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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 230430A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 704533643)
  2. GRB 230511D: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705537623)
  3. GRB 230512A: Tiled Swift observations
  4. GRB 230512A: Fermi-LAT detection
  5. GRB 230512A: AstroSat CZTI detection
  6. GRB 230512A: Fermi GBM Final Localization
  7. GRB 230510A: GIT optical upper limits
  8. GRB 230510A: LCOGT Optical Upper Limit
  9. GRB 230511D: Fermi GBM Final Real-time Localization
  10. GRB 230510A: Swift/UVOT Observations
  11. IceCube-230511A: IceCube observation of a high-energy neutrino candidate
  12. GRB 230510B: AstroSat CZTI detection
  13. GRB 230511C: Fermi GBM Final Localization
  14. Fermi trigger No 705503315: Global MASTER-Net observations report
  15. GRB 230511B: Fermi GBM Final Real-time Localization
  16. Fermi trigger No 705496510: Global MASTER-Net observations report
  17. GRB 230511A: Fermi GBM Final Real-time Localization
  18. GRB 230510A: Fermi GBM detection
  19. Fermi trigger No 705446499: Global MASTER-Net observations report
  20. GRB 230510A: Gaoyazi/GOT optical upper limit
  21. GRB 230510B: CALET Gamma-Ray Burst Monitor detection
  22. GRB 230510A: CALET Gamma-Ray Burst Monitor detection
  23. GRB 230510A: Nanshan/NEXT optical afterglow detection
  24. GRB 230510B: MAXI/GSC detection
  25. GRB 230510B: Fermi GBM Final Real-time Localization
  26. GRB 230506B: Fermi GBM detection
  27. GRB 230510A: Swift-XRT refined Analysis
  28. GRB 230510A: Enhanced Swift-XRT position
  29. GRB 230506C: Fermi GBM detection
  30. Fermi trigger No 705413051: Global MASTER-Net observations report
  31. Fermi Gamma-ray Burst Monitor trigger 230510133/705381054 is not a GRB
  32. GRB 230510A: Swift detection of a burst
  33. GRB 230510A: Fermi GBM Final Real-time Localization
  34. GRB 230506B: Swift/UVOT further analysis
  35. GRB 230506C: T193-OHP MISTRAL tentative redshift
  36. GRB 230506C: SAO RAS optical observations
  37. GRB 230307A: JWST second-epoch observations
  38. IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
  39. Fermi-LAT gamma-ray observations of IceCube-230506A
  40. GRB 230506C: Swift-XRT refined Analysis
  41. GRB 230506C: Swift-BAT refined analysis
  42. GRB 230506B: Swift-BAT refined analysis
  43. GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
  44. GRB 230506B: LCOGT Optical Upper Limits
  45. GRB 230506C: Swift/UVOT Upper Limits
  46. GRB 230506C: NUTTelA-TAO / BSTI Early Optical Limits
  47. GRB 230506B: Swift-XRT refined Analysis
  48. GRB 230506C: Swift-XRT analysis
  49. GRB 230506C: Candidate afterglow observation by D50
  50. GRB 230506C: TSHAO possible afterglow candidate
  51. GRB 230506B: Swift/UVOT Detection
  52. IceCube-230506A: IceCube observation of a high-energy neutrino candidate
  53. GRB 230506C: Swift detection of a burst
  54. Swift GRB230506.71: Global MASTER-Net observations report
  55. GRB 230506B: Swift detection of a burst
  56. GRB 230506B: MASTER optical observations
  57. GRB 230506B: Swift detection of a burst
  58. GRB 230506A: Fermi GBM Final Real-time Localization
  59. GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
  60. Fermi trigger No 704837952: Global MASTER-Net observations report
  61. GRB 230430A: A short GRB from a neutron star merger
  62. GRB 230427A: Swift-BAT refined analysis
  63. GRB 230503A: Fermi GBM Final Real-time Localization
  64. Konus-Wind detection of GRB 230430A
  65. IceCube-Cascade 230430A: Upper limits from a search for additional neutrino events in IceCube
  66. IPN triangulation of GRB 230430A (short)
  67. GRB 230420A: AROMA-N Optical Upper Limit
  68. GRB 230430B: Fermi GBM Final Localization
  69. GRB 230430A: Fermi GBM observation
  70. GRB 230430A: AstroSat CZTI detection
  71. GRB 230430A: Fermi GBM Final Real-time Localization
  72. GRB 230427A: NOT optical upper limit
  73. GRB 230427A: TSHAO, SAO RAS, AbAO optical upper limit
  74. GRB 230427A: Swift/UVOT Detection
  75. Duplicate of GCN 33369
  76. GRB 230427A: Gaoyazi/GOT optical upper limit
  77. GRB 230427A: OHP/T193 spectroscopy observations of WISEA J101316.01+481158.7
  78. GRB 230427A: Nanshan/HMT optical upper limit
  79. GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
  80. GRB 230427A: OSIRIS+/GTC observations
  81. GRB 230427A: Swift-XRT refined Analysis
  82. GRB 230426A: VZLUSAT-2 detection
  83. Fermi trigger No 704365743: Global MASTER-Net observations report
  84. GRB 230428A: Fermi GBM Final Real-time Localization
  85. GRB 230427A: GIT optical upper limit
  86. GRB 230427A: Bassano Bresciano Observatory upper limit
  87. GRB 230427A: GMG upper limit
  88. GRB 230427A : OHP/T193 optical upper limit
  89. GRB 230427A: BOOTES-5/JGT afterglow detection
  90. GRB 230423A(trigger #1165354): Swift-BAT refined analysis
  91. GRB 230427A: AKO Upper Limit
  92. Swift GRB230427.44: Global MASTER-Net observations report
  93. GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
  94. GRB 230427A: MITSuME Akeno optical upper limits
  95. GRB 230426A: Fermi GBM Detection
  96. GRB 230427A: Enhanced Swift-XRT position
  97. GRB 230427A: Swift detection of a burst with an optical counterpart
  98. GRB 230426A: AstroSat CZTI detection
  99. Fermi trigger No 704233744: Global MASTER-Net observations report
  100. GRB 230426A: Fermi GBM Final Real-time Localization

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