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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. IPN triangulation of GRB 230815B
  2. GRB 230816A: Nanshan/HMT optical afterglow detection
  3. GRB 230815A: SOAR/Goodman follow-up imaging
  4. Swift GRB230816.67: Global MASTER-Net observations report
  5. GRB 230816A: Swift detection of a burst
  6. GRB 230815A: Swift-BAT refined analysis
  7. GRB 230815B: GECAM-B and GECAM-C detection of a burst
  8. GRB 230815B: AstroSat CZTI detection
  9. GRB230815A: Swift/UVOT upper limits
  10. GRB 230812B: GAD Observatory optical observations (upper limit)
  11. GRB 230815A: Swift-XRT refined Analysis
  12. GRB 230812B: iTelescope optical upper limit
  13. GRB 230812B: continued SAO RAS optical observation
  14. GRB230815A: BOOTES-6/DPRT optical upper limit
  15. GRB 230815A: Fermi GBM detection
  16. Swift GRB 230815A: Global MASTER-Net observations report
  17. Fermi GRB 230814A: Global MASTER-Net observations report
  18. GRB 230815A: Enhanced Swift-XRT position
  19. GRB 230812B: Iota Scorpii Observatory, La Spezia, Italy
  20. GRB 230812B: Tautenburg observations
  21. GRB 230815A: Swift detection of a burst
  22. GRB 230812B: AMI-LA radio detection of afterglow candidate
  23. GRB 230812B: continued AbAO optical afterglow observations
  24. GRB 230812B: Optical observaions from Rozhen Observatory
  25. GRB 230812B: Further Bassano Bresciano Observatory optical observations
  26. LIGO/Virgo/KAGRA S230814ah: Identification of a GW compact binary merger candidate
  27. GRB 230812B: further SAO RAS optical observations
  28. GRB 230812B: Upper limits from a neutrino search with IceCube
  29. LIGO/Virgo/KAGRA S230814r: Updated Sky localization
  30. GRB 230812B: GRANDMA further observations of ZTF23aaxeacr candidate afterglow
  31. GRB 230814A: BALROG localization (Fermi Trigger 713732101 / GRB 230814788)
  32. GRB 230812B: CrAO ZTSh optical observations
  33. GRB 230814A: Fermi GBM Final Real-time Localization
  34. GRB 230812B: Koshka Zeiss-1000 optical observations
  35. GRB 230812B: GIT optical follow-up
  36. GRB 230812B: Leavitt Observatory optical observations
  37. GRB 230812B : optical observations from Observatoire de Haute-Provence
  38. GRB 230812B: Bassano Bresciano Observatory optical observations
  39. GRB 230812B: Faulkes Telescope North optical afterglow follow-up
  40. GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
  41. GRB 230812B: rest-frame energetics from Konus-Wind observation
  42. GRB 230812B: OASDG optical observations
  43. GRB 230812B: AbAO optical observations
  44. LIGO/Virgo/KAGRA S230814r: Identification of a GW compact binary merger candidate
  45. GRB 230812B: Spectroscopy from NOT
  46. GRB 230812B: Redshift from OSIRIS+/GTC
  47. GRB 230812B: Montarrenti Observatory optical observations
  48. LIGO/Virgo/KAGRA S230812aj: two counterpart neutrino candidates from IceCube neutrino searches
  49. GRB 230812B: SAO RAS optical observations
  50. GRB 230812B: Detected Optical Afterglow Candidate
  51. GRB 230812B: GMG - GRANDMA observations
  52. Konus-Wind detection of GRB 230812B
  53. GRB230812B: AGILE/MCAL detection
  54. GRB 230812B: GECAM-C observation of a very bright burst
  55. GRB 230812B: Swift-XRT afterglow detection
  56. GRB 230812: Swift/UVOT Detection
  57. GOTO confirmation and possible host galaxy of GRB230812B optical afterglow
  58. GRB 230812B: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi GRB (Trigger 713559497)
  59. Fermi GRB 230812B: MASTER optical counterpart
  60. GRB 230812B: KAIT Optical Afterglow Candidate
  61. GRB 230812B: Improved Swift/XRT localization
  62. GRB 230812B: Preliminary Swift/XRT localization
  63. GRB 230812B: Fermi-LAT detection
  64. GRB 230812B: Fermi GBM Observation of a very bright burst
  65. LAT GRB230812.79: Global MASTER-Net observations report
  66. Fermi GRB 230812B: Global MASTER-Net observations report
  67. GRB 230812B: Tiled Swift observations
  68. GRB 230812B: Fermi GBM detection of an extremely bright GRB
  69. GRB 230812B: Fermi GBM Final Real-time Localization
  70. ZTF23aaoohpy/AT2023lcr: JWST spectroscopy confirmation of an associated type Ic-BL supernova
  71. Fermi trigger No 713525317: Global MASTER-Net observations report
  72. GRB 230812A: Fermi GBM Final Real-time Localization
  73. LIGO/Virgo/KAGRA S230811n: Updated Sky localization
  74. GRB 230808A: Fermi GBM Detection
  75. LIGO/Virgo/KAGRA S230811n: Identification of a GW compact binary merger candidate
  76. GRB 230805B: Swift-BAT refined analysis
  77. LIGO/Virgo/KAGRA S230810af: Retraction of GW compact binary merger candidate
  78. GRB 230805B: Iota Scorpii Observatory, La Spezia, Italy upper limit
  79. GRB 230805B: AstroSat CZTI detection
  80. GRB 230808A: Swift/BAT-GUANO detection of a burst
  81. Fermi trigger No 713136868: Global MASTER-Net observations report
  82. GRB 230808B: Fermi GBM Final Real-time Localization
  83. The Fermi GBM Trigger 713134237 / 230807868 is not associated with LIGO/Virgo/KAGRA S230807f.
  84. Fermi trigger No 713205976: Global MASTER-Net observations report
  85. ZTF23aaoohpy/AT2023lcr: JWST observations consistent with the presence of a supernova
  86. GRB 230808A: Fermi GBM Final Real-time Localization
  87. GRB 230805B : MITSuME Akeno optical upper limits
  88. LIGO/Virgo/KAGRA S230808i: retraction of a GW unmodeled transient candidate
  89. LIGO/Virgo/KAGRA S230808i: Identification of a GW unmodeled transient candidate
  90. LIGO/Virgo/KAGRA S230807f: Updated Sky localization and EM Bright Classification
  91. transient SPT-SVJ025406.5-702837: ATCA follow-up observations
  92. Fermi GRB 230807A: Global MASTER-Net observations report
  93. Fermi trigger No 713134237: Global MASTER-Net observations report
  94. GRB 230807A: Fermi GBM Final Real-time Localization
  95. LIGO/Virgo/KAGRA S230807f: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo/KAGRA S230805x: Upper limits from Swift/BAT-GUANO
  97. Konus-Wind detection of GRB 230803A
  98. GRB 230805B: Fermi GBM observation
  99. GRB 230805B : OHP/T193 optical upper limit
  100. LIGO/Virgo/KAGRA S230806ak: Updated Sky localization and EM Bright Classification

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