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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 210723A: Swift-XRT refined Analysis
  2. GRB 210722A: D50 optical detection
  3. Swift GRB 210723A: Global MASTER-Net observations report
  4. GRB 210722A: Fermi GBM observation
  5. GRB 210722A: Swift-BAT refined analysis
  6. GRB 210722A: Kitab optical observations, light curve
  7. GRB 210722A: Redshift from OSIRIS/GTC
  8. GRB 210723A: Prompt enhanced Swift-XRT position
  9. GRB 210723A: Swift detection of a burst
  10. GRB 210722A: RATIR Optical Observations
  11. GRB 210722A: Swift-XRT refined Analysis
  12. GRB 210722A: Swift/UVOT Detection
  13. GRB 210722A: GIT optical detection and preliminary analysis
  14. Swift GRB 210722A: Global MASTER-Net observations report
  15. GRB 210702A: ALMA detection of mm-band rebrightening
  16. GRB 210722A: Assy optical detection
  17. GRB 210702A: ATCA detection of radio rebrightening
  18. GRB 210722A: Nanshan/NEXT optical afterglow observations
  19. GRB 210722A: Swift detection of a burst with a bright optical counterpart
  20. Fermi trigger No 648602917: Global MASTER-Net observations report
  21. Fermi-LAT Gamma-ray Observations of IceCube-210717A
  22. GRB 210719A: GECAM detection
  23. IceCube-210717A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  24. Fermi trigger No 648359752: Global MASTER-Net observations report
  25. Fermi trigger No 648278666: Global MASTER-Net observations report
  26. IceCube-210717A: IceCube observation of a high-energy neutrino candidate track-like event
  27. Konus-Wind detection of GRB 210714A
  28. Fermi trigger No 647942198: MASTER optical afterglow detection
  29. GRB 210704A: Zeiss-1000/SAO-RAS optical observations
  30. GRB 210715B: DDOTI Upper Limits on the Afterglow
  31. Fermi trigger No 648033323: Global MASTER-Net observations report
  32. Fermi trigger No 648024201: Global MASTER-Net observations report
  33. Fermi trigger No 647942198: Global MASTER-Net observations report
  34. GRB 210712A: Swift-BAT refined analysis
  35. GECAM detection of a short burst from SGR J1935+2154
  36. Recent activity of SGR 1935+2154 as observed by CGBM
  37. GRB 210712A: Swift-XRT refined Analysis
  38. GRB 210712A: Swift/UVOT Upper Limits
  39. GRB 210712A: BOOTES-3/YA optical upper limit
  40. Fermi trigger No 647805873: Global MASTER-Net observations report
  41. GRB 210712A: Enhanced Swift-XRT position
  42. GRB 210704A: classification as long GRB and redshift estimating
  43. GRB 210704A: Lowell Discovery Telescope Optical Observations
  44. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 10
  45. GECAM detection of a short burst from SGR J1935+2154
  46. Fermi trigger No 647775795: Global MASTER-Net observations report
  47. GRB 210712A: Swift detection of a burst
  48. GRB 210709A: AstroSat CZTI detection
  49. GRB 210704A: Continued Gemini-North NIR K-band Detections
  50. GRB 210704A: INTEGRAL observations
  51. GRB 210704A: NOT optical observations and color change
  52. GRB210704A: Gemini near-infrared upper limits
  53. Fermi trigger No 647653174: Global MASTER-Net observations report
  54. GRB 210704A: Assy optical afterglow upper limit
  55. Fermi trigger No 647641569: Global MASTER-Net observations report
  56. Fermi trigger No 647624281: Global MASTER-Net observations report
  57. GECAM detection of a short burst from SGR J1935+2154
  58. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
  59. MAXI GRB210709.93: Global MASTER-Net observations report
  60. Fermi trigger No 647522278: Global MASTER-Net observations report
  61. GRB 210704A: Gemini-North Infrared Source Detection
  62. GRB 210704A: further TNG optical observations
  63. GRB 210706A: Swift/XRT afterglow confirmation
  64. GECAM detection of a short burst from SGR 1935+2154
  65. GRB 210708B: Swift-BAT refined analysis
  66. Fermi GRB 210709A: Global MASTER-Net observations report
  67. GRB 210709A: Fermi GBM Final Real-time Localization
  68. Swift GRB 210708B: Global MASTER-Net observations report
  69. GRB 210708A: Swift/UVOT Upper Limits
  70. GRB 210702A: ATCA detection
  71. GRB 210702A: ALMA detection
  72. GRB 210708A: Swift-BAT refined analysis
  73. Fermi GBM Sub-Threshold Detection of GRB 210708A
  74. Fermi GBM Sub-Threshold Detection of GRB 210707A
  75. IceCube-210629A - Spectroscopic observation of AT2021osi
  76. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 7
  77. GRB 210708B: Swift detection of a possible burst
  78. GRB 210708A: Swift-XRT refined Analysis
  79. GECAM detection of a short burst from SGR 1935+2154
  80. GRB 210707A: A long GRB detected by INTEGRAL
  81. GRB 210708A: Swift detection of a burst
  82. Swift GRB210708.10: Global MASTER-Net observations report
  83. GRB 210704A: CAHA 2.2m telescope optical limit
  84. Fermi trigger No 647365516: Global MASTER-Net observations report
  85. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 6
  86. Fermi trigger No 647271699: Global MASTER-Net observations report
  87. Fermi GBM Observations of SGR J1935+2154
  88. Swift-BAT detection of a burst from SGR 1935+2154
  89. GRB 210706A: Fermi GBM observation
  90. GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
  91. Konus-Wind detection of GRB 210706A
  92. GRB 210706A: GIT optical upper limits
  93. GRB 210704A: OAJ T80 multi-color detections
  94. GECAM detection of a bright short burst from SGR 1935+2154
  95. GRB 210706A: Swift-XRT afterglow detection
  96. Integral GRB210707.02: Global MASTER-Net observations report
  97. GRB 210706A: Swift ToO observations
  98. Fermi trigger No 647252274: Global MASTER-Net observations report
  99. INTEGRAL detection of a burst from SGR 1935+2154
  100. Integral GRB210706.72: Global MASTER-Net observations report

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