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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 230506C: Fermi GBM detection
  2. Fermi trigger No 705413051: Global MASTER-Net observations report
  3. Fermi Gamma-ray Burst Monitor trigger 230510133/705381054 is not a GRB
  4. GRB 230510A: Swift detection of a burst
  5. GRB 230510A: Fermi GBM Final Real-time Localization
  6. GRB 230506B: Swift/UVOT further analysis
  7. GRB 230506C: T193-OHP MISTRAL tentative redshift
  8. GRB 230506C: SAO RAS optical observations
  9. GRB 230307A: JWST second-epoch observations
  10. IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
  11. Fermi-LAT gamma-ray observations of IceCube-230506A
  12. GRB 230506C: Swift-XRT refined Analysis
  13. GRB 230506C: Swift-BAT refined analysis
  14. GRB 230506B: Swift-BAT refined analysis
  15. GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
  16. GRB 230506B: LCOGT Optical Upper Limits
  17. GRB 230506C: Swift/UVOT Upper Limits
  18. GRB 230506C: NUTTelA-TAO / BSTI Early Optical Limits
  19. GRB 230506B: Swift-XRT refined Analysis
  20. GRB 230506C: Swift-XRT analysis
  21. GRB 230506C: Candidate afterglow observation by D50
  22. GRB 230506C: TSHAO possible afterglow candidate
  23. GRB 230506B: Swift/UVOT Detection
  24. IceCube-230506A: IceCube observation of a high-energy neutrino candidate
  25. GRB 230506C: Swift detection of a burst
  26. Swift GRB230506.71: Global MASTER-Net observations report
  27. GRB 230506B: Swift detection of a burst
  28. GRB 230506B: MASTER optical observations
  29. GRB 230506B: Swift detection of a burst
  30. GRB 230506A: Fermi GBM Final Real-time Localization
  31. GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
  32. Fermi trigger No 704837952: Global MASTER-Net observations report
  33. GRB 230430A: A short GRB from a neutron star merger
  34. GRB 230427A: Swift-BAT refined analysis
  35. GRB 230503A: Fermi GBM Final Real-time Localization
  36. Konus-Wind detection of GRB 230430A
  37. IceCube-Cascade 230430A: Upper limits from a search for additional neutrino events in IceCube
  38. IPN triangulation of GRB 230430A (short)
  39. GRB 230420A: AROMA-N Optical Upper Limit
  40. GRB 230430B: Fermi GBM Final Localization
  41. GRB 230430A: Fermi GBM observation
  42. GRB 230430A: AstroSat CZTI detection
  43. GRB 230430A: Fermi GBM Final Real-time Localization
  44. GRB 230427A: NOT optical upper limit
  45. GRB 230427A: TSHAO, SAO RAS, AbAO optical upper limit
  46. GRB 230427A: Swift/UVOT Detection
  47. Duplicate of GCN 33369
  48. GRB 230427A: Gaoyazi/GOT optical upper limit
  49. GRB 230427A: OHP/T193 spectroscopy observations of WISEA J101316.01+481158.7
  50. GRB 230427A: Nanshan/HMT optical upper limit
  51. GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
  52. GRB 230427A: OSIRIS+/GTC observations
  53. GRB 230427A: Swift-XRT refined Analysis
  54. GRB 230426A: VZLUSAT-2 detection
  55. Fermi trigger No 704365743: Global MASTER-Net observations report
  56. GRB 230428A: Fermi GBM Final Real-time Localization
  57. GRB 230427A: GIT optical upper limit
  58. GRB 230427A: Bassano Bresciano Observatory upper limit
  59. GRB 230427A: GMG upper limit
  60. GRB 230427A : OHP/T193 optical upper limit
  61. GRB 230427A: BOOTES-5/JGT afterglow detection
  62. GRB 230423A(trigger #1165354): Swift-BAT refined analysis
  63. GRB 230427A: AKO Upper Limit
  64. Swift GRB230427.44: Global MASTER-Net observations report
  65. GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
  66. GRB 230427A: MITSuME Akeno optical upper limits
  67. GRB 230426A: Fermi GBM Detection
  68. GRB 230427A: Enhanced Swift-XRT position
  69. GRB 230427A: Swift detection of a burst with an optical counterpart
  70. GRB 230426A: AstroSat CZTI detection
  71. Fermi trigger No 704233744: Global MASTER-Net observations report
  72. GRB 230426A: Fermi GBM Final Real-time Localization
  73. GRB 230423A: Swift/UVOT Upper Limits
  74. GRB 230425A: Fermi GBM Final Real-time Localization
  75. GRB 230423A: Swift-XRT refined Analysis
  76. GRB 230420A: Lowell Discovery Telescope Optical Detection
  77. GRB 230423A: Swift-XRT afterglow detection
  78. Erroneous submission
  79. Swift Trigger 1165354 is probably not a GRB
  80. GRB 221009A: Late-time JWST Observations and Detection of Supernova Emission
  81. GRB 230421A: Fermi GBM observation
  82. Konus-Wind detection of GRB 230418A
  83. GRB 230420A: Swift/UVOT Upper Limits
  84. GRB 230421: Swift/BAT-GUANO arcminute localization
  85. GRB230420A: VLT optical observation
  86. GRB 230420A: Swift-BAT refined analysis
  87. Duplicate of GCN 33668
  88. GRB 230421A: Fermi GBM Final Real-time Localization
  89. GRB 230420A: Swift-XRT refined Analysis
  90. GRB 230420A: MITSuME Akeno optical observation
  91. GRB 230420A: NOT optical afterglow confirmation
  92. GRB 230420A: Gaoyazi/GOT optical upper limit
  93. GRB 230420A: BOOTES-5/JGT optical afterglow detection
  94. GRB 230420A: LCOGT Optical Upper Limit
  95. GRB 230420A: Enhanced Swift-XRT position
  96. GRB230414B: VIRT Optical Upper Limit
  97. IPN triangulation of GRB 230418A (short)
  98. GRB 230420A: Swift detection of a burst
  99. GRB 230418A: AstroSat CZTI detection
  100. GRB 230418A: AGILE detection

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