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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"

6797 results found.

  1. GRB 230328B: Swift-XRT refined Analysis
  2. GRB 230328B: Fermi GBM observation
  3. GRB 230325A: Swift-XRT refined Analysis
  4. GRB 230320B: Fermi GBM Observation
  5. GRB 230322B: Swift-XRT refined Analysis
  6. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  7. GRB 230307A: Swift/UVOT detection
  8. GRB 230307A: Swift-XRT afterglow detection
  9. Alert from the HAWC Burst Monitor HAWC-230311A
  10. GRB 230308A: Fermi GBM detection
  11. GRB 230307A: ASO-S/HXI detection
  12. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  13. GRB 230307A: Swift/BAT upper limits on the early afterglow
  14. GRB 230307A: Swift-XRT observations
  15. GRB 230307A: AstroSat CZTI detection
  16. Fermi-LAT gamma-ray observations of IceCube-230306A
  17. GRB 230228A: Swift-XRT refined Analysis
  18. GRB 230217A: Swift/UVOT Upper Limits
  19. GRB 230217A: Swift-XRT afterglow detection
  20. Fermi-LAT gamma-ray observations of IceCube-230220A
  21. GRB 230217A: Gemini-South Optical Observation
  22. GRB 230217A: Fermi GBM observation
  23. Fermi-LAT gamma-ray observations of IceCube-230217A
  24. GRB 230217A: Swift-XRT observations
  25. GRB 230216A: Swift-XRT refined Analysis
  26. GRB 230209B: Fermi GBM Observation
  27. Swift Trigger 1153670 is probably not a GRB
  28. GRB 221009A: Continued Swift Observations
  29. GRB 230204B: Swift/UVOT Upper Limits
  30. GRB 230204B: Fermi GBM detection
  31. GRB 230204B: Swift-XRT afterglow detection
  32. GRB 230205A: Swift-XRT refined Analysis
  33. GRB 230204B: GIT discovery of the likely optical afterglow
  34. GRB 230204A: Swift-XRT refined Analysis
  35. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  36. Fermi-LAT gamma-ray observations of IceCube-230201A
  37. GRB 230129A: AstroSat CZTI detection
  38. GRB 230124A: Fermi GBM Observation
  39. Fermi-LAT gamma-ray observations of IceCube-230122A
  40. GRB 230123A: Swift-XRT refined Analysis
  41. GRB 230116C: Swift-XRT observations
  42. GRB 230116B: Fermi GBM observation
  43. GRB 230116D: 3.6m DOT optical upper limit
  44. GRB 230116D: SAO RAS further observations
  45. GRB 230116D: Swift-XRT refined Analysis
  46. GRB 230116D: GIT optical follow-up
  47. GRB 230116C: Swift detection of a burst
  48. Fermi-LAT gamma-ray observations of IceCube-230112A
  49. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  50. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  51. GRB 230111A: Fermi GBM Observation
  52. GRB 230102A: Fermi GBM Observation
  53. GRB 221231A: Fermi GBM Observation
  54. GRB 221231A: Swift-XRT afterglow detection
  55. GRB 221231A: Swift-XRT observations
  56. Fermi-LAT gamma-ray observations of IceCube-221229A
  57. GRB 221226A: Fermi GBM detection
  58. GRB 221226B: Fermi GBM Observation
  59. GRB 221226B: Swift-XRT refined Analysis
  60. Fermi-LAT gamma-ray observations of IceCube-221224A
  61. Fermi-LAT gamma-ray observations of IceCube-221223A
  62. GRB 221218A: 3.6m DOT optical upper limit
  63. GRB 221215A: Fermi GBM Detection
  64. Fermi-LAT gamma-ray observations of IceCube-221216A
  65. GRB 221216A: Fermi GBM observation
  66. GRB 221216A: Swift-XRT refined Analysis
  67. Fermi-LAT gamma-ray observations of IceCube-221210A
  68. GRB 221215A: Swift-XRT observations
  69. GRB 221209A: Fermi GBM observation
  70. GRB 221206B: Fermi GBM observation
  71. GRB 221206B: Swift-XRT observations
  72. GRB 221201A: Fermi GBM observation
  73. GRB 221202A: Swift-XRT refined Analysis
  74. GRB 221201A: Swift-XRT refined Analysis
  75. GRB 221126A: Fermi GBM observation
  76. Alert from the HAWC Burst Monitor HAWC-221128A
  77. Fermi-LAT gamma-ray observations of IceCube-221124A
  78. Alert from the HAWC Burst Monitor HAWC-221123A
  79. GRB 221120A: Fermi GBM observation
  80. GRB 221120A: Swift-XRT refined Analysis
  81. GRB 221120A: GIT upper limits on optical afterglow
  82. GRB 221119A: Fermi GBM detection
  83. GRB 221119A: Fermi-LAT detection
  84. GRB 221115A: Fermi GBM detection
  85. GRB 221110A: Swift-XRT refined Analysis
  86. GRB 221107A: Fermi GBM Observation
  87. GRB 221009A: Extended Bad Time Intervals for Fermi LAT data
  88. Fermi-LAT gamma-ray observations of IceCube-221104A
  89. GRB 221029A: Fermi GBM observation
  90. GRB 221028A: Swift-XRT refined Analysis
  91. GRB 221028A: 1.3m DFOT Optical upper limit
  92. GRB 221028A: HCT optical upper limit
  93. GRB 221028A: GIT optical upper limit
  94. GRB 221027B: Swift-XRT refined Analysis
  95. GRB 221027A: Fermi GBM detection
  96. GRB 221027A: Fermi-LAT detection
  97. GRB 221025A: Fermi GBM Observation
  98. GRB 221022A: Swift-XRT observations
  99. GRB 221024A: Swift-XRT refined Analysis
  100. GRB 221023A: Fermi GBM Observation

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Download all Circulars as a .tar.gz archive (updated once a day):
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