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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"

2921 results found.

  1. GRB 210826A: Swift-XRT observations
  2. GRB 210820A: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  3. Fermi GRB 210822B: Global MASTER-Net observations report
  4. GRB 210822A: Nanshan/NEXT optical observations
  5. Fermi trigger No 650046564: Global MASTER-Net observations report
  6. GRB 210807B: Fermi GBM Final Real-time Localization
  7. Fermi trigger No 649814537: Global MASTER-Net observations report
  8. Fermi trigger No 649519043: Global MASTER-Net observations report
  9. Swift GRB210731.62: Global MASTER-Net observations report
  10. GRB 210730A: Swift-BAT refined analysis
  11. GRB 210730A: Swift detection of a burst near M82
  12. GRB 210714A: Fermi GBM observation
  13. Fermi trigger No 648959581: Global MASTER-Net observations report
  14. GRB 210722A: continued Assy optical observations
  15. Fermi trigger No 648868114: Global MASTER-Net observations report
  16. Swift GRB210724.84: Global MASTER-Net observations report
  17. GRB 210722A: Assy optical detection
  18. GRB 210722A: Swift detection of a burst with a bright optical counterpart
  19. Fermi trigger No 648602917: Global MASTER-Net observations report
  20. Recent activity of SGR 1935+2154 as observed by CGBM
  21. Fermi trigger No 647805873: Global MASTER-Net observations report
  22. GRB 210709A: AstroSat CZTI detection
  23. Fermi trigger No 647653174: Global MASTER-Net observations report
  24. Fermi trigger No 647624281: Global MASTER-Net observations report
  25. Swift GRB 210708B: Global MASTER-Net observations report
  26. GRB 210704A: Assy optical afterglow candidate
  27. Fermi trigger No 647108723: Global MASTER-Net observations report
  28. GRB210702A: MeerLICHT multi-colour photometry
  29. IceCube-210629A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  30. Fermi trigger No 646443989: Global MASTER-Net observations report
  31. Fermi GRB 210627B: Global MASTER-Net observations report
  32. Fermi GRB 210627A: Global MASTER-Net observations report
  33. Fermi GRB 210625A: Global MASTER-Net observations report
  34. Fermi trigger No 646189108: Global MASTER-Net observations report
  35. GRB 210619B: Abbey Ridge Observatory optical afterglow observation
  36. GRB 210619B: Liverpool telescope imaging of a red afterglow
  37. Swift GRB210619.99: Global MASTER-Net OT detection
  38. Swift GRB210619.99: Global MASTER-Net observations report
  39. GRB 210618A: Swift-XRT observations
  40. Fermi GRB 210615A: Global MASTER-Net observations report
  41. Follow-up on HAWC Transient Monitoring Alert J0020+3108
  42. GRB210610B: SARA-KP 0.9m Optical Afterglow Detection
  43. Fermi trigger No 645047470: Global MASTER-Net observations report
  44. Konus-Wind detection of GRB 210606B
  45. GRB 210606B: Fermi GBM detection
  46. Fermi trigger No 644449593: Global MASTER-Net observations report
  47. MAXI GRB210602.50: Global MASTER-Net observations report
  48. Fermi trigger No 644359567: Global MASTER-Net observations report
  49. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  50. MAXI GRB210528.95: Global MASTER-Net observations report
  51. GRB 210521A: MAXI/GSC detection
  52. Fermi GRB 210519A: Global MASTER-Net observations report
  53. IceCube Alert 210519.86: Global MASTER-Net observations report
  54. Fermi trigger No 643065622: Global MASTER-Net observations report
  55. Fermi trigger No 642991619: Global MASTER-Net observations report
  56. IceCube-210516A: No significant detection in HAWC
  57. Fermi GRB 210516A: Global MASTER-Net observations report
  58. AMON IC_HAWC NuEm-210515A / NuEm-210515B : No neutrino counterpart detected with ANTARES
  59. Fermi GRB 210515B: Global MASTER-Net observations report
  60. Fermi GRB 210515A: Global MASTER-Net observations report
  61. GRB 210515B: Fermi GBM Final Real-time Localization
  62. Fermi GRB 210511A: Global MASTER-Net observations report
  63. GRB 210511B: Fermi GBM Final Real-time Localization
  64. Fermi GRB 210510A: Global MASTER-Net observations report
  65. GRB 200716A: Swift/BAT-GUANO archival detection and arcminute localization
  66. Fermi GRB 210507A: Global MASTER-Net observations report
  67. GRB 210504A: MITSuME Akeno optical upper limits
  68. Fermi GRB 210501A: Global MASTER-Net observations report
  69. Fermi trigger No 641601187: Global MASTER-Net observations report
  70. GRB 210430B: Fermi GBM Final Real-time Localization
  71. Swift GRB210430.45: Global MASTER-Net observations report
  72. GRB 210430A: Swift detection of a burst
  73. IPN triangulation of GRB 210424B (short/hard)
  74. GRB 210422B: Fermi GBM Final Localization
  75. GRB 210420B: Assy optical observations
  76. GRB 210421B: AstroSat CZTI detection
  77. GRB 210421B: AstroSat CZTI detection
  78. GRB 210420B: Correction to AST3-3 YaoAn magnitude
  79. GRB 210420B: Swift-XRT refined Analysis
  80. GRB 210420B: DDOTI Detection of the Afterglow
  81. GRB 210420B: Multiband photometry from NOT
  82. GRB 210420B: Montarrenti Observatory optical afterglow detection
  83. GRB 210420B: AST3-3 YaoAn Optical Observation
  84. GRB 210420B: Optical observations
  85. GRB 210411C: LCO Optical Afterglow Candidate
  86. Fermi GRB 210411B: Global MASTER-Net observations report
  87. Fermi GRB 210411A: Global MASTER-Net observations report
  88. Fermi GRB 210410A: Global MASTER-Net observations report
  89. Fermi trigger No 639093861: Global MASTER-Net observations report
  90. Swift GRB210402.92: Global MASTER-Net observations report
  91. Fermi GRB 210324B: Global MASTER-Net observations report
  92. GRB 210320A: MAXI/GSC detection
  93. Fermi GRB 210317A: Global MASTER-Net observations report
  94. Fermi trigger No 637521056: Global MASTER-Net observations report
  95. Konus-Wind detection of GRB 210305A
  96. GRB 210307A: Swift detection of a burst
  97. GRB 210306A: iTelescope optical afterglow observations
  98. Fermi trigger No 636459103: Global MASTER-Net observations report
  99. Fermi trigger No 636168178: Global MASTER-Net observations report
  100. Integral GRB210227.19: Global MASTER-Net OT detection

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