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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"

3031 results found.

  1. Fermi trigger No 642991619: Global MASTER-Net observations report
  2. Fermi GRB 210516A: Global MASTER-Net observations report
  3. Fermi GRB 210515B: Global MASTER-Net observations report
  4. Fermi GRB 210515A: Global MASTER-Net observations report
  5. GRB 210514A: update on the BAT trigger time and burst duration
  6. GRB210510A: Optical afterglow candidate from the Zwicky Transient Facility
  7. IceCube-210510A: No candidate counterparts from the Zwicky Transient Facility
  8. Fermi GRB 210511A: Global MASTER-Net observations report
  9. Fermi GRB 210510A: Global MASTER-Net observations report
  10. Swift trigger 1047857 is 4U 1700-377
  11. Fermi GRB 210507A: Global MASTER-Net observations report
  12. Fermi GRB 210501A: Global MASTER-Net observations report
  13. Fermi trigger No 641601187: Global MASTER-Net observations report
  14. Fermi GRB 210430B: Global MASTER-Net observations report
  15. GRB 210420B: follow-up photometry of optical afterglow at INASAN/Simeiz
  16. GRB 210422A: Swift detection of a burst
  17. GRB 210420B: Tautenburg observations
  18. Fermi GRB 210420A: Global MASTER-Net observations report
  19. Swift GRB 210421A: Global MASTER-Net observations report
  20. GRB 210413B: LOAO optical upper limit
  21. GRB 210411B: AstroSat CZTI detection
  22. Fermi GRB 210411B: Global MASTER-Net observations report
  23. GRB 210406A: 10.4m GTC follow-up observation
  24. GRB 210411B: Fermi GBM Final Real-time Localization
  25. Fermi GRB 210411A: Global MASTER-Net observations report
  26. GRB 210406B: Fermi GBM detection
  27. GRB 210324C: AstroSat CZTI detection
  28. GRB 210320A: MAXI/GSC detection
  29. GRB 210318A: Swift detection of a burst
  30. Fermi trigger No 637521056: Global MASTER-Net observations report
  31. Fermi GRB 210312A: Global MASTER-Net observations report
  32. GRB 210306A: continued Mondy optical observations
  33. Fermi trigger No 636926765: Global MASTER-Net observations report
  34. GRB 210306A: iTelescope T24 optical observations
  35. Trigger 1035744: Swift detection of Sco X-1 due to Star Tracker loss of lock
  36. Fermi trigger No 636459103: Global MASTER-Net observations report
  37. GRB 210217A: 3.6m DOT optical observations
  38. Integral GRB210227.20: Global MASTER-Net observations report
  39. GRB 210226A: Swift-BAT refined analysis
  40. GRB 210217A: Swift detection of a burst with an optical counterpart
  41. IceCube Alert 210213.78: Global MASTER-Net observations report
  42. GRB 210213A: Fermi GBM Final Real-time Localization
  43. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations
  44. GRB 210211A: Swift/UVOT Detection
  45. Fermi GRB 210210B: Global MASTER-Net observations report
  46. IceCube-210210A: Two Candidate Counterparts from the Zwicky Transient Facility
  47. GRB 210207B: AbAO optical upper limit
  48. GRB 210204A (ZTF21aagwbjr/AT2021buv): Mondy and AbAO optical observations
  49. GRB 210205A: Swift detection of a burst
  50. GRB 210204B: Fermi GBM Final Real-time Localization
  51. GRB 210127A: Fermi GBM Final Real-time Localization
  52. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  53. Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
  54. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-210111A
  55. GRB 210110A: MAXI/GSC detection
  56. Fermi trigger No 631602681: Global MASTER-Net observations report
  57. GRB 210105A: Fermi GBM Final Real-time Localization
  58. Fermi GRB 210102C: Global MASTER-Net observations report
  59. MAXI GRB210102.38: Global MASTER-Net observations report
  60. GRB 201216C: TSHAO, Terskol, Mondy optical upper limits
  61. Fermi GRB 201229B: Global MASTER-Net observations report
  62. Baksan Neutrino Observatory Alert 201228.36: Global MASTER-Net observations report
  63. Fermi GRB 201228B: Global MASTER-Net observations report
  64. Fermi trigger No 630681391: Global MASTER-Net observations report
  65. IceCube-201222A: No Candidate Counterparts from the Zwicky Transient Facility
  66. Baksan Neutrino Observatory Alert 201223.60: Global MASTER-Net observations report
  67. GRB 201221D: LCOGT upper limits
  68. GRB 201221E: Fermi GBM Final Real-time Localization
  69. correction to GCN 29110 - Fermi GBM Sub-Threshold Detection of GRB 201221A
  70. Fermi GBM Sub-Threshold Detection of GRB 201221A
  71. Konus-Wind detection of GRB 201216C
  72. Baksan Neutrino Observatory Alert 201216.94: Global MASTER-Net observations report
  73. GRB 201216C: VLT afterglow candidate discovery
  74. GRB 201015A: optical observations and supernova identification
  75. IceCube-201209A: No Candidate Counterparts from the Zwicky Transient Facility
  76. GRB 201209A: Swift detection of a burst
  77. Fermi GRB 201208A: Global MASTER-Net observations report
  78. IceCube-201130A: No Candidate Counterparts from the Zwicky Transient Facility
  79. IceCube-201130A: No significant detection in HAWC
  80. GRB201130A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 628407054)
  81. Fermi trigger No 628140709: Global MASTER-Net observations report
  82. Fermi GRB 201121A: Global MASTER-Net observations report
  83. Fermi GRB 201120B: Global MASTER-Net observations report
  84. Fermi trigger No 627198169: Global MASTER-Net observations report
  85. GRB 201116A: Fermi-LAT detection
  86. IceCube Alert 201115.09: Global MASTER-Net observations report
  87. GRB 201116A: BALROG localization (Fermi Trigger 627180592 / GRB 201116035)
  88. GRB 201116A: Fermi GBM Final Real-time Localization
  89. IceCube-201114A: No neutrino counterpart candidates in ANTARES search
  90. Fermi-LAT Gamma-ray Observations of NuEm-201107A
  91. Konus-Wind observation of GRB 201103B
  92. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-201107A
  93. Fermi trigger No 626247072: Global MASTER-Net observations report
  94. GRB 201103B (ZTF20acozryr/AT2020yxz): Nanshan/NEXT-0.6m optical observations
  95. IPN triangulation of GRB 201103B (consistent with ZTF20acozryr/AT2020yxz)
  96. GRB 201105B: Fermi GBM observation
  97. ZTF20acozryr/AT2020yxz: Zwicky Transient Facility discovery of a fast optical transient with no associated GRB
  98. GRB 201026A: Swift detection of a burst
  99. GRB 201020B: follow-up observations with Savelli Telescope
  100. GRB 201024A: Redshift from GTC/OSIRIS

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