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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"

2722 results found.

  1. Swift trigger 1047857 is 4U 1700-377
  2. Fermi GRB 210507A: Global MASTER-Net observations report
  3. Fermi GRB 210501A: Global MASTER-Net observations report
  4. Fermi trigger No 641601187: Global MASTER-Net observations report
  5. Fermi GRB 210430B: Global MASTER-Net observations report
  6. GRB 210420B: follow-up photometry of optical afterglow at INASAN/Simeiz
  7. GRB 210422A: Swift detection of a burst
  8. GRB 210420B: Tautenburg observations
  9. Fermi GRB 210420A: Global MASTER-Net observations report
  10. Swift GRB 210421A: Global MASTER-Net observations report
  11. GRB 210413B: LOAO optical upper limit
  12. GRB 210411B: AstroSat CZTI detection
  13. Fermi GRB 210411B: Global MASTER-Net observations report
  14. GRB 210406A: 10.4m GTC follow-up observation
  15. GRB 210411B: Fermi GBM Final Real-time Localization
  16. Fermi GRB 210411A: Global MASTER-Net observations report
  17. GRB 210406B: Fermi GBM detection
  18. GRB 210324C: AstroSat CZTI detection
  19. GRB 210320A: MAXI/GSC detection
  20. GRB 210318A: Swift detection of a burst
  21. Fermi trigger No 637521056: Global MASTER-Net observations report
  22. Fermi GRB 210312A: Global MASTER-Net observations report
  23. GRB 210306A: continued Mondy optical observations
  24. Fermi trigger No 636926765: Global MASTER-Net observations report
  25. GRB 210306A: iTelescope T24 optical observations
  26. Trigger 1035744: Swift detection of Sco X-1 due to Star Tracker loss of lock
  27. Fermi trigger No 636459103: Global MASTER-Net observations report
  28. GRB 210217A: 3.6m DOT optical observations
  29. Integral GRB210227.20: Global MASTER-Net observations report
  30. GRB 210226A: Swift-BAT refined analysis
  31. GRB 210217A: Swift detection of a burst with an optical counterpart
  32. IceCube Alert 210213.78: Global MASTER-Net observations report
  33. GRB 210213A: Fermi GBM Final Real-time Localization
  34. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations
  35. GRB 210211A: Swift/UVOT Detection
  36. Fermi GRB 210210B: Global MASTER-Net observations report
  37. IceCube-210210A: Two Candidate Counterparts from the Zwicky Transient Facility
  38. GRB 210207B: AbAO optical upper limit
  39. GRB 210204A (ZTF21aagwbjr/AT2021buv): Mondy and AbAO optical observations
  40. GRB 210205A: Swift detection of a burst
  41. GRB 210204B: Fermi GBM Final Real-time Localization
  42. GRB 210127A: Fermi GBM Final Real-time Localization
  43. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  44. Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
  45. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-210111A
  46. GRB 210110A: MAXI/GSC detection
  47. Fermi trigger No 631602681: Global MASTER-Net observations report
  48. GRB 210105A: Fermi GBM Final Real-time Localization
  49. Fermi GRB 210102C: Global MASTER-Net observations report
  50. MAXI GRB210102.38: Global MASTER-Net observations report
  51. GRB 201216C: TSHAO, Terskol, Mondy optical upper limits
  52. Fermi GRB 201229B: Global MASTER-Net observations report
  53. Baksan Neutrino Observatory Alert 201228.36: Global MASTER-Net observations report
  54. Fermi GRB 201228B: Global MASTER-Net observations report
  55. Fermi trigger No 630681391: Global MASTER-Net observations report
  56. IceCube-201222A: No Candidate Counterparts from the Zwicky Transient Facility
  57. Baksan Neutrino Observatory Alert 201223.60: Global MASTER-Net observations report
  58. GRB 201221D: LCOGT upper limits
  59. GRB 201221E: Fermi GBM Final Real-time Localization
  60. correction to GCN 29110 - Fermi GBM Sub-Threshold Detection of GRB 201221A
  61. Fermi GBM Sub-Threshold Detection of GRB 201221A
  62. Konus-Wind detection of GRB 201216C
  63. Baksan Neutrino Observatory Alert 201216.94: Global MASTER-Net observations report
  64. GRB 201216C: VLT afterglow candidate discovery
  65. GRB 201015A: optical observations and supernova identification
  66. IceCube-201209A: No Candidate Counterparts from the Zwicky Transient Facility
  67. GRB 201209A: Swift detection of a burst
  68. Fermi GRB 201208A: Global MASTER-Net observations report
  69. IceCube-201130A: No Candidate Counterparts from the Zwicky Transient Facility
  70. IceCube-201130A: No significant detection in HAWC
  71. GRB201130A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 628407054)
  72. Fermi trigger No 628140709: Global MASTER-Net observations report
  73. Fermi GRB 201121A: Global MASTER-Net observations report
  74. Fermi GRB 201120B: Global MASTER-Net observations report
  75. Fermi trigger No 627198169: Global MASTER-Net observations report
  76. GRB 201116A: Fermi-LAT detection
  77. IceCube Alert 201115.09: Global MASTER-Net observations report
  78. GRB 201116A: BALROG localization (Fermi Trigger 627180592 / GRB 201116035)
  79. GRB 201116A: Fermi GBM Final Real-time Localization
  80. IceCube-201114A: No neutrino counterpart candidates in ANTARES search
  81. Fermi-LAT Gamma-ray Observations of NuEm-201107A
  82. Konus-Wind observation of GRB 201103B
  83. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-201107A
  84. Fermi trigger No 626247072: Global MASTER-Net observations report
  85. GRB 201103B (ZTF20acozryr/AT2020yxz): Nanshan/NEXT-0.6m optical observations
  86. IPN triangulation of GRB 201103B (consistent with ZTF20acozryr/AT2020yxz)
  87. GRB 201105B: Fermi GBM observation
  88. ZTF20acozryr/AT2020yxz: Zwicky Transient Facility discovery of a fast optical transient with no associated GRB
  89. GRB 201026A: Swift detection of a burst
  90. GRB 201020B: follow-up observations with Savelli Telescope
  91. GRB 201024A: Redshift from GTC/OSIRIS
  92. IceCube-201021A: No significant detection in HAWC
  93. IceCube-201021A: One candidate counterpart from the Zwicky Transient Facility
  94. Konus-Wind detection of GRB 201020A
  95. IceCube-201021A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  96. GRB 201020A: DOAO optical afterglow observations
  97. GRB 201020A: Fermi GBM observation
  98. GRB 201020A: Swift detection of a burst with an optical counterpart.
  99. GRB 201008A: Swift-XRT afterglow detection
  100. GRB 201016A: Fermi GBM detection

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