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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 230818A: Leavitt Observatory upper limit
  2. GRB 230818A: Swift-XRT refined Analysis
  3. GRB 230818A: Bassano Bresciano Observatory optical observations
  4. GRB 230818A: KGO RC-25 optical observations
  5. GRB 230818A: Swift/UVOT Detection
  6. GRB 230818A: NOT photometry and spectroscopy
  7. GRB 230818A: Enhanced Swift-XRT position
  8. GRB 230818A: SAO RAS Zeiss-1000 observations
  9. Fermi GRB 230818A: Global MASTER-Net observations report
  10. Fermi trigger No 713974668: Global MASTER-Net observations report
  11. GRB 230818A: GOTO optical afterglow detection
  12. GRB 230818A: Swift detection of a burst
  13. GRB 230818A: Fermi GBM Final Real-time Localization
  14. Swift GRB230818.98: Global MASTER-Net observations report
  15. Swift GRB230818.98: Global MASTER-Net OT detection
  16. GRB 230812B: SAO RAS observations, possible re-brightening
  17. GRB 230816A: Swift-BAT refined analysis
  18. GRB 230816A: SVOM/C-GFT optical detection
  19. GRB 230817A: AstroSat CZTI detection
  20. GRB 230812B: SAO RAS optical observations
  21. GRB 230816A: Swift-XRT refined Analysis
  22. GRB 230816A: Osservatorio Astronomico "Nastro Verde" optical observations
  23. GRB 230812B: NOEMA detection
  24. GRB 230815A: VLT/HAWK-I near-infrared afterglow detection
  25. Fermi GRB 230817A: Global MASTER-Net observations report
  26. GRB 230817A: BALROG localization (Fermi Trigger 713966581 / GRB 230817502)
  27. GRB 230817A: Fermi GBM Final Real-time Localization
  28. GRB 230812B: optical photometry from Konkoly
  29. GRB 230816A: Enhanced Swift-XRT position
  30. GRB 230812B: SAO RAS optical observations
  31. GRB230816A: Possible host and GIT detection of optical counterpart
  32. GRB 230816A: Tautenburg observations
  33. GRB 230816A: AKO Optical Observations
  34. GRB 230816A: TShAO and Assy optical observations
  35. GRB 230816A: SAO RAS optical observations
  36. Swift GRB230816.80: Global MASTER-Net observations report
  37. IPN triangulation of GRB 230815B
  38. GRB 230816A: Nanshan/HMT optical afterglow detection
  39. GRB 230815A: SOAR/Goodman follow-up imaging
  40. Swift GRB230816.67: Global MASTER-Net observations report
  41. GRB 230816A: Swift detection of a burst
  42. GRB 230815A: Swift-BAT refined analysis
  43. GRB 230815B: GECAM-B and GECAM-C detection of a burst
  44. GRB 230815B: AstroSat CZTI detection
  45. GRB230815A: Swift/UVOT upper limits
  46. GRB 230812B: GAD Observatory optical observations (upper limit)
  47. GRB 230815A: Swift-XRT refined Analysis
  48. GRB 230812B: iTelescope optical upper limit
  49. GRB 230812B: continued SAO RAS optical observation
  50. GRB230815A: BOOTES-6/DPRT optical upper limit
  51. GRB 230815A: Fermi GBM detection
  52. Swift GRB 230815A: Global MASTER-Net observations report
  53. Fermi GRB 230814A: Global MASTER-Net observations report
  54. GRB 230815A: Enhanced Swift-XRT position
  55. GRB 230812B: Iota Scorpii Observatory, La Spezia, Italy
  56. GRB 230812B: Tautenburg observations
  57. GRB 230815A: Swift detection of a burst
  58. GRB 230812B: AMI-LA radio detection of afterglow candidate
  59. GRB 230812B: continued AbAO optical afterglow observations
  60. GRB 230812B: Optical observaions from Rozhen Observatory
  61. GRB 230812B: Further Bassano Bresciano Observatory optical observations
  62. LIGO/Virgo/KAGRA S230814ah: Identification of a GW compact binary merger candidate
  63. GRB 230812B: further SAO RAS optical observations
  64. GRB 230812B: Upper limits from a neutrino search with IceCube
  65. LIGO/Virgo/KAGRA S230814r: Updated Sky localization
  66. GRB 230812B: GRANDMA further observations of ZTF23aaxeacr candidate afterglow
  67. GRB 230814A: BALROG localization (Fermi Trigger 713732101 / GRB 230814788)
  68. GRB 230812B: CrAO ZTSh optical observations
  69. GRB 230814A: Fermi GBM Final Real-time Localization
  70. GRB 230812B: Koshka Zeiss-1000 optical observations
  71. GRB 230812B: GIT optical follow-up
  72. GRB 230812B: Leavitt Observatory optical observations
  73. GRB 230812B : optical observations from Observatoire de Haute-Provence
  74. GRB 230812B: Bassano Bresciano Observatory optical observations
  75. GRB 230812B: Faulkes Telescope North optical afterglow follow-up
  76. GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
  77. GRB 230812B: rest-frame energetics from Konus-Wind observation
  78. GRB 230812B: OASDG optical observations
  79. GRB 230812B: AbAO optical observations
  80. LIGO/Virgo/KAGRA S230814r: Identification of a GW compact binary merger candidate
  81. GRB 230812B: Spectroscopy from NOT
  82. GRB 230812B: Redshift from OSIRIS+/GTC
  83. GRB 230812B: Montarrenti Observatory optical observations
  84. LIGO/Virgo/KAGRA S230812aj: two counterpart neutrino candidates from IceCube neutrino searches
  85. GRB 230812B: SAO RAS optical observations
  86. GRB 230812B: Detected Optical Afterglow Candidate
  87. GRB 230812B: GMG - GRANDMA observations
  88. Konus-Wind detection of GRB 230812B
  89. GRB230812B: AGILE/MCAL detection
  90. GRB 230812B: GECAM-C observation of a very bright burst
  91. GRB 230812B: Swift-XRT afterglow detection
  92. GRB 230812: Swift/UVOT Detection
  93. GOTO confirmation and possible host galaxy of GRB230812B optical afterglow
  94. GRB 230812B: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi GRB (Trigger 713559497)
  95. Fermi GRB 230812B: MASTER optical counterpart
  96. GRB 230812B: KAIT Optical Afterglow Candidate
  97. GRB 230812B: Improved Swift/XRT localization
  98. GRB 230812B: Preliminary Swift/XRT localization
  99. GRB 230812B: Fermi-LAT detection
  100. GRB 230812B: Fermi GBM Observation of a very bright burst

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