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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. Fermi GRB 230814A: Global MASTER-Net observations report
  2. GRB 230815A: Enhanced Swift-XRT position
  3. GRB 230812B: Iota Scorpii Observatory, La Spezia, Italy
  4. GRB 230812B: Tautenburg observations
  5. GRB 230815A: Swift detection of a burst
  6. GRB 230812B: AMI-LA radio detection of afterglow candidate
  7. GRB 230812B: continued AbAO optical afterglow observations
  8. GRB 230812B: Optical observaions from Rozhen Observatory
  9. GRB 230812B: Further Bassano Bresciano Observatory optical observations
  10. LIGO/Virgo/KAGRA S230814ah: Identification of a GW compact binary merger candidate
  11. GRB 230812B: further SAO RAS optical observations
  12. GRB 230812B: Upper limits from a neutrino search with IceCube
  13. LIGO/Virgo/KAGRA S230814r: Updated Sky localization
  14. GRB 230812B: GRANDMA further observations of ZTF23aaxeacr candidate afterglow
  15. GRB 230814A: BALROG localization (Fermi Trigger 713732101 / GRB 230814788)
  16. GRB 230812B: CrAO ZTSh optical observations
  17. GRB 230814A: Fermi GBM Final Real-time Localization
  18. GRB 230812B: Koshka Zeiss-1000 optical observations
  19. GRB 230812B: GIT optical follow-up
  20. GRB 230812B: Leavitt Observatory optical observations
  21. GRB 230812B : optical observations from Observatoire de Haute-Provence
  22. GRB 230812B: Bassano Bresciano Observatory optical observations
  23. GRB 230812B: Faulkes Telescope North optical afterglow follow-up
  24. GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
  25. GRB 230812B: rest-frame energetics from Konus-Wind observation
  26. GRB 230812B: OASDG optical observations
  27. GRB 230812B: AbAO optical observations
  28. LIGO/Virgo/KAGRA S230814r: Identification of a GW compact binary merger candidate
  29. GRB 230812B: Spectroscopy from NOT
  30. GRB 230812B: Redshift from OSIRIS+/GTC
  31. GRB 230812B: Montarrenti Observatory optical observations
  32. LIGO/Virgo/KAGRA S230812aj: two counterpart neutrino candidates from IceCube neutrino searches
  33. GRB 230812B: SAO RAS optical observations
  34. GRB 230812B: Detected Optical Afterglow Candidate
  35. GRB 230812B: GMG - GRANDMA observations
  36. Konus-Wind detection of GRB 230812B
  37. GRB230812B: AGILE/MCAL detection
  38. GRB 230812B: GECAM-C observation of a very bright burst
  39. GRB 230812B: Swift-XRT afterglow detection
  40. GRB 230812: Swift/UVOT Detection
  41. GOTO confirmation and possible host galaxy of GRB230812B optical afterglow
  42. GRB 230812B: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi GRB (Trigger 713559497)
  43. Fermi GRB 230812B: MASTER optical counterpart
  44. GRB 230812B: KAIT Optical Afterglow Candidate
  45. GRB 230812B: Improved Swift/XRT localization
  46. GRB 230812B: Preliminary Swift/XRT localization
  47. GRB 230812B: Fermi-LAT detection
  48. GRB 230812B: Fermi GBM Observation of a very bright burst
  49. LAT GRB230812.79: Global MASTER-Net observations report
  50. Fermi GRB 230812B: Global MASTER-Net observations report
  51. GRB 230812B: Tiled Swift observations
  52. GRB 230812B: Fermi GBM detection of an extremely bright GRB
  53. GRB 230812B: Fermi GBM Final Real-time Localization
  54. ZTF23aaoohpy/AT2023lcr: JWST spectroscopy confirmation of an associated type Ic-BL supernova
  55. Fermi trigger No 713525317: Global MASTER-Net observations report
  56. GRB 230812A: Fermi GBM Final Real-time Localization
  57. LIGO/Virgo/KAGRA S230811n: Updated Sky localization
  58. GRB 230808A: Fermi GBM Detection
  59. LIGO/Virgo/KAGRA S230811n: Identification of a GW compact binary merger candidate
  60. GRB 230805B: Swift-BAT refined analysis
  61. LIGO/Virgo/KAGRA S230810af: Retraction of GW compact binary merger candidate
  62. GRB 230805B: Iota Scorpii Observatory, La Spezia, Italy upper limit
  63. GRB 230805B: AstroSat CZTI detection
  64. GRB 230808A: Swift/BAT-GUANO detection of a burst
  65. Fermi trigger No 713136868: Global MASTER-Net observations report
  66. GRB 230808B: Fermi GBM Final Real-time Localization
  67. The Fermi GBM Trigger 713134237 / 230807868 is not associated with LIGO/Virgo/KAGRA S230807f.
  68. Fermi trigger No 713205976: Global MASTER-Net observations report
  69. ZTF23aaoohpy/AT2023lcr: JWST observations consistent with the presence of a supernova
  70. GRB 230808A: Fermi GBM Final Real-time Localization
  71. GRB 230805B : MITSuME Akeno optical upper limits
  72. LIGO/Virgo/KAGRA S230808i: retraction of a GW unmodeled transient candidate
  73. LIGO/Virgo/KAGRA S230808i: Identification of a GW unmodeled transient candidate
  74. LIGO/Virgo/KAGRA S230807f: Updated Sky localization and EM Bright Classification
  75. transient SPT-SVJ025406.5-702837: ATCA follow-up observations
  76. Fermi GRB 230807A: Global MASTER-Net observations report
  77. Fermi trigger No 713134237: Global MASTER-Net observations report
  78. GRB 230807A: Fermi GBM Final Real-time Localization
  79. LIGO/Virgo/KAGRA S230807f: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo/KAGRA S230805x: Upper limits from Swift/BAT-GUANO
  81. Konus-Wind detection of GRB 230803A
  82. GRB 230805B: Fermi GBM observation
  83. GRB 230805B : OHP/T193 optical upper limit
  84. LIGO/Virgo/KAGRA S230806ak: Updated Sky localization and EM Bright Classification
  85. GRB 230806A: Fermi GBM Final Localization
  86. GRB 230805B: Enhanced Swift-XRT position
  87. LIGO/Virgo/KAGRA S230806ak: Identification of a GW compact binary merger candidate
  88. GRB 230805B: Swift/UVOT Upper Limits
  89. Fermi trigger No 712991593: Global MASTER-Net observations report
  90. GRB 230805B: Bassano Bresciano observatory upper limit
  91. Fermi trigger No 712987357: Global MASTER-Net observations report
  92. GRB 230805B: BOOTES-6/DPRT optical upper limit and 1.5m OSN detection
  93. GRB 230805B: NOT optical afterglow confirmation
  94. GRB 230805B: Swift-XRT refined Analysis
  95. Fermi GRB 230805A: Global MASTER-Net observations report
  96. GRB 230805B: SAO RAS optical observations
  97. Fermi trigger No 712927418: Global MASTER-Net observations report
  98. Swift GRB 230805B: Global MASTER-Net observations report
  99. LIGO/Virgo/KAGRA S230805x: Updated Sky localization
  100. GRB 230805B: Swift detection of a burst

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