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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. Fermi-LAT gamma-ray observations of IceCube-230416A
  2. GRB 230414B: Nickel and KAIT telescope optical observations
  3. Duplicate of GCN 33640
  4. Duplicate of GCN 33640
  5. GRB 230414B Swift-BAT refined analysis
  6. Duplicate of GCN 33642
  7. GRB 230415A: Fermi GBM detection
  8. GRB 230414B: Swift/UVOT Detection
  9. GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
  10. IceCube-230416A: Upper limits from a search for additional neutrino events in IceCube
  11. GRB 230415A: Swift/BAT-GUANO detection
  12. New GCN Circulars Portal for Rapid Communications on Astronomical Transients is Online
  13. VIRT optical transient detection
  14. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  15. GRB 230307A: iTelescope optical upper limit (likely)
  16. GRB 230414B: Montarrenti Observatory late time optical afterglow detection
  17. IceCube-230416A: IceCube observation of a high-energy neutrino candidate
  18. Fermi trigger No 703284533: Global MASTER-Net observations report
  19. GRB 230414B: Lulin 40cm-SLT optical limit
  20. GRB 230414B: Bassano Bresciano Observatory optical observations
  21. GRB 230414B: Redshift from OSIRIS/GTC
  22. GRB 230414B: AbAO optical observations
  23. GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
  24. GRB 230414B: Swift-XRT refined Analysis
  25. GRB 230414B: Dabancheng/GHOST optical observations
  26. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230414A
  27. GRB 230414B: slow optical light curve decay
  28. GRB 230414B: SAO RAS optical observations
  29. GRB 230414B: Enhanced Swift-XRT position
  30. GRB 230414B: 1.3m DFOT Optical observations
  31. Fermi GRB 230414A: Global MASTER-Net observations report
  32. GRB 230414B: GROWTH India Telescope afterglow confirmation
  33. GRB 230414B (correction GRB name in the GCN 33615): Mondy optical afterglow candidate
  34. GRB 230414B: Nanshan/HMT optical afterglow detection
  35. GRB 230414A: Mondy optical afterglow candidate
  36. Swift GRB 230414B: Global MASTER-Net observations report
  37. GRB 230414B: Prompt enhanced Swift-XRT position
  38. GRB 230414B: Swift detection of a burst
  39. IceCube-230405A: BOOTES-4/MET Optical Upper Limits
  40. GRB 230414A: Fermi GBM Final Real-time Localization
  41. GRB 230328B: redshift lower limit estimating
  42. GRB 230409B: Mondy optical upper limit
  43. GRB 230409B: OHP/T193 optical upper limit
  44. GRB 230410B: VZLUSAT-2 detection
  45. GRB 230409D: VZLUSAT-2 detection
  46. GRB 230410B: AGILE detection of a burst
  47. GRB 230410A: Fermi GBM Final Real-time Localization
  48. Fermi GRB 230409C: Global MASTER-Net observations report
  49. Fermi GRB 230409A: Global MASTER-Net observations report
  50. GRB 230409C: Fermi GBM Final Real-time Localization
  51. GRB 230409B: Swift-XRT refined Analysis
  52. GRB 230409B: Swift-BAT refined analysis
  53. Fermi trigger No 702745263: Global MASTER-Net observations report
  54. Swift GRB 230409B: Global MASTER-Net observations report
  55. GRB 230409B: Swift/UVOT Detection
  56. GRB 230409B: Enhanced Swift-XRT position
  57. MAXI GRB230408.82: Global MASTER-Net observations report
  58. GRB 230409B: Swift detection of a burst
  59. GRB 230409A: Fermi GBM Final Real-time Localization
  60. GRB 230405B: VZLUSAT-2 detection
  61. IceCube-230405A: Upper limits from a search for additional neutrino events in IceCube
  62. Fermi-LAT gamma-ray observations of IceCube-230405A
  63. Konus-Wind detection of GRB 230405B
  64. GRB 230405B: AGILE detection
  65. GRB 230405B: Swift-XRT refined Analysis
  66. GRB 230405B: Fermi GBM Observation
  67. GRB 230405B: MeerLICHT upper limits
  68. IceCube Alert 230405.56: Global MASTER-Net observations report
  69. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  70. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  71. GRB 230307A: good match with kilonova models
  72. GRB 230307A: short mininum variability timescale compatible with a merger origin
  73. GRB 230405B: Swift/UVOT Upper Limits
  74. GRB 230405B: AstroSat CZTI detection
  75. GRB 230405B: Enhanced Swift-XRT position
  76. Swift GRB 230405B: Global MASTER-Net observations report
  77. GRB 230405B: Prompt enhanced Swift-XRT position
  78. GRB 230405B: Swift detection of a burst
  79. GRB 230405B: Fermi GBM Final Real-time Localization
  80. GRB 230307A: JWST observations consistent with the presence of a kilonova
  81. Fermi GRB 230405A: Global MASTER-Net observations report
  82. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  83. GRB 230405A: Fermi GBM Final Real-time Localization
  84. GRB 230404A: AstroSat CZTI detection
  85. GRB 230404A: Fermi GBM Final Real-time Localization
  86. GRB 230402A: CALET Gamma-Ray Burst Monitor detection
  87. GRB 230402A: AstroSat CZTI detection
  88. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  89. IceCube-230401A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB 230328B: Multa observatory optical afterglow observation
  91. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  92. GRB 230228A: detection by GTC of the potential host galaxy
  93. GRB 230328B: Swift/UVOT Detection
  94. GRB 230402A: AGILE detection
  95. Fermi GRB 230402A: Global MASTER-Net observations report
  96. GRB 230402A: Fermi GBM Final Real-time Localization
  97. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  98. GRB 230307A: Bad Time Intervals for Fermi GBM data
  99. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  100. GRB 230328B: CAHA 2.2m/CAFOS detection

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