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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"

28092 results found.

  1. GRB 201116A: OSN Afterglow Candidate
  2. Swift Trigger 1006917 is Be/X-ray binary pulsar 1A 0535+262
  3. IceCube Alert 201115.67: Global MASTER-Net observations report
  4. IceCube-201115A: Upper limits from a search for additional neutrino events in IceCube
  5. IceCube-201114A: Upper limits from a search for additional neutrino events in IceCube
  6. IceCube-201115A: No significant detection in HAWC
  7. IceCube-201114A: No significant detection in HAWC
  8. IceCube-201115A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  9. IceCube-201114A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  10. INTEGRAL Weak#8811: AROMA-N Optical Observation
  11. IceCube-201115A: No neutrino counterpart candidates in ANTARES search
  12. IceCube Alert 201115.09: Global MASTER-Net observations report
  13. Fermi-LAT Gamma-ray Observations of IceCube-201115A
  14. GRB 201116A: BALROG localization (Fermi Trigger 627180592 / GRB 201116035)
  15. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  16. VLASS identifies possible radio counterparts to IceCube-201115A, including a bright BL Lac candidate
  17. Swift-XRT observations of IceCube 201114A
  18. IceCube-201114A: No neutrino counterpart candidates in ANTARES search
  19. GRB 201114A: AstroSat CZTI detection
  20. Fermi-LAT Gamma-ray Observations of NuEm-201107A
  21. ZTF20acozryr/AT2020yxz (GRB 201103B): Flattening of the optical light curve
  22. Swift Trigger 1005428: Detection of SGR 1830-0645
  23. ZTF20acozryr (GRB 201103B): GROWTH-India Telescope optical observations
  24. GRB 201104B: continued TSHAO optical observation
  25. GRB 201104B: MITSuME Akeno optical observation
  26. GRB 201103B: GMG observation (2nd epoch)
  27. GRB201103B: GMG observation
  28. GRB 201104A: Swift-XRT observations
  29. Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
  30. GRB 201104B: Kitab optical observations
  31. GRB 201103B (ZTF20acozryr/AT2020yxz): Xinglong-2.16m optical observations
  32. Fermi trigger No 626247072: Global MASTER-Net observations report
  33. GRB 201104B: TSHAO optical observation
  34. GRB 201104B: Swift/UVOT Detection
  35. GRB 201104B: Swift-XRT refined Analysis
  36. GRB 201103B (ZTF20acozryr/AT2020yxz): Nanshan/NEXT-0.6m optical observations
  37. GRB 201105A: Swift detected burst and BAT refined analysis
  38. IPN triangulation of GRB 201103B (consistent with ZTF20acozryr/AT2020yxz)
  39. GRB 201105B: Fermi GBM observation
  40. GRB 201105A: BALROG localization (Fermi Trigger 626247072 / GRB 201105230)
  41. ZTF20acozryr/AT2020yxz: Zwicky Transient Facility discovery of a fast optical transient with no associated GRB
  42. GRB 201104B: VLT/X-shooter redshift
  43. GRB 201104B: Swift-BAT refined analysis
  44. Swift Trigger 1004219: Detection of SGR 1830-0645
  45. GRB 201104A: BALROG localization (Fermi Trigger 626140861 / GRB 201104001)
  46. GRB 201104A: Fermi GBM observation
  47. GRB 201104B: Swift/UVOT Detection
  48. GRB 201104B: MASTER optical observation
  49. GRB 201104B: Swift detection of a burst
  50. GRB 201015A: Late X-ray Detections with Chandra
  51. GRB 201031B: BALROG localization (Fermi Trigger 625859489 / GRB 201031744)
  52. GRB 201029A: Swift-BAT refined analysis
  53. IceCube 201021A: Swift follow-up of Fermi J1725.5+1312
  54. GRB 201029A: Swift/UVOT Upper Limits
  55. GRB 201029A: Fermi GBM detection
  56. GRB 201029A: Swift-XRT refined Analysis
  57. GRB 201029A: BOOTES-1 optical upper limit
  58. GRB 201029A: Enhanced Swift-XRT position
  59. GRB 201029A: Swift detection of a burst
  60. GRB 201027A: MITSuME Akeno optical upper limits
  61. GRB 201027A: Swift-BAT refined analysis
  62. GRB 201026A: Swift-BAT refined analysis
  63. GRB 201027A: Swift/UVOT Upper Limits
  64. GRB 201027A: Swift-XRT refined Analysis
  65. GRB 201026A: Fermi GBM detection
  66. GRB 201026A: Swift-XRT refined Analysis
  67. Baksan Neutrino Observatory Alert 201027.41: Global MASTER-Net observations report
  68. GRB 201026A: Swift/UVOT Upper Limits
  69. GRB 201027A: Enhanced Swift-XRT position
  70. GRB 201026A: Enhanced Swift-XRT position
  71. GRB 201020A: 1.3m DFOT, optical upper limits
  72. GRB 201027A: Swift detection of a burst
  73. GRB 201026A: NanShan/NEXT-0.6m optical upper limit
  74. GRB 201026A: Swift detection of a burst
  75. GRB 201024A: MITSuME Akeno optical upper limits
  76. GRB 201024A: Swift-BAT refined analysis
  77. GRB 201020B: HCT and GIT continued optical follow-up observations
  78. GRB 201024A: Swift-XRT refined Analysis
  79. GRB 201024A: Swift/UVOT Detection
  80. GRB 201020B: follow-up observations with Savelli Telescope
  81. GRB 201024A: VIRT optical observations
  82. GRB 201024A: Enhanced Swift-XRT position
  83. GRB 201020B: Redshift from GTC/OSIRIS
  84. GRB 201024A: Redshift from GTC/OSIRIS
  85. GRB 201024A: Swift detection of a burst with an optical afterglow
  86. Swift GRB201024A: Global MASTER-Net OT detection
  87. IceCube-201021A: No significant detection in HAWC
  88. IceCube-201021A: Optical counterpart of WISEA J172314.13+142101.5
  89. GRB 201021C: Swift-BAT refined analysis
  90. GRB 201021C: Swift-XRT refined Analysis
  91. GRB 201020B: GROWTH-India Telescope optical observations
  92. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  93. GRB 201020B: Konkoly Obs. optical detection
  94. Swift-XRT observations of IceCube 201021A (2)
  95. GRB 201020A: GROWTH-India Telescope late-time optical upper limit
  96. IceCube-201021A: Upper limits from a search for additional neutrino events in IceCube
  97. GRB 201021C: Swift/UVOT Detection
  98. Konus-Wind detection of GRB 201020A
  99. GRB 201020B: Swift/UVOT Detection
  100. GRB 201020A: Swift/UVOT Observations

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