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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. GECAM detection of a short burst from SGR J1935+2154
  2. Recent activity of SGR 1935+2154 as observed by CGBM
  3. GRB 210712A: Swift-XRT refined Analysis
  4. GRB 210712A: Swift/UVOT Upper Limits
  5. GRB 210712A: BOOTES-3/YA optical upper limit
  6. Fermi trigger No 647805873: Global MASTER-Net observations report
  7. GRB 210712A: Enhanced Swift-XRT position
  8. GRB 210704A: classification as long GRB and redshift estimating
  9. GRB 210704A: Lowell Discovery Telescope Optical Observations
  10. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 10
  11. GECAM detection of a short burst from SGR J1935+2154
  12. Fermi trigger No 647775795: Global MASTER-Net observations report
  13. GRB 210712A: Swift detection of a burst
  14. GRB 210709A: AstroSat CZTI detection
  15. GRB 210704A: Continued Gemini-North NIR K-band Detections
  16. GRB 210704A: INTEGRAL observations
  17. GRB 210704A: NOT optical observations and color change
  18. GRB210704A: Gemini near-infrared upper limits
  19. Fermi trigger No 647653174: Global MASTER-Net observations report
  20. GRB 210704A: Assy optical afterglow upper limit
  21. Fermi trigger No 647641569: Global MASTER-Net observations report
  22. Fermi trigger No 647624281: Global MASTER-Net observations report
  23. GECAM detection of a short burst from SGR J1935+2154
  24. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
  25. MAXI GRB210709.93: Global MASTER-Net observations report
  26. Fermi trigger No 647522278: Global MASTER-Net observations report
  27. GRB 210704A: Gemini-North Infrared Source Detection
  28. GRB 210704A: further TNG optical observations
  29. GRB 210706A: Swift/XRT afterglow confirmation
  30. GECAM detection of a short burst from SGR 1935+2154
  31. GRB 210708B: Swift-BAT refined analysis
  32. Fermi GRB 210709A: Global MASTER-Net observations report
  33. GRB 210709A: Fermi GBM Final Real-time Localization
  34. Swift GRB 210708B: Global MASTER-Net observations report
  35. GRB 210708A: Swift/UVOT Upper Limits
  36. GRB 210702A: ATCA detection
  37. GRB 210702A: ALMA detection
  38. GRB 210708A: Swift-BAT refined analysis
  39. Fermi GBM Sub-Threshold Detection of GRB 210708A
  40. Fermi GBM Sub-Threshold Detection of GRB 210707A
  41. IceCube-210629A - Spectroscopic observation of AT2021osi
  42. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 7
  43. GRB 210708B: Swift detection of a possible burst
  44. GRB 210708A: Swift-XRT refined Analysis
  45. GECAM detection of a short burst from SGR 1935+2154
  46. GRB 210707A: A long GRB detected by INTEGRAL
  47. GRB 210708A: Swift detection of a burst
  48. Swift GRB210708.10: Global MASTER-Net observations report
  49. GRB 210704A: CAHA 2.2m telescope optical limit
  50. Fermi trigger No 647365516: Global MASTER-Net observations report
  51. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 6
  52. Fermi trigger No 647271699: Global MASTER-Net observations report
  53. Fermi GBM Observations of SGR J1935+2154
  54. Swift-BAT detection of a burst from SGR 1935+2154
  55. GRB 210706A: Fermi GBM observation
  56. GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
  57. Konus-Wind detection of GRB 210706A
  58. GRB 210706A: GIT optical upper limits
  59. GRB 210704A: OAJ T80 multi-color detections
  60. GECAM detection of a bright short burst from SGR 1935+2154
  61. GRB 210706A: Swift-XRT afterglow detection
  62. Integral GRB210707.02: Global MASTER-Net observations report
  63. GRB 210706A: Swift ToO observations
  64. Fermi trigger No 647252274: Global MASTER-Net observations report
  65. INTEGRAL detection of a burst from SGR 1935+2154
  66. Integral GRB210706.72: Global MASTER-Net observations report
  67. GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
  68. GRB 210704A: OSIRIS/GTC spectroscopy
  69. GRB 210704A: CAHA 2.2m Afterglow Detection
  70. GRB 210704A: RATIR optical upper limits
  71. GRB 210704A: Swift/UVOT Upper Limits
  72. Konus-Wind detection of GRB 210704A
  73. GRB 210704B: AstroSat CZTI detection
  74. GRB 210619B: ALMA detection
  75. GRB 210704A: TNG detection of the optical afterglow candidate
  76. GRB 210704A: Assy optical afterglow candidate
  77. GRB 210704A: DDOTI upper limit
  78. GRB 210704B: Fermi GBM detection
  79. GRB 210704A: possible local hosts
  80. GRB 210704A: Fermi GBM detection
  81. GRB 210704A: Swift-XRT afterglow detection
  82. GRB 210704A: AstroSat CZTI detection
  83. IceCube-210516A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  84. IceCube-210510A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  85. GRB 210704A: Fermi-LAT detection
  86. GRB 210704A: Swift ToO observations
  87. GRB 210705A: AGILE/MCAL detection of a burst
  88. GRB 210704A: AGILE/MCAL detection
  89. Fermi trigger No 647108723: Global MASTER-Net observations report
  90. Fermi trigger No 647120009: Global MASTER-Net observations report
  91. GRB 210704A: BALROG localization (Fermi Trigger 647120009 / GRB 210704815)
  92. GRB 210702A, Swift-BAT refined analysis
  93. GRB 210702A: BOOTES-3/YA optical counterpart observations
  94. Konus-Wind detection of GRB 210702A
  95. GRB 210702A: Chilescope optical observations
  96. GRB 210702A: iTelescope optical afterglow observations
  97. GRB 210702A: AGILE detection
  98. GRB 210702A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 210619B: JCMT SCUBA-2 sub-mm observations
  100. GRB 210610B: JCMT SCUBA-2 sub-mm observations

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