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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 201019B: Fermi GBM correction to GCN 28687
  2. GRB 201014A: 3.6m DOT Optical Observations
  3. GRB 201015A: 6 GHz VLA radio afterglow candidate detection
  4. GRB 201019A: Fermi GBM Final Real-time Localization
  5. GRB 201013A: 3.6m DOT Optical Observations
  6. GRB 201014A: MMT afterglow detection
  7. GRB 201017A: MITSuME Akeno optical upper limits
  8. GRB 201019A: Fermi GBM Final Real-time Localization
  9. GRB 201017A: Swift-BAT refined analysis
  10. GRB 201015A: GROWTH-India Telescope (GIT) upper limit
  11. GRB 201015A: HCT optical photometric follow-up
  12. GRB 201017A: Assy and Mondy optical observations, possible afterglow detection
  13. GRB 201017A: Swift-XRT refined Analysis
  14. GRB 201015A: Xinglong-2.16m optical observations
  15. GRB 201015A: MMT afterglow imaging
  16. GRB 201017A: Fermi GBM detection
  17. GRB 201015A NUTTelA-TAO / BSTI Early Measurements (Preliminary)
  18. GRB 201015A: Assy and Mondy optical observations
  19. GRB 201017A: Xinglong TNT upper limit
  20. GRB 201017A: Enhanced Swift-XRT position
  21. Trigger 1000631: Swift detection of Cen X-3
  22. GRB 201015A: classification as long GRB
  23. Swift GRB 201017A: Global MASTER-Net observations report
  24. GRB 201017A: Swift detection of a burst
  25. GRB 201017A: Fermi GBM Final Real-time Localization
  26. GRB 201015A: FRAM-ORM afterglow detection
  27. Fermi GBM Sub-Threshold Detection of GRB 201015A
  28. GRB 201015A: Swift/UVOT Detection
  29. GRB 201015A: redshift confirmation
  30. GRB 201015A: Swift-XRT refined Analysis
  31. MAGIC observations of GRB 201015A: hint of very high energy gamma-ray signal
  32. GRB 201015A: Swift-BAT refined analysis (a soft short pulse with a tail emission)
  33. IceCube-201014A: No significant detection in HAWC
  34. GRB 201015A: CrAO/ZTSH optical observations
  35. GRB 201014A: Nanshan/NEXT optical observations
  36. GRB 201014A: Lowell Discovery Telescope afterglow imaging
  37. GRB201015A: Nanshan/NEXT early optical observations
  38. Konus-Wind observation of GRB 201013A
  39. GRB 201016A: AstroSat CZTI detection
  40. GRB 201014A: Redshift from GTC/OSIRIS
  41. GRB 201015A: Redshift from GTC/OSIRIS
  42. GRB 201008A: Swift-XRT afterglow detection
  43. GRB 201015A: Enhanced Swift-XRT position
  44. GRB 201016A: Fermi GBM detection
  45. GRB 201015A: BOOTES-1 early optical afterglow detection
  46. GRB 201014A: Swift/UVOT Upper Limits
  47. Fermi GRB 201016B: Global MASTER-Net observations report
  48. GRB 201016B: BALROG localization (Fermi Trigger 624510986 / GRB 201016136)
  49. GRB 201016A: BALROG localization (Fermi Trigger 624500874 / GRB 201016019)
  50. GRB 201016B: Fermi GBM Final Real-time Localization
  51. GRB 201015A: GOTO confirmation of afterglow detection
  52. GRB 201014A: Swift-XRT refined Analysis
  53. GRB 201015A: NOT optical afterglow confirmation
  54. GRB 201016A: Fermi GBM Final Real-time Localization
  55. GRB 201015A: Swift-XRT observations
  56. Swift GRB 201015A: Global MASTER-Net observations report
  57. Swift GRB201015.95: Global MASTER-Net OT detection
  58. GRB 201015A: Swift detection of a burst
  59. IceCube-201014A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 201014A: BOOTES-1 and -2 early optical upper limits
  61. GRB 201014A: Swift-BAT refined analysis
  62. GRB 201014A (Swift trigger =1000255): CrAO/ZTSH optical afterglow discovery
  63. IceCube Alert 201014.09: Global MASTER-Net observations report
  64. Swift-BAT trigger 1000255: XRT afterglow detection of GRB 201014A
  65. GRB 201013A: Insight-HXMT/HE detection
  66. IceCube-201014A: No neutrino counterpart candidates in ANTARES search
  67. Swift Trigger 1000255 is probably not a GRB
  68. Fermi-LAT Gamma-ray Observations of IceCube-201014A
  69. GRB 201013A: TSHAO and AbAO optical observations, afterglow confirmation
  70. GRB 201013A: AstroSat CZTI detection
  71. IceCube-201014A: Not observable by GBM
  72. GRB 201013A: CALET Gamma-Ray Burst Monitor detection
  73. IceCube-201014A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  74. IceCube-201014A - IceCube observation of a high-energy neutrino candidate track-like event
  75. GRB 201013A: FRAM-ORM possible afterglow candidate
  76. GRB 201013A: Swift-BAT refined analysis
  77. GRB 201013A: Swift/UVOT Upper Limits
  78. Swift GRB 201013A: Global MASTER-Net observations report
  79. GRB 201013A: Swift-XRT refined Analysis
  80. SGR 1830-0645: Swift/UVOT Upper Limits
  81. IceCube-201007A: No candidate counterparts from the Zwicky Transient Facility
  82. GRB 201013A: Enhanced Swift-XRT position
  83. GRB 201013A: Swift detection of a burst
  84. GRB 201011A: Fermi GBM detection of a likely Long GRB in the direction of SGR 1830-0645
  85. Fermi trigger No 624139481: AGILE detection
  86. GRB 201012A: Fermi GBM Final Real-time Localization
  87. SGR 1830-0645: pre-discovery detection in Swift/BAT
  88. Fermi trigger No 624139481: Global MASTER-Net observations report
  89. SGR 1830-0645 / GRB 201010A: 1.5m OSN optical upper limit
  90. Fermi trigger No 624121589: Global MASTER-Net observations report
  91. SGR 1830-0645: Swift-BAT refined analysis
  92. GRB 201006A: Chandra upper limit on the X-ray afterglow
  93. SGR 1830-0645 / GRB 201010A: Kitab optical non-detection
  94. GRB 201010A: Enhanced Swift-XRT position
  95. Swift GRB201010.62: Global MASTER-Net observations report
  96. Swift detection of a new SGR 1830-0645 or a short GRB 201010A
  97. IceCube-200929A: JCMT/SCUBA2 observations
  98. IceCube-201007A: No significant detection in HAWC
  99. GRB 201008B: Fermi GBM Final Localization
  100. IceCube-201007A: Upper limits from a search for additional neutrino events in IceCube

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