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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. Duplicate of GCN 33640
  2. GRB 230414B Swift-BAT refined analysis
  3. Duplicate of GCN 33642
  4. GRB 230415A: Fermi GBM detection
  5. GRB 230414B: Swift/UVOT Detection
  6. GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
  7. IceCube-230416A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 230415A: Swift/BAT-GUANO detection
  9. New GCN Circulars Portal for Rapid Communications on Astronomical Transients is Online
  10. VIRT optical transient detection
  11. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  12. GRB 230307A: iTelescope optical upper limit (likely)
  13. GRB 230414B: Montarrenti Observatory late time optical afterglow detection
  14. IceCube-230416A: IceCube observation of a high-energy neutrino candidate
  15. Fermi trigger No 703284533: Global MASTER-Net observations report
  16. GRB 230414B: Lulin 40cm-SLT optical limit
  17. GRB 230414B: Bassano Bresciano Observatory optical observations
  18. GRB 230414B: Redshift from OSIRIS/GTC
  19. GRB 230414B: AbAO optical observations
  20. GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
  21. GRB 230414B: Swift-XRT refined Analysis
  22. GRB 230414B: Dabancheng/GHOST optical observations
  23. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230414A
  24. GRB 230414B: slow optical light curve decay
  25. GRB 230414B: SAO RAS optical observations
  26. GRB 230414B: Enhanced Swift-XRT position
  27. GRB 230414B: 1.3m DFOT Optical observations
  28. Fermi GRB 230414A: Global MASTER-Net observations report
  29. GRB 230414B: GROWTH India Telescope afterglow confirmation
  30. GRB 230414B (correction GRB name in the GCN 33615): Mondy optical afterglow candidate
  31. GRB 230414B: Nanshan/HMT optical afterglow detection
  32. GRB 230414A: Mondy optical afterglow candidate
  33. Swift GRB 230414B: Global MASTER-Net observations report
  34. GRB 230414B: Prompt enhanced Swift-XRT position
  35. GRB 230414B: Swift detection of a burst
  36. IceCube-230405A: BOOTES-4/MET Optical Upper Limits
  37. GRB 230414A: Fermi GBM Final Real-time Localization
  38. GRB 230328B: redshift lower limit estimating
  39. GRB 230409B: Mondy optical upper limit
  40. GRB 230409B: OHP/T193 optical upper limit
  41. GRB 230410B: VZLUSAT-2 detection
  42. GRB 230409D: VZLUSAT-2 detection
  43. GRB 230410B: AGILE detection of a burst
  44. GRB 230410A: Fermi GBM Final Real-time Localization
  45. Fermi GRB 230409C: Global MASTER-Net observations report
  46. Fermi GRB 230409A: Global MASTER-Net observations report
  47. GRB 230409C: Fermi GBM Final Real-time Localization
  48. GRB 230409B: Swift-XRT refined Analysis
  49. GRB 230409B: Swift-BAT refined analysis
  50. Fermi trigger No 702745263: Global MASTER-Net observations report
  51. Swift GRB 230409B: Global MASTER-Net observations report
  52. GRB 230409B: Swift/UVOT Detection
  53. GRB 230409B: Enhanced Swift-XRT position
  54. MAXI GRB230408.82: Global MASTER-Net observations report
  55. GRB 230409B: Swift detection of a burst
  56. GRB 230409A: Fermi GBM Final Real-time Localization
  57. GRB 230405B: VZLUSAT-2 detection
  58. IceCube-230405A: Upper limits from a search for additional neutrino events in IceCube
  59. Fermi-LAT gamma-ray observations of IceCube-230405A
  60. Konus-Wind detection of GRB 230405B
  61. GRB 230405B: AGILE detection
  62. GRB 230405B: Swift-XRT refined Analysis
  63. GRB 230405B: Fermi GBM Observation
  64. GRB 230405B: MeerLICHT upper limits
  65. IceCube Alert 230405.56: Global MASTER-Net observations report
  66. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  67. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  68. GRB 230307A: good match with kilonova models
  69. GRB 230307A: short mininum variability timescale compatible with a merger origin
  70. GRB 230405B: Swift/UVOT Upper Limits
  71. GRB 230405B: AstroSat CZTI detection
  72. GRB 230405B: Enhanced Swift-XRT position
  73. Swift GRB 230405B: Global MASTER-Net observations report
  74. GRB 230405B: Prompt enhanced Swift-XRT position
  75. GRB 230405B: Swift detection of a burst
  76. GRB 230405B: Fermi GBM Final Real-time Localization
  77. GRB 230307A: JWST observations consistent with the presence of a kilonova
  78. Fermi GRB 230405A: Global MASTER-Net observations report
  79. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  80. GRB 230405A: Fermi GBM Final Real-time Localization
  81. GRB 230404A: AstroSat CZTI detection
  82. GRB 230404A: Fermi GBM Final Real-time Localization
  83. GRB 230402A: CALET Gamma-Ray Burst Monitor detection
  84. GRB 230402A: AstroSat CZTI detection
  85. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  86. IceCube-230401A: Upper limits from a search for additional neutrino events in IceCube
  87. GRB 230328B: Multa observatory optical afterglow observation
  88. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  89. GRB 230228A: detection by GTC of the potential host galaxy
  90. GRB 230328B: Swift/UVOT Detection
  91. GRB 230402A: AGILE detection
  92. Fermi GRB 230402A: Global MASTER-Net observations report
  93. GRB 230402A: Fermi GBM Final Real-time Localization
  94. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  95. GRB 230307A: Bad Time Intervals for Fermi GBM data
  96. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  97. GRB 230328B: CAHA 2.2m/CAFOS detection
  98. IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 230328B: 3.6m DOT multiband optical observation
  100. Fermi trigger No 701883729: Global MASTER-Net observations report

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