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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"

7301 results found.

  1. IceCube-201130A: Optical and NIR Imaging Follow-up by Kanata Telescope
  2. GRB 201209A: KAIT Optical Upper Limit
  3. GRB 201209A: Swift detection of a burst
  4. GRB 201208A: Swift ToO observations
  5. IceCube-201130A: No Candidate Counterparts from the Zwicky Transient Facility
  6. GRB 201203A: KAIT Optical Upper Limit
  7. GRB 201203A: Swift detection of a burst
  8. IceCube-201130A: Not observable by Fermi-GBM
  9. GRB 201128B: Swift ToO observations
  10. IceCube-201130A: IceCube observation of a high-energy neutrino candidate event
  11. GRB 201128A: Swift detection of a burst
  12. IceCube-201114A: Updated photometry for three DECam candidate optical counterparts
  13. AMON IC_HAWC NuEm-201124A: No Neutrino Counterpart detected with ANTARES
  14. IceCube-201114A: DECam observations and candidate optical counterpart
  15. IceCube-201120A: Upper limits from Fermi-GBM Observations
  16. IceCube-201120A: IceCube observation of a high-energy neutrino candidate event
  17. GRB 201116A: NOT optical observations
  18. GRB 201116A: OSN Afterglow Candidate
  19. Swift Trigger 1006917 is Be/X-ray binary pulsar 1A 0535+262
  20. GRB 201116A: Tiled Swift observations
  21. IceCube-201115A: No neutrino counterpart candidates in ANTARES search
  22. IceCube-201115A: not observable by Fermi-GBM
  23. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  24. IceCube-201114A: Upper limits from Fermi GBM Observations
  25. VLASS identifies possible radio counterparts to IceCube-201115A, including a bright BL Lac candidate
  26. IceCube-201114A: No neutrino counterpart candidates in ANTARES search
  27. IceCube-201115A: IceCube observation of a high-energy neutrino candidate event
  28. IceCube-201114A - IceCube observation of a high-energy neutrino candidate event
  29. GRB 201104A: Swift-XRT observations
  30. Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
  31. GRB 201104C: Swift ToO observations
  32. ZTF20acozryr/AT2020yxz: Zwicky Transient Facility discovery of a fast optical transient with no associated GRB
  33. GRB 201104A: Tiled Swift observations
  34. GRB 201029A: Swift detection of a burst
  35. GRB 201020A: 1.3m DFOT, optical upper limits
  36. GRB 201027A: Swift detection of a burst
  37. GRB 201026A: Swift detection of a burst
  38. GRB 201024A: Swift detection of a burst with an optical afterglow
  39. IceCube-201021A: One candidate counterpart from the Zwicky Transient Facility
  40. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  41. GRB 201014A: 2.0m HCT upper limit
  42. IceCube-201021A: No neutrino counterpart candidates in ANTARES search
  43. IceCube-201021A: Upper limits from Fermi-GBM Observations
  44. GRB 201021C: Swift detection of a burst with an optical counterpart
  45. HAWC-201019A: No Neutrino Counterpart detected with ANTARES
  46. GRB200826A: GMOS-N detection of a supernova bump
  47. GRB 201020B: Swift ToO observations
  48. IceCube-201021A: IceCube observation of a high-energy neutrino candidate event
  49. GRB 201020A: Swift detection of a burst with an optical counterpart.
  50. GRB 201015A: 6 GHz VLA radio afterglow candidate detection
  51. GRB 201013A: 3.6m DOT Optical Observations
  52. GRB 201017A: Assy and Mondy optical observations, possible afterglow detection
  53. GRB 201017A: Swift detection of a burst
  54. GRB 201015A: NOT optical afterglow confirmation
  55. IceCube-201014A: No neutrino counterpart candidates in ANTARES search
  56. Swift Trigger 1000255 is probably not a GRB
  57. IceCube-201014A: Not observable by GBM
  58. IceCube-201014A - IceCube observation of a high-energy neutrino candidate track-like event
  59. GRB 201013A: FRAM-ORM possible afterglow candidate
  60. GRB 201013A: Swift/UVOT Upper Limits
  61. IceCube-201007A: No candidate counterparts from the Zwicky Transient Facility
  62. GRB 201013A: Swift detection of a burst
  63. Swift detection of a new SGR 1830-0645 or a short GRB 201010A
  64. GRB 201008A: Swift ToO observations
  65. IceCube-201007A: Upper limits from Fermi-GBM Observations
  66. IceCube-201007A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRB 201006A: Swift detection of a burst
  68. IceCube-200926A: No candidate counterparts from the Zwicky Transient Facility
  69. GRB 201001A: Swift detection of a burst
  70. IceCube-200929A: Upper limits from Fermi-GBM Observations
  71. IceCube-200929A: No neutrino counterpart candidates in ANTARES search
  72. IceCube-200929A: IceCube observation of a high-energy neutrino candidate event
  73. IceCube-200926B: Upper limits from Fermi-GBM Observations
  74. IceCube-200926A: Upper limits from Fermi-GBM Observations
  75. IceCube-200926A: No Candidate Counterparts from the Zwicky Transient Facility
  76. IceCube-200926B: No neutrino counterpart candidates in ANTARES search
  77. IceCube-200926B: IceCube observation of a high-energy neutrino candidate event
  78. IceCube-200926A: IceCube observation of a high-energy neutrino candidate event
  79. Swift GRB 200925B: Global MASTER-Net OT detection
  80. GRB 200925B: OSN Afterglow Candidate Discovery
  81. GRB 200925B: Swift detection of a burst
  82. IceCube-200921A: Upper limits from Fermi-GBM Observations
  83. IceCube-200921A: IceCube observation of a high-energy neutrino candidate event
  84. IceCube-200916A - ZTF20acaapwk/SN2020tno classified as SN Ia
  85. IceCube-200916A: AbAO observations of optical candidates ZTF20acaapwk/AT2020tno, ZTF20acaapwo/AT2020tnp
  86. IceCube-200916A: No neutrino counterpart candidates in ANTARES search
  87. IceCube-200916A: Two Candidate Counterparts from the Zwicky Transient Facility
  88. IceCube-200916A: Upper limits from Fermi-GBM Observations
  89. GRB 200917A: Swift detection of a burst
  90. IceCube-200916A - IceCube observation of a high-energy neutrino candidate track-like event
  91. GRB 200914A: Swift ToO observations
  92. IceCube-200911A: No neutrino counterpart candidates in ANTARES search
  93. IceCube-200911A: not observable by Fermi-GBM
  94. IceCube-200911A: IceCube observation of a high-energy neutrino candidate event
  95. GRB 200907B: Swift detection of a short burst
  96. GRB 200906A: Swift detection of a burst
  97. ZTF20abtxwfx/AT2020sev : AstroSat CZTI non-detection of a transient
  98. GRB 200901B: Swift detection of a burst
  99. GRB 200826A: Lowell Discovery Telescope observations of ZTF20abwysqy
  100. GRB 200829A: Swift detection of a burst with an optical afterglow

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