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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. IceCube-230511A: IceCube observation of a high-energy neutrino candidate
  2. GRB 230510B: AstroSat CZTI detection
  3. GRB 230511C: Fermi GBM Final Localization
  4. Fermi trigger No 705503315: Global MASTER-Net observations report
  5. GRB 230511B: Fermi GBM Final Real-time Localization
  6. Fermi trigger No 705496510: Global MASTER-Net observations report
  7. GRB 230511A: Fermi GBM Final Real-time Localization
  8. GRB 230510A: Fermi GBM detection
  9. Fermi trigger No 705446499: Global MASTER-Net observations report
  10. GRB 230510A: Gaoyazi/GOT optical upper limit
  11. GRB 230510B: CALET Gamma-Ray Burst Monitor detection
  12. GRB 230510A: CALET Gamma-Ray Burst Monitor detection
  13. GRB 230510A: Nanshan/NEXT optical afterglow detection
  14. GRB 230510B: MAXI/GSC detection
  15. GRB 230510B: Fermi GBM Final Real-time Localization
  16. GRB 230506B: Fermi GBM detection
  17. GRB 230510A: Swift-XRT refined Analysis
  18. GRB 230510A: Enhanced Swift-XRT position
  19. GRB 230506C: Fermi GBM detection
  20. Fermi trigger No 705413051: Global MASTER-Net observations report
  21. Fermi Gamma-ray Burst Monitor trigger 230510133/705381054 is not a GRB
  22. GRB 230510A: Swift detection of a burst
  23. GRB 230510A: Fermi GBM Final Real-time Localization
  24. GRB 230506B: Swift/UVOT further analysis
  25. GRB 230506C: T193-OHP MISTRAL tentative redshift
  26. GRB 230506C: SAO RAS optical observations
  27. GRB 230307A: JWST second-epoch observations
  28. IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
  29. Fermi-LAT gamma-ray observations of IceCube-230506A
  30. GRB 230506C: Swift-XRT refined Analysis
  31. GRB 230506C: Swift-BAT refined analysis
  32. GRB 230506B: Swift-BAT refined analysis
  33. GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
  34. GRB 230506B: LCOGT Optical Upper Limits
  35. GRB 230506C: Swift/UVOT Upper Limits
  36. GRB 230506C: NUTTelA-TAO / BSTI Early Optical Limits
  37. GRB 230506B: Swift-XRT refined Analysis
  38. GRB 230506C: Swift-XRT analysis
  39. GRB 230506C: Candidate afterglow observation by D50
  40. GRB 230506C: TSHAO possible afterglow candidate
  41. GRB 230506B: Swift/UVOT Detection
  42. IceCube-230506A: IceCube observation of a high-energy neutrino candidate
  43. GRB 230506C: Swift detection of a burst
  44. Swift GRB230506.71: Global MASTER-Net observations report
  45. GRB 230506B: Swift detection of a burst
  46. GRB 230506B: MASTER optical observations
  47. GRB 230506B: Swift detection of a burst
  48. GRB 230506A: Fermi GBM Final Real-time Localization
  49. GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
  50. Fermi trigger No 704837952: Global MASTER-Net observations report
  51. GRB 230430A: A short GRB from a neutron star merger
  52. GRB 230427A: Swift-BAT refined analysis
  53. GRB 230503A: Fermi GBM Final Real-time Localization
  54. Konus-Wind detection of GRB 230430A
  55. IceCube-Cascade 230430A: Upper limits from a search for additional neutrino events in IceCube
  56. IPN triangulation of GRB 230430A (short)
  57. GRB 230420A: AROMA-N Optical Upper Limit
  58. GRB 230430B: Fermi GBM Final Localization
  59. GRB 230430A: Fermi GBM observation
  60. GRB 230430A: AstroSat CZTI detection
  61. GRB 230430A: Fermi GBM Final Real-time Localization
  62. GRB 230427A: NOT optical upper limit
  63. GRB 230427A: TSHAO, SAO RAS, AbAO optical upper limit
  64. GRB 230427A: Swift/UVOT Detection
  65. Duplicate of GCN 33369
  66. GRB 230427A: Gaoyazi/GOT optical upper limit
  67. GRB 230427A: OHP/T193 spectroscopy observations of WISEA J101316.01+481158.7
  68. GRB 230427A: Nanshan/HMT optical upper limit
  69. GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
  70. GRB 230427A: OSIRIS+/GTC observations
  71. GRB 230427A: Swift-XRT refined Analysis
  72. GRB 230426A: VZLUSAT-2 detection
  73. Fermi trigger No 704365743: Global MASTER-Net observations report
  74. GRB 230428A: Fermi GBM Final Real-time Localization
  75. GRB 230427A: GIT optical upper limit
  76. GRB 230427A: Bassano Bresciano Observatory upper limit
  77. GRB 230427A: GMG upper limit
  78. GRB 230427A : OHP/T193 optical upper limit
  79. GRB 230427A: BOOTES-5/JGT afterglow detection
  80. GRB 230423A(trigger #1165354): Swift-BAT refined analysis
  81. GRB 230427A: AKO Upper Limit
  82. Swift GRB230427.44: Global MASTER-Net observations report
  83. GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
  84. GRB 230427A: MITSuME Akeno optical upper limits
  85. GRB 230426A: Fermi GBM Detection
  86. GRB 230427A: Enhanced Swift-XRT position
  87. GRB 230427A: Swift detection of a burst with an optical counterpart
  88. GRB 230426A: AstroSat CZTI detection
  89. Fermi trigger No 704233744: Global MASTER-Net observations report
  90. GRB 230426A: Fermi GBM Final Real-time Localization
  91. GRB 230423A: Swift/UVOT Upper Limits
  92. GRB 230425A: Fermi GBM Final Real-time Localization
  93. GRB 230423A: Swift-XRT refined Analysis
  94. GRB 230420A: Lowell Discovery Telescope Optical Detection
  95. GRB 230423A: Swift-XRT afterglow detection
  96. Erroneous submission
  97. Swift Trigger 1165354 is probably not a GRB
  98. GRB 221009A: Late-time JWST Observations and Detection of Supernova Emission
  99. GRB 230421A: Fermi GBM observation
  100. Konus-Wind detection of GRB 230418A

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