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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-231004A - IceCube observation of a high-energy neutrino candidate track-like event
  2. transient AT2023sva: radio observations with AMI-LA
  3. GRB 231004A: Fermi GBM Final Real-time Localization
  4. GRB 231003A is not a GRB
  5. GRB 231003A: Fermi GBM Final Real-time Localization
  6. LIGO/Virgo/KAGRA S231001aq: Upper limits from Swift/BAT-GUANO
  7. LIGO/Virgo/KAGRA S230930al: Upper limits from Swift/BAT-GUANO
  8. LIGO/Virgo/KAGRA S230928cb: Upper limits from Swift/BAT-GUANO
  9. GRB 230827B: 10.4m GTC spectroscopic redshift
  10. LIGO/Virgo/KAGRA S231001aq: Updated Sky localization
  11. LIGO/Virgo/KAGRA S230930al: Updated Sky localization
  12. LIGO/Virgo/KAGRA S230928cb: Updated Sky localization
  13. LIGO/Virgo/KAGRA S231001aq: Identification of a GW compact binary merger candidate
  14. GRB 230930A: Fermi GBM Final Real-time Localization
  15. LIGO/Virgo/KAGRA S230930al: Identification of a GW compact binary merger candidate
  16. NuEm-230927A: Swift-XRT follow-up
  17. LIGO/Virgo/KAGRA S230928cb: Identification of a GW compact binary merger candidate
  18. AT2023sva / GRB230916B: GIT observations of the afterglow
  19. transient AT2023sva: A Binary Driven Hypernova with a possible associated supernova
  20. LIGO/Virgo/KAGRA S230927be: Updated Sky localization
  21. LIGO/Virgo/KAGRA S230927l: Updated Sky localization
  22. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230927A
  23. LIGO/Virgo/KAGRA S230927be: Identification of a GW compact binary merger candidate
  24. Swift Triggers 1192745 and 1192747 are not astrophysical events
  25. LIGO/Virgo/KAGRA S230927l: Identification of a GW compact binary merger candidate
  26. Swift Triggers 1192740, 1192742 and 1192743 are not astrophysical events
  27. Swift Triggers 1192735 and 1192737 are not astrophysical events
  28. LIGO/Virgo/KAGRA S230922q: Updated Sky localization
  29. Konus-Wind detection of GRB 230919A
  30. LIGO/Virgo/KAGRA S230924an: Upper limits from Swift/BAT-GUANO
  31. LIGO/Virgo/KAGRA S230920al: Upper limits from Swift/BAT-GUANO
  32. LIGO/Virgo/KAGRA S230919bj: Upper limits from Swift/BAT-GUANO
  33. Fermi Gamma-ray Burst Monitor trigger 717299390/230925076 is not a GRB
  34. Fermi Gamma-ray Burst Monitor trigger 230925241/717313591 is not a GRB
  35. LIGO/Virgo/KAGRA S230922g: DECam GW-MMADS candidates
  36. GRB 230812B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
  37. LIGO/Virgo/KAGRA S230924an: Updated Sky localization
  38. LIGO/Virgo/KAGRA S230924an: Identification of a GW compact binary merger candidate
  39. LIGO/Virgo/KAGRA S230917af: GRAWITA wide-field observations
  40. LIGO/Virgo/KAGRA S230922g: Updated Sky localization
  41. LIGO/Virgo/KAGRA S230922g: Identification of a GW compact binary merger candidate
  42. LIGO/Virgo/KAGRA S230922q: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S230917af: Zwicky Transient Facility observations
  44. GRB 230921A: Fermi GBM Final Real-time Localization
  45. GRB 230918B: VLT/X-shooter classification of AT 2023tbf (GOTO23aky) as a dwarf nova
  46. IPN triangulation of GRB 230919A (short)
  47. LIGO/Virgo/KAGRA S230904n: Classification of the candidate AT2023rkw with DBSP
  48. GRB 230919A: Fermi GBM Observation
  49. Correction to Fermi GBM Statement for Trigger 716527670/230916144
