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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 230728A: Fermi GBM Observation
  2. GRB 230728A: LCOGT Optical Upper Limit
  3. GRB 230728A: Swift/UVOT Upper Limits
  4. GRB 230728A: Swift-XRT refined Analysis
  5. GRB 230728A: Enhanced Swift-XRT position
  6. GRB 230728A: NOT optical observations and possible host galaxy
  7. IceCube-230724A: No counterparts from the Zwicky Transient Facility
  8. GRB 230727A: AstroSat CZTI detection
  9. GRB 230728A: Swift detection of a burst
  10. Swift GRB230728.12: Global MASTER-Net observations report
  11. GRB 230727A: Swift/BAT-GUANO detection of a burst
  12. Fermi-LAT gamma-ray observations of IceCube-230725A
  13. Fermi-LAT gamma-ray observations of IceCube-230724A
  14. Fermi trigger No 712143685: Global MASTER-Net observations report
  15. IceCube-230727A - IceCube observation of a high-energy neutrino candidate track-like event
  16. GRB 230727A: Fermi GBM Final Real-time Localization
  17. IceCube-230725A: Upper limits from a search for additional neutrino events in IceCube
  18. IceCube-230724A: Upper limits from a search for additional neutrino events in IceCube
  19. Integral GRB230726.26: Global MASTER-Net observations report
  20. GRB 230723B: Further CAHA observations and host galaxy detection
  21. LIGO/Virgo/KAGRA S230726a: Updated Sky localization
  22. Konus-Wind detection of GRB 230723A
  23. GRB 230723B: MITSuME Akeno optical afterglow candidate detection
  24. GRB 230723B: ATCA rapid radio follow-up
  25. LIGO/Virgo/KAGRA S230726b: one counterpart neutrino candidate from IceCube neutrino searches
  26. IceCube-230724A - IceCube observation of a high-energy neutrino candidate track-like event
  27. LIGO/Virgo/KAGRA S230726a: Identification of a GW compact binary merger candidate
  28. IBAS trigger number 10337: not a real GRB
  29. Integral GRB230725.99: Global MASTER-Net observations report
  30. IceCube-230725A - IceCube observation of a high-energy neutrino candidate track-like event
  31. IceCube Alert 230725.90: Global MASTER-Net observations report
  32. GRB 230723B: GAD Observatory, La Spezia, Italy upper limit
  33. IPN triangulation of GRB 230723A (short)
  34. Fermi Gamma-ray Burst Monitor trigger 711982704/230725540 is not a GRB
  35. GRB 230725B: Fermi GBM Final Real-time Localization
  36. GRB 230725A: Fermi GBM Final Real-time Localization
  37. GRB 230723B: Leavitt Observatory upper limit
  38. GRB 230723B: Osservatorio Astronomico Nastro Verde upper limit
  39. GRB 230723B: Montarrenti Observatory upper limit
  40. GRB 230723B: Optical afterglow candidate from CAHA
  41. GRB 230723B: Bassano Bresciano Observatory upper limit
  42. GRB 230723B: Fermi GBM observation
  43. GRB 230723B: Swift-XRT refined Analysis
  44. GRB 230723B: non-detections from Observatoire de Haute-Provence
  45. IceCube Alert 230724.08: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S230723ac: Updated Sky localization
  47. Fermi trigger No 711853834: Global MASTER-Net observations report
  48. GRB 230724A: Fermi GBM Final Real-time Localization
  49. Fermi trigger No 711805358: Global MASTER-Net observations report
  50. GRB 230723B: Optical limit from CAHA
  51. GRB 230723B: Swift/UVOT Upper Limits
  52. Swift GRB 230723B: Global MASTER-Net observations report
  53. Swift-XRT position for GRB 230723B
  54. GRB 230723A: AGILE/MCAL detection
  55. GRB 230723B: Swift-XRT observations
  56. LIGO/Virgo/KAGRA S230723ac: Identification of a GW compact binary merger candidate
  57. GRB 230723B: Swift detection of a burst
  58. Fermi GRB 230723A: Global MASTER-Net observations report
  59. GRB 230723A: Fermi GBM Final Real-time Localization
  60. Swift GRB230720.30: Global MASTER-Net observations report
  61. IPN triangulation of GRB 230715D
  62. Swift Trigger 1180063 is not a GRB
  63. Swift Trigger 1180060 is not a GRB
  64. Swift Trigger 1180055 is not a GRB
  65. GRB 230718A: Final Localization Correction
  66. GRB 230718A: Fermi GBM Final Real-time Localization
  67. Fermi Gamma-ray Burst Monitor trigger 711329677/230717982 is not a GRB
  68. IPN triangulation of GRB 230712C (short)
  69. IPN triangulation of GRB 230712A (short)
  70. LIGO/Virgo/KAGRA S230708z: Updated Sky localization
  71. GRB 230717A: Fermi GBM Final Real-time Localization
  72. LIGO/Virgo/KAGRA S230715bw: Retraction of GW compact binary merger candidate
  73. Fermi trigger No 711088412: Global MASTER-Net observations report
  74. GRB 230715A: Fermi GBM Final Real-time Localization
  75. Fermi GRB 230713A: Global MASTER-Net observations report
  76. IceCube-230707A : MAXI upper limit and NICER follow-up observation of Swift J1753.5-0127
  77. GRB 230713A: Fermi GBM Final Real-time Localization
  78. LIGO/Virgo/KAGRA S230709bi: Updated Sky localization
  79. LIGO/Virgo/KAGRA S230708t: Updated Sky localization
  80. GRB 230709B: CALET Gamma-Ray Burst Monitor detection
  81. GRB 230703A: CALET Gamma-Ray Burst Monitor detection
  82. GRB 230709C: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  83. IceCube-230708A: Upper limits from Swift/BAT-GUANO
  84. GRB 230712B: Fermi GBM Final Localization
  85. LIGO/Virgo/KAGRA S230712a: Retraction of GW compact binary merger candidate
  86. GRB 230707A: Swift/BAT-GUANO position correction
  87. GRB 230712A: Fermi GBM Final Real-time Localization
  88. IceCube-230708A - Correction to GCN Circular 34170
  89. Fermi trigger No 710741042: Global MASTER-Net observations report
  90. GRB 230709C: GRBAlpha detection
  91. GRB 230709B: GRBAlpha detection
  92. GRB 230709C: Fermi GBM Detection
  93. GRB 230709C: Fermi GBM Final Localization
  94. GRB 230707B: Fermi GBM Observation
  95. GRB 230710A: Fermi GBM Final Real-time Localization
  96. LIGO/Virgo/KAGRA S230708z: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S230708t: Identification of a GW compact binary merger candidate
  98. IceCube-230707A: No candidates detected by Swift-XRT
  99. Swift Trigger 1178410 is not an astrophysical event
  100. GRB 230709C: AstroSat CZTI detection

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