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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 210722A: Fermi GBM observation
  2. GRB 210722A: Swift-BAT refined analysis
  3. GRB 210722A: Kitab optical observations, light curve
  4. GRB 210722A: Redshift from OSIRIS/GTC
  5. GRB 210723A: Prompt enhanced Swift-XRT position
  6. GRB 210723A: Swift detection of a burst
  7. GRB 210722A: RATIR Optical Observations
  8. GRB 210722A: Swift-XRT refined Analysis
  9. GRB 210722A: Swift/UVOT Detection
  10. GRB 210722A: GIT optical detection and preliminary analysis
  11. Swift GRB 210722A: Global MASTER-Net observations report
  12. GRB 210702A: ALMA detection of mm-band rebrightening
  13. GRB 210722A: Assy optical detection
  14. GRB 210702A: ATCA detection of radio rebrightening
  15. GRB 210722A: Nanshan/NEXT optical afterglow observations
  16. GRB 210722A: Swift detection of a burst with a bright optical counterpart
  17. Fermi trigger No 648602917: Global MASTER-Net observations report
  18. Fermi-LAT Gamma-ray Observations of IceCube-210717A
  19. GRB 210719A: GECAM detection
  20. IceCube-210717A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  21. Fermi trigger No 648359752: Global MASTER-Net observations report
  22. Fermi trigger No 648278666: Global MASTER-Net observations report
  23. IceCube-210717A: IceCube observation of a high-energy neutrino candidate track-like event
  24. Konus-Wind detection of GRB 210714A
  25. Fermi trigger No 647942198: MASTER optical afterglow detection
  26. GRB 210704A: Zeiss-1000/SAO-RAS optical observations
  27. GRB 210715B: DDOTI Upper Limits on the Afterglow
  28. Fermi trigger No 648033323: Global MASTER-Net observations report
  29. Fermi trigger No 648024201: Global MASTER-Net observations report
  30. Fermi trigger No 647942198: Global MASTER-Net observations report
  31. GRB 210712A: Swift-BAT refined analysis
  32. GECAM detection of a short burst from SGR J1935+2154
  33. Recent activity of SGR 1935+2154 as observed by CGBM
  34. GRB 210712A: Swift-XRT refined Analysis
  35. GRB 210712A: Swift/UVOT Upper Limits
  36. GRB 210712A: BOOTES-3/YA optical upper limit
  37. Fermi trigger No 647805873: Global MASTER-Net observations report
  38. GRB 210712A: Enhanced Swift-XRT position
  39. GRB 210704A: classification as long GRB and redshift estimating
  40. GRB 210704A: Lowell Discovery Telescope Optical Observations
  41. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 10
  42. GECAM detection of a short burst from SGR J1935+2154
  43. Fermi trigger No 647775795: Global MASTER-Net observations report
  44. GRB 210712A: Swift detection of a burst
  45. GRB 210709A: AstroSat CZTI detection
  46. GRB 210704A: Continued Gemini-North NIR K-band Detections
  47. GRB 210704A: INTEGRAL observations
  48. GRB 210704A: NOT optical observations and color change
  49. GRB210704A: Gemini near-infrared upper limits
  50. Fermi trigger No 647653174: Global MASTER-Net observations report
  51. GRB 210704A: Assy optical afterglow upper limit
  52. Fermi trigger No 647641569: Global MASTER-Net observations report
  53. Fermi trigger No 647624281: Global MASTER-Net observations report
  54. GECAM detection of a short burst from SGR J1935+2154
  55. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
  56. MAXI GRB210709.93: Global MASTER-Net observations report
  57. Fermi trigger No 647522278: Global MASTER-Net observations report
  58. GRB 210704A: Gemini-North Infrared Source Detection
  59. GRB 210704A: further TNG optical observations
  60. GRB 210706A: Swift/XRT afterglow confirmation
  61. GECAM detection of a short burst from SGR 1935+2154
  62. GRB 210708B: Swift-BAT refined analysis
  63. Fermi GRB 210709A: Global MASTER-Net observations report
  64. GRB 210709A: Fermi GBM Final Real-time Localization
  65. Swift GRB 210708B: Global MASTER-Net observations report
  66. GRB 210708A: Swift/UVOT Upper Limits
  67. GRB 210702A: ATCA detection
  68. GRB 210702A: ALMA detection
  69. GRB 210708A: Swift-BAT refined analysis
  70. Fermi GBM Sub-Threshold Detection of GRB 210708A
  71. Fermi GBM Sub-Threshold Detection of GRB 210707A
  72. IceCube-210629A - Spectroscopic observation of AT2021osi
  73. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 7
  74. GRB 210708B: Swift detection of a possible burst
  75. GRB 210708A: Swift-XRT refined Analysis
  76. GECAM detection of a short burst from SGR 1935+2154
  77. GRB 210707A: A long GRB detected by INTEGRAL
  78. GRB 210708A: Swift detection of a burst
  79. Swift GRB210708.10: Global MASTER-Net observations report
  80. GRB 210704A: CAHA 2.2m telescope optical limit
  81. Fermi trigger No 647365516: Global MASTER-Net observations report
  82. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 6
  83. Fermi trigger No 647271699: Global MASTER-Net observations report
  84. Fermi GBM Observations of SGR J1935+2154
  85. Swift-BAT detection of a burst from SGR 1935+2154
  86. GRB 210706A: Fermi GBM observation
  87. GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
  88. Konus-Wind detection of GRB 210706A
  89. GRB 210706A: GIT optical upper limits
  90. GRB 210704A: OAJ T80 multi-color detections
  91. GECAM detection of a bright short burst from SGR 1935+2154
  92. GRB 210706A: Swift-XRT afterglow detection
  93. Integral GRB210707.02: Global MASTER-Net observations report
  94. GRB 210706A: Swift ToO observations
  95. Fermi trigger No 647252274: Global MASTER-Net observations report
  96. INTEGRAL detection of a burst from SGR 1935+2154
  97. Integral GRB210706.72: Global MASTER-Net observations report
  98. GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
  99. GRB 210704A: OSIRIS/GTC spectroscopy
  100. GRB 210704A: CAHA 2.2m Afterglow Detection

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