  50. Fermi GBM Statement for Trigger 716527670/230916144
  51. GRB 230919A: Swift/BAT-GUANO detection of a possibly short burst outside the coded FOV
  52. LIGO/Virgo/KAGRA S230920al: Updated Sky localization
  53. LIGO/Virgo/KAGRA S230919bj: Updated Sky localization
  54. transient AT2023sva: imaging and spectroscopic observations from MISTRAL at Observatoire de Haute-Provence
  55. GRB 230812B : optical observations from MISTRAL at Observatoire de Haute-Provence
  56. GRB 230919A: AstroSat CZTI detection
  57. LIGO/Virgo/KAGRA S230920al: Identification of a GW compact binary merger candidate
  58. AT2023sva: redshift from OSIRIS+/GTC of the ZTF afterglow
  59. LIGO/Virgo/KAGRA S230919bj: Identification of a GW compact binary merger candidate
  60. GRB 230918B: GOTO detection of a fast-rising transient in the GBM localisation region
  61. GRB 230919A: Fermi GBM Final Real-time Localization
  62. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  63. Detection of self-absorbed radio emission from GRB 230812B with the JVLA + uGMRT
  64. GRB 230918B: Fermi GBM Final Real-time Localization
  65. GRB 230918A (short): Glowbug gamma-ray detection
  66. GRB 230916B: Glowbug gamma-ray detection
  67. AT 2023sva: NOT observations of the ZTF candidate afterglow
  68. ZTF and SEDM Observations of the Candidate Optical Afterglow AT 2023sva
  69. GRB 230915A: Fermi GBM observation
  70. LIGO/Virgo/KAGRA S230918aq: Retraction of GW compact binary merger candidate
  71. GRB 230812B: Radio observations with the uGMRT
  72. GRB 230918A: Fermi GBM Final Real-time Localization
  73. GRB 230917A: AstroSat CZTI detection
  74. Swift Triggers 1192480, 1192481, 1192482 and 1192483 are not astrophysical events
  75. LIGO/Virgo/KAGRA S230917af: MAXI/GSC observations
  76. GRB 230915B: Glowbug gamma-ray detection
  77. GRB 230916A: NuSTAR Discovery of Prompt Emission from a Potential GRB
  78. GRB 230911A: Fermi GBM Observation
  79. Swift GRB230916.18: Global MASTER-Net observations report
  80. Fermi trigger No 716572242: Global MASTER-Net observations report
  81. LIGO/Virgo/KAGRA S230904n: Correction of the coordinates of the ZTF candidate counterpart
  82. Fermi trigger No 716544961: Global MASTER-Net observations report
  83. Fermi-LAT gamma-ray observations of IceCube-230914A
  84. GRB 230915A: Swift/BAT-GUANO detection of a burst
  85. LIGO/Virgo/KAGRA S230914ak: Upper limits from Swift/BAT-GUANO
  86. GRB 230911D: GRBAlpha detection
  87. Swift GRB230916.19: Global MASTER-Net observations report
  88. Swift GRB230916.18: Global MASTER-Net observations report
  89. Swift Triggers 1192234, 1192235 and 1192236 are not astrophysical events
  90. Swift GRB230916.13: Global MASTER-Net observations report
  91. Swift GRB230916.12: Global MASTER-Net observations report
  92. Swift GRB230916.11: Global MASTER-Net observations report
  93. Swift Trigger 1192233 is not a GRB
  94. GRB 230906A: optical counterpart
  95. IceCube-230914A: Upper limits from a search for additional neutrino events in IceCube
  96. GRB 230911A: Swift-XRT afterglow detection
  97. Fermi trigger No 716449174: Global MASTER-Net observations report
  98. GRB 230913A: CALET Gamma-Ray Burst Monitor detection
  99. IceCube Alert 230914.22: Global MASTER-Net observations report
  100. Swift Trigger 1192088 is not an astrophysical event

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