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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 210719A: GECAM detection
  2. IceCube-210717A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  3. Fermi trigger No 648359752: Global MASTER-Net observations report
  4. Fermi trigger No 648278666: Global MASTER-Net observations report
  5. IceCube-210717A: IceCube observation of a high-energy neutrino candidate track-like event
  6. Konus-Wind detection of GRB 210714A
  7. Fermi trigger No 647942198: MASTER optical afterglow detection
  8. GRB 210704A: Zeiss-1000/SAO-RAS optical observations
  9. GRB 210715B: DDOTI Upper Limits on the Afterglow
  10. Fermi trigger No 648033323: Global MASTER-Net observations report
  11. Fermi trigger No 648024201: Global MASTER-Net observations report
  12. Fermi trigger No 647942198: Global MASTER-Net observations report
  13. GRB 210712A: Swift-BAT refined analysis
  14. GECAM detection of a short burst from SGR J1935+2154
  15. Recent activity of SGR 1935+2154 as observed by CGBM
  16. GRB 210712A: Swift-XRT refined Analysis
  17. GRB 210712A: Swift/UVOT Upper Limits
  18. GRB 210712A: BOOTES-3/YA optical upper limit
  19. Fermi trigger No 647805873: Global MASTER-Net observations report
  20. GRB 210712A: Enhanced Swift-XRT position
  21. GRB 210704A: classification as long GRB and redshift estimating
  22. GRB 210704A: Lowell Discovery Telescope Optical Observations
  23. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 10
  24. GECAM detection of a short burst from SGR J1935+2154
  25. Fermi trigger No 647775795: Global MASTER-Net observations report
  26. GRB 210712A: Swift detection of a burst
  27. GRB 210709A: AstroSat CZTI detection
  28. GRB 210704A: Continued Gemini-North NIR K-band Detections
  29. GRB 210704A: INTEGRAL observations
  30. GRB 210704A: NOT optical observations and color change
  31. GRB210704A: Gemini near-infrared upper limits
  32. Fermi trigger No 647653174: Global MASTER-Net observations report
  33. GRB 210704A: Assy optical afterglow upper limit
  34. Fermi trigger No 647641569: Global MASTER-Net observations report
  35. Fermi trigger No 647624281: Global MASTER-Net observations report
  36. GECAM detection of a short burst from SGR J1935+2154
  37. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
  38. MAXI GRB210709.93: Global MASTER-Net observations report
  39. Fermi trigger No 647522278: Global MASTER-Net observations report
  40. GRB 210704A: Gemini-North Infrared Source Detection
  41. GRB 210704A: further TNG optical observations
  42. GRB 210706A: Swift/XRT afterglow confirmation
  43. GECAM detection of a short burst from SGR 1935+2154
  44. GRB 210708B: Swift-BAT refined analysis
  45. Fermi GRB 210709A: Global MASTER-Net observations report
  46. GRB 210709A: Fermi GBM Final Real-time Localization
  47. Swift GRB 210708B: Global MASTER-Net observations report
  48. GRB 210708A: Swift/UVOT Upper Limits
  49. GRB 210702A: ATCA detection
  50. GRB 210702A: ALMA detection
  51. GRB 210708A: Swift-BAT refined analysis
  52. Fermi GBM Sub-Threshold Detection of GRB 210708A
  53. Fermi GBM Sub-Threshold Detection of GRB 210707A
  54. IceCube-210629A - Spectroscopic observation of AT2021osi
  55. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 7
  56. GRB 210708B: Swift detection of a possible burst
  57. GRB 210708A: Swift-XRT refined Analysis
  58. GECAM detection of a short burst from SGR 1935+2154
  59. GRB 210707A: A long GRB detected by INTEGRAL
  60. GRB 210708A: Swift detection of a burst
  61. Swift GRB210708.10: Global MASTER-Net observations report
  62. GRB 210704A: CAHA 2.2m telescope optical limit
  63. Fermi trigger No 647365516: Global MASTER-Net observations report
  64. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 6
  65. Fermi trigger No 647271699: Global MASTER-Net observations report
  66. Fermi GBM Observations of SGR J1935+2154
  67. Swift-BAT detection of a burst from SGR 1935+2154
  68. GRB 210706A: Fermi GBM observation
  69. GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
  70. Konus-Wind detection of GRB 210706A
  71. GRB 210706A: GIT optical upper limits
  72. GRB 210704A: OAJ T80 multi-color detections
  73. GECAM detection of a bright short burst from SGR 1935+2154
  74. GRB 210706A: Swift-XRT afterglow detection
  75. Integral GRB210707.02: Global MASTER-Net observations report
  76. GRB 210706A: Swift ToO observations
  77. Fermi trigger No 647252274: Global MASTER-Net observations report
  78. INTEGRAL detection of a burst from SGR 1935+2154
  79. Integral GRB210706.72: Global MASTER-Net observations report
  80. GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
  81. GRB 210704A: OSIRIS/GTC spectroscopy
  82. GRB 210704A: CAHA 2.2m Afterglow Detection
  83. GRB 210704A: RATIR optical upper limits
  84. GRB 210704A: Swift/UVOT Upper Limits
  85. Konus-Wind detection of GRB 210704A
  86. GRB 210704B: AstroSat CZTI detection
  87. GRB 210619B: ALMA detection
  88. GRB 210704A: TNG detection of the optical afterglow candidate
  89. GRB 210704A: Assy optical afterglow candidate
  90. GRB 210704A: DDOTI upper limit
  91. GRB 210704B: Fermi GBM detection
  92. GRB 210704A: possible local hosts
  93. GRB 210704A: Fermi GBM detection
  94. GRB 210704A: Swift-XRT afterglow detection
  95. GRB 210704A: AstroSat CZTI detection
  96. IceCube-210516A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  97. IceCube-210510A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  98. GRB 210704A: Fermi-LAT detection
  99. GRB 210704A: Swift ToO observations
  100. GRB 210705A: AGILE/MCAL detection of a burst

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