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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"

27412 results found.

  1. GRB 230314A: TURBO Optical Upper Limit
  2. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  3. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  4. IPN triangulation of GRB 230309A
  5. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  6. VZLUSAT-2 detection of SGR 1806-20
  7. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  8. GRB 230307A: Swift/UVOT detection
  9. GRB 230313A: BALROG localization (Fermi Trigger 700400328 / GRB 230313485)
  10. GRB 230307A: Swift-XRT afterglow detection
  11. Swift GRB230311.85: Global MASTER-Net observations report
  12. Triggers 1159434, 1159435 and 1159437: Swift detection of Sco X-1 due to Star Tracker loss of lock
  13. Alert from the HAWC Burst Monitor HAWC-230311A
  14. TESS Detection of the Optical Afterglow of GRB230307A
  15. GRB 230307A: GECKO optical observations and detections of the afterglow
  16. GRB 230307A: MAXI/GSC upper limit
  17. Fermi GRB 230310A: Global MASTER-Net observations report
  18. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  19. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  20. GRB 230307A: AstroSat LAXPC detection
  21. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  22. GRB 230308A: AGILE/MCAL detection
  23. GRB 230307A: optical upper limit
  24. Swift Trigger 1159108 is not a GRB
  25. GRB 230307A: Swift/BAT upper limits on the early afterglow
  26. GRB 230307A: Upper limits from a neutrino search with IceCube
  27. GRB 230307A: Swift-XRT observations
  28. Fermi GRB 230307A: Global MASTER-Net observations report
  29. GRB 230228A: VIRT Optical Upper Limit
  30. GRB 230307A: VZLUSAT-2 detection
  31. GRB 230308A: BALROG localization (Fermi Trigger 699975152 / GRB 230308564)
  32. GRB 230307A: BALROG localization (Fermi Trigger 699896651/ GRB 230307656)
  33. GRB 230307A: AstroSat CZTI detection
  34. IPN triangulation of GRB 230307A (long/very bright)
  35. Solar Orbiter STIX observation of GRB 230307A
  36. IceCube-230306A: Upper limits from a search for additional neutrino events in IceCube
  37. Fermi-LAT gamma-ray observations of IceCube-230306A
  38. GRB 230307A: Fermi GBM detection of a very bright GRB
  39. GRB 230307A: GECAM detection of an extremely bright burst
  40. GRB 230228A: Swift-BAT refined analysis
  41. GRB 230228A: Swift/UVOT Upper Limits
  42. GRB 230301B: Fermi GBM Final Real-time Localization
  43. GRB 230228A: Fermi GBM Observation
  44. GRB 230301A: Fermi GBM Final Real-time Localization
  45. GRB 230228A: Swift-XRT refined Analysis
  46. GRB 230228A: Mondy optical upper limit
  47. GRB 230228A: Enhanced Swift-XRT position
  48. GRB 230228A: Nanshan/NEXT optical upper limit
  49. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  50. GRB 230228A: Swift detection of a possibly short burst
  51. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  52. GRB 230216A Mondy Observations
  53. IceCube-230220A: Upper limits from a search for additional neutrino events in IceCube
  54. GRB 230217A: Swift/UVOT Upper Limits
  55. GRB 230216A: Swift/UVOT Upper Limits
  56. GRB 230220A: Correction to GCN 33352
  57. GRB 230217A: Swift-XRT afterglow detection
  58. Fermi-LAT gamma-ray observations of IceCube-230220A
  59. GRB 230217A: Swift-BAT refined analysis
  60. IceCube-230217A: Upper limits from a search for additional neutrino events in IceCube
  61. GRB 230220A: MAXI/GSC detection
  62. Fermi-LAT gamma-ray observations of IceCube-230217A
  63. GRB 230217A: Swift-XRT observations
  64. GRB 230216B: AstroSat CZTI detection
  65. GRB 230217A: Swift detection of a short burst
  66. GRB 230216A: Swift-BAT refined analysis
  67. GRB 230216A: Swift-XRT refined Analysis
  68. GRB 230205A: Lowell Discovery Telescope Observations
  69. GRB 230204B: Lowell Discovery Telescope Observations
  70. GRB 230216A: Enhanced Swift-XRT position
  71. GRB 230216A: AKO Upper Limit
  72. GRB 230216A: Zadko observatory - Gingin optical observations
  73. GRB 230216A: Swift detection of a burst
  74. GRB 230209B: Fermi GBM Observation
  75. IPN triangulation of GRB 230209B
  76. GRB 230204B: ATCA radio detection
  77. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  78. Swift Trigger 1153670 is probably not a GRB
  79. GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
  80. GRB 221009A: Continued Swift Observations
  81. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  82. GRB 230204B: MASTER early OT detection
  83. GRB 230207B: Swift/BAT-GUANO detection outside the coded FOV
  84. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  85. GRB 230207B: AGILE detection of a burst
  86. GRB 230204B: LCOGT Optical Upper Limits
  87. GRB 230204B: Swift/UVOT Upper Limits
  88. GRB 230205A: Swift/UVOT Upper Limits
  89. GRB 230204B: Fermi GBM detection
  90. GRB 230205A: LCOGT Optical Upper Limits
  91. GRB 230204B: Swift-XRT afterglow detection
  92. GRB 230204B: 3.6m DOT optical observation
  93. GRB 230205A: OHP/T193 optical observations
  94. GRB 230205A: Swift-BAT refined analysis (T90 = 2.3 s)
  95. GRB 230204A: Swift-BAT refined analysis
  96. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  97. GRB 230205A: Swift-XRT refined Analysis
  98. GRB 230205A: Enhanced Swift-XRT position
  99. GRB 230205A: Swift detection of a burst
  100. GRB 230204B: GIT discovery of the likely optical afterglow

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