GRB 201120A: Fermi GBM Final Localization
  81. IceCube-201120A: Upper limits from Fermi-GBM Observations
  82. Fermi trigger No 627557935: Global MASTER-Net observations report
  83. Baksan Neutrino Observatory Alert 201120.43: Global MASTER-Net observations report
  84. IceCube Alert 201120.41: Global MASTER-Net observations report
  85. IceCube-201120A: IceCube observation of a high-energy neutrino candidate event
  86. ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations
  87. ZTF20acozryr/AT2020yxz (GRB 201103B): correction to the GCN #28883 CrAO/ZTSh optical observations
  88. IceCube 201114A: Swift followup of Fermi J0703.5+0505
  89. GRB 201116A: CALET Gamma-Ray Burst Monitor detection
  90. INTEGRAL Weak#8825: AROMA-N Optical Observation
  91. Fermi trigger No 627438255: Global MASTER-Net observations report
  92. Konus-Wind detection of GRB 201116A
  93. Trigger 1007266: Swift detection of 1A 0535+262
  94. Fermi-LAT Gamma-ray Observations of IceCube-201114A
  95. GRB 201116A: NOT optical observations
  96. GRB 201116A: Swift-XRT afterglow detection
  97. GRB 201116A: OSN Afterglow Candidate
  98. Swift Trigger 1006917 is Be/X-ray binary pulsar 1A 0535+262
  99. IceCube Alert 201115.67: Global MASTER-Net observations report
  100. Fermi trigger No 627198169: Global MASTER-Net observations report

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