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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"

2857 results found.

  1. GRB 200716A: Swift/BAT-GUANO archival detection and arcminute localization
  2. Fermi GRB 210507A: Global MASTER-Net observations report
  3. GRB 210504A: MITSuME Akeno optical upper limits
  4. Fermi GRB 210501A: Global MASTER-Net observations report
  5. Fermi trigger No 641601187: Global MASTER-Net observations report
  6. GRB 210430B: Fermi GBM Final Real-time Localization
  7. Swift GRB210430.45: Global MASTER-Net observations report
  8. GRB 210430A: Swift detection of a burst
  9. IPN triangulation of GRB 210424B (short/hard)
  10. GRB 210422B: Fermi GBM Final Localization
  11. GRB 210420B: Assy optical observations
  12. GRB 210421B: AstroSat CZTI detection
  13. GRB 210421B: AstroSat CZTI detection
  14. GRB 210420B: Correction to AST3-3 YaoAn magnitude
  15. GRB 210420B: Swift-XRT refined Analysis
  16. GRB 210420B: DDOTI Detection of the Afterglow
  17. GRB 210420B: Multiband photometry from NOT
  18. GRB 210420B: Montarrenti Observatory optical afterglow detection
  19. GRB 210420B: AST3-3 YaoAn Optical Observation
  20. GRB 210420B: Optical observations
  21. GRB 210411C: LCO Optical Afterglow Candidate
  22. Fermi GRB 210411B: Global MASTER-Net observations report
  23. Fermi GRB 210411A: Global MASTER-Net observations report
  24. Fermi GRB 210410A: Global MASTER-Net observations report
  25. Fermi trigger No 639093861: Global MASTER-Net observations report
  26. Swift GRB210402.92: Global MASTER-Net observations report
  27. Fermi GRB 210324B: Global MASTER-Net observations report
  28. GRB 210320A: MAXI/GSC detection
  29. Fermi GRB 210317A: Global MASTER-Net observations report
  30. Fermi trigger No 637521056: Global MASTER-Net observations report
  31. Konus-Wind detection of GRB 210305A
  32. GRB 210307A: Swift detection of a burst
  33. GRB 210306A: iTelescope optical afterglow observations
  34. Fermi trigger No 636459103: Global MASTER-Net observations report
  35. Fermi trigger No 636168178: Global MASTER-Net observations report
  36. Integral GRB210227.19: Global MASTER-Net OT detection
  37. GRB 210222B: MASTER OT observation
  38. GRB 210222B: GOTO confirmation of afterglow detection
  39. Swift GRB210222.94: Global MASTER-Net observations report
  40. Fermi GBM Sub-Threshold Detection of GRB 210217A
  41. GRB 210217A: Swift-BAT refined analysis
  42. GRB 210217A: Swift detection of a burst with an optical counterpart
  43. GRB 210208A: 1.3m DFOT Optical upper limit
  44. GRB 210211A: ePESSTO+ NTT optical observations
  45. IceCube Alert 210213.78: Global MASTER-Net observations report
  46. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations
  47. GRB 210207B: AstroSat CZTI detection
  48. GRB 210207B: Swift-BAT refined analysis
  49. Konus-Wind detection of GRB 210204A (correction to GCN 29415)
  50. GRB 210207A: Fermi GBM Final Real-time Localization
  51. Fermi GRB 210204B: Global MASTER-Net observations report
  52. Fermi GRB 210204A: Global MASTER-Net observations report
  53. GRB 140320B: Swift-XRT refined Analysis
  54. GRB 210104A: DOAO optical afterglow observations
  55. Fermi GRB 210101A: Global MASTER-Net observations report
  56. Fermi trigger No 631118376: Global MASTER-Net observations report
  57. Fermi GRB 201229B: Global MASTER-Net observations report
  58. Fermi GRB 201228B: Global MASTER-Net observations report
  59. GRB 201228B: Fermi GBM Final Real-time Localization
  60. Fermi GRB 201222B: Global MASTER-Net observations report
  61. GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
  62. GRB 201221D: candidate optical counterpart from the NOT
  63. GRB 201221A: Swift-BAT refined analysis
  64. GRB 201221D: Prompt enhanced Swift-XRT position
  65. GRB 201221A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 5.7
  66. GRB 201209A: Mondy optical observations, afterglow confirmation
  67. GRB 201214A: 1.3m DFOT, optical upper limits
  68. Baksan Neutrino Observatory Alert 201216.94: Global MASTER-Net observations report
  69. Fermi GRB 201214B: Global MASTER-Net observations report
  70. Fermi GRB 201208A: Global MASTER-Net observations report
  71. IceCube-201130A: No significant detection in HAWC
  72. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  73. Swift-XRT observations of IceCube 201130A
  74. GRB 201128A: Swift-BAT refined analysis
  75. GRB 201120B: Fermi GBM Final Localization
  76. ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations
  77. IceCube-201114A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  78. ZTF20acozryr/AT2020yxz (GRB 201103B): Mondy, Kitab, TSHAO optical observations
  79. Konus-Wind detection of GRB 201105A
  80. GRB 201104C: Fermi GBM Final Real-time Localization
  81. GRB 201104A: Fermi GBM Final Real-time Localization
  82. Swift GRB201027.05: Global MASTER-Net observations report
  83. IceCube-201021A: No neutrino counterpart candidates in ANTARES search
  84. IceCube-201021A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  85. Alert from the HAWC Burst Monitor HAWC-201019A
  86. Fermi GRB 201020B: Global MASTER-Net observations report
  87. GRB 201015A: Assy and Mondy optical observations
  88. IceCube-201014A: No neutrino counterpart candidates in ANTARES search
  89. GRB 201006A: Chandra upper limit on the X-ray afterglow
  90. Fermi GRB 201007A: Global MASTER-Net observations report
  91. Baksan Neutrino Observatory Alert 201006.88: Global MASTER-Net observations report
  92. GRB 201006A: Fermi GBM detection
  93. Fermi trigger No 623470566: Global MASTER-Net observations report
  94. Fermi GRB 200925A: Global MASTER-Net observations report
  95. Fermi GRB 200924A: Global MASTER-Net observations report
  96. Fermi GRB 200923A: Global MASTER-Net observations report
  97. IPN triangulation of GRB 200920B (short)
  98. GRB 200917A: GROWTH-India Telescope optical upper limit.
  99. IceCube-200916A: No neutrino counterpart candidates in ANTARES search
  100. GRB 200917A: Enhanced Swift-XRT position

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