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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 210704A: NOT optical observations and color change
  2. GRB210704A: Gemini near-infrared upper limits
  3. Fermi trigger No 647653174: Global MASTER-Net observations report
  4. GRB 210704A: Assy optical afterglow upper limit
  5. Fermi trigger No 647641569: Global MASTER-Net observations report
  6. Fermi trigger No 647624281: Global MASTER-Net observations report
  7. GECAM detection of a short burst from SGR J1935+2154
  8. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
  9. MAXI GRB210709.93: Global MASTER-Net observations report
  10. Fermi trigger No 647522278: Global MASTER-Net observations report
  11. GRB 210704A: Gemini-North Infrared Source Detection
  12. GRB 210704A: further TNG optical observations
  13. GRB 210706A: Swift/XRT afterglow confirmation
  14. GECAM detection of a short burst from SGR 1935+2154
  15. GRB 210708B: Swift-BAT refined analysis
  16. Fermi GRB 210709A: Global MASTER-Net observations report
  17. GRB 210709A: Fermi GBM Final Real-time Localization
  18. Swift GRB 210708B: Global MASTER-Net observations report
  19. GRB 210708A: Swift/UVOT Upper Limits
  20. GRB 210702A: ATCA detection
  21. GRB 210702A: ALMA detection
  22. GRB 210708A: Swift-BAT refined analysis
  23. Fermi GBM Sub-Threshold Detection of GRB 210708A
  24. Fermi GBM Sub-Threshold Detection of GRB 210707A
  25. IceCube-210629A - Spectroscopic observation of AT2021osi
  26. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 7
  27. GRB 210708B: Swift detection of a possible burst
  28. GRB 210708A: Swift-XRT refined Analysis
  29. GECAM detection of a short burst from SGR 1935+2154
  30. GRB 210707A: A long GRB detected by INTEGRAL
  31. GRB 210708A: Swift detection of a burst
  32. Swift GRB210708.10: Global MASTER-Net observations report
  33. GRB 210704A: CAHA 2.2m telescope optical limit
  34. Fermi trigger No 647365516: Global MASTER-Net observations report
  35. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 6
  36. Fermi trigger No 647271699: Global MASTER-Net observations report
  37. Fermi GBM Observations of SGR J1935+2154
  38. Swift-BAT detection of a burst from SGR 1935+2154
  39. GRB 210706A: Fermi GBM observation
  40. GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
  41. Konus-Wind detection of GRB 210706A
  42. GRB 210706A: GIT optical upper limits
  43. GRB 210704A: OAJ T80 multi-color detections
  44. GECAM detection of a bright short burst from SGR 1935+2154
  45. GRB 210706A: Swift-XRT afterglow detection
  46. Integral GRB210707.02: Global MASTER-Net observations report
  47. GRB 210706A: Swift ToO observations
  48. Fermi trigger No 647252274: Global MASTER-Net observations report
  49. INTEGRAL detection of a burst from SGR 1935+2154
  50. Integral GRB210706.72: Global MASTER-Net observations report
  51. GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
  52. GRB 210704A: OSIRIS/GTC spectroscopy
  53. GRB 210704A: CAHA 2.2m Afterglow Detection
  54. GRB 210704A: RATIR optical upper limits
  55. GRB 210704A: Swift/UVOT Upper Limits
  56. Konus-Wind detection of GRB 210704A
  57. GRB 210704B: AstroSat CZTI detection
  58. GRB 210619B: ALMA detection
  59. GRB 210704A: TNG detection of the optical afterglow candidate
  60. GRB 210704A: Assy optical afterglow candidate
  61. GRB 210704A: DDOTI upper limit
  62. GRB 210704B: Fermi GBM detection
  63. GRB 210704A: possible local hosts
  64. GRB 210704A: Fermi GBM detection
  65. GRB 210704A: Swift-XRT afterglow detection
  66. GRB 210704A: AstroSat CZTI detection
  67. IceCube-210516A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  68. IceCube-210510A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  69. GRB 210704A: Fermi-LAT detection
  70. GRB 210704A: Swift ToO observations
  71. GRB 210705A: AGILE/MCAL detection of a burst
  72. GRB 210704A: AGILE/MCAL detection
  73. Fermi trigger No 647108723: Global MASTER-Net observations report
  74. Fermi trigger No 647120009: Global MASTER-Net observations report
  75. GRB 210704A: BALROG localization (Fermi Trigger 647120009 / GRB 210704815)
  76. GRB 210702A, Swift-BAT refined analysis
  77. GRB 210702A: BOOTES-3/YA optical counterpart observations
  78. Konus-Wind detection of GRB 210702A
  79. GRB 210702A: Chilescope optical observations
  80. GRB 210702A: iTelescope optical afterglow observations
  81. GRB 210702A: AGILE detection
  82. GRB 210702A: CALET Gamma-Ray Burst Monitor detection
  83. GRB 210619B: JCMT SCUBA-2 sub-mm observations
  84. GRB 210610B: JCMT SCUBA-2 sub-mm observations
  85. GRB 210610A: JCMT SCUBA-2 sub-mm observations
  86. GRB 210702A: Swift-XRT refined Analysis
  87. GRB 210702A: VLT/X-shooter redshift
  88. GRB 210702A: preliminary Swift/UVOT photometry
  89. GRB 210702A: Swift/UVOT redshift
  90. GRB210702A: MeerLICHT multi-colour photometry
  91. Swift GRB 210702A: Global MASTER-Net observations report
  92. Swift GRB210702.80: Global MASTER-Net OT detection
  93. GRB 210702A: Swift detection of a burst with a bright optical counterpart
  94. IceCube-210629A: Upper limits from a search for additional neutrino events in IceCube
  95. IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
  96. IceCube-210629A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  97. Fermi-LAT Gamma-ray Observations of IceCube-210629A
  98. IceCube-210629A: Upper limits from Fermi-GBM Observations
  99. GRB 210627B: GECAM detection
  100. IceCube Alert 210629.76: Global MASTER-Net observations report

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