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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 230812B: SAO RAS optical observations
  2. GRB230816A: Possible host and GIT detection of optical counterpart
  3. GRB 230816A: Tautenburg observations
  4. GRB 230816A: AKO Optical Observations
  5. GRB 230816A: TShAO and Assy optical observations
  6. GRB 230816A: SAO RAS optical observations
  7. Swift GRB230816.80: Global MASTER-Net observations report
  8. IPN triangulation of GRB 230815B
  9. GRB 230816A: Nanshan/HMT optical afterglow detection
  10. GRB 230815A: SOAR/Goodman follow-up imaging
  11. Swift GRB230816.67: Global MASTER-Net observations report
  12. GRB 230816A: Swift detection of a burst
  13. GRB 230815A: Swift-BAT refined analysis
  14. GRB 230815B: GECAM-B and GECAM-C detection of a burst
  15. GRB 230815B: AstroSat CZTI detection
  16. GRB230815A: Swift/UVOT upper limits
  17. GRB 230812B: GAD Observatory optical observations (upper limit)
  18. GRB 230815A: Swift-XRT refined Analysis
  19. GRB 230812B: iTelescope optical upper limit
  20. GRB 230812B: continued SAO RAS optical observation
  21. GRB230815A: BOOTES-6/DPRT optical upper limit
  22. GRB 230815A: Fermi GBM detection
  23. Swift GRB 230815A: Global MASTER-Net observations report
  24. Fermi GRB 230814A: Global MASTER-Net observations report
  25. GRB 230815A: Enhanced Swift-XRT position
  26. GRB 230812B: Iota Scorpii Observatory, La Spezia, Italy
  27. GRB 230812B: Tautenburg observations
  28. GRB 230815A: Swift detection of a burst
  29. GRB 230812B: AMI-LA radio detection of afterglow candidate
  30. GRB 230812B: continued AbAO optical afterglow observations
  31. GRB 230812B: Optical observaions from Rozhen Observatory
  32. GRB 230812B: Further Bassano Bresciano Observatory optical observations
  33. LIGO/Virgo/KAGRA S230814ah: Identification of a GW compact binary merger candidate
  34. GRB 230812B: further SAO RAS optical observations
  35. GRB 230812B: Upper limits from a neutrino search with IceCube
  36. LIGO/Virgo/KAGRA S230814r: Updated Sky localization
  37. GRB 230812B: GRANDMA further observations of ZTF23aaxeacr candidate afterglow
  38. GRB 230814A: BALROG localization (Fermi Trigger 713732101 / GRB 230814788)
  39. GRB 230812B: CrAO ZTSh optical observations
  40. GRB 230814A: Fermi GBM Final Real-time Localization
  41. GRB 230812B: Koshka Zeiss-1000 optical observations
  42. GRB 230812B: GIT optical follow-up
  43. GRB 230812B: Leavitt Observatory optical observations
  44. GRB 230812B : optical observations from Observatoire de Haute-Provence
  45. GRB 230812B: Bassano Bresciano Observatory optical observations
  46. GRB 230812B: Faulkes Telescope North optical afterglow follow-up
  47. GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
  48. GRB 230812B: rest-frame energetics from Konus-Wind observation
  49. GRB 230812B: OASDG optical observations
  50. GRB 230812B: AbAO optical observations
  51. LIGO/Virgo/KAGRA S230814r: Identification of a GW compact binary merger candidate
  52. GRB 230812B: Spectroscopy from NOT
  53. GRB 230812B: Redshift from OSIRIS+/GTC
  54. GRB 230812B: Montarrenti Observatory optical observations
  55. LIGO/Virgo/KAGRA S230812aj: two counterpart neutrino candidates from IceCube neutrino searches
  56. GRB 230812B: SAO RAS optical observations
  57. GRB 230812B: Detected Optical Afterglow Candidate
  58. GRB 230812B: GMG - GRANDMA observations
  59. Konus-Wind detection of GRB 230812B
  60. GRB230812B: AGILE/MCAL detection
  61. GRB 230812B: GECAM-C observation of a very bright burst
  62. GRB 230812B: Swift-XRT afterglow detection
  63. GRB 230812: Swift/UVOT Detection
  64. GOTO confirmation and possible host galaxy of GRB230812B optical afterglow
  65. GRB 230812B: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi GRB (Trigger 713559497)
  66. Fermi GRB 230812B: MASTER optical counterpart
  67. GRB 230812B: KAIT Optical Afterglow Candidate
  68. GRB 230812B: Improved Swift/XRT localization
  69. GRB 230812B: Preliminary Swift/XRT localization
  70. GRB 230812B: Fermi-LAT detection
  71. GRB 230812B: Fermi GBM Observation of a very bright burst
  72. LAT GRB230812.79: Global MASTER-Net observations report
  73. Fermi GRB 230812B: Global MASTER-Net observations report
  74. GRB 230812B: Tiled Swift observations
  75. GRB 230812B: Fermi GBM detection of an extremely bright GRB
  76. GRB 230812B: Fermi GBM Final Real-time Localization
  77. ZTF23aaoohpy/AT2023lcr: JWST spectroscopy confirmation of an associated type Ic-BL supernova
  78. Fermi trigger No 713525317: Global MASTER-Net observations report
  79. GRB 230812A: Fermi GBM Final Real-time Localization
  80. LIGO/Virgo/KAGRA S230811n: Updated Sky localization
  81. GRB 230808A: Fermi GBM Detection
  82. LIGO/Virgo/KAGRA S230811n: Identification of a GW compact binary merger candidate
  83. GRB 230805B: Swift-BAT refined analysis
  84. LIGO/Virgo/KAGRA S230810af: Retraction of GW compact binary merger candidate
  85. GRB 230805B: Iota Scorpii Observatory, La Spezia, Italy upper limit
  86. GRB 230805B: AstroSat CZTI detection
  87. GRB 230808A: Swift/BAT-GUANO detection of a burst
  88. Fermi trigger No 713136868: Global MASTER-Net observations report
  89. GRB 230808B: Fermi GBM Final Real-time Localization
  90. The Fermi GBM Trigger 713134237 / 230807868 is not associated with LIGO/Virgo/KAGRA S230807f.
  91. Fermi trigger No 713205976: Global MASTER-Net observations report
  92. ZTF23aaoohpy/AT2023lcr: JWST observations consistent with the presence of a supernova
  93. GRB 230808A: Fermi GBM Final Real-time Localization
  94. GRB 230805B : MITSuME Akeno optical upper limits
  95. LIGO/Virgo/KAGRA S230808i: retraction of a GW unmodeled transient candidate
  96. LIGO/Virgo/KAGRA S230808i: Identification of a GW unmodeled transient candidate
  97. LIGO/Virgo/KAGRA S230807f: Updated Sky localization and EM Bright Classification
  98. transient SPT-SVJ025406.5-702837: ATCA follow-up observations
  99. Fermi GRB 230807A: Global MASTER-Net observations report
  100. Fermi trigger No 713134237: Global MASTER-Net observations report

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