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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 230725B: Fermi GBM Final Real-time Localization
  2. GRB 230725A: Fermi GBM Final Real-time Localization
  3. GRB 230723B: Leavitt Observatory upper limit
  4. GRB 230723B: Osservatorio Astronomico Nastro Verde upper limit
  5. GRB 230723B: Montarrenti Observatory upper limit
  6. GRB 230723B: Optical afterglow candidate from CAHA
  7. GRB 230723B: Bassano Bresciano Observatory upper limit
  8. GRB 230723B: Fermi GBM observation
  9. GRB 230723B: Swift-XRT refined Analysis
  10. GRB 230723B: non-detections from Observatoire de Haute-Provence
  11. IceCube Alert 230724.08: Global MASTER-Net observations report
  12. LIGO/Virgo/KAGRA S230723ac: Updated Sky localization
  13. Fermi trigger No 711853834: Global MASTER-Net observations report
  14. GRB 230724A: Fermi GBM Final Real-time Localization
  15. Fermi trigger No 711805358: Global MASTER-Net observations report
  16. GRB 230723B: Optical limit from CAHA
  17. GRB 230723B: Swift/UVOT Upper Limits
  18. Swift GRB 230723B: Global MASTER-Net observations report
  19. Swift-XRT position for GRB 230723B
  20. GRB 230723A: AGILE/MCAL detection
  21. GRB 230723B: Swift-XRT observations
  22. LIGO/Virgo/KAGRA S230723ac: Identification of a GW compact binary merger candidate
  23. GRB 230723B: Swift detection of a burst
  24. Fermi GRB 230723A: Global MASTER-Net observations report
  25. GRB 230723A: Fermi GBM Final Real-time Localization
  26. Swift GRB230720.30: Global MASTER-Net observations report
  27. IPN triangulation of GRB 230715D
  28. Swift Trigger 1180063 is not a GRB
  29. Swift Trigger 1180060 is not a GRB
  30. Swift Trigger 1180055 is not a GRB
  31. GRB 230718A: Final Localization Correction
  32. GRB 230718A: Fermi GBM Final Real-time Localization
  33. Fermi Gamma-ray Burst Monitor trigger 711329677/230717982 is not a GRB
  34. IPN triangulation of GRB 230712C (short)
  35. IPN triangulation of GRB 230712A (short)
  36. LIGO/Virgo/KAGRA S230708z: Updated Sky localization
  37. GRB 230717A: Fermi GBM Final Real-time Localization
  38. LIGO/Virgo/KAGRA S230715bw: Retraction of GW compact binary merger candidate
  39. Fermi trigger No 711088412: Global MASTER-Net observations report
  40. GRB 230715A: Fermi GBM Final Real-time Localization
  41. Fermi GRB 230713A: Global MASTER-Net observations report
  42. IceCube-230707A : MAXI upper limit and NICER follow-up observation of Swift J1753.5-0127
  43. GRB 230713A: Fermi GBM Final Real-time Localization
  44. LIGO/Virgo/KAGRA S230709bi: Updated Sky localization
  45. LIGO/Virgo/KAGRA S230708t: Updated Sky localization
  46. GRB 230709B: CALET Gamma-Ray Burst Monitor detection
  47. GRB 230703A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 230709C: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  49. IceCube-230708A: Upper limits from Swift/BAT-GUANO
  50. GRB 230712B: Fermi GBM Final Localization
  51. LIGO/Virgo/KAGRA S230712a: Retraction of GW compact binary merger candidate
  52. GRB 230707A: Swift/BAT-GUANO position correction
  53. GRB 230712A: Fermi GBM Final Real-time Localization
  54. IceCube-230708A - Correction to GCN Circular 34170
  55. Fermi trigger No 710741042: Global MASTER-Net observations report
  56. GRB 230709C: GRBAlpha detection
  57. GRB 230709B: GRBAlpha detection
  58. GRB 230709C: Fermi GBM Detection
  59. GRB 230709C: Fermi GBM Final Localization
  60. GRB 230707B: Fermi GBM Observation
  61. GRB 230710A: Fermi GBM Final Real-time Localization
  62. LIGO/Virgo/KAGRA S230708z: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S230708t: Identification of a GW compact binary merger candidate
  64. IceCube-230707A: No candidates detected by Swift-XRT
  65. Swift Trigger 1178410 is not an astrophysical event
  66. GRB 230709C: AstroSat CZTI detection
  67. LIGO/Virgo/KAGRA S230708cf: Updated Sky localization
  68. GRB 230707B: CALET Gamma-Ray Burst Monitor detection
  69. GRB 230703A detected with multiple GRID detectors
  70. GRB 230709C: BALROG localization (Fermi Trigger 710617111 / GRB 230709735)
  71. LIGO/Virgo/KAGRA S230707ai: Updated Sky localization
  72. IceCube-230707A: No candidates from the Zwicky Transient Facility
  73. Fermi-LAT gamma-ray observations of IceCube-230708A
  74. Fermi-LAT gamma-ray observations of IceCube-230707B
  75. Fermi-LAT gamma-ray observations of IceCube-230707A
  76. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  77. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  78. GRB 230709B: BALROG localization (Fermi Trigger 710614579 / GRB 230709706)
  79. IceCube-230708A: Upper limits from a search for additional neutrino events in IceCube
  80. IceCube-230707B: Upper limits from a search for additional neutrino events in IceCube
  81. IceCube-230707A: Upper limits from a search for additional neutrino events in IceCube
  82. LIGO/Virgo/KAGRA S230709bi: Identification of a GW compact binary merger candidate
  83. Swift Trigger 1178410: possible GRB 230709A
  84. LIGO/Virgo/KAGRA S230708cf: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S230708bi: Retraction of GW compact binary merger candidate
  86. GRB 230628C: GRID Detection
  87. IceCube-230708A - IceCube observation of a high-energy neutrino candidate track-like event
  88. GRB 230707B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  89. GRB 230707A: Swift-XRT observations
  90. IceCube Alert 230708.35: Global MASTER-Net observations report
  91. IceCube-230707B - IceCube observation of a high-energy neutrino candidate track-like event
  92. GRB 230707B: Fermi GBM Final Real-time Localization
  93. IceCube Alert 230707.71: Global MASTER-Net observations report
  94. IceCube-230707A - IceCube observation of a high-energy neutrino candidate track-like event
  95. GRB 230707A: Fermi GBM Detection
  96. LIGO/Virgo/KAGRA S230707ai: Identification of a GW compact binary merger candidate
  97. GRB 230707A: Swift ToO observations
  98. GRB 230707A: Swift/BAT-GUANO arcminute localization of a burst
  99. ZTF23aaoohpy/AT2023lcr : HCT follow-up observations
  100. Fermi GRB 230707A: Global MASTER-Net observations report

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