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New GCN Circulars features for September 2023! See news and announcements

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').
  1. GRB 230723B: GAD Observatory, La Spezia, Italy upper limit
  2. IPN triangulation of GRB 230723A (short)
  3. Fermi Gamma-ray Burst Monitor trigger 711982704/230725540 is not a GRB
  4. GRB 230725B: Fermi GBM Final Real-time Localization
  5. GRB 230725A: Fermi GBM Final Real-time Localization
  6. GRB 230723B: Leavitt Observatory upper limit
  7. GRB 230723B: Osservatorio Astronomico Nastro Verde upper limit
  8. GRB 230723B: Montarrenti Observatory upper limit
  9. GRB 230723B: Optical afterglow candidate from CAHA
  10. GRB 230723B: Bassano Bresciano Observatory upper limit
  11. GRB 230723B: Fermi GBM observation
  12. GRB 230723B: Swift-XRT refined Analysis
  13. GRB 230723B: non-detections from Observatoire de Haute-Provence
  14. IceCube Alert 230724.08: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S230723ac: Updated Sky localization
  16. Fermi trigger No 711853834: Global MASTER-Net observations report
  17. GRB 230724A: Fermi GBM Final Real-time Localization
  18. Fermi trigger No 711805358: Global MASTER-Net observations report
  19. GRB 230723B: Optical limit from CAHA
  20. GRB 230723B: Swift/UVOT Upper Limits
  21. Swift GRB 230723B: Global MASTER-Net observations report
  22. Swift-XRT position for GRB 230723B
  23. GRB 230723A: AGILE/MCAL detection
  24. GRB 230723B: Swift-XRT observations
  25. LIGO/Virgo/KAGRA S230723ac: Identification of a GW compact binary merger candidate
  26. GRB 230723B: Swift detection of a burst
  27. Fermi GRB 230723A: Global MASTER-Net observations report
  28. GRB 230723A: Fermi GBM Final Real-time Localization
  29. Swift GRB230720.30: Global MASTER-Net observations report
  30. IPN triangulation of GRB 230715D
  31. Swift Trigger 1180063 is not a GRB
  32. Swift Trigger 1180060 is not a GRB
  33. Swift Trigger 1180055 is not a GRB
  34. GRB 230718A: Final Localization Correction
  35. GRB 230718A: Fermi GBM Final Real-time Localization
  36. Fermi Gamma-ray Burst Monitor trigger 711329677/230717982 is not a GRB
  37. IPN triangulation of GRB 230712C (short)
  38. IPN triangulation of GRB 230712A (short)
  39. LIGO/Virgo/KAGRA S230708z: Updated Sky localization
  40. GRB 230717A: Fermi GBM Final Real-time Localization
  41. LIGO/Virgo/KAGRA S230715bw: Retraction of GW compact binary merger candidate
  42. Fermi trigger No 711088412: Global MASTER-Net observations report
  43. GRB 230715A: Fermi GBM Final Real-time Localization
  44. Fermi GRB 230713A: Global MASTER-Net observations report
  45. IceCube-230707A : MAXI upper limit and NICER follow-up observation of Swift J1753.5-0127
  46. GRB 230713A: Fermi GBM Final Real-time Localization
  47. LIGO/Virgo/KAGRA S230709bi: Updated Sky localization
  48. LIGO/Virgo/KAGRA S230708t: Updated Sky localization
  49. GRB 230709B: CALET Gamma-Ray Burst Monitor detection
  50. GRB 230703A: CALET Gamma-Ray Burst Monitor detection
  51. GRB 230709C: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  52. IceCube-230708A: Upper limits from Swift/BAT-GUANO
  53. GRB 230712B: Fermi GBM Final Localization
  54. LIGO/Virgo/KAGRA S230712a: Retraction of GW compact binary merger candidate
  55. GRB 230707A: Swift/BAT-GUANO position correction
  56. GRB 230712A: Fermi GBM Final Real-time Localization
  57. IceCube-230708A - Correction to GCN Circular 34170
  58. Fermi trigger No 710741042: Global MASTER-Net observations report
  59. GRB 230709C: GRBAlpha detection
  60. GRB 230709B: GRBAlpha detection
  61. GRB 230709C: Fermi GBM Detection
  62. GRB 230709C: Fermi GBM Final Localization
  63. GRB 230707B: Fermi GBM Observation
  64. GRB 230710A: Fermi GBM Final Real-time Localization
  65. LIGO/Virgo/KAGRA S230708z: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo/KAGRA S230708t: Identification of a GW compact binary merger candidate
  67. IceCube-230707A: No candidates detected by Swift-XRT
  68. Swift Trigger 1178410 is not an astrophysical event
  69. GRB 230709C: AstroSat CZTI detection
  70. LIGO/Virgo/KAGRA S230708cf: Updated Sky localization
  71. GRB 230707B: CALET Gamma-Ray Burst Monitor detection
  72. GRB 230703A detected with multiple GRID detectors
  73. GRB 230709C: BALROG localization (Fermi Trigger 710617111 / GRB 230709735)
  74. LIGO/Virgo/KAGRA S230707ai: Updated Sky localization
  75. IceCube-230707A: No candidates from the Zwicky Transient Facility
  76. Fermi-LAT gamma-ray observations of IceCube-230708A
  77. Fermi-LAT gamma-ray observations of IceCube-230707B
  78. Fermi-LAT gamma-ray observations of IceCube-230707A
  79. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  80. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  81. GRB 230709B: BALROG localization (Fermi Trigger 710614579 / GRB 230709706)
  82. IceCube-230708A: Upper limits from a search for additional neutrino events in IceCube
  83. IceCube-230707B: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube-230707A: Upper limits from a search for additional neutrino events in IceCube
  85. LIGO/Virgo/KAGRA S230709bi: Identification of a GW compact binary merger candidate
  86. Swift Trigger 1178410: possible GRB 230709A
  87. LIGO/Virgo/KAGRA S230708cf: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo/KAGRA S230708bi: Retraction of GW compact binary merger candidate
  89. GRB 230628C: GRID Detection
  90. IceCube-230708A - IceCube observation of a high-energy neutrino candidate track-like event
  91. GRB 230707B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  92. GRB 230707A: Swift-XRT observations
  93. IceCube Alert 230708.35: Global MASTER-Net observations report
  94. IceCube-230707B - IceCube observation of a high-energy neutrino candidate track-like event
  95. GRB 230707B: Fermi GBM Final Real-time Localization
  96. IceCube Alert 230707.71: Global MASTER-Net observations report
  97. IceCube-230707A - IceCube observation of a high-energy neutrino candidate track-like event
  98. GRB 230707A: Fermi GBM Detection
  99. LIGO/Virgo/KAGRA S230707ai: Identification of a GW compact binary merger candidate
  100. GRB 230707A: Swift ToO observations

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