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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 200901A: Swift/UVOT Detection
  2. GRB 200901A: Swift-XRT refined Analysis
  3. GRB 200901A: Fermi GBM observation
  4. GRB 200901B: Enhanced Swift-XRT position
  5. GRB 200829A: Swift/UVOT-XRT photometric redshift
  6. GRB 200901B: Swift detection of a burst
  7. GRB 200901A: Swift-XRT observations
  8. GRB 200901A: Swift detection of a burst
  9. Swift GRB200901.16: Global MASTER-Net observations report
  10. GRB 200829A: Koshka Zeiss-1000 optical observations
  11. Fermi GBM trigger 620564765/200831463 is not a GRB
  12. GRB 200829A: Liverpool Telescope observations
  13. GRB 200829A: Continued Nanshan/NEXT optical observations
  14. GRB 200829A: Kitab optical upper limit
  15. GRB 200829A: further SAO RAS optical observations
  16. Fermi GRB 200830A: Global MASTER-Net observations report
  17. GRB 200829A: Fermi GBM detection
  18. GRB 200829A: Swift-BAT refined analysis
  19. GRB 200829A: Nanshan/NEXT optical observations
  20. Konus-Wind detection of GRB 200829A (a clone of GRB 200826B?)
  21. GRB 200829A: SAO RAS optical observations
  22. GRB 200830A: BALROG localization (Fermi Trigger 620474063 / GRB 200830413)
  23. GRB 200830A: Fermi GBM Final Real-time Localization
  24. GRB 200826A
  25. GRB 200829A: THO optical observatios
  26. GRB 200829A: Swift-XRT refined Analysis
  27. GRB200829A: optical afterglow detection
  28. GRB 200829A: Global MASTER-Net OT detection
  29. GRB 200829A: AGILE/MCAL detection
  30. GRB 200829A: Enhanced Swift-XRT position
  31. GRB 200826A: Lowell Discovery Telescope observations of ZTF20abwysqy
  32. GRB 200829A: Swift/UVOT Detection
  33. Fermi trigger No 620402299: Global MASTER-Net observations report
  34. Swift GRB 200829A: Global MASTER-Net observations report
  35. GRB 200829A: TSHAO optical observations
  36. GRB 200829A: Swift detection of a burst with an optical afterglow
  37. GRB 200826A: Kitab optical observations
  38. Zwicky Transient Facility discovery of ZTF20abtxwfx/AT2020sev, a fast optical transient and candidate afterglow
  39. Konus-Wind detection of GRB 200826B
  40. IPN triangulation of GRB 200826B
  41. GRB 200826A: VLA Detection at 6 GHz
  42. GRB 200826A: further analysis of the Konus-Wind data and classification
  43. GRB 200826A: Swift-XRT afterglow detection
  44. GRB 200824A: Insight-HXMT/HE detection
  45. GRB 200826B: Fermi GBM detection
  46. Fermi GRB 200826B: Global MASTER-Net observations report
  47. Fermi GRB 200824A: Global MASTER-Net observations report
  48. GRB200826A: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi Short GRB (Trigger 620108997)
  49. Konus-Wind detection of GRB 200826A
  50. GRB200826A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 620108997)
  51. GRB 200826B: Fermi GBM Final Real-time Localization
  52. IPN triangulation of GRB 200826A (short/bright)
  53. GRB 200826A: Tiled Swift observations
  54. GRB 200826A: AGILE detection
  55. GRB 200826A: AstroSat CZTI detection
  56. GRB 200826A: Fermi GBM observation
  57. GRB 200826A: BALROG localization (Fermi Trigger 620108997 / GRB 200826187)
  58. Fermi GRB 200826A: Global MASTER-Net observations report
  59. GRB 200826A: Fermi GBM Final Real-time Localization
  60. GRB 200824A: Fermi GBM Final Real-time Localization
  61. Swift Trigger 992444 is due to detector noise
  62. GRB 200819A: Swift/UVOT Upper Limits
  63. Swift GRB200821.55: Global MASTER-Net observations report
  64. IceCube-200806A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  65. Swift Trigger 992444: a possible GRB 200821A
  66. Konus-Wind observation of GRB 200815A
  67. GRB 200819A: Swift-BAT refined analysis
  68. GRB 200815A: MASTER optical observations
  69. IPN triangulation of GRB 200815A (short)
  70. GRB 200819A: Optical Observations from HCT
  71. GRB 200819A: Swift-XRT refined Analysis
  72. GRB 200819A: MITSuME Ishigaki optical upper limits
  73. GRB 200729A: Lowell Discovery Telescope observations
  74. GRB 200819A: MITSuME Akeno optical upper limits
  75. Baksan Neutrino Observatory Alert 200819.88: Global MASTER-Net observations report
  76. GRB 200819A / Swift J0125.7+6303: Ondrejov Perek-2m optical limit
  77. GRB 200819A: Kitab, TSHAO optical upper limit
  78. GRB 200819A: Enhanced Swift-XRT position
  79. Swift GRB 200819A: Global MASTER-Net observations report
  80. GRB 200819A: Swift detection of a burst
  81. Baksan Neutrino Observatory Alert 200819.09: Global MASTER-Net observations report
  82. GRB 200818A: Fermi GBM Final Localization
  83. Fermi trigger No 619487843: Global MASTER-Net observations report
  84. Swift Trigger 990358 is due to detector noise
  85. Swift Trigger 989458 is due to detector noise
  86. HAWC-200814A: Retraction of burst alert
  87. Fermi GRB 200817A: Global MASTER-Net observations report
  88. GRB 200815A: CALET Gamma-Ray Burst Monitor detection of a short burst
  89. GRB 200817A: Fermi GBM Final Real-time Localization
  90. Swift trigger 990358 is not an astrophysical source
  91. Swift GRB200816.17: Global MASTER-Net observations report
  92. Fermi trigger No 619270776: Global MASTER-Net observations report
  93. Swift trigger 989458 is likely not an astrophysical source
  94. HAWC alert 200815.26: MASTER optical observations
  95. Alert from the HAWC Burst Monitor HAWC-200814A
  96. IceCube200806A: No significant detection in HAWC
  97. GRB 200811A: Fermi GBM Final Real-time Localization
  98. GRB 200811A: BALROG localization (Fermi Trigger 618851447 / GRB 200811632)
  99. GRB 200809B: Fermi GBM detection
  100. Fermi GRB 200809B: Global MASTER-Net observations report

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