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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. LIGO/Virgo/KAGRA S230927l: Updated Sky localization
  2. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230927A
  3. LIGO/Virgo/KAGRA S230927be: Identification of a GW compact binary merger candidate
  4. Swift Triggers 1192745 and 1192747 are not astrophysical events
  5. LIGO/Virgo/KAGRA S230927l: Identification of a GW compact binary merger candidate
  6. Swift Triggers 1192740, 1192742 and 1192743 are not astrophysical events
  7. Swift Triggers 1192735 and 1192737 are not astrophysical events
  8. LIGO/Virgo/KAGRA S230922q: Updated Sky localization
  9. Konus-Wind detection of GRB 230919A
  10. LIGO/Virgo/KAGRA S230924an: Upper limits from Swift/BAT-GUANO
  11. LIGO/Virgo/KAGRA S230920al: Upper limits from Swift/BAT-GUANO
  12. LIGO/Virgo/KAGRA S230919bj: Upper limits from Swift/BAT-GUANO
  13. Fermi Gamma-ray Burst Monitor trigger 717299390/230925076 is not a GRB
  14. Fermi Gamma-ray Burst Monitor trigger 230925241/717313591 is not a GRB
  15. LIGO/Virgo/KAGRA S230922g: DECam GW-MMADS candidates
  16. GRB 230812B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
  17. LIGO/Virgo/KAGRA S230924an: Updated Sky localization
  18. LIGO/Virgo/KAGRA S230924an: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo/KAGRA S230917af: GRAWITA wide-field observations
  20. LIGO/Virgo/KAGRA S230922g: Updated Sky localization
  21. LIGO/Virgo/KAGRA S230922g: Identification of a GW compact binary merger candidate
  22. LIGO/Virgo/KAGRA S230922q: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S230917af: Zwicky Transient Facility observations
  24. GRB 230921A: Fermi GBM Final Real-time Localization
  25. GRB 230918B: VLT/X-shooter classification of AT 2023tbf (GOTO23aky) as a dwarf nova
  26. IPN triangulation of GRB 230919A (short)
  27. LIGO/Virgo/KAGRA S230904n: Classification of the candidate AT2023rkw with DBSP
  28. GRB 230919A: Fermi GBM Observation
  29. Correction to Fermi GBM Statement for Trigger 716527670/230916144
  30. Fermi GBM Statement for Trigger 716527670/230916144
  31. GRB 230919A: Swift/BAT-GUANO detection of a possibly short burst outside the coded FOV
  32. LIGO/Virgo/KAGRA S230920al: Updated Sky localization
  33. LIGO/Virgo/KAGRA S230919bj: Updated Sky localization
  34. transient AT2023sva: imaging and spectroscopic observations from MISTRAL at Observatoire de Haute-Provence
  35. GRB 230812B : optical observations from MISTRAL at Observatoire de Haute-Provence
  36. GRB 230919A: AstroSat CZTI detection
  37. LIGO/Virgo/KAGRA S230920al: Identification of a GW compact binary merger candidate
  38. AT2023sva: redshift from OSIRIS+/GTC of the ZTF afterglow
  39. LIGO/Virgo/KAGRA S230919bj: Identification of a GW compact binary merger candidate
  40. GRB 230918B: GOTO detection of a fast-rising transient in the GBM localisation region
  41. GRB 230919A: Fermi GBM Final Real-time Localization
  42. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  43. Detection of self-absorbed radio emission from GRB 230812B with the JVLA + uGMRT
  44. GRB 230918B: Fermi GBM Final Real-time Localization
  45. GRB 230918A (short): Glowbug gamma-ray detection
  46. GRB 230916B: Glowbug gamma-ray detection
  47. AT 2023sva: NOT observations of the ZTF candidate afterglow
  48. ZTF and SEDM Observations of the Candidate Optical Afterglow AT 2023sva
  49. GRB 230915A: Fermi GBM observation
  50. LIGO/Virgo/KAGRA S230918aq: Retraction of GW compact binary merger candidate
  51. GRB 230812B: Radio observations with the uGMRT
  52. GRB 230918A: Fermi GBM Final Real-time Localization
  53. GRB 230917A: AstroSat CZTI detection
  54. Swift Triggers 1192480, 1192481, 1192482 and 1192483 are not astrophysical events
  55. LIGO/Virgo/KAGRA S230917af: MAXI/GSC observations
  56. GRB 230915B: Glowbug gamma-ray detection
  57. GRB 230916A: NuSTAR Discovery of Prompt Emission from a Potential GRB
  58. GRB 230911A: Fermi GBM Observation
  59. Swift GRB230916.18: Global MASTER-Net observations report
  60. Fermi trigger No 716572242: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S230904n: Correction of the coordinates of the ZTF candidate counterpart
  62. Fermi trigger No 716544961: Global MASTER-Net observations report
  63. Fermi-LAT gamma-ray observations of IceCube-230914A
  64. GRB 230915A: Swift/BAT-GUANO detection of a burst
  65. LIGO/Virgo/KAGRA S230914ak: Upper limits from Swift/BAT-GUANO
  66. GRB 230911D: GRBAlpha detection
  67. Swift GRB230916.19: Global MASTER-Net observations report
  68. Swift GRB230916.18: Global MASTER-Net observations report
  69. Swift Triggers 1192234, 1192235 and 1192236 are not astrophysical events
  70. Swift GRB230916.13: Global MASTER-Net observations report
  71. Swift GRB230916.12: Global MASTER-Net observations report
  72. Swift GRB230916.11: Global MASTER-Net observations report
  73. Swift Trigger 1192233 is not a GRB
  74. GRB 230906A: optical counterpart
  75. IceCube-230914A: Upper limits from a search for additional neutrino events in IceCube
  76. GRB 230911A: Swift-XRT afterglow detection
  77. Fermi trigger No 716449174: Global MASTER-Net observations report
  78. GRB 230913A: CALET Gamma-Ray Burst Monitor detection
  79. IceCube Alert 230914.22: Global MASTER-Net observations report
  80. Swift Trigger 1192088 is not an astrophysical event
  81. Fermi trigger No 716419312: Global MASTER-Net observations report
  82. GRB 230913A: Glowbug gamma-ray detection
  83. LIGO/Virgo/KAGRA S230914ak: Updated Sky localization
  84. GRB 230812B: Bad Time Intervals for Fermi GBM data
  85. IceCube-230914A - IceCube observation of a high-energy neutrino candidate track-like event
  86. LIGO/Virgo/KAGRA S230914ak: Identification of a GW compact binary merger candidate
  87. Swift Trigger 1191994 is not an astrophysical event
  88. Swift GRB230913.70: Global MASTER-Net observations report
  89. GRB 230913A: Fermi GBM Observation
  90. LIGO/Virgo/KAGRA S230904n: One ZTF candidate counterpart to coincident neutrino event
  91. Swift Trigger 1191904 is not a GRB
  92. Swift GRB230913.70: Global MASTER-Net observations report
  93. Swift Trigger 1191903 is not an astrophysical event
  94. GRB 230911A: Swift ToO observations
  95. GRB 230913A: Swift/BAT-GUANO arcminute localization of a burst
  96. Fermi GRB 230913A: Global MASTER-Net observations report
  97. GRB 230911A: GOTO optical counterpart candidate
  98. GRB 230913A: Fermi GBM Final Real-time Localization
  99. GRB 230908A: CALET Gamma-Ray Burst Monitor detection
  100. GRB 230911D: NuSTAR Detection of Prompt Emission

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