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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"

43605 results found.

  1. GRB 150428B: MASTER-net prompt optical observation
  2. Fermi GBM trigger 150424722 is not a GRB
  3. GRB 150428A: MASTER-net early optical observation
  4. GRB 150428A: Swift-XRT refined Analysis
  5. GRB 150428B: Swift-BAT refined analysis
  6. GRB 150428C: Tiled Swift observations
  7. GRB 150428A: Swift-BAT refined analysis
  8. GRB 150428B: Enhanced Swift-XRT position
  9. GRB 150428C/MAXI J0400+678: MAXI/GSC detection
  10. GRB 150428A: Danish1.56m optical observations
  11. GRB 150428A: RATIR optical observations
  12. GRB 150428A: P60 observations
  13. GRB 150428A: Enhanced Swift-XRT position
  14. GRB 150428A: GROND Dark Burst Host Candidate
  15. GRB 150428B: Swift detection of a burst
  16. GRB 150428A: Swift detection of a burst
  17. Trigger 639199: Swift detection of IGRJ16418-4532
  18. GRB 150424A: RATIR Observations
  19. GRB 150424A: Swift-BAT refined analysis
  20. GRB 150424A: Swift-XRT refined Analysis
  21. GRB 150424A: spectral lag, extended-time emission
  22. GRB 150424A: 10.4m GTC spectroscopy
  23. GRB 150424A: GROND detects strong fading
  24. GRB 150424A: NOT optical observations
  25. GRB 150423A: VLT/X-shooter spectroscopy and tentative redshift
  26. GRB 150423A: Continued RATIR optical afterglow monitoring
  27. GRB 150424B: Fermi GBM detection
  28. Konus-Wind observation of GRB 150424A
  29. GRB 150424A: Swift/UVOT Observations
  30. GRB 150423A: TSHAO optical observations
  31. GRB 150424A: Enhanced Swift-XRT position
  32. GRB 150424B: Tiled Swift observations
  33. GRB 150423A: WHT observations
  34. GRB 150424B: MAXI/GSC detection
  35. GRB 150424A: Keck detection of optical afterglow
  36. GRB 150423A: Keck redshift of neighboring galaxy
  37. GRB 150424A: Swift detection of a short burst
  38. GRB 150423A: UKIRT NIR observations
  39. GRB 150423A: Swift-BAT refined analysis
  40. GRB 150423A: VLT detection
  41. GRB 150423A: Swift-XRT refined Analysis
  42. GRB 150423A: RATIR optical afterglow monitoring
  43. GRB 150423A: Enhanced Swift-XRT position
  44. GRB 150422A: Fermi GBM detection
  45. GRB 150423A: Keck optical afterglow confirmation
  46. GRB 150423A: GROND afterglow candidate
  47. GRB 150413A: Konus-Wind and Swift/BAT joint spectral analysis
  48. GRB 150423A: GROND observation
  49. GRB 150423A: Swift detection of a short burst
  50. Konus-Wind observation of GRB 150418A
  51. GRB150418A: Swift/UVOT did not detect a new source
  52. Further Swift XRT observations of GRB 150418A
  53. Swift trigger 638589 is probably not an astrophysical source
  54. GRB 150413A: Swift-XRT observations
  55. GRB 150418A: Swift-XRT observations
  56. GRB 150413A: RTT150 optical observations
  57. GRB 150418A: Tiled Swift observations
  58. GRB 150418A: MAXI/GSC detection
  59. GRB 150413A: ISON-Ussuriysk optical observations
  60. GRB 150416A: Fermi GBM detection
  61. Confirmation that Swift trigger 638217 is not an astrophysical source
  62. GRB 150413A: SAO RAS observations
  63. Swift Trigger 638217 is probably not an astrophysical source
  64. GRB 150416A: Fermi-LAT detection
  65. GRB 150413A: Refined redshift
  66. GRB 150413A: GMG observation
  67. GRB 150413A: AMI 15 GHz detection of possible radio counterpart
  68. GRB 150413A: additional P60 observations
  69. GRB 150413A : Virtual Telescope optical observations
  70. GRB 150413A
  71. GRB 150413A: Bassano Bresciano Observatory optical observations
  72. Konus-Wind observation of a bright burst from SGR 1935+2154
  73. GRB 150413A: T7 and T18 optical observations
  74. GRB 150413A: Swift-BAT refined analysis
  75. GRB150413A, optical observations
  76. IPN Triangulation of a bright burst from SGR 1935+2154
  77. GRB 150413A: optical observations
  78. GRB 150413A: redshift determination with the 2.2m CAHA
  79. GRB 150413A: P60 photometry
  80. GRB 150413A: Khureltogot optical observations
  81. GRB 150413A: Tautenburg observations
  82. GRB 150413A: Nanshan optical and radio follow-ups
  83. GRB 150413A: Khureltogot optical observations
  84. GRB 150413A: MAXI/GSC detection
  85. GRB 150413A: MASTER very bright unusual OT observations
  86. GRB 150413A: MASTER bright OT detection
  87. GRB 150413A: Swift detection of a burst
  88. Swift trigger 637807 is probably not an astrophysical source
  89. Swift detection of SAX J1808.4-3658
  90. Swift GRB150402A: further XRT observations
  91. GRB 150407A: Swift-XRT observations
  92. GRB 150407A: optical observations
  93. GRB 150407A: Swift detection of a possible burst
  94. GRB 150407A: Swift ToO observations
  95. GRB 150403A: MASTER-net optical observation
  96. Swift triggered on a source in Terzan 5 (trigger=637212)
  97. GRB 150404A: Fermi GBM detection
  98. Konus-Wind observation of GRB 150403A
  99. Fermi trigger 449861706: MASTER-SAAO possible candidate to OT of Short GRB
  100. GRB 150403A: Swift-BAT refined analysis

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