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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').
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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-231014A - IceCube observation of a high-energy neutrino candidate track-like event
  2. LIGO/Virgo/KAGRA S231014r: Identification of a GW compact binary merger candidate
  3. Correction in GCN 34814: GRB 231012B (not GRB 231012A)
  4. GRB 231012A: Fermi GBM Final Real-time Localization
  5. GRB 231012A: Fermi GBM Final Real-time Localization
  6. GRB 231004A: Glowbug gamma-ray detection
  7. LIGO/Virgo/KAGRA S231001aq: Updated Sky localization
  8. IceCube-231004A: One Candidate Counterpart from the Zwicky Transient Facility
  9. LIGO/Virgo/KAGRA S231005j: Upper limits from Swift/BAT-GUANO
  10. LIGO/Virgo/KAGRA S231008ap: Updated Sky localization
  11. LIGO/Virgo/KAGRA S231008ap: Identification of a GW compact binary merger candidate
  12. IceCube-231004A: Upper limits from a search for additional neutrino events in IceCube
  13. IceCube-231004A: No significant detection in HAWC
  14. GRB 231004A: CALET Gamma-Ray Burst Monitor detection
  15. Fermi-LAT gamma-ray observations of IceCube-231004A
  16. LIGO/Virgo/KAGRA S231005ah: Updated Sky localization
  17. LIGO/Virgo/KAGRA S231005ah: Identification of a GW compact binary merger candidate
  18. LIGO/Virgo/KAGRA S231005j: Updated Sky localization
  19. LIGO/Virgo/KAGRA S231005j: Identification of a GW compact binary merger candidate
  20. Update of IceCube-231004A - Corrected direciton
  21. IceCube-231004A - IceCube observation of a high-energy neutrino candidate track-like event
  22. transient AT2023sva: radio observations with AMI-LA
  23. GRB 231004A: Fermi GBM Final Real-time Localization
  24. GRB 231003A is not a GRB
  25. GRB 231003A: Fermi GBM Final Real-time Localization
  26. LIGO/Virgo/KAGRA S231001aq: Upper limits from Swift/BAT-GUANO
  27. LIGO/Virgo/KAGRA S230930al: Upper limits from Swift/BAT-GUANO
  28. LIGO/Virgo/KAGRA S230928cb: Upper limits from Swift/BAT-GUANO
  29. GRB 230827B: 10.4m GTC spectroscopic redshift
  30. LIGO/Virgo/KAGRA S231001aq: Updated Sky localization
  31. LIGO/Virgo/KAGRA S230930al: Updated Sky localization
  32. LIGO/Virgo/KAGRA S230928cb: Updated Sky localization
  33. LIGO/Virgo/KAGRA S231001aq: Identification of a GW compact binary merger candidate
  34. GRB 230930A: Fermi GBM Final Real-time Localization
  35. LIGO/Virgo/KAGRA S230930al: Identification of a GW compact binary merger candidate
  36. NuEm-230927A: Swift-XRT follow-up
  37. LIGO/Virgo/KAGRA S230928cb: Identification of a GW compact binary merger candidate
  38. AT2023sva / GRB230916B: GIT observations of the afterglow
  39. transient AT2023sva: A Binary Driven Hypernova with a possible associated supernova
  40. LIGO/Virgo/KAGRA S230927be: Updated Sky localization
  41. LIGO/Virgo/KAGRA S230927l: Updated Sky localization
  42. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230927A
  43. LIGO/Virgo/KAGRA S230927be: Identification of a GW compact binary merger candidate
  44. Swift Triggers 1192745 and 1192747 are not astrophysical events
  45. LIGO/Virgo/KAGRA S230927l: Identification of a GW compact binary merger candidate
  46. Swift Triggers 1192740, 1192742 and 1192743 are not astrophysical events
  47. Swift Triggers 1192735 and 1192737 are not astrophysical events
  48. LIGO/Virgo/KAGRA S230922q: Updated Sky localization
  49. Konus-Wind detection of GRB 230919A
