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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. LIGO/Virgo S190412m: HAWC follow-up
  2. LIGO/Virgo S190412m: Identification of a GW binary merger candidate
  3. LIGO/Virgo S190408an: GROND Observations of MASTER OT J154209.55-431742.2
  4. IceCube-190331A: Swift-XRT Follow-up Observations
  5. LIGO/Virgo S190408an: DDOTI/OAN Optical Observations
  6. LIGO/Virgo ST190408an: Fermi-LAT search for a high-energy gamma-ray counterpart
  7. GRB 190409A: Swift detection of a possible burst
  8. LIGO/Virgo S190408an: MASTER OT is 27 day old ATLAS SN candidate and unrelated
  9. LIGO/Virgo S190408an: Identification of a GW binary merger candidate
  10. Search for neutrino counterparts to GW candidate S190408an with IceCube
  11. LIGO-Virgo S190408an: HAWC follow-up
  12. GRB 190404C: Swift-XRT observations
  13. GRB 190404B: Tiled Swift observations
  14. LIGO/Virgo: Announcing the start of Observing Run 3 (O3) and the beginning of the public gravitational-wave alert era
  15. GRB 190331B: Swift ToO observations
  16. IceCube-190331A - IceCube observation of a high-energy neutrino candidate event
  17. MAGIC follow-up of the X-ray flares of LS I +61�303 dete
  18. Swift Trigger 895503 is not a GRB
  19. Swift Trigger 895257: Detection of GRO J2058+42 in outburst
  20. Further Chandra observations of GW170817 ~581-583 days since merger
  21. GRB 190324A: Swift/UVOT afterglow candidate
  22. Correction: Chandra observations of GW170817 ~581 days since merger
  23. Chandra observations of GW170817 ~581 days since merger
  24. Swift Trigger 894268: Detection of GRO J2058+42 in outburst
  25. GRB 190311A: Mondy optical observations
  26. GRB 190311A: Swift detection of a burst with optical counterpart
  27. GRB 190306A: Tiled Swift observations
  28. GRB 190305A: Tiled Swift observations
  29. INTEGRAL observation of IceCube-190221A
  30. IceCube-190221A: Swift-XRT Follow-up Observations
  31. GRB 190219A: CrAO and AbAO optical upper limit
  32. GRB 190220B: Kitab Observatory optical upper limit
  33. IceCube-190221A - IceCube observation of a high-energy neutrino candidate event
  34. GRB 190220B: BOOTES-4 optical observation
  35. GRB 190219A: NOT optical afterglow candidate
  36. GRB 190220A: Swift detection of a burst with an optical counterpart
  37. GRB 190219A: Swift detection of a burst
  38. GRB 190203A: COATLI Optical Observations
  39. GRB 190204A: COATLI Optical Detection of the Fading Afterglow
  40. GRB 190202A: R and I band observation from HCT
  41. GRB 190204A: Swift detection of a burst with a possible optical counterpart
  42. Swift Trigger 887541: Swift detection of Swift J1728.9-3613
  43. GRB 190203A: Koshka Zeiss-1000 optical upper limit
  44. GRB 190203A: Swift detection of a burst with an optical counterpart
  45. GRB 190202A: Swift detection of a burst with an optical counterpart
  46. Improved IPN error box for GRB 190129B
  47. GRB 190129B: DDOTI Detection of the Possible Afterglow and Suggestion of Fading
  48. GRB 190129B: Swift/UVOT Upper Limits
  49. GRB 190129B: ePESSTO NTT optical observations
  50. GRB 190129B: GROND possible host candidate
  51. GRB 190129B: Swift-XRT candidate afterglow detection
  52. GRB 190129B: Tiled Swift observations
  53. INTEGRAL observation of IceCube-190124A
  54. Trigger 886266: Another Swift trigger on MAXI J1348-630
  55. GRB 190114C: Optical follow-up from HCT
  56. Swift Trigger 885960: A third Swift trigger on MAXI J1348-630
  57. Search for counterpart to IceCube-190124A with ANTARES
  58. IceCube-190124A - IceCube observation of a high-energy neutrino candidate event
  59. GRB 190123A: Swift detection of a burst
  60. Trigger 884906: Swift detection of MAXI J1631-479
  61. GRB 190114C: Optical detection from HCT
  62. GRB 190114C: A type 1 BdHN with TeV emission
  63. INTEGRAL observation of IceCube-190104A
  64. GRB 190114C: Swift detection of a very bright burst with a bright optical counterpart
  65. GRB 190114B: Swift detection of a burst
  66. GRB 190114A: Possible UVOT Detection
  67. GRB 190114A: Swift detection of a burst
  68. GRB 190109B: Swift detection of a burst
  69. GRB 190109A: Swift detection of a burst
  70. IceCube-190104A: Swift-XRT observations
  71. GRB 190106A: Swift detection of a burst with an optical counterpart
  72. Search for counterpart to IceCube-190104A with ANTARES
  73. IceCube-190104A - IceCube observation of a high-energy neutrino candidate event
  74. GRB 190103B: Swift detection of a burst
  75. GRB 181225A: KAIT Follow-Up Observations with Upper Limit
  76. GRB 181228A: KAIT Optical Upper Limit
  77. GRB 181228A: Swift detection of a burst
  78. GRB 181222B: Swift ToO observations
  79. GRB 181225A: Swift observations and X-ray candidate afterglow
  80. GRB 181225A: Swift ToO observations
  81. Trigger 878548: Swift detection of AX 1631.9-4752
  82. Swift Trigger 878504 is not astrophysical
  83. GRB181213A: Swift/UVOT Detection
  84. Swift Trigger 874754 is likely not an astrophysical event
  85. Fermi-GBM Observations During Four New GW-Detected BBH Mergers (Correction)
  86. Fermi-GBM Observations During Four New GW-Detected BBH Mergers
  87. GRB 181203A: Swift detection of a burst
  88. GRB 181202A: Swift detection of a burst with an optical counterpart
  89. GRB 181201A: Swift ToO observations
  90. GRB 181126A: Swift detection of a burst
  91. GRB 181123B: Swift detection of a short burst
  92. Swift Trigger 872470 is probably not a GRB
  93. GRB 181110A: Swift detection of a burst with an optical counterpart
  94. Swift Trigger 871103 is not an astrophysical event
  95. Fermi GRB 181105.31: Global MASTER Net optical observations
  96. GRB 181103A: Swift detection of a burst
  97. Fermi-LAT Gamma-ray Observations of IceCube-181023A
  98. IceCube-181023A - IceCube observation of a high-energy neutrino candidate event
  99. GRB 181023A: KAIT Optical Upper Limit
  100. GRB 181023A: Swift detection of a burst

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