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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"

28058 results found.

  1. GRB 210421A: Swift-BAT refined analysis
  2. GRB 210421B: Swift-XRT observations
  3. GRB 210420B: continued Tautenburg observations
  4. GRB 210421A: GECAM detection
  5. GRB 210421A: Swift/UVOT Upper Limits
  6. GRB 210420B: follow-up photometry of the optical afterglow at Konkoly
  7. GRB 210421A: MITSuME Akeno optical upper limits
  8. GRB 210420B: Swift-BAT refined analysis
  9. GRB 210421B: Swift/BAT-GUANO detection and arcminute localization
  10. GRB 210420B: Swift-XRT refined Analysis
  11. GRB 210421A: Swift-XRT refined Analysis
  12. Fermi GRB 210421C: Global MASTER-Net observations report
  13. GRB 210419C: Swift/UVOT Upper Limits
  14. GRB 210421A: Enhanced Swift-XRT position
  15. GRB 210420B: RATIR Optical and NIR Observations
  16. GRB 210420B: Tautenburg observations
  17. GRB 210420B: Swift/UVOT Detection
  18. GRB 210413B: MITSuME Okayama optical upper limits
  19. GRB 210419C: MITSuME Akeno optical upper limits
  20. GRB 210420B: DDOTI Detection of the Afterglow
  21. GRB 210421A: DDOTI Upper Limit
  22. GRB 210419C: Swift-BAT refined analysis
  23. GRB 210420B: Multiband photometry from NOT
  24. GRB 210420B: Montarrenti Observatory optical afterglow detection
  25. GRB 210421A: Swift detection of a burst
  26. GRB 210420B: Optical observations
  27. GRB 210420B: MASTER optical counterpart detection
  28. GRB 210419C: RATIR Optical and NIR Upper Limits
  29. GRB 210419C: Montarrenti Observatory Upper Limit
  30. GRB 210419A: Swift/UVOT Upper Limits
  31. GRB 210419C: Enhanced Swift-XRT position
  32. GRB 210419A: Swift-BAT refined analysis
  33. GRB 210419A: Swift-XRT refined Analysis
  34. GRB 210419C: Swift detection of a burst
  35. GRB 210419A: Enhanced Swift-XRT position
  36. GRB 210419A: LCO Optical Upper Limit
  37. GRB 210419A: Swift detection of a burst
  38. GRB 210413B: Swift-XRT observations
  39. GRB 210413B: LOAO optical upper limit
  40. GRB 210411C: A very significant early X-ray afterglow
  41. GRB 210413A: GECAM detection
  42. GRB 210411C: Swift/UVOT Detection
  43. GRB 210411C: Swift-BAT refined analysis
  44. GRB 210411C: Swift-XRT refined Analysis
  45. GRB 210410A: MITSuME Akeno optical upper limits
  46. Swift GRB 210411C: Global MASTER-Net observations report
  47. GRB 210411C: LCO Optical Afterglow Candidate
  48. GRB 210411C: Enhanced Swift-XRT position
  49. GRB 210411D: BALROG localization (Fermi Trigger 639851475 / GRB 210411688)
  50. GRB 210411C: Swift detection of a burst with an optical counterpart
  51. GRB 210410A: Swift-BAT refined analysis
  52. GRB 210410A: Swift-XRT refined Analysis
  53. GRB 210410A: Fermi GBM detection
  54. GRB 210410A: Swift/UVOT Upper Limits
  55. GRB 210406A: Swift-XRT observations
  56. GRB 210410A: RATIR Optical and NIR Observations
  57. GRB 210409A: GECAM detection
  58. GRB 210410A: Fermi-LAT detection
  59. Swift Triggers 1042031 and 1042032 are not astrophysical events
  60. GRB 210406A: Mondy optical afterglow candidate
  61. GRB 210406B: Fermi GBM detection
  62. Konus-Wind detection of GRB 210406A
  63. GRB 210406A: Fermi GBM detection
  64. GRB 210406A: Mondy optical upper limit
  65. GRB 210406A: Konkoly Obs. optical upper limit
  66. GRB 210406A: A long GRB detected by INTEGRAL
  67. GRB 210402A: MASTER prompt and follow up optical observation
  68. GRB 210402A: Swift/UVOT Upper Limits
  69. GRB 210402A: Fermi GBM detection
  70. GRB 210402A: Further NOT optical observations
  71. GRB 210402A: Swift-BAT refined analysis
  72. GRB 210404.141: DDOTI Upper Limits
  73. GRB 210207B: Prompt and very late time observations with HCT.
  74. GRB 210401A: GECAM detection
  75. GRB 210402A: NOT optical afterglow candidate
  76. GRB 210403A: Swift-BAT refined analysis
  77. GRB 210402A: LBT observations
  78. GRB 210402A: DDOTI Upper Limits
  79. GRB 210402A: Swift-XRT refined Analysis
  80. GRB 210402A: Montarrenti Observatory upper limit
  81. GRB 210402A: NOT optical upper limits
  82. GRB 210402A: Swift detection of a burst
  83. GRB 210401A: Fermi GBM Final Real-time Localization
  84. GRB 210328A: GECAM detection
  85. GRB 210330A: GECAM detection
  86. GRB 210328A: BALROG localization (Fermi Trigger / GRB 210328865)
  87. GRB 210326A: Insight-HXMT/HE detection
  88. GRB 210323A: Insight-HXMT/HE detection
  89. GRB 210323A: MASTER optical observation
  90. GRB 210323A: Swift-BAT refined analysis
  91. GRB 210324C: BALROG localization (Fermi Trigger 638308803 / GRB 210324833)
  92. Short GRB 210323A: GTC Observations
  93. GRB 210323A: Swift/UVOT Upper Limits
  94. GRB 210323A: Classification and redshift estimation
  95. GRB 210323A: Kitab optical upper limit
  96. GRB 210323A: Fermi GBM detection
  97. GRB 210323A: Mondy optical observations, counterpart detection
  98. GRB 210318A: Swift/UVOT Upper Limits
  99. GRB 210323A: Swift-XRT refined Analysis
  100. GRB 210323A: Enhanced Swift-XRT position

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