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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"

7446 results found.

  1. GRB 220926A: Swift detection of a burst
  2. IceCube-220907A: Classification of AT2022oyn as a Type Ia supernova
  3. GRB 220921A: Tiled Swift observations
  4. IceCube-220918A - IceCube observation of a high-energy neutrino candidate track-like event
  5. GRB 220909A: Swift ToO observations
  6. GRB 220909A: Swift/BAT-GUANO candidate arcminute localization
  7. IceCube-220907A: One Candidate Counterpart from the Zwicky Transient Facility
  8. GRB 220831A: ATCA 5/9 GHz radio observations
  9. IceCube-220907A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 220831A: Swift-UVOT Upper Limits
  11. Introducing Self-Service Configuration of GCN Notices over Email for Transient Alerts
  12. GRB 220831A: DECam detection of a possible optical counterpart
  13. GRB 220831A: Swift ToO observations
  14. IceCube-220822A: Classification of AT2022saw as a Type Ia supernova
  15. GRB 220826A: Swift detection of a burst with an optical counterpart
  16. IceCube-220822A: One Candidate Counterpart from the Zwicky Transient Facility
  17. IceCube-220822A - IceCube observation of a high-energy neutrino candidate track-like event
  18. GRB 220810A: Further Swift-XRT observations
  19. GRB 220813A: Swift detection of a burst with an optical counterpart
  20. GRB 220810A: Swift-XRT observations
  21. GRB 220810A: Swift ToO observations
  22. GRB 220810A: MeerLICHT detection of two afterglow candidates
  23. GRB 220730A: Swift detection of a short hard burst
  24. Introducing new GCN Kafka broker and web site for transient alerts, https://gcn.nasa.gov
  25. GRB 220715B: Swift detection of a burst
  26. GRB 220714B: UVOT afterglow discovery
  27. GRB 220714B: Swift detection of a burst
  28. GRB 220712B: NOT optical afterglow confirmation
  29. GRB 220710A: Swift ToO observations
  30. GRB 220711B: NOT optical observations
  31. GRB 220711B: Swift detection of a burst
  32. IceCube-220624A: Classification of AT2022nit as a type Ia supernova and AT2021bei as an AGN
  33. GRB 220708B: Swift ToO observations
  34. GRB 220627A: ATCA detection of radio counterpart
  35. GRB 220706A: Swift detection of a burst
  36. GRB 220701A: Keck/LRIS Optical Upper Limit
  37. GRB 200701A: KAIT Optical Upper Limit
  38. GRB 220701A: Swift detection of a burst
  39. Fermi-LAT Gamma-ray Observations of IceCube-220627A
  40. IceCube-220629A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 220627A: Swift-XRT afterglow detection
  42. IceCube-220624A: One Candidate Counterpart from Swift/XRT follow up observations
  43. GRB 220627A: VLT MUSE redshift
  44. GRB 220627A: MeerLICHT candidate optical afterglow
  45. Fermi-LAT Gamma-ray Observations of IceCube-220624A and and detection of a new gamma-ray source, Fermi J1458.0+4119
  46. GRB 220627A: Swift ToO observations
  47. GRB 220627A: MeerLICHT detection of two afterglow candidates
  48. IceCube-220627A - IceCube observation of a high-energy neutrino candidate track-like event
  49. IceCube-220624A: No Candidate Counterparts from the Zwicky Transient Facility
  50. IceCube-220624A - IceCube observation of a high-energy neutrino candidate track-like event
  51. GRB 220617A: TNG optical observations
  52. GRB 220611A optical counterpart
  53. GRB 220618A: Swift detection of a burst
  54. GRB 220617B: Swift ToO observations
  55. GRB 220611A: Swift detection of a burst
  56. GRB 220606B: Gemini South Optical Observations
  57. GRB 220606B: Swift follow-up observations
  58. GRB 220606B: GUANO coordinate correction to GCN 32167
  59. GRB 220606B: Swift ToO observations
  60. GRB 220606B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  61. GRB 220527A: Swift ToO observations
  62. IceCube-220524A - IceCube observation of a high-energy neutrino candidate track-like event
  63. VLA observations of GW170817 at ~4.8 years after the merger
  64. GRB 220521A: Swift detection of a burst
  65. Continued Chandra monitoring of GW170817 at ~4.8 yr post-merger
  66. GRB 220518A: Swift detection of a burst
  67. GRB 220514B: Tiled Swift observations
  68. GRB 220514A: MeerLICHT optical afterglow candidate
  69. IceCube-220513A: No Candidate Counterparts from the Zwicky Transient Facility
  70. IceCube-220513A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 220511A: Swift ToO observations
  72. IceCube-220509A - IceCube observation of a high-energy neutrino candidate track-like event
  73. GRB 220506A: Tiled Swift observations
  74. IceCube-220405B - ZTF19aavnpjv unrelated
  75. IceCube-220501A: No Candidate Counterparts from the Zwicky Transient Facility
  76. IceCube-220501A - IceCube observation of a high-energy neutrino candidate track-like event
  77. GRB 220430A: CAHA 2.2m telescope optical limit
  78. GRB 220430A: Swift detection of a burst or Swift J0630.4+0932
  79. GRB 220426A: Tiled Swift observations
  80. GRB 220427A: Swift detection of a burst with an optical counterpart
  81. Fermi-LAT Gamma-ray Observations of IceCube-220425A
  82. IceCube-220425A: MASTER: flaring blazar TXS 1742-078 as the possible neutrino source candidate
  83. IceCube-220425A - IceCube observation of a high-energy neutrino candidate track-like event
  84. IceCube-220424A - IceCube observation of a high-energy neutrino candidate track-like event
  85. IceCube-220421A - IceCube observation of a high-energy neutrino candidate track-like event
  86. GRB 220418B: Swift ToO observations
  87. GRB 220418B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  88. GRB 220412B: TNG optical observations
  89. GRB 220412A: Continued RATIR Observations and Steepening of the Light Curve
  90. GRB 220412A: BOOTES-network optical upper limits
  91. GRB 220412A: RATIR Observations of the Fading Afterglow
  92. GRB 220412B: Swift detection of a short burst
  93. GRB 220412A: RATIR Afterglow Candidate
  94. GRB 220412A: Swift detection of a burst
  95. GRB 220408A: NOT optical observations and archival detection
  96. GRB 220403C: Swift ToO observations
  97. GRB 220408A: Swift detection of a burst with an optical counterpart, possibly associated with M51
  98. IceCube-220405A: No Candidate Counterparts from the Zwicky Transient Facility
  99. IceCube-220405B: No Candidate Counterparts from the Zwicky Transient Facility
  100. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event

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