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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"

6098 results found.

  1. Swift-XRT observations of IceCube 201130A
  2. GRB 201128A: Swift-XRT refined Analysis
  3. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
  4. Fermi-LAT Gamma-ray Observations of IceCube-201120A
  5. IceCube-201120A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  6. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  7. ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations
  8. IceCube 201114A: Swift followup of Fermi J0703.5+0505
  9. Fermi-LAT Gamma-ray Observations of IceCube-201114A
  10. GRB 201116A: NOT optical observations
  11. GRB 201116A: Swift-XRT afterglow detection
  12. IceCube-201115A: No significant detection in HAWC
  13. IceCube-201114A: No significant detection in HAWC
  14. GRB 201116A: Fermi-LAT detection
  15. IceCube-201115A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  16. IceCube-201114A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  17. Fermi-LAT Gamma-ray Observations of IceCube-201115A
  18. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  19. Swift-XRT observations of IceCube 201114A
  20. Fermi-LAT Gamma-ray Observations of NuEm-201107A
  21. ZTF20acozryr (GRB 201103B): GROWTH-India Telescope optical observations
  22. GRB 201109A: Fermi GBM detection
  23. GRB 201104A: Swift-XRT observations
  24. Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
  25. GRB 201015A: Swift-XRT late time observations
  26. GRB 201104B: Swift-XRT refined Analysis
  27. GRB 201105B: Fermi GBM observation
  28. GRB 201104A: Fermi GBM observation
  29. GRB 201104A: Fermi-LAT detection
  30. IceCube 201021A: Swift follow-up of Fermi J1725.5+1312
  31. GRB 201029A: Fermi GBM detection
  32. GRB 201029A: Swift-XRT refined Analysis
  33. GRB 201027A: Swift-XRT refined Analysis
  34. GRB 201026A: Fermi GBM detection
  35. GRB 201026A: Swift-XRT refined Analysis
  36. GRB 201026A: Swift/UVOT Upper Limits
  37. GRB201024A: rebrightening after initial steep decline
  38. GRB 201020B: HCT and GIT continued optical follow-up observations
  39. GRB 201024A: Swift-XRT refined Analysis
  40. GRB 201020B: follow-up observations with Savelli Telescope
  41. GRB 201020B: follow-up observations at Konkoly
  42. IceCube-201021A: No significant detection in HAWC
  43. GRB 201021C: Swift-XRT refined Analysis
  44. GRB 201020B: GROWTH-India Telescope optical observations
  45. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  46. GRB 201020B: Konkoly Obs. optical detection
  47. GRB 201021C: Fermi GBM detection
  48. GRB 201020A: GROWTH-India Telescope late-time optical upper limit
  49. GRB 201014A: 2.0m HCT upper limit
  50. GRB 201020B: Swift-XRT afterglow detection
  51. IceCube-201021A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  52. Swift-XRT observations of IceCube 201021A
  53. GRB 201020B: Fermi-LAT detection
  54. GRB 201020A: DOAO optical afterglow observations
  55. GRB 201020A: GROWTH-India Telescope optical observations
  56. GRB 201020B: Fermi GBM detection
  57. Alert from the HAWC Burst Monitor HAWC-201019A
  58. GRB 201020A: Swift-XRT refined Analysis
  59. GRB 201020A: Fermi GBM observation
  60. GRB 201014A: SAO RAS optical observations
  61. GRB 201017A: SAO RAS optical observations
  62. GRB 201017A: GROWTH-India optical upper limit
  63. GRB 201013A: 3.6m DOT Optical Observations
  64. GRB 201015A: GROWTH-India Telescope (GIT) upper limit
  65. GRB 201017A: Swift-XRT refined Analysis
  66. GRB 201017A: Fermi GBM detection
  67. GRB 201017A: Xinglong TNT upper limit
  68. GRB 201015A: Swift-XRT refined Analysis
  69. IceCube-201014A: No significant detection in HAWC
  70. GRB 201008A: Swift-XRT afterglow detection
  71. GRB 201016A: Fermi GBM detection
  72. GRB 201014A: Swift-XRT refined Analysis
  73. Swift-BAT trigger 1000255: XRT afterglow detection of GRB 201014A
  74. Fermi-LAT Gamma-ray Observations of IceCube-201014A
  75. IceCube-201014A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  76. GRB 201013A: Swift-XRT refined Analysis
  77. GRB 201011A: Fermi GBM detection of a likely Long GRB in the direction of SGR 1830-0645
  78. GRB 201006A: Chandra upper limit on the X-ray afterglow
  79. IceCube-201007A: No significant detection in HAWC
  80. GRB 201008A: Swift-XRT observations
  81. IceCube-200926A: Upper limits from Insight-HXMT Observations
  82. Fermi-LAT Gamma-ray Observations of IceCube-201007A
  83. Swift-XRT observations of IceCube 201007A
  84. IceCube-201007A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  85. GRB 201006A: GROWTH-India Telescope optical upper limit
  86. GRB 201006A: Swift-XRT refined Analysis
  87. GRB 201006A: Swift/UVOT Upper Limits
  88. GRB 201006A: Fermi GBM detection
  89. IceCube-200926B: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  90. IceCube-200929A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  91. IceCube-200929A: No significant detection in HAWC
  92. GRB 201001A: Swift-XRT refined Analysis
  93. GRB 201001A: Fermi GBM observation
  94. Swift-XRT observations of IceCube 200929A
  95. Fermi-LAT Gamma-ray Observations of IceCube-200929A
  96. IceCube-200926B: No significant detection in HAWC
  97. IceCube-200926A: No significant detection in HAWC
  98. Fermi-LAT Gamma-ray Observations of IceCube-200926B
  99. Swift-XRT observations of IceCube 200926A
  100. Fermi-LAT Gamma-ray Observations of IceCube-200926A

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