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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"

3401 results found.

  1. Fermi GBM observation of a bright flare in the direction of SGR 1935+2154
  2. Fermi trigger No 652927551: Global MASTER-Net observations report
  3. Fermi trigger No 652911693: Global MASTER-Net observations report
  4. Fermi trigger No 652906639: Global MASTER-Net observations report
  5. Fermi GRB 210909A: Global MASTER-Net observations report
  6. Fermi trigger No 652585475: Global MASTER-Net observations report
  7. GRB 210610A: Maidanak and AbAO optical observations
  8. Fermi GRB 210904A: Global MASTER-Net observations report
  9. Fermi GRB 210827A: Global MASTER-Net observations report
  10. Fermi GRB 210827B: Global MASTER-Net observations report
  11. GRB 210820A: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  12. Swift GRB 210820A: Global MASTER-Net observations report
  13. Swift GRB210818.68: Global MASTER-Net observations report
  14. Konus-Wind detection of GRB 210818A
  15. Fermi GRB 210812A: Global MASTER-Net observations report
  16. IceCube Alert 210811.09: Global MASTER-Net observations report
  17. Fermi GRB 210807C: Global MASTER-Net observations report
  18. GRB 210807C: Swift detection of a burst
  19. Fermi trigger No 649814537: Global MASTER-Net observations report
  20. Fermi trigger No 649627691: Global MASTER-Net observations report
  21. GRB 210801A: Fermi GBM detection
  22. GRB 210731A: Swift-BAT refined analysis
  23. GRB 210801A: BALROG localization (Fermi Trigger 649519043 / GRB 210801581)
  24. Swift GRB210731.93: Global MASTER-Net observations report
  25. GRB 210730A: TNG optical observations
  26. GRB 210730A: Fermi GBM observation
  27. GRB 210730A: AstroSat CZTI detection
  28. GRB 210730A: Swift detection of a burst near M82
  29. Fermi trigger No 649072251: Global MASTER-Net observations report
  30. Fermi trigger No 648959581: Global MASTER-Net observations report
  31. Fermi trigger No 648278666: Global MASTER-Net observations report
  32. GRB 210712A: Swift-BAT refined analysis
  33. Fermi trigger No 647805873: Global MASTER-Net observations report
  34. GRB 210704A: Lowell Discovery Telescope Optical Observations
  35. Fermi trigger No 647624281: Global MASTER-Net observations report
  36. MAXI GRB210709.93: Global MASTER-Net observations report
  37. Fermi trigger No 647365516: Global MASTER-Net observations report
  38. Integral GRB210707.02: Global MASTER-Net observations report
  39. GRB 210704A: OSIRIS/GTC spectroscopy
  40. Konus-Wind detection of GRB 210704A
  41. GRB 210704A: TNG detection of the optical afterglow candidate
  42. GRB 210704A: Assy optical afterglow candidate
  43. GRB 210702A: iTelescope optical afterglow observations
  44. GRB 210627B: GECAM detection
  45. Fermi GRB 210627B: Global MASTER-Net observations report
  46. GRB 210627B: BALROG localization (Fermi Trigger 646509445/ GRB 210627748)
  47. GRB 210627B: Fermi GBM Final Real-time Localization
  48. Fermi GRB 210627A: Global MASTER-Net observations report
  49. Fermi GRB 210626A: Global MASTER-Net observations report
  50. GRB 150428A: late-time radio observations
  51. Fermi trigger No 646189108: Global MASTER-Net observations report
  52. Fermi trigger No 646194855: Global MASTER-Net observations report
  53. Fermi GRB 210622B: Global MASTER-Net observations report
  54. GRB 210619B: Liverpool Telescope r'-band observations
  55. Fermi trigger No 645857659: Global MASTER-Net observations report
  56. Swift GRB210619.99: Global MASTER-Net observations report
  57. Fermi GRB 210615A: Global MASTER-Net observations report
  58. Swift-BAT Trigger 1055000/GRB210612.54: MASTER optical source observation
  59. GRB 210610B: Swift-BAT refined analysis
  60. Fermi trigger No 645047470: Global MASTER-Net observations report
  61. GRB 210610A: MITSuME Ishigaki optical observation
  62. GRB 210607A/MAXI J1733-222: MAXI/GSC detection
  63. MAXI GRB210607.82: Global MASTER-Net observations report
  64. Konus-Wind detection of GRB 210602A
  65. Fermi GRB 210606A: Global MASTER-Net observations report
  66. SGR J1555.2-5402: Swift-BAT refined analysis
  67. MAXI GRB210602.50: Global MASTER-Net observations report
  68. GRB 210602A: CALET Gamma-Ray Burst Monitor detection
  69. Fermi trigger No 644359567: Global MASTER-Net observations report
  70. GRB 210602A: MAXI/GSC detection
  71. Fermi GRB 210601A: Global MASTER-Net observations report
  72. Fermi GRB 210529B: Global MASTER-Net observations report
  73. GRB 210528B: DDOTI Upper Limits on the Afterglow
  74. GRB 210528B: MITSuME Akeno optical upper limits
  75. MAXI GRB210528.95: Global MASTER-Net observations report
  76. GRB 210528B: MAXI/GSC detection
  77. Fermi GRB 210528A: Global MASTER-Net observations report
  78. MAXI GRB210521.54: Global MASTER-Net observations report
  79. GRB 210521A: MAXI/GSC detection
  80. Fermi trigger No 643065622: Global MASTER-Net observations report
  81. Fermi GRB 210518A: Global MASTER-Net observations report
  82. Konus-Wind detection of GRB 210514A
  83. Fermi trigger No 642991619: Global MASTER-Net observations report
  84. Fermi GRB 210516A: Global MASTER-Net observations report
  85. GRB 210515C: Swift-XRT refined Analysis
  86. GRB 210515C: Swift detection of a burst
  87. Fermi GRB 210515B: Global MASTER-Net observations report
  88. Fermi GRB 210515A: Global MASTER-Net observations report
  89. Fermi trigger No 642538568: Global MASTER-Net observations report
  90. IPN triangulation of GRB 210427A
  91. Fermi GRB 210511A: Global MASTER-Net observations report
  92. GRB 210511A: Fermi GBM Final Real-time Localization
  93. Fermi GRB 210510A: Global MASTER-Net observations report
  94. GRB 210509A: Swift-BAT refined analysis
  95. Fermi GRB 210507A: Global MASTER-Net observations report
  96. ZTF21aayokph (AT2021lfa): Mondy and Koshka observatory optical observations
  97. Lowell Discovery Telescope Observations of ZTF21aayokph (AT2021lfa)
  98. ZTF21aayokph (AT2021lfa): Assy optical observations
  99. Swift Detection of MAXI J1803-298 including an optical counterpart
  100. MAXI GRB210501.83: Global MASTER-Net observations report

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