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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. The Fermi GBM Trigger 713134237 / 230807868 is not associated with LIGO/Virgo/KAGRA S230807f.
  2. Fermi trigger No 713205976: Global MASTER-Net observations report
  3. ZTF23aaoohpy/AT2023lcr: JWST observations consistent with the presence of a supernova
  4. GRB 230808A: Fermi GBM Final Real-time Localization
  5. GRB 230805B : MITSuME Akeno optical upper limits
  6. LIGO/Virgo/KAGRA S230808i: retraction of a GW unmodeled transient candidate
  7. LIGO/Virgo/KAGRA S230808i: Identification of a GW unmodeled transient candidate
  8. LIGO/Virgo/KAGRA S230807f: Updated Sky localization and EM Bright Classification
  9. transient SPT-SVJ025406.5-702837: ATCA follow-up observations
  10. Fermi GRB 230807A: Global MASTER-Net observations report
  11. Fermi trigger No 713134237: Global MASTER-Net observations report
  12. GRB 230807A: Fermi GBM Final Real-time Localization
  13. LIGO/Virgo/KAGRA S230807f: Identification of a GW compact binary merger candidate
  14. LIGO/Virgo/KAGRA S230805x: Upper limits from Swift/BAT-GUANO
  15. Konus-Wind detection of GRB 230803A
  16. GRB 230805B: Fermi GBM observation
  17. GRB 230805B : OHP/T193 optical upper limit
  18. LIGO/Virgo/KAGRA S230806ak: Updated Sky localization and EM Bright Classification
  19. GRB 230806A: Fermi GBM Final Localization
  20. GRB 230805B: Enhanced Swift-XRT position
  21. LIGO/Virgo/KAGRA S230806ak: Identification of a GW compact binary merger candidate
  22. GRB 230805B: Swift/UVOT Upper Limits
  23. Fermi trigger No 712991593: Global MASTER-Net observations report
  24. GRB 230805B: Bassano Bresciano observatory upper limit
  25. Fermi trigger No 712987357: Global MASTER-Net observations report
  26. GRB 230805B: BOOTES-6/DPRT optical upper limit and 1.5m OSN detection
  27. GRB 230805B: NOT optical afterglow confirmation
  28. GRB 230805B: Swift-XRT refined Analysis
  29. Fermi GRB 230805A: Global MASTER-Net observations report
  30. GRB 230805B: SAO RAS optical observations
  31. Fermi trigger No 712927418: Global MASTER-Net observations report
  32. Swift GRB 230805B: Global MASTER-Net observations report
  33. LIGO/Virgo/KAGRA S230805x: Updated Sky localization
  34. GRB 230805B: Swift detection of a burst
  35. GRB 230805A: Fermi GBM Final Real-time Localization
  36. LIGO/Virgo/KAGRA S230805x: Identification of a GW compact binary merger candidate
  37. LIGO/Virgo/KAGRA S230802aq: Updated Sky localization and EM Bright Classification
  38. GRB 230802B: AstroSat CZTI detection
  39. GRB 230802A: Fermi GBM observation
  40. GRB 230802A: Swift-BAT refined analysis
  41. GRB 230804A: Fermi GBM Final Real-time Localization
  42. Fermi trigger No 712798043: Global MASTER-Net observations report
  43. IPN triangulation of GRB 230803A
  44. GRB 230802A: Swift/UVOT Upper Limits
  45. GRB 230803A: AstroSat CZTI detection
  46. LIGO/Virgo/KAGRA S230802aq: AstroSat CZTI non-detection and upper limits
  47. Fermi trigger No 712718833: Global MASTER-Net observations report
  48. GRB 230803A: Fermi GBM Final Real-time Localization
  49. Fermi trigger No 712713532: Global MASTER-Net observations report
  50. Fermi trigger No 712651827: Global MASTER-Net observations report
  51. GRB 230802B: Fermi GBM Final Localization
  52. Swift GRB 230802A: Global MASTER-Net observations report
  53. GRB 230802A: BOOTES-5/JGT optical upper limit
  54. LIGO/Virgo/KAGRA S230802aq: Upper limits from Fermi-GBM Observations
  55. GRB 230802A: Swift-XRT refined Analysis
  56. GRB 230802A: Enhanced Swift-XRT position
  57. LIGO/Virgo S230802aq: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  58. LIGO/Virgo/KAGRA S230802aq: Coverage and upper limits from MAXI/GSC observations
  59. LIGO/Virgo/KAGRA S230802aq: Identification of a GW compact binary merger candidate
  60. GRB 230802A: Swift detection of a burst
  61. IceCube-230724A: JCMT/SCUBA-2 submm observations
  62. IceCube-230707A: JCMT/SCUBA-2 submm observations
  63. LIGO/Virgo/KAGRA S230731an: Upper limits from Swift/BAT-GUANO
  64. GRB 230723A: SPT-3G millimeter-band transient event inconsistent with IPN position
  65. LIGO/Virgo/KAGRA S230731an: AstroSat CZTI non-detection and upper limits
  66. LIGO/Virgo/KAGRA S230731an: not observable by Fermi-GBM
  67. LIGO/Virgo/KAGRA S230731an: Updated Sky Localization and EM Bright Classification, and Correction to Source Classification
  68. GRB 230731A: Fermi GBM Final Real-time Localization
  69. LIGO/Virgo/KAGRA S230731an: Coverage and upper limits from MAXI/GSC observations
  70. LIGO/Virgo/KAGRA S230731an: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S230729z: Updated Sky localization
  72. GRB 230723A: Detection of candidate millimeter-band radiation by SPT-3G
  73. Fermi trigger No 712390645: Global MASTER-Net observations report
  74. GRB 230728A: Swift-BAT refined analysis
  75. Fermi-LAT gamma-ray observations of IceCube-230727A
  76. GRB 230723B: Swift-BAT refined analysis
  77. Fermi trigger No 712306969: Global MASTER-Net observations report
  78. GRB 230723B: MITSuME Ishigaki optical observation
  79. IceCube-230727A: No candidates from the Zwicky Transient Facility
  80. LIGO/Virgo/KAGRA S230729z: Identification of a GW compact binary merger candidate
  81. IceCube-230727A: Upper limits from a search for additional neutrino events in IceCube
  82. GRB 230728A: BOOTES-1 optical upper limit
  83. GRB 230728A: Fermi GBM Observation
  84. GRB 230728A: LCOGT Optical Upper Limit
  85. GRB 230728A: Swift/UVOT Upper Limits
  86. GRB 230728A: Swift-XRT refined Analysis
  87. GRB 230728A: Enhanced Swift-XRT position
  88. GRB 230728A: NOT optical observations and possible host galaxy
  89. IceCube-230724A: No counterparts from the Zwicky Transient Facility
  90. GRB 230727A: AstroSat CZTI detection
  91. GRB 230728A: Swift detection of a burst
  92. Swift GRB230728.12: Global MASTER-Net observations report
  93. GRB 230727A: Swift/BAT-GUANO detection of a burst
  94. Fermi-LAT gamma-ray observations of IceCube-230725A
  95. Fermi-LAT gamma-ray observations of IceCube-230724A
  96. Fermi trigger No 712143685: Global MASTER-Net observations report
  97. IceCube-230727A - IceCube observation of a high-energy neutrino candidate track-like event
  98. GRB 230727A: Fermi GBM Final Real-time Localization
  99. IceCube-230725A: Upper limits from a search for additional neutrino events in IceCube
  100. IceCube-230724A: Upper limits from a search for additional neutrino events in IceCube

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