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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"

26042 results found.

  1. GRB 230320B: GRBAlpha detection
  2. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  3. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  4. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  5. IPN triangulation of GRB 230309A
  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 230307A: soft X-ray detection with LEIA
  10. GRB 230307A: Swift-XRT afterglow detection
  11. Swift GRB230311.85: Global MASTER-Net observations report
  12. Swift GRB230311.83: Global MASTER-Net observations report
  13. Further improved IPN localization for GRB 230307A
  14. Swift GRB230311.81: Global MASTER-Net observations report
  15. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  16. Swift GRB230311.84: Global MASTER-Net observations report
  17. Swift Trigger 1159438 is also due to the Star Tracker loss of lock.
  18. Swift GRB230311.82: Global MASTER-Net observations report
  19. Triggers 1159434, 1159435 and 1159437: Swift detection of Sco X-1 due to Star Tracker loss of lock
  20. TESS Detection of the Optical Afterglow of GRB230307A
  21. Trigger 1159327: Swift detection of SGR1806-20
  22. GRB 230307A: GECKO optical observations and detections of the afterglow
  23. GRB 230307A: MAXI/GSC upper limit
  24. GRB 230307A: Gemini-South Confirmation of the Optical Afterglow
  25. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  26. GRB 230307A: Erratum of the GCN 33441
  27. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  28. GRB 230307A: Possible optical afterglow
  29. GRB 230307A: ASO-S/HXI detection
  30. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  31. GRB 230307A: optical upper limit
  32. GRB 230217A: ATCA rapid-response radio detection
  33. Swift Trigger 1159108 is not a GRB
  34. GRB 230307A: Swift/BAT upper limits on the early afterglow
  35. GRB 230307A: Swift-XRT observations
  36. GRB 230228A: VIRT Optical Upper Limit
  37. Improved IPN localization for GRB 230307A
  38. GRB 230307A: Tiled Swift observations
  39. IPN triangulation of GRB 230307A (long/very bright)
  40. GRB 230228A: 6 GHz VLA radio upper limit
  41. GRB 230228A: Swift-BAT refined analysis
  42. GRB 230228A: Swift/UVOT Upper Limits
  43. GRB 230228A: Fermi GBM Observation
  44. GRB 230228A: OSN optical upper limit
  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: Prompt enhanced Swift-XRT position
  51. GRB 230228A: Swift detection of a possibly short burst
  52. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  53. GRB 230216A Mondy Observations
  54. GRB 230205A: VLA radio afterglow confirmation
  55. GRB 230217A: Swift/UVOT Upper Limits
  56. GRB 230216A: Swift/UVOT Upper Limits
  57. GRB 230217A: Continued Gemini Observations
  58. GRB 230217A: Swift-XRT afterglow detection
  59. GRB 230217A: Swift-BAT refined analysis
  60. GRB 230217A: AstroSat CZTI detection
  61. GRB 230217A: Gemini South optical upper limits
  62. GRB 230217A: 6 GHz VLA observations
  63. GRB 230217A: Fermi GBM observation
  64. Konus-Wind detection of GRB 230217A
  65. GRB 230217A: Swift-XRT observations
  66. GRB 230217A: AGILE/MCAL detection
  67. GRB 230207B: CALET Gamma-Ray Burst Monitor detection
  68. GRB 230216A: SVOM/C-GFT optical upper limit
  69. GRB 230217A: Swift detection of a short burst
  70. GRB 230216A: Swift-BAT refined analysis
  71. GRB 230216A: Swift-XRT refined Analysis
  72. GRB 230205A: Lowell Discovery Telescope Observations
  73. Swift GRB 230216A: Global MASTER-Net observations report
  74. GRB 230216A: Enhanced Swift-XRT position
  75. GRB 230216A: AKO Upper Limit
  76. GRB 230216A: Zadko observatory - Gingin optical observations
  77. GRB 230216A: Swift detection of a burst
  78. GRB 230209B: AGILE detection
  79. GRB 230209B: Fermi GBM Observation
  80. IPN triangulation of GRB 230209B
  81. GRB 230204B: CALET Gamma-Ray Burst Monitor detection
  82. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  83. Swift Trigger 1153670 is probably not a GRB
  84. GRB 230205A: 6 GHz VLA observations
  85. GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
  86. GRB 221009A: Continued Swift Observations
  87. GRB 230207B: Detection by GRBAlpha
  88. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  89. GRB 230207B: Swift/BAT-GUANO detection outside the coded FOV
  90. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  91. GRB 230204B: Swift/UVOT Upper Limits
  92. GRB 230205A: Swift/UVOT Upper Limits
  93. GRB 230204B: Fermi GBM detection
  94. GRB 230205A: LCOGT Optical Upper Limits
  95. GRB 230204B: Swift-XRT afterglow detection
  96. GRB 230205A: SVOM/C-GFT optical upper limit
  97. GRB 230204B: VLT/X-shooter redshift
  98. GRB 230205A: Swift-BAT refined analysis (T90 = 2.3 s)
  99. GRB 230204A: Swift-BAT refined analysis
  100. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group

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