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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 230723B: Swift-XRT observations
  2. LIGO/Virgo/KAGRA S230723ac: Identification of a GW compact binary merger candidate
  3. GRB 230723B: Swift detection of a burst
  4. Fermi GRB 230723A: Global MASTER-Net observations report
  5. GRB 230723A: Fermi GBM Final Real-time Localization
  6. Swift GRB230720.30: Global MASTER-Net observations report
  7. IPN triangulation of GRB 230715D
  8. Swift Trigger 1180063 is not a GRB
  9. Swift Trigger 1180060 is not a GRB
  10. Swift Trigger 1180055 is not a GRB
  11. GRB 230718A: Final Localization Correction
  12. GRB 230718A: Fermi GBM Final Real-time Localization
  13. Fermi Gamma-ray Burst Monitor trigger 711329677/230717982 is not a GRB
  14. IPN triangulation of GRB 230712C (short)
  15. IPN triangulation of GRB 230712A (short)
  16. LIGO/Virgo/KAGRA S230708z: Updated Sky localization
  17. GRB 230717A: Fermi GBM Final Real-time Localization
  18. LIGO/Virgo/KAGRA S230715bw: Retraction of GW compact binary merger candidate
  19. Fermi trigger No 711088412: Global MASTER-Net observations report
  20. GRB 230715A: Fermi GBM Final Real-time Localization
  21. Fermi GRB 230713A: Global MASTER-Net observations report
  22. IceCube-230707A : MAXI upper limit and NICER follow-up observation of Swift J1753.5-0127
  23. GRB 230713A: Fermi GBM Final Real-time Localization
  24. LIGO/Virgo/KAGRA S230709bi: Updated Sky localization
  25. LIGO/Virgo/KAGRA S230708t: Updated Sky localization
  26. GRB 230709B: CALET Gamma-Ray Burst Monitor detection
  27. GRB 230703A: CALET Gamma-Ray Burst Monitor detection
  28. GRB 230709C: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  29. IceCube-230708A: Upper limits from Swift/BAT-GUANO
  30. GRB 230712B: Fermi GBM Final Localization
  31. LIGO/Virgo/KAGRA S230712a: Retraction of GW compact binary merger candidate
  32. GRB 230707A: Swift/BAT-GUANO position correction
  33. GRB 230712A: Fermi GBM Final Real-time Localization
  34. IceCube-230708A - Correction to GCN Circular 34170
  35. Fermi trigger No 710741042: Global MASTER-Net observations report
  36. GRB 230709C: GRBAlpha detection
  37. GRB 230709B: GRBAlpha detection
  38. GRB 230709C: Fermi GBM Detection
  39. GRB 230709C: Fermi GBM Final Localization
  40. GRB 230707B: Fermi GBM Observation
  41. GRB 230710A: Fermi GBM Final Real-time Localization
  42. LIGO/Virgo/KAGRA S230708z: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S230708t: Identification of a GW compact binary merger candidate
  44. IceCube-230707A: No candidates detected by Swift-XRT
  45. Swift Trigger 1178410 is not an astrophysical event
  46. GRB 230709C: AstroSat CZTI detection
  47. LIGO/Virgo/KAGRA S230708cf: Updated Sky localization
  48. GRB 230707B: CALET Gamma-Ray Burst Monitor detection
  49. GRB 230703A detected with multiple GRID detectors
  50. GRB 230709C: BALROG localization (Fermi Trigger 710617111 / GRB 230709735)
  51. LIGO/Virgo/KAGRA S230707ai: Updated Sky localization
  52. IceCube-230707A: No candidates from the Zwicky Transient Facility
  53. Fermi-LAT gamma-ray observations of IceCube-230708A
  54. Fermi-LAT gamma-ray observations of IceCube-230707B
  55. Fermi-LAT gamma-ray observations of IceCube-230707A
  56. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  57. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  58. GRB 230709B: BALROG localization (Fermi Trigger 710614579 / GRB 230709706)
  59. IceCube-230708A: Upper limits from a search for additional neutrino events in IceCube
  60. IceCube-230707B: Upper limits from a search for additional neutrino events in IceCube
  61. IceCube-230707A: Upper limits from a search for additional neutrino events in IceCube
  62. LIGO/Virgo/KAGRA S230709bi: Identification of a GW compact binary merger candidate
  63. Swift Trigger 1178410: possible GRB 230709A
  64. LIGO/Virgo/KAGRA S230708cf: Identification of a GW compact binary merger candidate
  65. LIGO/Virgo/KAGRA S230708bi: Retraction of GW compact binary merger candidate
  66. GRB 230628C: GRID Detection
  67. IceCube-230708A - IceCube observation of a high-energy neutrino candidate track-like event
  68. GRB 230707B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  69. GRB 230707A: Swift-XRT observations
  70. IceCube Alert 230708.35: Global MASTER-Net observations report
  71. IceCube-230707B - IceCube observation of a high-energy neutrino candidate track-like event
  72. GRB 230707B: Fermi GBM Final Real-time Localization
  73. IceCube Alert 230707.71: Global MASTER-Net observations report
  74. IceCube-230707A - IceCube observation of a high-energy neutrino candidate track-like event
  75. GRB 230707A: Fermi GBM Detection
  76. LIGO/Virgo/KAGRA S230707ai: Identification of a GW compact binary merger candidate
  77. GRB 230707A: Swift ToO observations
  78. GRB 230707A: Swift/BAT-GUANO arcminute localization of a burst
  79. ZTF23aaoohpy/AT2023lcr : HCT follow-up observations
  80. Fermi GRB 230707A: Global MASTER-Net observations report
  81. GRB 230707A: Fermi GBM Final Real-time Localization
  82. LIGO/Virgo/KAGRA S230706ah: Updated Sky localization
  83. Integral GRB230706.70: Global MASTER-Net observations report
  84. LIGO/Virgo/KAGRA S230704f: Updated Sky localization
  85. LIGO/Virgo/KAGRA S230630bq: Updated Sky localization
  86. IBAS trigger number 10311: not a real GRB
  87. LIGO/Virgo/KAGRA S230702an: Updated Sky localization
  88. GRB 230625A: Detection by GRID
  89. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  90. LIGO/Virgo/KAGRA S230706ah: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S230627c: GECKO optical follow-up observations of host galaxy candidates and ZTF23aaptsuy/AT2023lxu
  92. ZTF23aaoohpy/AT2023lcr: AMI-LA radio detection
  93. Fermi trigger No 710117592: Global MASTER-Net observations report
  94. GRB 230626A: VZLUSAT-2 detection
  95. LVK S230619bd/GBM-230619: Upper limits from a two-week IceCube neutrino search
  96. GRB 230328B: LBT detection of the likely host galaxy
  97. LIGO/Virgo/KAGRA S230704f: Identification of a GW compact binary merger candidate
  98. Konus-Wind detection of GRB 220623A
  99. GRB 230701B: AstroSat CZTI detection
  100. LIGO/Virgo/KAGRA S230627c: observations of ZTF23aaptsuy/AT2023lx in AbAO observatory

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