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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: NOEMA detection
  2. GRB 230815A: VLT/HAWK-I near-infrared afterglow detection
  3. Fermi GRB 230817A: Global MASTER-Net observations report
  4. GRB 230817A: BALROG localization (Fermi Trigger 713966581 / GRB 230817502)
  5. GRB 230817A: Fermi GBM Final Real-time Localization
  6. GRB 230812B: optical photometry from Konkoly
  7. GRB 230816A: Enhanced Swift-XRT position
  8. GRB 230812B: SAO RAS optical observations
  9. GRB230816A: Possible host and GIT detection of optical counterpart
  10. GRB 230816A: Tautenburg observations
  11. GRB 230816A: AKO Optical Observations
  12. GRB 230816A: TShAO and Assy optical observations
  13. GRB 230816A: SAO RAS optical observations
  14. Swift GRB230816.80: Global MASTER-Net observations report
  15. IPN triangulation of GRB 230815B
  16. GRB 230816A: Nanshan/HMT optical afterglow detection
  17. GRB 230815A: SOAR/Goodman follow-up imaging
  18. Swift GRB230816.67: Global MASTER-Net observations report
  19. GRB 230816A: Swift detection of a burst
  20. GRB 230815A: Swift-BAT refined analysis
  21. GRB 230815B: GECAM-B and GECAM-C detection of a burst
  22. GRB 230815B: AstroSat CZTI detection
  23. GRB230815A: Swift/UVOT upper limits
  24. GRB 230812B: GAD Observatory optical observations (upper limit)
  25. GRB 230815A: Swift-XRT refined Analysis
  26. GRB 230812B: iTelescope optical upper limit
  27. GRB 230812B: continued SAO RAS optical observation
  28. GRB230815A: BOOTES-6/DPRT optical upper limit
  29. GRB 230815A: Fermi GBM detection
  30. Swift GRB 230815A: Global MASTER-Net observations report
  31. Fermi GRB 230814A: Global MASTER-Net observations report
  32. GRB 230815A: Enhanced Swift-XRT position
  33. GRB 230812B: Iota Scorpii Observatory, La Spezia, Italy
  34. GRB 230812B: Tautenburg observations
  35. GRB 230815A: Swift detection of a burst
  36. GRB 230812B: AMI-LA radio detection of afterglow candidate
  37. GRB 230812B: continued AbAO optical afterglow observations
  38. GRB 230812B: Optical observaions from Rozhen Observatory
  39. GRB 230812B: Further Bassano Bresciano Observatory optical observations
  40. LIGO/Virgo/KAGRA S230814ah: Identification of a GW compact binary merger candidate
  41. GRB 230812B: further SAO RAS optical observations
  42. GRB 230812B: Upper limits from a neutrino search with IceCube
  43. LIGO/Virgo/KAGRA S230814r: Updated Sky localization
  44. GRB 230812B: GRANDMA further observations of ZTF23aaxeacr candidate afterglow
  45. GRB 230814A: BALROG localization (Fermi Trigger 713732101 / GRB 230814788)
  46. GRB 230812B: CrAO ZTSh optical observations
  47. GRB 230814A: Fermi GBM Final Real-time Localization
  48. GRB 230812B: Koshka Zeiss-1000 optical observations
  49. GRB 230812B: GIT optical follow-up
  50. GRB 230812B: Leavitt Observatory optical observations
  51. GRB 230812B : optical observations from Observatoire de Haute-Provence
  52. GRB 230812B: Bassano Bresciano Observatory optical observations
  53. GRB 230812B: Faulkes Telescope North optical afterglow follow-up
  54. GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
  55. GRB 230812B: rest-frame energetics from Konus-Wind observation
  56. GRB 230812B: OASDG optical observations
  57. GRB 230812B: AbAO optical observations
  58. LIGO/Virgo/KAGRA S230814r: Identification of a GW compact binary merger candidate
  59. GRB 230812B: Spectroscopy from NOT
  60. GRB 230812B: Redshift from OSIRIS+/GTC
  61. GRB 230812B: Montarrenti Observatory optical observations
  62. LIGO/Virgo/KAGRA S230812aj: two counterpart neutrino candidates from IceCube neutrino searches
  63. GRB 230812B: SAO RAS optical observations
  64. GRB 230812B: Detected Optical Afterglow Candidate
  65. GRB 230812B: GMG - GRANDMA observations
  66. Konus-Wind detection of GRB 230812B
  67. GRB230812B: AGILE/MCAL detection
  68. GRB 230812B: GECAM-C observation of a very bright burst
  69. GRB 230812B: Swift-XRT afterglow detection
  70. GRB 230812: Swift/UVOT Detection
  71. GOTO confirmation and possible host galaxy of GRB230812B optical afterglow
  72. GRB 230812B: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi GRB (Trigger 713559497)
  73. Fermi GRB 230812B: MASTER optical counterpart
  74. GRB 230812B: KAIT Optical Afterglow Candidate
  75. GRB 230812B: Improved Swift/XRT localization
  76. GRB 230812B: Preliminary Swift/XRT localization
  77. GRB 230812B: Fermi-LAT detection
  78. GRB 230812B: Fermi GBM Observation of a very bright burst
  79. LAT GRB230812.79: Global MASTER-Net observations report
  80. Fermi GRB 230812B: Global MASTER-Net observations report
  81. GRB 230812B: Tiled Swift observations
  82. GRB 230812B: Fermi GBM detection of an extremely bright GRB
  83. GRB 230812B: Fermi GBM Final Real-time Localization
  84. ZTF23aaoohpy/AT2023lcr: JWST spectroscopy confirmation of an associated type Ic-BL supernova
  85. Fermi trigger No 713525317: Global MASTER-Net observations report
  86. GRB 230812A: Fermi GBM Final Real-time Localization
  87. LIGO/Virgo/KAGRA S230811n: Updated Sky localization
  88. GRB 230808A: Fermi GBM Detection
  89. LIGO/Virgo/KAGRA S230811n: Identification of a GW compact binary merger candidate
  90. GRB 230805B: Swift-BAT refined analysis
  91. LIGO/Virgo/KAGRA S230810af: Retraction of GW compact binary merger candidate
  92. GRB 230805B: Iota Scorpii Observatory, La Spezia, Italy upper limit
  93. GRB 230805B: AstroSat CZTI detection
  94. GRB 230808A: Swift/BAT-GUANO detection of a burst
  95. Fermi trigger No 713136868: Global MASTER-Net observations report
  96. GRB 230808B: Fermi GBM Final Real-time Localization
  97. The Fermi GBM Trigger 713134237 / 230807868 is not associated with LIGO/Virgo/KAGRA S230807f.
  98. Fermi trigger No 713205976: Global MASTER-Net observations report
  99. ZTF23aaoohpy/AT2023lcr: JWST observations consistent with the presence of a supernova
  100. GRB 230808A: Fermi GBM Final Real-time Localization

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