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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').
  1. GRB 210702A: Chilescope optical observations
  2. GRB 210702A: iTelescope optical afterglow observations
  3. GRB 210702A: AGILE detection
  4. GRB 210702A: CALET Gamma-Ray Burst Monitor detection
  5. GRB 210619B: JCMT SCUBA-2 sub-mm observations
  6. GRB 210610B: JCMT SCUBA-2 sub-mm observations
  7. GRB 210610A: JCMT SCUBA-2 sub-mm observations
  8. GRB 210702A: Swift-XRT refined Analysis
  9. GRB 210702A: VLT/X-shooter redshift
  10. GRB 210702A: preliminary Swift/UVOT photometry
  11. GRB 210702A: Swift/UVOT redshift
  12. GRB210702A: MeerLICHT multi-colour photometry
  13. Swift GRB 210702A: Global MASTER-Net observations report
  14. Swift GRB210702.80: Global MASTER-Net OT detection
  15. GRB 210702A: Swift detection of a burst with a bright optical counterpart
  16. IceCube-210629A: Upper limits from a search for additional neutrino events in IceCube
  17. IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
  18. IceCube-210629A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  19. Fermi-LAT Gamma-ray Observations of IceCube-210629A
  20. IceCube-210629A: Upper limits from Fermi-GBM Observations
  21. GRB 210627B: GECAM detection
  22. IceCube Alert 210629.76: Global MASTER-Net observations report
  23. GRB 210619B: Sayan observatory 1.6-m telescope observations
  24. IceCube-210629A - IceCube observation of a high-energy neutrino candidate track-like event
  25. GRB 210626A: Swift/XRT afterglow confirmation
  26. GRB 210626A: Fermi GBM observation
  27. GRB 210626A: CAHA 2.2m telescope optical limit
  28. GRB 210619B: Deep CAHA 2.2m detection and late-time light curve behavior
  29. GRB 210626A: Ondrejov D50 optical limit
  30. GRB 210626A: GIT optical upper limit
  31. Fermi trigger No 646443989: Global MASTER-Net observations report
  32. Fermi GRB 210627B: Global MASTER-Net observations report
  33. GRB 210627B: BALROG localization (Fermi Trigger 646509445/ GRB 210627748)
  34. GRB 210627B: Fermi GBM Final Real-time Localization
  35. Fermi GRB 210627A: Global MASTER-Net observations report
  36. GRB 210627A: Fermi GBM Final Real-time Localization
  37. GRB 210626A: Swift-XRT afterglow detection
  38. Fermi trigger No 646322348: Global MASTER-Net observations report
  39. Fermi GRB 210626A: Global MASTER-Net observations report
  40. GRB 210626A: Swift ToO observations
  41. GRB 210626A: Swift/BAT-GUANO detection and arcminute localization
  42. GRB 150428A: late-time radio observations
  43. GRB 210626A: Fermi GBM Final Real-time Localization
  44. GRB 210618A: 1.5m OSN optical upper limit
  45. Fermi GRB 210625A: Global MASTER-Net observations report
  46. GRB210619B: optical afterglow detection from Konkoly Observatory
  47. GRB 210625A: Fermi GBM Final Real-time Localization
  48. IPN triangulation of GRB 210624A (short)
  49. GRB 210622A: Swift-XRT observations
  50. GRB 210610B: T-CAT optical observations
  51. GRB 210619B: ASIM observation
  52. Fermi trigger No 646189108: Global MASTER-Net observations report
  53. Fermi GBM observation of a bright burst in the direction of SGR 1935+2154
  54. GRB 210618A: Swift-XRT afterglow detection
  55. Fermi trigger No 646194855: Global MASTER-Net observations report
  56. GRB 210622A: Swift ToO observations
  57. GRB 210619B: Even further SAO RAS optical observations
  58. GRB 210619B: Mini-MegaTORTORA early optical observations
  59. Fermi GRB 210622B: Global MASTER-Net observations report
  60. GRB 210622A: Fermi GBM detection
  61. GRB 210619B: Abbey Ridge Observatory optical afterglow observation
  62. GRB 210619B: SPI-ACS/INTEGRAL observations
  63. GRB 210619B: Further SAO RAS optical observations
  64. GRB 210622A: Swift/BAT-GUANO detection and arcminute localization of a long burst
  65. GRB 210619B: possibility of lensed visible afterglow?
  66. GECAM detection of GRB 210622B
  67. GRB 210619B: AbAO optical observations
  68. GRB 210622B: Fermi GBM Final Real-time Localization
  69. GRB 210622A: Fermi GBM Final Real-time Localization
  70. Swift Trigger 1057131: detection of a burst from SGR Swift J1555.2-5402
  71. Swift GRB210621.71: Global MASTER-Net observations report
  72. GRB 210619B: NOT optical observations
  73. GRB 210619B: 1.5m OSN optical observation
  74. GRB 210619B: iTelescope optical afterglow observation
  75. GRB 210619B: SAO RAS optical observations
  76. GRB 210619B: SEDM Optical Observations
  77. GRB 210619B: TNG NIR observations of the afterglow
  78. GRB 210619B: REM optical/NIR afterglow detection
  79. Fermi GRB 210621A: Global MASTER-Net observations report
  80. GRB 210619B: GIT optical follow-up and confirmation of jet-break
  81. GRB 210621A: Fermi GBM Final Real-time Localization
  82. GRB 210619B: CALET Gamma-Ray Burst Monitor detection
  83. GRB 210619B: SRG/ART-XC detection
  84. GRB 210619B: Swift-BAT refined analysis
  85. GRB 210619B: steepening of the decay observed at the D50
  86. GRB 210619B: Liverpool Telescope First Hour Observations
  87. GRB 210619B: Fermi GBM detection
  88. GRB 210619B: Swift/UVOT Detection
  89. GRB 210619B: Xinglong TNT optical observations
  90. Konus-Wind detection of GRB 210619B
  91. GRB 210619B: CAHA 2.2m photometric monitoring
  92. GRB 210619B: Liverpool Telescope r'-band observations
  93. GRB 210619B: KAIT Optical Detection
  94. GRB 210619B: Redshift from OSIRIS/GTC
  95. GRB 210619B: Liverpool telescope imaging of a red afterglow
  96. GRB 210619B: Fermi-LAT detection
  97. GRB 210619B: Swift-XRT refined Analysis
  98. GRB 210619B: SARA-KP 0.9m Optical Afterglow Detection
  99. GRB 210619B: Enhanced Swift-XRT position
  100. Fermi trigger No 645857659: Global MASTER-Net observations report

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