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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"

3106 results found.

  1. GRB 210406B: Fermi GBM detection
  2. GRB 210324C: AstroSat CZTI detection
  3. GRB 210320A: MAXI/GSC detection
  4. GRB 210318A: Swift detection of a burst
  5. Fermi trigger No 637521056: Global MASTER-Net observations report
  6. Fermi GRB 210312A: Global MASTER-Net observations report
  7. GRB 210306A: continued Mondy optical observations
  8. Fermi trigger No 636926765: Global MASTER-Net observations report
  9. GRB 210306A: iTelescope T24 optical observations
  10. Trigger 1035744: Swift detection of Sco X-1 due to Star Tracker loss of lock
  11. Fermi trigger No 636459103: Global MASTER-Net observations report
  12. GRB 210217A: 3.6m DOT optical observations
  13. Integral GRB210227.20: Global MASTER-Net observations report
  14. GRB 210226A: Swift-BAT refined analysis
  15. GRB 210217A: Swift detection of a burst with an optical counterpart
  16. IceCube Alert 210213.78: Global MASTER-Net observations report
  17. GRB 210213A: Fermi GBM Final Real-time Localization
  18. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations
  19. GRB 210211A: Swift/UVOT Detection
  20. Fermi GRB 210210B: Global MASTER-Net observations report
  21. IceCube-210210A: Two Candidate Counterparts from the Zwicky Transient Facility
  22. GRB 210207B: AbAO optical upper limit
  23. GRB 210204A (ZTF21aagwbjr/AT2021buv): Mondy and AbAO optical observations
  24. GRB 210205A: Swift detection of a burst
  25. GRB 210204B: Fermi GBM Final Real-time Localization
  26. GRB 210127A: Fermi GBM Final Real-time Localization
  27. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  28. Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
  29. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-210111A
  30. GRB 210110A: MAXI/GSC detection
  31. Fermi trigger No 631602681: Global MASTER-Net observations report
  32. GRB 210105A: Fermi GBM Final Real-time Localization
  33. Fermi GRB 210102C: Global MASTER-Net observations report
  34. MAXI GRB210102.38: Global MASTER-Net observations report
  35. GRB 201216C: TSHAO, Terskol, Mondy optical upper limits
  36. Fermi GRB 201229B: Global MASTER-Net observations report
  37. Baksan Neutrino Observatory Alert 201228.36: Global MASTER-Net observations report
  38. Fermi GRB 201228B: Global MASTER-Net observations report
  39. Fermi trigger No 630681391: Global MASTER-Net observations report
  40. IceCube-201222A: No Candidate Counterparts from the Zwicky Transient Facility
  41. Baksan Neutrino Observatory Alert 201223.60: Global MASTER-Net observations report
  42. GRB 201221D: LCOGT upper limits
  43. GRB 201221E: Fermi GBM Final Real-time Localization
  44. correction to GCN 29110 - Fermi GBM Sub-Threshold Detection of GRB 201221A
  45. Fermi GBM Sub-Threshold Detection of GRB 201221A
  46. Konus-Wind detection of GRB 201216C
  47. Baksan Neutrino Observatory Alert 201216.94: Global MASTER-Net observations report
  48. GRB 201216C: VLT afterglow candidate discovery
  49. GRB 201015A: optical observations and supernova identification
  50. IceCube-201209A: No Candidate Counterparts from the Zwicky Transient Facility
  51. GRB 201209A: Swift detection of a burst
  52. Fermi GRB 201208A: Global MASTER-Net observations report
  53. IceCube-201130A: No Candidate Counterparts from the Zwicky Transient Facility
  54. IceCube-201130A: No significant detection in HAWC
  55. GRB201130A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 628407054)
  56. Fermi trigger No 628140709: Global MASTER-Net observations report
  57. Fermi GRB 201121A: Global MASTER-Net observations report
  58. Fermi GRB 201120B: Global MASTER-Net observations report
  59. Fermi trigger No 627198169: Global MASTER-Net observations report
  60. GRB 201116A: Fermi-LAT detection
  61. IceCube Alert 201115.09: Global MASTER-Net observations report
  62. GRB 201116A: BALROG localization (Fermi Trigger 627180592 / GRB 201116035)
  63. GRB 201116A: Fermi GBM Final Real-time Localization
  64. IceCube-201114A: No neutrino counterpart candidates in ANTARES search
  65. Fermi-LAT Gamma-ray Observations of NuEm-201107A
  66. Konus-Wind observation of GRB 201103B
  67. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-201107A
  68. Fermi trigger No 626247072: Global MASTER-Net observations report
  69. GRB 201103B (ZTF20acozryr/AT2020yxz): Nanshan/NEXT-0.6m optical observations
  70. IPN triangulation of GRB 201103B (consistent with ZTF20acozryr/AT2020yxz)
  71. GRB 201105B: Fermi GBM observation
  72. ZTF20acozryr/AT2020yxz: Zwicky Transient Facility discovery of a fast optical transient with no associated GRB
  73. GRB 201026A: Swift detection of a burst
  74. GRB 201020B: follow-up observations with Savelli Telescope
  75. GRB 201024A: Redshift from GTC/OSIRIS
  76. IceCube-201021A: No significant detection in HAWC
  77. IceCube-201021A: One candidate counterpart from the Zwicky Transient Facility
  78. Konus-Wind detection of GRB 201020A
  79. IceCube-201021A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  80. GRB 201020A: DOAO optical afterglow observations
  81. GRB 201020A: Fermi GBM observation
  82. GRB 201020A: Swift detection of a burst with an optical counterpart.
  83. GRB 201008A: Swift-XRT afterglow detection
  84. GRB 201016A: Fermi GBM detection
  85. GRB 201013A: TSHAO and AbAO optical observations, afterglow confirmation
  86. GRB 201013A: FRAM-ORM possible afterglow candidate
  87. IceCube-201007A: No candidate counterparts from the Zwicky Transient Facility
  88. GRB 201013A: Swift detection of a burst
  89. GRB 201008A: Swift-XRT observations
  90. Fermi trigger No 623470566: Global MASTER-Net observations report
  91. Fermi trigger No 623493962: Global MASTER-Net observations report
  92. IceCube-200926A: No candidate counterparts from the Zwicky Transient Facility
  93. IceCube-200929A: No significant detection in HAWC
  94. IceCube-200929A: No neutrino counterpart candidates in ANTARES search
  95. IceCube-200926B: No significant detection in HAWC
  96. IceCube-200926A: No Candidate Counterparts from the Zwicky Transient Facility
  97. IceCube Alert 200926.33: Global MASTER-Net observations report
  98. Fermi GRB 200925A: Global MASTER-Net observations report
  99. Fermi GRB 200924A: Global MASTER-Net observations report
  100. Fermi GRB 200923A: Global MASTER-Net observations report

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