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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"

6792 results found.

  1. GRB 210610B: Further SAO RAS optical observations
  2. GRB 210610A: SAO RAS optical observations
  3. GRB 210610B: optical observations from Burke-Gaffney Observatory and Abbey Ridge Observatory
  4. GRB 210421B: Fermi GBM detection
  5. GRB 201228B: Fermi GBM observation
  6. GRB 210610A: CAHA 2.2m observations and light-curve behavior
  7. GRB 210606A: Fermi GBM detection
  8. GRB 210605B: Fermi GBM detection
  9. GRB 210610B: Swift-XRT refined Analysis
  10. GRB 210610B: Fermi GBM detection
  11. Konus-Wind detection of GRB 210610A
  12. Konus-Wind detection of GRB 210610B
  13. GRB 210610A: Swift-XRT refined Analysis
  14. GRB 210610B: iTelescope optical afterglow observations
  15. GRB 210606A: Swift-XRT afterglow detection
  16. GRB 210610A: GIT optical detection
  17. Fermi-LAT Gamma-ray Observations of IceCube-210608A
  18. GRB 210606B: Fermi GBM detection
  19. GRB 210605B: Swift-XRT observations
  20. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
  21. Swift J1555.2-5402: Swift XRT refined analysis of the new SGR
  22. NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
  23. GRB 210528A: Fermi GBM detection
  24. GRB 210527A: GIT optical upper limit
  25. GRB 210527A: Swift-XRT refined Analysis
  26. GRB 210520A: Swift-XRT observations
  27. GRB210413B: further Swift-XRT observations
  28. GRB 210520A: Fermi GBM detection
  29. GRB 210520A: Fermi-LAT detection
  30. Fermi GBM observation of a bright burst from magneta
  31. Fermi-LAT Gamma-ray Observations of IceCube-210516A
  32. GRB 210517A: Swift-XRT refined Analysis
  33. IceCube-210516A: No significant detection in HAWC
  34. GRB 210515C: Swift-XRT refined Analysis
  35. GRB 210514A: Swift-XRT refined Analysis
  36. GRB 210514A: update on the BAT trigger time and burst duration
  37. GRB 210511B: Fermi GBM observation
  38. Fermi-LAT Gamma-ray Observations of IceCube-210510A
  39. GRB 210509A: Swift-XRT refined Analysis
  40. Fermi-LAT Gamma-ray Observations of IceCube-210503A and detection of a new gamma-ray source, Fermi J0931.9+3633
  41. GRB 210506A: Swift-XRT observations
  42. Alert from the HAWC Burst Monitor HAWC-210507A
  43. GRB 210504A: Swift-XRT refined Analysis
  44. GRB 210504A: MITSuME Akeno optical upper limits
  45. GRB 210413B: Swift/UVOT Observations
  46. GRB 210323B: Swift-XRT observations
  47. Swift Trigger 1045571 is not a GRB
  48. GRB 210422B: Fermi GBM Final Localization
  49. GRB 210421B: Swift-XRT observations
  50. GRB 210420B: Swift-XRT refined Analysis
  51. GRB 210421A: Swift-XRT refined Analysis
  52. GRB 210419A: Swift-XRT refined Analysis
  53. GRB 210413B: Swift-XRT observations
  54. GRB 210410A: A twin of short GRB 090510 with complementary observations
  55. GRB 210411C: Swift-XRT refined Analysis
  56. GRB 210410A: Swift-XRT refined Analysis
  57. GRB 210410A: Fermi GBM detection
  58. GRB 210406A: Swift-XRT observations
  59. GRB 210410A: Fermi-LAT detection
  60. GRB 210406B: Fermi GBM detection
  61. GRB 210406A: Fermi GBM detection
  62. GRB 210402A: Fermi GBM detection
  63. GRB 210402A: Swift-XRT refined Analysis
  64. GRB 210323A: Fermi GBM detection
  65. GRB 210323A: Swift-XRT refined Analysis
  66. GRB 210321A: Swift-XRT refined Analysis
  67. GRB 210318A: Swift-XRT refined Analysis
  68. GRB 210318B: Fermi GBM detection
  69. GRB210318B: Swift detection of a burst
  70. GRB 210226A: GIT optical upper limit
  71. GRB 210306A: HCT optical upper limit
  72. GRB 210306B: Fermi GBM detection
  73. GRB 210305A: Fermi GBM observation
  74. GRB 210308A: Fermi GBM detection
  75. GRB 210305A: Swift-XRT refined Analysis
  76. GRB 210307A: Swift-XRT refined Analysis
  77. GRB 210306A: Swift-XRT refined Analysis
  78. GRB 210306A: Fermi GBM observation
  79. GRB 210306A: iTelescope T24 optical observations
  80. GRB 210306A: Fermi-LAT detection
  81. GRB 210306A: iTelescope optical afterglow observations
  82. GRB 210217A: 3.6m DOT optical observations
  83. GRB 210226A: Fermi GBM detection
  84. GRB 210226A: Swift-XRT refined Analysis
  85. GRB 210218A: Swift-XRT confirmation of afterglow
  86. GRB 210222B: Swift-XRT refined Analysis
  87. GRB 210218A: Swift/UVOT observations
  88. GRB 210218A: Swift-XRT observations
  89. GRB 210217A: Swift-XRT refined Analysis
  90. GRB 210205A: observations with the 3.6m DOT, a potential dark burst?
  91. Fermi/GBM observation of a burst from SGR 1830-0645
  92. GRB 210210A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  93. GRB 210212A: Swift-XRT refined Analysis
  94. GRB 210204A: observations with the 3.6m Devasthal Optical Telescope and possible jet break
  95. GRB 210211A: Swift-XRT refined Analysis
  96. GRB 210211A: Fermi GBM observation
  97. Swift-XRT observations of IceCube-210210A
  98. Fermi-LAT Gamma-ray Observations of IceCube-210210A
  99. IceCube-210210A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  100. GRB 210210A: Swift-XRT refined Analysis

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