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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"

6667 results found.

  1. GRB 210112A: Swift-XRT refined Analysis
  2. NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  3. Correction to GCN 29278: GRB 201216C XRT refined analysis
  4. GRB 201216C: Swift-XRT refined Analysis
  5. GRB 210102B: further Swift-XRT observations
  6. GRB 210104A: iTelescope optical upper limit
  7. GW170817: HST observations at 3.4 years from merger
  8. GRB 210104A: Swift-XRT refined Analysis
  9. GRB 210104B: Swift-XRT refined Analysis
  10. GRB 210104A: DOAO optical afterglow observations
  11. GRB 210104A: Nanshan/NEXT optical powerlaw decay
  12. GRB 210104A: Fermi GBM detection
  13. GRB 210102B: Swift-XRT observations
  14. GRB 210102C: Fermi GBM detection
  15. GRB 201227A: Chilescope optical observations, possible optical counterpart
  16. GRB 201227A: GRAWITA VST-ESO PARANAL observations
  17. GRB 201227A: Fermi GBM observation
  18. GRB 201229A: SAO RAS optical observations
  19. GRB 201227A: Swift-XRT observations
  20. GRB 201229A: Swift-XRT refined Analysis
  21. GRB 201104B: Maidanak and CrAO optical observations
  22. GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
  23. GRB 201223A: Swift-XRT refined Analysis
  24. GRB 201223A: GROWTH-India Telescope (GIT) photometric follow-up.
  25. GRB 201223A: iTelescope optical afterglow observations
  26. GRB 201223A: Fermi GBM Detection
  27. Swift-XRT observations of Icecube 201222A
  28. IceCube-201222A: No significant detection in HAWC
  29. IceCube-201221A: No significant detection in HAWC
  30. GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  31. GRB 201221D: Fermi GBM detection
  32. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  33. GRB 201216A - further Swift-XRT observations
  34. Fermi-LAT Gamma-ray Observations of IceCube-201222A
  35. Fermi-LAT Gamma-ray Observations of IceCube-201221A
  36. IceCube-201222A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  37. GRB 201221D: Swift-XRT refined Analysis
  38. GRB 201221A: Swift/UVOT Upper Limits
  39. GRB 201221A: Swift-XRT refined Analysis
  40. IceCube-201221A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  41. GRB 201214A: Swift-XRT afterglow detection
  42. GRB 201214A: 1.3m DFOT, optical upper limits
  43. GRB201216C: No significant detection in HAWC
  44. GRB 201216C: Fermi-LAT upper limit
  45. GRB 201216C: Fermi GBM detection
  46. GRB 201216A: Fermi GBM detection
  47. GRB 201216A: Swift-XRT observations
  48. Chandra observations of GW170817 at ~3.3 years since merger (Full report)
  49. GRB 201214B: Swift-XRT observations
  50. GRB 201214A: Swift-XRT observations
  51. IceCube-201209: No significant detection in HAWC
  52. Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
  53. Long-lasting X-ray emission from GW170817 detected by Chandra
  54. GRB 201203A: 1.3m DFOT, optical upper limits
  55. Fermi-LAT Gamma-ray Observations of IceCube-201209A
  56. Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
  57. GRB 201208A: Swift-XRT afterglow detection
  58. GRB 201208A: Fermi GBM observation
  59. IceCube-201209A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  60. GRB 201209A: Swift-XRT refined Analysis
  61. GRB 201208A: Fermi-LAT detection
  62. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  63. GRB 201203A: GROWTH-India Telescope optical upper limit.
  64. GRB 201203A: Swift-XRT afterglow detection
  65. IceCube-201130A: No significant detection in HAWC
  66. IceCube-201130A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  67. GRB 201128B: Swift-XRT observations
  68. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  69. Fermi-LAT Gamma-ray Observations of IceCube-201130A
  70. Swift-XRT observations of IceCube 201130A
  71. GRB 201128A: Swift-XRT refined Analysis
  72. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
  73. Fermi-LAT Gamma-ray Observations of IceCube-201120A
  74. IceCube-201120A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  75. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  76. ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations
  77. IceCube 201114A: Swift followup of Fermi J0703.5+0505
  78. Fermi-LAT Gamma-ray Observations of IceCube-201114A
  79. GRB 201116A: NOT optical observations
  80. GRB 201116A: Swift-XRT afterglow detection
  81. IceCube-201115A: No significant detection in HAWC
  82. IceCube-201114A: No significant detection in HAWC
  83. GRB 201116A: Fermi-LAT detection
  84. IceCube-201115A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  85. IceCube-201114A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  86. Fermi-LAT Gamma-ray Observations of IceCube-201115A
  87. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  88. Swift-XRT observations of IceCube 201114A
  89. Fermi-LAT Gamma-ray Observations of NuEm-201107A
  90. ZTF20acozryr (GRB 201103B): GROWTH-India Telescope optical observations
  91. GRB 201109A: Fermi GBM detection
  92. GRB 201104A: Swift-XRT observations
  93. Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
  94. GRB 201015A: Swift-XRT late time observations
  95. GRB 201104B: Swift-XRT refined Analysis
  96. GRB 201105B: Fermi GBM observation
  97. GRB 201104A: Fermi GBM observation
  98. GRB 201104A: Fermi-LAT detection
  99. IceCube 201021A: Swift follow-up of Fermi J1725.5+1312
  100. GRB 201029A: Fermi GBM detection

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