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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 210321A: Swift/UVOT Detection
  2. Konus-Wind detection of GRB 210321A
  3. GRB 210318B: Swift/UVOT Upper Limits
  4. GRB 210321A: DDOTI Position Correction
  5. IceCube Alert 210322.11: Global MASTER-Net observations report
  6. GRB 210321A: CrAO optical upper limit
  7. GRB 210321A: Swift-BAT refined analysis
  8. IceCube 135113_19489408.amon: Swift-XRT observations
  9. GRB 210321A: Mondy optical observations
  10. IceCube Astrotrack Bronze 135113_19489408.amon is likely background
  11. GRB 210321A: Xinglong GWAC-F60A optical observation
  12. GRB 210321A: Swift-XRT refined Analysis
  13. GRB 210321A: Redshift from OSIRIS/GTC
  14. GRB 210321A: NOT optical afterglow detection and redshift limit
  15. GRB 210321A: MASTER optical observation
  16. MAXI GRB210320.89: Global MASTER-Net observations report
  17. GRB 210321A: Enhanced Swift-XRT position
  18. GRB 210321A: DDOTI Afterglow Confirmation
  19. GRB 210321A: Swift/UVOT Detection
  20. GRB 210321A: Swift-XRT observations
  21. GRB 210321A: Swift detection of a burst
  22. GRB 210320A: MAXI/GSC detection
  23. GRB 210318B: MITSuME Okayama optical upper limits
  24. GRB 201216C: VIRT optical observations
  25. GRB 200524A: Redshift from Gemini-North
  26. GRB 210318A: Swift-BAT refined analysis
  27. GRB 210318A: Swift-XRT refined Analysis
  28. GRB 210318A: Enhanced Swift-XRT position
  29. Swift GRB210318.13: Global MASTER-Net observations report
  30. GRB 210318B: Fermi GBM detection
  31. Fermi trigger No 637729731: Global MASTER-Net observations report
  32. GRB 210318B: Swift-BAT refined analysis
  33. Swift GRB 210318A: Global MASTER-Net observations report
  34. Konus-Wind detection of GRB 210318B
  35. GRB210318B: Swift detection of a burst
  36. GRB 210318A: Swift detection of a burst
  37. Fermi GRB 210317A: Global MASTER-Net observations report
  38. GRB 210317A: GECAM detection
  39. GRB 210317A: Fermi GBM Final Real-time Localization
  40. Fermi trigger No 637521056: Global MASTER-Net observations report
  41. GRB 210306A: GIT optical follow-up
  42. GRB 210226A: GIT optical upper limit
  43. GRB 210312B: Redshift from OSIRIS/GTC
  44. GRB 210306A: HCT optical upper limit
  45. GRB 210312B: GTC photometry
  46. GRB 210312B: MASTER OT confirmation
  47. GRB210312B (Integral alert 9073): Candidate optical afterglow by Ondrejov D50
  48. GRB 210312B: A long GRB detected by INTEGRAL
  49. Integral GRB210312.87: Global MASTER-Net observations report
  50. Fermi GRB 210312A: Global MASTER-Net observations report
  51. INTEGRAL SPI-ACS on 2021-03-12 (04)11-08:15) are due to calibration activity
  52. GRB 210312A: Fermi GBM Final Real-time Localization
  53. GRB 210306A: LBT observations
  54. GRB 210306A: Tautenburg observations
  55. Konus-Wind detection of GRB 210308A
  56. Konus-Wind detection of GRB 210306A
  57. Konus-Wind detection of GRB 210305A
  58. GRB 171205A: Continued ATCA observations
  59. Fermi trigger No 637027080: Global MASTER-Net observations report
  60. GRB 210306A: Early Spectroscopy of the Optical Afterglow
  61. GRB 210306B: Fermi GBM detection
  62. GRB 210306A: Swift/UVOT Detection
  63. GRB 210306A: continued Mondy optical observations
  64. GRB 210308A: Mondy and AbAO optical observations
  65. GRB 210308A: Swift-BAT refined analysis
  66. GRB 210307A: Swift-BAT refined analysis
  67. Fermi trigger No 636926765: Global MASTER-Net observations report
  68. GRB 210308A: Swift/UVOT Detection
  69. GRB 210307A: Swift/UVOT Upper Limits
  70. GRB 210305A: Fermi GBM observation
  71. Swift GRB 210308A: Global MASTER-Net observations report
  72. GRB 210308A: Fermi GBM detection
  73. GRB 210305A: Swift-XRT refined Analysis
  74. GRB 210307A: Swift-XRT refined Analysis
  75. GRB 210308A: Nanshan/NEXT optical upper limits
  76. GRB 210306A: Swift-XRT refined Analysis
  77. GRB 210308A: MITSuME Okayama optical upper limits
  78. GRB 210306A: continued Mondy optical observations
  79. GRB 210308A: Swift detection of a burst with an optical counterpart
  80. GRB 210306A: 1.3m DFOT observations
  81. GRB 210306A: Swift-BAT refined analysis
  82. GRB 210306A: Mondy optical observations
  83. GRB 210305A: Swift/UVOT Upper Limits
  84. GRB 210307B: GECAM detection
  85. GRB 210307A: LCO Optical Upper Limits
  86. GRB 210306B: Swift-BAT refined analysis
  87. GRB 210305A: Swift-BAT refined analysis
  88. GRB 210307A: Swift detection of a burst
  89. Swift GRB210307.36: Global MASTER-Net observations report
  90. GRB 210306A: MITSuME Akeno optical observation
  91. GRB 210306A: NEXT optical observations
  92. Swift GRB 210306A: Global MASTER-Net observations report
  93. GRB 210306A: Fermi GBM observation
  94. GRB 210306A: Tautenburg observations
  95. GRB 210306A: iTelescope T24 optical observations
  96. GRB 210306A: Fermi-LAT detection
  97. GRB 210306B: Swift detection of a burst
  98. GRB 210306A: LCO Optical Afterglow Detection
  99. GRB 210306A: iTelescope optical afterglow observations
  100. GRB 210306A: DDOTI Afterglow Confirmation

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