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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 foobar
  2. GRB foobar
  3. LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
  4. LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
  5. GRB foobar
  6. GRB foobar
  7. PKS2326-505, millimeter wavelength flare, transient
  8. GRB foo 3
  9. GRB foo 2
  10. GRB foo
  11. GRB foo
  12. GRB foo
  13. GRB foo
  14. GRB test
  15. GRB foo
  16. GRB foobar
  17. GRB foobar
  18. GRB foobar
  19. GRB foobar
  20. GRB foobar
  21. GRB test
  22. MAGIC test
  23. GRB test
  24. GRB foo
  25. Test GCN GW submission
  26. GRB test 2
  27. GRB test
  28. GRB test
  29. Test GW GCN hermes submission 2
  30. Test GW GCN hermes submission
  31. Test GW GCN hermes submission
  32. A GRB test
  33. TEST GW GCN hermes submission
  34. GRB 170817A: an awesome GCN Circular
  35. VIRT optical transient detection
  36. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  37. GRB 230307A: iTelescope optical upper limit (likely)
  38. GRB 230414B: Montarrenti Observatory late time optical afterglow detection
  39. IceCube-230416A: IceCube observation of a high-energy neutrino candidate
  40. Fermi trigger No 703284533: Global MASTER-Net observations report
  41. GRB 230414B: Lulin 40cm-SLT optical limit
  42. GRB 230414B: Bassano Bresciano Observatory optical observations
  43. GRB 230414B: Redshift from OSIRIS/GTC
  44. GRB 230414B: AbAO optical observations
  45. GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
  46. GRB 230414B: Swift-XRT refined Analysis
  47. GRB 230414B: Dabancheng/GHOST optical observations
  48. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230414A
  49. GRB 230414B: slow optical light curve decay
  50. GRB 230414B: SAO RAS optical observations
  51. GRB 230414B: Enhanced Swift-XRT position
  52. GRB 230414B: 1.3m DFOT Optical observations
  53. Fermi GRB 230414A: Global MASTER-Net observations report
  54. GRB 230414B: GROWTH India Telescope afterglow confirmation
  55. GRB 230414B (correction GRB name in the GCN 33615): Mondy optical afterglow candidate
  56. GRB 230414B: Nanshan/HMT optical afterglow detection
  57. GRB 230414A: Mondy optical afterglow candidate
  58. Swift GRB 230414B: Global MASTER-Net observations report
  59. GRB 230414B: Prompt enhanced Swift-XRT position
  60. GRB 230414B: Swift detection of a burst
  61. IceCube-230405A: BOOTES-4/MET Optical Upper Limits
  62. GRB 230414A: Fermi GBM Final Real-time Localization
  63. GRB 230328B: redshift lower limit estimating
  64. GRB 230409B: Mondy optical upper limit
  65. GRB 230409B: OHP/T193 optical upper limit
  66. GRB 230410B: VZLUSAT-2 detection
  67. GRB 230409D: VZLUSAT-2 detection
  68. GRB 230410B: AGILE detection of a burst
  69. GRB 230410A: Fermi GBM Final Real-time Localization
  70. Fermi GRB 230409C: Global MASTER-Net observations report
  71. Fermi GRB 230409A: Global MASTER-Net observations report
  72. GRB 230409C: Fermi GBM Final Real-time Localization
  73. GRB 230409B: Swift-XRT refined Analysis
  74. GRB 230409B: Swift-BAT refined analysis
  75. Fermi trigger No 702745263: Global MASTER-Net observations report
  76. Swift GRB 230409B: Global MASTER-Net observations report
  77. GRB 230409B: Swift/UVOT Detection
  78. GRB 230409B: Enhanced Swift-XRT position
  79. MAXI GRB230408.82: Global MASTER-Net observations report
  80. GRB 230409B: Swift detection of a burst
  81. GRB 230409A: Fermi GBM Final Real-time Localization
  82. GRB 230405B: VZLUSAT-2 detection
  83. IceCube-230405A: Upper limits from a search for additional neutrino events in IceCube
  84. Fermi-LAT gamma-ray observations of IceCube-230405A
  85. Konus-Wind detection of GRB 230405B
  86. GRB 230405B: AGILE detection
  87. GRB 230405B: Swift-XRT refined Analysis
  88. GRB 230405B: Fermi GBM Observation
  89. GRB 230405B: MeerLICHT upper limits
  90. IceCube Alert 230405.56: Global MASTER-Net observations report
  91. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  92. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  93. GRB 230307A: good match with kilonova models
  94. GRB 230307A: short mininum variability timescale compatible with a merger origin
  95. GRB 230405B: Swift/UVOT Upper Limits
  96. GRB 230405B: AstroSat CZTI detection
  97. GRB 230405B: Enhanced Swift-XRT position
  98. Swift GRB 230405B: Global MASTER-Net observations report
  99. GRB 230405B: Prompt enhanced Swift-XRT position
  100. GRB 230405B: Swift detection of a burst

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