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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 171222A: Swift-BAT refined analysis
  2. GRB 171222A: AROMA-N optical observation
  3. GRB 171223A: Fermi GBM detection
  4. GRB 171222A: Fermi GBM detection
  5. GRB 171222A: Nanshan-0.36m optical upper limit
  6. GRB 171222A: Swift/UVOT Upper Limits
  7. GRB 171222A: Nanshan-1m optical afterglow detection
  8. GRB 171222A: MASTER-Net OT observations
  9. GRB 171222A: Redshift from 10.4m GTC/OSIRIS
  10. GRB 171222A: Swift-XRT refined Analysis
  11. GRB 171205A: SMARTS optical/IR supernova monitoring
  12. GRB 171222A: NOT Optical Afterglow
  13. GRB 171216B CALET Gamma-Ray Burst Monitor detection
  14. GRB 171210A CALET Gamma-Ray Burst Monitor detection
  15. GRB 171222A: Enhanced Swift-XRT position
  16. GRB 171222A: Swift detection of a burst
  17. GMRT Radio detection of GRB 171205A
  18. IPN Triangulation of GRB 171216B
  19. GRB 171216A: Swift/UVOT Upper Limits
  20. GRB 171210A: Further Swift-XRT observations
  21. GRB 171216A: Swift-XRT refined Analysis
  22. GRB 171216A: Swift-BAT refined analysis
  23. GRB 171205A: RATAN observations
  24. GRB 171216A: Enhanced Swift-XRT position
  25. GRB 171216A: Swift detection of a burst
  26. Swift Trigger 797070: KAIT Optical Observations
  27. Swift Trigger 797070 is probably not a GRB
  28. GRB 171212A/Swift J1935.7+2036: Swift-BAT refined analysis
  29. GRB 171205A: ALMA observations
  30. GRB 171212A: Swift-XRT refined Analysis
  31. GRB 171211A iTelescope observation
  32. GRB 171212B: Fermi GBM observation
  33. GRB 171212A/Swift J1935.7+2036: Swift/UVOT Upper Limits
  34. GRB 171212B: Fermi-LAT detection
  35. GRB 171212A/Swift J1935.7+2036: TSHAO optical observations
  36. GRB 171212A: Enhanced Swift-XRT position
  37. Konus-Wind observation of GRB 171210A
  38. GRB 171212A: Swift detection of a burst or a Galactic transient
  39. GRB 171205A: JCMT SCUBA-2 sub-mm observations
  40. GRB 171211A: Swift-BAT refined analysis
  41. GRB 171211A: Swift-XRT refined Analysis
  42. GRB 171211A: Swift/UVOT Upper Limits
  43. GRB 171210A: MASTER-Net optical observations
  44. GRB 171209A: MASTER-Net optical observations
  45. GRB 171211A: Enhanced Swift-XRT position
  46. GRB 171210A: Swift-XRT and UVOT observations
  47. GRB 171211A: Swift detection of a possibly short burst
  48. GRB 171210A: Fermi GBM detection
  49. GRB 171210A: Swift ToO observations
  50. Correction to GCN 22184: GRB 171205A: Swift-BAT refined analysis
  51. GRB 171209A: Lulin 1m telescope observations
  52. GRB 171209A: Swift-BAT refined analysis
  53. GRB 171210A: Fermi-LAT detection
  54. Konus-Wind observation of GRB 171205A
  55. GRB 171205A: MASTER-Net OT recent photometry
  56. GRB 171205A: iTelescope optical observations
  57. GRB 171205A: Mondy optical observations
  58. GRB 171205A: SAO-RAS optical observations
  59. GMRT upper limit on GRB 171205A
  60. GRB 171209A: Swift/UVOT Analysis of the burst
  61. Swift trigger 796115 is not astrophysical
  62. GRB 171209A: Swift-XRT refined Analysis
  63. GRB 171209A: Enhanced Swift-XRT position
  64. Swift Trigger 796115 is probably not a GRB
  65. GRB 171205A: VLA detection
  66. GRB 171205A: UKIRT near-IR observations
  67. GRB 171209A: LCO 1-m telescope observations
  68. GRB 171209A: Swift detection of a burst
  69. Swift Trigger 796098 is probably a noise peak near M31
  70. LIGO/Virgo GW170817: X-ray observations confirm prediction made from radio data
  71. GRB 171124A CALET Gamma-Ray Burst Monitor detection
  72. GRB 171120A CALET Gamma-Ray Burst Monitor detection
  73. GRB 171106A CALET Gamma-Ray Burst Monitor detection
  74. LIGO/Virgo GW170817: Further Hubble Space Telescope observations
  75. LIGO/Virgo G298048: Brightening X-ray Emission from GW170817/GRB170817A/SSS17a
  76. GRB 171205A: TSHAO optical observations
  77. GRB 171205A: Detection of the emerging SN
  78. LIGO/Virgo GW170817: Chandra X-ray brightening of the counterpart 108 days since merger
  79. GRB 171205A: Continued Swift/UVOT Observations
  80. LIGO/Virgo G298048: Late-time detection of the X-ray afterglow with Chandra
  81. Fermi GBM trigger 534174346/171205573 is not a GRB
  82. GRB 171205A: MASTER-SAAO optical observations of unusual OT
  83. GRB 171205A: GROND observations of the optical/NIR transient
  84. GRB 171205A: LCO 1-m telescope observations
  85. GRB171205A hyperluminal radio afterglow?
  86. GRB 171205A: GMG observations (2nd night)
  87. GRB 171205A: Host galaxy photometric properties
  88. GRB 171205A: CHILESCOPE optical observations
  89. GRB 171205A: SMARTS optical/IR afterglow observations
  90. Possible blackbody component in the X-ray spectrum of GRB171205A
  91. GRB 171205A: GOTO detection of the optical counterpart
  92. GRB 171205A: TNG NIR detections
  93. GRB 171205A: LSGT optical afterglow follow-up observation
  94. GRB 171205A: NOEMA detection of a bright mm afterglow
  95. GRB 171205A: GMG observation
  96. Fermi Gamma-ray Burst Monitor trigger 534174346/171205573 is not a GRB
  97. GRB 171205A: Swift-BAT refined analysis
  98. GRB 171205A: Swift-XRT refined Analysis
  99. GRB 171205A: RATIR Optical and NIR Observations
  100. GRB 171205A: Swift/UVOT Detection

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