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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"
  1. IceCube-201114A: Upper limits from a search for additional neutrino events in IceCube
  2. IceCube-201115A: No significant detection in HAWC
  3. IceCube-201114A: No significant detection in HAWC
  4. GRB 201116A: Fermi-LAT detection
  5. GRB 201116A: Tiled Swift observations
  6. LAT GRB201116.03: Global MASTER-Net observations report
  7. IceCube-201115A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  8. IceCube-201114A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  9. INTEGRAL Weak#8811: AROMA-N Optical Observation
  10. IceCube-201115A: No neutrino counterpart candidates in ANTARES search
  11. IceCube Alert 201115.09: Global MASTER-Net observations report
  12. Fermi-LAT Gamma-ray Observations of IceCube-201115A
  13. GRB 201116A: BALROG localization (Fermi Trigger 627180592 / GRB 201116035)
  14. GRB 201116A: Fermi GBM Final Real-time Localization
  15. IceCube-201115A: not observable by Fermi-GBM
  16. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  17. IceCube-201114A: Upper limits from Fermi GBM Observations
  18. VLASS identifies possible radio counterparts to IceCube-201115A, including a bright BL Lac candidate
  19. IceCube GCN alert 134701_49508272.amon retraction
  20. Swift-XRT observations of IceCube 201114A
  21. IceCube-201114A: No neutrino counterpart candidates in ANTARES search
  22. IceCube-201115A: IceCube observation of a high-energy neutrino candidate event
  23. IceCube Alert 201114.63: Global MASTER-Net observations report
  24. IceCube-201114A - IceCube observation of a high-energy neutrino candidate event
  25. ZTF20acozryr/AT2020yxz (GRB 201103B): CrAO/ZTSh optical observations
  26. GRB 201114A: AstroSat CZTI detection
  27. Fermi-LAT Gamma-ray Observations of NuEm-201107A
  28. ZTF20acozryr/AT2020yxz (GRB 201103B): Mondy continued optical observations
  29. Fermi GRB 201111A: Global MASTER-Net observations report
  30. Konus-Wind observation of GRB 201109A
  31. ZTF20acozryr/AT2020yxz (GRB 201103B): Flattening of the optical light curve
  32. Swift Trigger 1005428: Detection of SGR 1830-0645
  33. GRB 201111A: Fermi GBM Final Real-time Localization
  34. IPN triangulation of GRB 201109A (short)
  35. ZTF20acozryr (GRB 201103B): GROWTH-India Telescope optical observations
  36. ZTF20acozryr/AT2020yxz (GRB 201103B): Mondy, Kitab, TSHAO optical observations
  37. GRB 201109A: Fermi GBM detection
  38. GRB 201104A: AstroSat CZTI detection
  39. Konus-Wind observation of GRB 201103B
  40. GRB 201104B: continued TSHAO optical observation
  41. GRB 201104B: MITSuME Akeno optical observation
  42. Fermi GRB 201109A: Global MASTER-Net observations report
  43. GRB 201109A: Fermi GBM Final Real-time Localization
  44. Fermi GRB 201108A: Global MASTER-Net observations report
  45. GRB 201108A: Fermi GBM Final Real-time Localization
  46. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-201107A
  47. Konus-Wind detection of GRB 201105A
  48. GRB 201103B: GMG observation (2nd epoch)
  49. ZTF20acozryr/AT2020yxz (GRB 201103B): Assy optical observations
  50. GRB201103B: GMG observation
  51. GRB 201104B: 1.3m DFOT optical observations
  52. GRB 201104A: Swift-XRT observations
  53. Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
  54. GRB 201015A: Swift-XRT late time observations
  55. GRB 201104B: Kitab optical observations
  56. Correction to GCN 28843: GBM report of GRB 201105B should have been GRB 201105A
  57. GRB 201103B (ZTF20acozryr/AT2020yxz): Xinglong-2.16m optical observations
  58. Fermi trigger No 626247072: Global MASTER-Net observations report
  59. GRB 201104B: TSHAO optical observation
  60. GRB 201104B: Swift/UVOT Detection
  61. GRB 201104B: Swift-XRT refined Analysis
  62. Correcton to GCN 28848: Swift observes ZTF20acozryr
  63. GRB 201104C: Swift ToO observations
  64. GRB 201103B (ZTF20acozryr/AT2020yxz): VLT/X-shooter redshift
  65. GRB 201103B (ZTF20acozryr/AT2020yxz): Nanshan/NEXT-0.6m optical observations
  66. GRB 201105A: Swift detected burst and BAT refined analysis
  67. IPN triangulation of GRB 201103B (consistent with ZTF20acozryr/AT2020yxz)
  68. GRB 201105B: Fermi GBM observation
  69. GRB 201105A: BALROG localization (Fermi Trigger 626247072 / GRB 201105230)
  70. ZTF20acozryr/AT2020yxz: Zwicky Transient Facility discovery of a fast optical transient with no associated GRB
  71. GRB 201104B: VLT/X-shooter redshift
  72. GRB 201104B: Swift-BAT refined analysis
  73. Swift Trigger 1004219: Detection of SGR 1830-0645
  74. GRB 201104A: BALROG localization (Fermi Trigger 626140861 / GRB 201104001)
  75. GRB 201104C: Fermi GBM Final Real-time Localization
  76. GRB 201104A: Tiled Swift observations
  77. GRB 201103B: AGILE detection
  78. GRB 201104A: Fermi GBM observation
  79. GRB 201104A: AGILE/MCAL detection
  80. GRB 201104A: Fermi-LAT detection
  81. GRB 201104B: Swift/UVOT Detection
  82. GRB 201104B: MASTER optical observation
  83. GRB 201104B: Swift detection of a burst
  84. Fermi GRB 201104A: Global MASTER-Net observations report
  85. GRB 201104A: Fermi GBM Final Real-time Localization
  86. GRB 201015A: Late X-ray Detections with Chandra
  87. Fermi GRB 201103A: Global MASTER-Net observations report
  88. GRB 201103A: Fermi GBM Final Real-time Localization
  89. Swift GRB 201031A: Global MASTER-Net observations report
  90. Swift Trigger 1003313 (a.k.a. GRB 201031A) is not an astrophysical event
  91. Fermi GRB 201031B: Global MASTER-Net observations report
  92. GRB 201031B: BALROG localization (Fermi Trigger 625859489 / GRB 201031744)
  93. GRB 201031B: Fermi GBM Final Real-time Localization
  94. GRB 201031A: Swift detection of a burst
  95. GRB 201029A: Swift-BAT refined analysis
  96. IceCube 201021A: Swift follow-up of Fermi J1725.5+1312
  97. Swift GRB 201029A: Global MASTER-Net observations report
  98. GRB 201029A: Swift/UVOT Upper Limits
  99. GRB 201029A: Fermi GBM detection
  100. GRB 201029A: Swift-XRT refined Analysis

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