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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 230512A: Zwicky Transient Facility non-detection of GRB afterglow candidate
  2. GRB 230512A: Liverpool Telescope observations
  3. GRB 230512A: GIT non detection of afterglow candidate
  4. GRB 230512A: Kitab possible afterglow candidate
  5. GRB 230512A: GRBAlpha detection
  6. GRB 230510A: GRBAlpha detection
  7. GRB 230513A: Fermi GBM Final Real-time Localization
  8. Fermi trigger No 705565670: Global MASTER-Net observations report
  9. Fermi-LAT gamma-ray observations of IceCube-230511A
  10. GRB 230510A: OHP/T193 and OHP/T120 optical observations
  11. GRB 230512A: Swift-XRT observations
  12. IceCube-230511A: Upper limits from a search for additional neutrino events in IceCube
  13. IceCube-Cascade 230511A: Upper limits from a search for additional neutrino events in IceCube
  14. GRB 230512A: GIT optical follow-up ZTF candidates
  15. GRB 230512A: Fermi GBM detection
  16. GRB 230512A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705565670)
  17. GRB 230430A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 704533643)
  18. GRB 230511D: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705537623)
  19. GRB 230512A: Tiled Swift observations
  20. GRB 230512A: Fermi-LAT detection
  21. GRB 230512A: AstroSat CZTI detection
  22. GRB 230512A: Fermi GBM Final Localization
  23. GRB 230510A: GIT optical upper limits
  24. GRB 230510A: LCOGT Optical Upper Limit
  25. GRB 230511D: Fermi GBM Final Real-time Localization
  26. GRB 230510A: Swift/UVOT Observations
  27. IceCube-230511A: IceCube observation of a high-energy neutrino candidate
  28. GRB 230510B: AstroSat CZTI detection
  29. GRB 230511C: Fermi GBM Final Localization
  30. Fermi trigger No 705503315: Global MASTER-Net observations report
  31. GRB 230511B: Fermi GBM Final Real-time Localization
  32. Fermi trigger No 705496510: Global MASTER-Net observations report
  33. GRB 230511A: Fermi GBM Final Real-time Localization
  34. GRB 230510A: Fermi GBM detection
  35. Fermi trigger No 705446499: Global MASTER-Net observations report
  36. GRB 230510A: Gaoyazi/GOT optical upper limit
  37. GRB 230510B: CALET Gamma-Ray Burst Monitor detection
  38. GRB 230510A: CALET Gamma-Ray Burst Monitor detection
  39. GRB 230510A: Nanshan/NEXT optical afterglow detection
  40. GRB 230510B: MAXI/GSC detection
  41. GRB 230510B: Fermi GBM Final Real-time Localization
  42. GRB 230506B: Fermi GBM detection
  43. GRB 230510A: Swift-XRT refined Analysis
  44. GRB 230510A: Enhanced Swift-XRT position
  45. GRB 230506C: Fermi GBM detection
  46. Fermi trigger No 705413051: Global MASTER-Net observations report
  47. Fermi Gamma-ray Burst Monitor trigger 230510133/705381054 is not a GRB
  48. GRB 230510A: Swift detection of a burst
  49. GRB 230510A: Fermi GBM Final Real-time Localization
  50. GRB 230506B: Swift/UVOT further analysis
  51. GRB 230506C: T193-OHP MISTRAL tentative redshift
  52. GRB 230506C: SAO RAS optical observations
  53. GRB 230307A: JWST second-epoch observations
  54. IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
  55. Fermi-LAT gamma-ray observations of IceCube-230506A
  56. GRB 230506C: Swift-XRT refined Analysis
  57. GRB 230506C: Swift-BAT refined analysis
  58. GRB 230506B: Swift-BAT refined analysis
  59. GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
  60. GRB 230506B: LCOGT Optical Upper Limits
  61. GRB 230506C: Swift/UVOT Upper Limits
  62. GRB 230506C: NUTTelA-TAO / BSTI Early Optical Limits
  63. GRB 230506B: Swift-XRT refined Analysis
  64. GRB 230506C: Swift-XRT analysis
  65. GRB 230506C: Candidate afterglow observation by D50
  66. GRB 230506C: TSHAO possible afterglow candidate
  67. GRB 230506B: Swift/UVOT Detection
  68. IceCube-230506A: IceCube observation of a high-energy neutrino candidate
  69. GRB 230506C: Swift detection of a burst
  70. Swift GRB230506.71: Global MASTER-Net observations report
  71. GRB 230506B: Swift detection of a burst
  72. GRB 230506B: MASTER optical observations
  73. GRB 230506B: Swift detection of a burst
  74. GRB 230506A: Fermi GBM Final Real-time Localization
  75. GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
  76. Fermi trigger No 704837952: Global MASTER-Net observations report
  77. GRB 230430A: A short GRB from a neutron star merger
  78. GRB 230427A: Swift-BAT refined analysis
  79. GRB 230503A: Fermi GBM Final Real-time Localization
  80. Konus-Wind detection of GRB 230430A
  81. IceCube-Cascade 230430A: Upper limits from a search for additional neutrino events in IceCube
  82. IPN triangulation of GRB 230430A (short)
  83. GRB 230420A: AROMA-N Optical Upper Limit
  84. GRB 230430B: Fermi GBM Final Localization
  85. GRB 230430A: Fermi GBM observation
  86. GRB 230430A: AstroSat CZTI detection
  87. GRB 230430A: Fermi GBM Final Real-time Localization
  88. GRB 230427A: NOT optical upper limit
  89. GRB 230427A: TSHAO, SAO RAS, AbAO optical upper limit
  90. GRB 230427A: Swift/UVOT Detection
  91. Duplicate of GCN 33369
  92. GRB 230427A: Gaoyazi/GOT optical upper limit
  93. GRB 230427A: OHP/T193 spectroscopy observations of WISEA J101316.01+481158.7
  94. GRB 230427A: Nanshan/HMT optical upper limit
  95. GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
  96. GRB 230427A: OSIRIS+/GTC observations
  97. GRB 230427A: Swift-XRT refined Analysis
  98. GRB 230426A: VZLUSAT-2 detection
  99. Fermi trigger No 704365743: Global MASTER-Net observations report
  100. GRB 230428A: Fermi GBM Final Real-time Localization

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