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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"

6406 results found.

  1. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  2. GRB 201203A: GROWTH-India Telescope optical upper limit.
  3. GRB 201203A: Swift-XRT afterglow detection
  4. IceCube-201130A: No significant detection in HAWC
  5. IceCube-201130A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  6. GRB 201128B: Swift-XRT observations
  7. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  8. Fermi-LAT Gamma-ray Observations of IceCube-201130A
  9. Swift-XRT observations of IceCube 201130A
  10. GRB 201128A: Swift-XRT refined Analysis
  11. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
  12. Fermi-LAT Gamma-ray Observations of IceCube-201120A
  13. IceCube-201120A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  14. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  15. ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations
  16. IceCube 201114A: Swift followup of Fermi J0703.5+0505
  17. Fermi-LAT Gamma-ray Observations of IceCube-201114A
  18. GRB 201116A: NOT optical observations
  19. GRB 201116A: Swift-XRT afterglow detection
  20. IceCube-201115A: No significant detection in HAWC
  21. IceCube-201114A: No significant detection in HAWC
  22. GRB 201116A: Fermi-LAT detection
  23. IceCube-201115A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  24. IceCube-201114A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  25. Fermi-LAT Gamma-ray Observations of IceCube-201115A
  26. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  27. Swift-XRT observations of IceCube 201114A
  28. Fermi-LAT Gamma-ray Observations of NuEm-201107A
  29. ZTF20acozryr (GRB 201103B): GROWTH-India Telescope optical observations
  30. GRB 201109A: Fermi GBM detection
  31. GRB 201104A: Swift-XRT observations
  32. Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
  33. GRB 201015A: Swift-XRT late time observations
  34. GRB 201104B: Swift-XRT refined Analysis
  35. GRB 201105B: Fermi GBM observation
  36. GRB 201104A: Fermi GBM observation
  37. GRB 201104A: Fermi-LAT detection
  38. IceCube 201021A: Swift follow-up of Fermi J1725.5+1312
  39. GRB 201029A: Fermi GBM detection
  40. GRB 201029A: Swift-XRT refined Analysis
  41. GRB 201027A: Swift-XRT refined Analysis
  42. GRB 201026A: Fermi GBM detection
  43. GRB 201026A: Swift-XRT refined Analysis
  44. GRB 201026A: Swift/UVOT Upper Limits
  45. GRB201024A: rebrightening after initial steep decline
  46. GRB 201020B: HCT and GIT continued optical follow-up observations
  47. GRB 201024A: Swift-XRT refined Analysis
  48. GRB 201020B: follow-up observations with Savelli Telescope
  49. GRB 201020B: follow-up observations at Konkoly
  50. IceCube-201021A: No significant detection in HAWC
  51. GRB 201021C: Swift-XRT refined Analysis
  52. GRB 201020B: GROWTH-India Telescope optical observations
  53. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  54. GRB 201020B: Konkoly Obs. optical detection
  55. GRB 201021C: Fermi GBM detection
  56. GRB 201020A: GROWTH-India Telescope late-time optical upper limit
  57. GRB 201014A: 2.0m HCT upper limit
  58. GRB 201020B: Swift-XRT afterglow detection
  59. IceCube-201021A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  60. Swift-XRT observations of IceCube 201021A
  61. GRB 201020B: Fermi-LAT detection
  62. GRB 201020A: DOAO optical afterglow observations
  63. GRB 201020A: GROWTH-India Telescope optical observations
  64. GRB 201020B: Fermi GBM detection
  65. Alert from the HAWC Burst Monitor HAWC-201019A
  66. GRB 201020A: Swift-XRT refined Analysis
  67. GRB 201020A: Fermi GBM observation
  68. GRB 201014A: SAO RAS optical observations
  69. GRB 201017A: SAO RAS optical observations
  70. GRB 201017A: GROWTH-India optical upper limit
  71. GRB 201013A: 3.6m DOT Optical Observations
  72. GRB 201015A: GROWTH-India Telescope (GIT) upper limit
  73. GRB 201017A: Swift-XRT refined Analysis
  74. GRB 201017A: Fermi GBM detection
  75. GRB 201017A: Xinglong TNT upper limit
  76. GRB 201015A: Swift-XRT refined Analysis
  77. IceCube-201014A: No significant detection in HAWC
  78. GRB 201008A: Swift-XRT afterglow detection
  79. GRB 201016A: Fermi GBM detection
  80. GRB 201014A: Swift-XRT refined Analysis
  81. Swift-BAT trigger 1000255: XRT afterglow detection of GRB 201014A
  82. Fermi-LAT Gamma-ray Observations of IceCube-201014A
  83. IceCube-201014A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  84. GRB 201013A: Swift-XRT refined Analysis
  85. GRB 201011A: Fermi GBM detection of a likely Long GRB in the direction of SGR 1830-0645
  86. GRB 201006A: Chandra upper limit on the X-ray afterglow
  87. IceCube-201007A: No significant detection in HAWC
  88. GRB 201008A: Swift-XRT observations
  89. IceCube-200926A: Upper limits from Insight-HXMT Observations
  90. Fermi-LAT Gamma-ray Observations of IceCube-201007A
  91. Swift-XRT observations of IceCube 201007A
  92. IceCube-201007A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  93. GRB 201006A: GROWTH-India Telescope optical upper limit
  94. GRB 201006A: Swift-XRT refined Analysis
  95. GRB 201006A: Swift/UVOT Upper Limits
  96. GRB 201006A: Fermi GBM detection
  97. IceCube-200926B: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  98. IceCube-200929A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  99. IceCube-200929A: No significant detection in HAWC
  100. GRB 201001A: Swift-XRT refined Analysis

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