  50. LIGO/Virgo/KAGRA S230924an: Upper limits from Swift/BAT-GUANO
  51. LIGO/Virgo/KAGRA S230920al: Upper limits from Swift/BAT-GUANO
  52. LIGO/Virgo/KAGRA S230919bj: Upper limits from Swift/BAT-GUANO
  53. Fermi Gamma-ray Burst Monitor trigger 717299390/230925076 is not a GRB
  54. Fermi Gamma-ray Burst Monitor trigger 230925241/717313591 is not a GRB
  55. LIGO/Virgo/KAGRA S230922g: DECam GW-MMADS candidates
  56. GRB 230812B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
  57. LIGO/Virgo/KAGRA S230924an: Updated Sky localization
  58. LIGO/Virgo/KAGRA S230924an: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S230917af: GRAWITA wide-field observations
  60. LIGO/Virgo/KAGRA S230922g: Updated Sky localization
  61. LIGO/Virgo/KAGRA S230922g: Identification of a GW compact binary merger candidate
  62. LIGO/Virgo/KAGRA S230922q: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S230917af: Zwicky Transient Facility observations
  64. GRB 230921A: Fermi GBM Final Real-time Localization
  65. GRB 230918B: VLT/X-shooter classification of AT 2023tbf (GOTO23aky) as a dwarf nova
  66. IPN triangulation of GRB 230919A (short)
  67. LIGO/Virgo/KAGRA S230904n: Classification of the candidate AT2023rkw with DBSP
  68. GRB 230919A: Fermi GBM Observation
  69. Correction to Fermi GBM Statement for Trigger 716527670/230916144
  70. Fermi GBM Statement for Trigger 716527670/230916144
  71. GRB 230919A: Swift/BAT-GUANO detection of a possibly short burst outside the coded FOV
  72. LIGO/Virgo/KAGRA S230920al: Updated Sky localization
  73. LIGO/Virgo/KAGRA S230919bj: Updated Sky localization
  74. transient AT2023sva: imaging and spectroscopic observations from MISTRAL at Observatoire de Haute-Provence
  75. GRB 230812B : optical observations from MISTRAL at Observatoire de Haute-Provence
  76. GRB 230919A: AstroSat CZTI detection
  77. LIGO/Virgo/KAGRA S230920al: Identification of a GW compact binary merger candidate
  78. AT2023sva: redshift from OSIRIS+/GTC of the ZTF afterglow
  79. LIGO/Virgo/KAGRA S230919bj: Identification of a GW compact binary merger candidate
  80. GRB 230918B: GOTO detection of a fast-rising transient in the GBM localisation region
  81. GRB 230919A: Fermi GBM Final Real-time Localization
  82. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  83. Detection of self-absorbed radio emission from GRB 230812B with the JVLA + uGMRT
  84. GRB 230918B: Fermi GBM Final Real-time Localization
  85. GRB 230918A (short): Glowbug gamma-ray detection
  86. GRB 230916B: Glowbug gamma-ray detection
  87. AT 2023sva: NOT observations of the ZTF candidate afterglow
  88. ZTF and SEDM Observations of the Candidate Optical Afterglow AT 2023sva
  89. GRB 230915A: Fermi GBM observation
  90. LIGO/Virgo/KAGRA S230918aq: Retraction of GW compact binary merger candidate
  91. GRB 230812B: Radio observations with the uGMRT
  92. GRB 230918A: Fermi GBM Final Real-time Localization
  93. GRB 230917A: AstroSat CZTI detection
  94. Swift Triggers 1192480, 1192481, 1192482 and 1192483 are not astrophysical events
  95. LIGO/Virgo/KAGRA S230917af: MAXI/GSC observations
  96. GRB 230915B: Glowbug gamma-ray detection
  97. GRB 230916A: NuSTAR Discovery of Prompt Emission from a Potential GRB
  98. GRB 230911A: Fermi GBM Observation
  99. Swift GRB230916.18: Global MASTER-Net observations report
  100. Fermi trigger No 716572242: Global MASTER-Net observations report

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