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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').
  1. Fermi trigger No 647942198: MASTER optical afterglow detection
  2. GRB 210704A: Zeiss-1000/SAO-RAS optical observations
  3. GRB 210715B: DDOTI Upper Limits on the Afterglow
  4. Fermi trigger No 648033323: Global MASTER-Net observations report
  5. Fermi trigger No 648024201: Global MASTER-Net observations report
  6. Fermi trigger No 647942198: Global MASTER-Net observations report
  7. GRB 210712A: Swift-BAT refined analysis
  8. GECAM detection of a short burst from SGR J1935+2154
  9. Recent activity of SGR 1935+2154 as observed by CGBM
  10. GRB 210712A: Swift-XRT refined Analysis
  11. GRB 210712A: Swift/UVOT Upper Limits
  12. GRB 210712A: BOOTES-3/YA optical upper limit
  13. Fermi trigger No 647805873: Global MASTER-Net observations report
  14. GRB 210712A: Enhanced Swift-XRT position
  15. GRB 210704A: classification as long GRB and redshift estimating
  16. GRB 210704A: Lowell Discovery Telescope Optical Observations
  17. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 10
  18. GECAM detection of a short burst from SGR J1935+2154
  19. Fermi trigger No 647775795: Global MASTER-Net observations report
  20. GRB 210712A: Swift detection of a burst
  21. GRB 210709A: AstroSat CZTI detection
  22. GRB 210704A: Continued Gemini-North NIR K-band Detections
  23. GRB 210704A: INTEGRAL observations
  24. GRB 210704A: NOT optical observations and color change
  25. GRB210704A: Gemini near-infrared upper limits
  26. Fermi trigger No 647653174: Global MASTER-Net observations report
  27. GRB 210704A: Assy optical afterglow upper limit
  28. Fermi trigger No 647641569: Global MASTER-Net observations report
  29. Fermi trigger No 647624281: Global MASTER-Net observations report
  30. GECAM detection of a short burst from SGR J1935+2154
  31. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
  32. MAXI GRB210709.93: Global MASTER-Net observations report
  33. Fermi trigger No 647522278: Global MASTER-Net observations report
  34. GRB 210704A: Gemini-North Infrared Source Detection
  35. GRB 210704A: further TNG optical observations
  36. GRB 210706A: Swift/XRT afterglow confirmation
  37. GECAM detection of a short burst from SGR 1935+2154
  38. GRB 210708B: Swift-BAT refined analysis
  39. Fermi GRB 210709A: Global MASTER-Net observations report
  40. GRB 210709A: Fermi GBM Final Real-time Localization
  41. Swift GRB 210708B: Global MASTER-Net observations report
  42. GRB 210708A: Swift/UVOT Upper Limits
  43. GRB 210702A: ATCA detection
  44. GRB 210702A: ALMA detection
  45. GRB 210708A: Swift-BAT refined analysis
  46. Fermi GBM Sub-Threshold Detection of GRB 210708A
  47. Fermi GBM Sub-Threshold Detection of GRB 210707A
  48. IceCube-210629A - Spectroscopic observation of AT2021osi
  49. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 7
  50. GRB 210708B: Swift detection of a possible burst
  51. GRB 210708A: Swift-XRT refined Analysis
  52. GECAM detection of a short burst from SGR 1935+2154
  53. GRB 210707A: A long GRB detected by INTEGRAL
  54. GRB 210708A: Swift detection of a burst
  55. Swift GRB210708.10: Global MASTER-Net observations report
  56. GRB 210704A: CAHA 2.2m telescope optical limit
  57. Fermi trigger No 647365516: Global MASTER-Net observations report
  58. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 6
  59. Fermi trigger No 647271699: Global MASTER-Net observations report
  60. Fermi GBM Observations of SGR J1935+2154
  61. Swift-BAT detection of a burst from SGR 1935+2154
  62. GRB 210706A: Fermi GBM observation
  63. GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
  64. Konus-Wind detection of GRB 210706A
  65. GRB 210706A: GIT optical upper limits
  66. GRB 210704A: OAJ T80 multi-color detections
  67. GECAM detection of a bright short burst from SGR 1935+2154
  68. GRB 210706A: Swift-XRT afterglow detection
  69. Integral GRB210707.02: Global MASTER-Net observations report
  70. GRB 210706A: Swift ToO observations
  71. Fermi trigger No 647252274: Global MASTER-Net observations report
  72. INTEGRAL detection of a burst from SGR 1935+2154
  73. Integral GRB210706.72: Global MASTER-Net observations report
  74. GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
  75. GRB 210704A: OSIRIS/GTC spectroscopy
  76. GRB 210704A: CAHA 2.2m Afterglow Detection
  77. GRB 210704A: RATIR optical upper limits
  78. GRB 210704A: Swift/UVOT Upper Limits
  79. Konus-Wind detection of GRB 210704A
  80. GRB 210704B: AstroSat CZTI detection
  81. GRB 210619B: ALMA detection
  82. GRB 210704A: TNG detection of the optical afterglow candidate
  83. GRB 210704A: Assy optical afterglow candidate
  84. GRB 210704A: DDOTI upper limit
  85. GRB 210704B: Fermi GBM detection
  86. GRB 210704A: possible local hosts
  87. GRB 210704A: Fermi GBM detection
  88. GRB 210704A: Swift-XRT afterglow detection
  89. GRB 210704A: AstroSat CZTI detection
  90. IceCube-210516A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  91. IceCube-210510A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  92. GRB 210704A: Fermi-LAT detection
  93. GRB 210704A: Swift ToO observations
  94. GRB 210705A: AGILE/MCAL detection of a burst
  95. GRB 210704A: AGILE/MCAL detection
  96. Fermi trigger No 647108723: Global MASTER-Net observations report
  97. Fermi trigger No 647120009: Global MASTER-Net observations report
  98. GRB 210704A: BALROG localization (Fermi Trigger 647120009 / GRB 210704815)
  99. GRB 210702A, Swift-BAT refined analysis
  100. GRB 210702A: BOOTES-3/YA optical counterpart observations

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