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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"

6520 results found.

  1. Chandra observations of GW170817 at ~3.3 years since merger (Full report)
  2. GRB 201214B: Swift-XRT observations
  3. GRB 201214A: Swift-XRT observations
  4. IceCube-201209: No significant detection in HAWC
  5. Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
  6. Long-lasting X-ray emission from GW170817 detected by Chandra
  7. GRB 201203A: 1.3m DFOT, optical upper limits
  8. Fermi-LAT Gamma-ray Observations of IceCube-201209A
  9. Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
  10. GRB 201208A: Swift-XRT afterglow detection
  11. GRB 201208A: Fermi GBM observation
  12. IceCube-201209A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  13. GRB 201209A: Swift-XRT refined Analysis
  14. GRB 201208A: Fermi-LAT detection
  15. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  16. GRB 201203A: GROWTH-India Telescope optical upper limit.
  17. GRB 201203A: Swift-XRT afterglow detection
  18. IceCube-201130A: No significant detection in HAWC
  19. IceCube-201130A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  20. GRB 201128B: Swift-XRT observations
  21. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  22. Fermi-LAT Gamma-ray Observations of IceCube-201130A
  23. Swift-XRT observations of IceCube 201130A
  24. GRB 201128A: Swift-XRT refined Analysis
  25. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
  26. Fermi-LAT Gamma-ray Observations of IceCube-201120A
  27. IceCube-201120A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  28. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  29. ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations
  30. IceCube 201114A: Swift followup of Fermi J0703.5+0505
  31. Fermi-LAT Gamma-ray Observations of IceCube-201114A
  32. GRB 201116A: NOT optical observations
  33. GRB 201116A: Swift-XRT afterglow detection
  34. IceCube-201115A: No significant detection in HAWC
  35. IceCube-201114A: No significant detection in HAWC
  36. GRB 201116A: Fermi-LAT detection
  37. IceCube-201115A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  38. IceCube-201114A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  39. Fermi-LAT Gamma-ray Observations of IceCube-201115A
  40. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  41. Swift-XRT observations of IceCube 201114A
  42. Fermi-LAT Gamma-ray Observations of NuEm-201107A
  43. ZTF20acozryr (GRB 201103B): GROWTH-India Telescope optical observations
  44. GRB 201109A: Fermi GBM detection
  45. GRB 201104A: Swift-XRT observations
  46. Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
  47. GRB 201015A: Swift-XRT late time observations
  48. GRB 201104B: Swift-XRT refined Analysis
  49. GRB 201105B: Fermi GBM observation
  50. GRB 201104A: Fermi GBM observation
  51. GRB 201104A: Fermi-LAT detection
  52. IceCube 201021A: Swift follow-up of Fermi J1725.5+1312
  53. GRB 201029A: Fermi GBM detection
  54. GRB 201029A: Swift-XRT refined Analysis
  55. GRB 201027A: Swift-XRT refined Analysis
  56. GRB 201026A: Fermi GBM detection
  57. GRB 201026A: Swift-XRT refined Analysis
  58. GRB 201026A: Swift/UVOT Upper Limits
  59. GRB201024A: rebrightening after initial steep decline
  60. GRB 201020B: HCT and GIT continued optical follow-up observations
  61. GRB 201024A: Swift-XRT refined Analysis
  62. GRB 201020B: follow-up observations with Savelli Telescope
  63. GRB 201020B: follow-up observations at Konkoly
  64. IceCube-201021A: No significant detection in HAWC
  65. GRB 201021C: Swift-XRT refined Analysis
  66. GRB 201020B: GROWTH-India Telescope optical observations
  67. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  68. GRB 201020B: Konkoly Obs. optical detection
  69. GRB 201021C: Fermi GBM detection
  70. GRB 201020A: GROWTH-India Telescope late-time optical upper limit
  71. GRB 201014A: 2.0m HCT upper limit
  72. GRB 201020B: Swift-XRT afterglow detection
  73. IceCube-201021A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  74. Swift-XRT observations of IceCube 201021A
  75. GRB 201020B: Fermi-LAT detection
  76. GRB 201020A: DOAO optical afterglow observations
  77. GRB 201020A: GROWTH-India Telescope optical observations
  78. GRB 201020B: Fermi GBM detection
  79. Alert from the HAWC Burst Monitor HAWC-201019A
  80. GRB 201020A: Swift-XRT refined Analysis
  81. GRB 201020A: Fermi GBM observation
  82. GRB 201014A: SAO RAS optical observations
  83. GRB 201017A: SAO RAS optical observations
  84. GRB 201017A: GROWTH-India optical upper limit
  85. GRB 201013A: 3.6m DOT Optical Observations
  86. GRB 201015A: GROWTH-India Telescope (GIT) upper limit
  87. GRB 201017A: Swift-XRT refined Analysis
  88. GRB 201017A: Fermi GBM detection
  89. GRB 201017A: Xinglong TNT upper limit
  90. GRB 201015A: Swift-XRT refined Analysis
  91. IceCube-201014A: No significant detection in HAWC
  92. GRB 201008A: Swift-XRT afterglow detection
  93. GRB 201016A: Fermi GBM detection
  94. GRB 201014A: Swift-XRT refined Analysis
  95. Swift-BAT trigger 1000255: XRT afterglow detection of GRB 201014A
  96. Fermi-LAT Gamma-ray Observations of IceCube-201014A
  97. IceCube-201014A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  98. GRB 201013A: Swift-XRT refined Analysis
  99. GRB 201011A: Fermi GBM detection of a likely Long GRB in the direction of SGR 1830-0645
  100. GRB 201006A: Chandra upper limit on the X-ray afterglow

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