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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. MAXI GRB210709.93: Global MASTER-Net observations report
  2. Fermi trigger No 647522278: Global MASTER-Net observations report
  3. GRB 210704A: Gemini-North Infrared Source Detection
  4. GRB 210704A: further TNG optical observations
  5. GRB 210706A: Swift/XRT afterglow confirmation
  6. GECAM detection of a short burst from SGR 1935+2154
  7. GRB 210708B: Swift-BAT refined analysis
  8. Fermi GRB 210709A: Global MASTER-Net observations report
  9. GRB 210709A: Fermi GBM Final Real-time Localization
  10. Swift GRB 210708B: Global MASTER-Net observations report
  11. GRB 210708A: Swift/UVOT Upper Limits
  12. GRB 210702A: ATCA detection
  13. GRB 210702A: ALMA detection
  14. GRB 210708A: Swift-BAT refined analysis
  15. Fermi GBM Sub-Threshold Detection of GRB 210708A
  16. Fermi GBM Sub-Threshold Detection of GRB 210707A
  17. IceCube-210629A - Spectroscopic observation of AT2021osi
  18. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 7
  19. GRB 210708B: Swift detection of a possible burst
  20. GRB 210708A: Swift-XRT refined Analysis
  21. GECAM detection of a short burst from SGR 1935+2154
  22. GRB 210707A: A long GRB detected by INTEGRAL
  23. GRB 210708A: Swift detection of a burst
  24. Swift GRB210708.10: Global MASTER-Net observations report
  25. GRB 210704A: CAHA 2.2m telescope optical limit
  26. Fermi trigger No 647365516: Global MASTER-Net observations report
  27. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 6
  28. Fermi trigger No 647271699: Global MASTER-Net observations report
  29. Fermi GBM Observations of SGR J1935+2154
  30. Swift-BAT detection of a burst from SGR 1935+2154
  31. GRB 210706A: Fermi GBM observation
  32. GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
  33. Konus-Wind detection of GRB 210706A
  34. GRB 210706A: GIT optical upper limits
  35. GRB 210704A: OAJ T80 multi-color detections
  36. GECAM detection of a bright short burst from SGR 1935+2154
  37. GRB 210706A: Swift-XRT afterglow detection
  38. Integral GRB210707.02: Global MASTER-Net observations report
  39. GRB 210706A: Swift ToO observations
  40. Fermi trigger No 647252274: Global MASTER-Net observations report
  41. INTEGRAL detection of a burst from SGR 1935+2154
  42. Integral GRB210706.72: Global MASTER-Net observations report
  43. GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
  44. GRB 210704A: OSIRIS/GTC spectroscopy
  45. GRB 210704A: CAHA 2.2m Afterglow Detection
  46. GRB 210704A: RATIR optical upper limits
  47. GRB 210704A: Swift/UVOT Upper Limits
  48. Konus-Wind detection of GRB 210704A
  49. GRB 210704B: AstroSat CZTI detection
  50. GRB 210619B: ALMA detection
  51. GRB 210704A: TNG detection of the optical afterglow candidate
  52. GRB 210704A: Assy optical afterglow candidate
  53. GRB 210704A: DDOTI upper limit
  54. GRB 210704B: Fermi GBM detection
  55. GRB 210704A: possible local hosts
  56. GRB 210704A: Fermi GBM detection
  57. GRB 210704A: Swift-XRT afterglow detection
  58. GRB 210704A: AstroSat CZTI detection
  59. IceCube-210516A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  60. IceCube-210510A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  61. GRB 210704A: Fermi-LAT detection
  62. GRB 210704A: Swift ToO observations
  63. GRB 210705A: AGILE/MCAL detection of a burst
  64. GRB 210704A: AGILE/MCAL detection
  65. Fermi trigger No 647108723: Global MASTER-Net observations report
  66. Fermi trigger No 647120009: Global MASTER-Net observations report
  67. GRB 210704A: BALROG localization (Fermi Trigger 647120009 / GRB 210704815)
  68. GRB 210702A, Swift-BAT refined analysis
  69. GRB 210702A: BOOTES-3/YA optical counterpart observations
  70. Konus-Wind detection of GRB 210702A
  71. GRB 210702A: Chilescope optical observations
  72. GRB 210702A: iTelescope optical afterglow observations
  73. GRB 210702A: AGILE detection
  74. GRB 210702A: CALET Gamma-Ray Burst Monitor detection
  75. GRB 210619B: JCMT SCUBA-2 sub-mm observations
  76. GRB 210610B: JCMT SCUBA-2 sub-mm observations
  77. GRB 210610A: JCMT SCUBA-2 sub-mm observations
  78. GRB 210702A: Swift-XRT refined Analysis
  79. GRB 210702A: VLT/X-shooter redshift
  80. GRB 210702A: preliminary Swift/UVOT photometry
  81. GRB 210702A: Swift/UVOT redshift
  82. GRB210702A: MeerLICHT multi-colour photometry
  83. Swift GRB 210702A: Global MASTER-Net observations report
  84. Swift GRB210702.80: Global MASTER-Net OT detection
  85. GRB 210702A: Swift detection of a burst with a bright optical counterpart
  86. IceCube-210629A: Upper limits from a search for additional neutrino events in IceCube
  87. IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
  88. IceCube-210629A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  89. Fermi-LAT Gamma-ray Observations of IceCube-210629A
  90. IceCube-210629A: Upper limits from Fermi-GBM Observations
  91. GRB 210627B: GECAM detection
  92. IceCube Alert 210629.76: Global MASTER-Net observations report
  93. GRB 210619B: Sayan observatory 1.6-m telescope observations
  94. IceCube-210629A - IceCube observation of a high-energy neutrino candidate track-like event
  95. GRB 210626A: Swift/XRT afterglow confirmation
  96. GRB 210626A: Fermi GBM observation
  97. GRB 210626A: CAHA 2.2m telescope optical limit
  98. GRB 210619B: Deep CAHA 2.2m detection and late-time light curve behavior
  99. GRB 210626A: Ondrejov D50 optical limit
  100. GRB 210626A: GIT optical upper limit

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