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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"

8293 results found.

  1. GRB 201026A: Swift detection of a burst
  2. GRB 201024A: Swift detection of a burst with an optical afterglow
  3. IceCube-201021A: No significant detection in HAWC
  4. IceCube-201021A: One candidate counterpart from the Zwicky Transient Facility
  5. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  6. IceCube-201021A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 201014A: 2.0m HCT upper limit
  8. IceCube-201021A: No neutrino counterpart candidates in ANTARES search
  9. IceCube-201021A: Upper limits from Fermi-GBM Observations
  10. GRB 201021C: Swift detection of a burst with an optical counterpart
  11. HAWC-201019A: No Neutrino Counterpart detected with ANTARES
  12. GRB200826A: GMOS-N detection of a supernova bump
  13. GRB 201020B: Swift ToO observations
  14. IceCube-201021A: IceCube observation of a high-energy neutrino candidate event
  15. GRB 201020A: Swift detection of a burst with an optical counterpart.
  16. GRB 201015A: 6 GHz VLA radio afterglow candidate detection
  17. GRB 201013A: 3.6m DOT Optical Observations
  18. GRB 201017A: Assy and Mondy optical observations, possible afterglow detection
  19. GRB 201017A: Swift detection of a burst
  20. Fermi GBM Sub-Threshold Detection of GRB 201015A
  21. IceCube-201014A: No significant detection in HAWC
  22. GRB 201015A: NOT optical afterglow confirmation
  23. IceCube-201014A: Upper limits from a search for additional neutrino events in IceCube
  24. IceCube-201014A: No neutrino counterpart candidates in ANTARES search
  25. Swift Trigger 1000255 is probably not a GRB
  26. GRB 201013A: TSHAO and AbAO optical observations, afterglow confirmation
  27. IceCube-201014A: Not observable by GBM
  28. IceCube-201014A - IceCube observation of a high-energy neutrino candidate track-like event
  29. GRB 201013A: FRAM-ORM possible afterglow candidate
  30. GRB 201013A: Swift/UVOT Upper Limits
  31. IceCube-201007A: No candidate counterparts from the Zwicky Transient Facility
  32. GRB 201013A: Swift detection of a burst
  33. Swift detection of a new SGR 1830-0645 or a short GRB 201010A
  34. IceCube-201007A: No significant detection in HAWC
  35. IceCube-201007A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 201008A: Swift ToO observations
  37. IceCube-201007A: Upper limits from Fermi-GBM Observations
  38. IceCube-201007A - IceCube observation of a high-energy neutrino candidate track-like event
  39. GRB 201006A: Swift detection of a burst
  40. IceCube-200926A: No candidate counterparts from the Zwicky Transient Facility
  41. IceCube-200929A: No significant detection in HAWC
  42. IceCube-200929A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 201001A: Swift detection of a burst
  44. IceCube-200929A: Upper limits from Fermi-GBM Observations
  45. IceCube-200929A: No neutrino counterpart candidates in ANTARES search
  46. IceCube-200926B: No significant detection in HAWC
  47. IceCube-200929A: IceCube observation of a high-energy neutrino candidate event
  48. IceCube-200926B: Upper limits from Fermi-GBM Observations
  49. IceCube-200926A: Upper limits from Fermi-GBM Observations
  50. IceCube-200926A: No significant detection in HAWC
  51. IceCube-200926B: Upper limits from a search for additional neutrino events in IceCube
  52. IceCube-200926A: Upper limits from a search for additional neutrino events in IceCube
  53. IceCube-200926A: No Candidate Counterparts from the Zwicky Transient Facility
  54. IceCube-200926B: No neutrino counterpart candidates in ANTARES search
  55. IceCube-200926B: IceCube observation of a high-energy neutrino candidate event
  56. IceCube-200926A: IceCube observation of a high-energy neutrino candidate event
  57. Swift GRB 200925B: Global MASTER-Net OT detection
  58. GRB 200925B: OSN Afterglow Candidate Discovery
  59. GRB 200925B: Swift detection of a burst
  60. GRB 200922A: chance superposition between optical afterglow and archival star
  61. IceCube-200921A: Upper limits from a search for additional neutrino events in IceCube
  62. GRB 200922A: Swift-BAT refined analysis
  63. IceCube-200921A: no significant detection in HAWC observations
  64. IceCube-200921A: Upper limits from Fermi-GBM Observations
  65. IceCube-200921A: IceCube observation of a high-energy neutrino candidate event
  66. IceCube-200916A - ZTF20acaapwk/SN2020tno classified as SN Ia
  67. IceCube-200916A: AbAO observations of optical candidates ZTF20acaapwk/AT2020tno, ZTF20acaapwo/AT2020tnp
  68. IceCube-200916A: Upper limits from a search for additional neutrino events in IceCube
  69. IceCube-200916A: No significant detection in HAWC
  70. IceCube-200916A: No neutrino counterpart candidates in ANTARES search
  71. Fermi-GBM Sub-Threshold Detection of GRB 200917A
  72. IceCube-200916A: Two Candidate Counterparts from the Zwicky Transient Facility
  73. IceCube-200916A: Upper limits from Fermi-GBM Observations
  74. GRB 200917A: Swift detection of a burst
  75. IceCube-200916A - IceCube observation of a high-energy neutrino candidate track-like event
  76. IceCube-200911A: No significant detection in HAWC
  77. GRB 200914A: Swift ToO observations
  78. IceCube-200911A: Upper limits from a search for additional neutrino events in IceCube
  79. IceCube-200911A: No neutrino counterpart candidates in ANTARES search
  80. IceCube-200911A: not observable by Fermi-GBM
  81. IceCube-200911A: IceCube observation of a high-energy neutrino candidate event
  82. GRB 200907B: Swift detection of a short burst
  83. GRB 200906A: Swift detection of a burst
  84. ZTF20abtxwfx/AT2020sev : AstroSat CZTI non-detection of a transient
  85. GRB 200901B: Swift detection of a burst
  86. GRB 200826A: Lowell Discovery Telescope observations of ZTF20abwysqy
  87. GRB 200829A: Swift detection of a burst with an optical afterglow
  88. Zwicky Transient Facility discovery of ZTF20abtxwfx/AT2020sev, a fast optical transient and candidate afterglow
  89. GRB 200826A: VLA Detection at 6 GHz
  90. GRB200826A: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi Short GRB (Trigger 620108997)
  91. GRB200826A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 620108997)
  92. GRB 200826A: Tiled Swift observations
  93. Swift Trigger 992444: a possible GRB 200821A
  94. GRB 200729A: Lowell Discovery Telescope observations
  95. GRB 200819A: Swift detection of a burst
  96. Swift trigger 990358 is not an astrophysical source
  97. Swift trigger 989458 is likely not an astrophysical source
  98. IceCube200806A: No significant detection in HAWC
  99. GRB 200809B: Swift ToO observations
  100. IceCube-200806A: Upper limits from a search for additional neutrino events in IceCube

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