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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').
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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"

6791 results found.

  1. GRB 220118A: Fermi GBM detection
  2. GRB 220118A: GIT optical observations
  3. GRB 220118A: Enhanced Swift-XRT position
  4. GRB 220118A: MITSuME Akeno optical observation
  5. Fermi-LAT Gamma-ray Observations of IceCube-220115A and detection of a new gamma-ray source, Fermi J2350.2+2620
  6. GRB 220117B: Swift-XRT refined Analysis
  7. GRB 220117A: Swift-XRT refined Analysis
  8. Konus-Wind detection of GRB 220101A
  9. GRB 220107A: SAO RAS optical observations
  10. Konus-Wind detection of GRB 220107A
  11. Confirmation of the X-ray afterglow of GRB 220107B
  12. GRB 220107A: further SAO RAS optical observations
  13. GRB 220107A: SAO RAS optical observations
  14. GRB 220101A: SAO RAS optical observations
  15. GRB 220107A: Swift/UVOT Detection
  16. GRB 220107B: Fermi GBM observations
  17. GRB 220107B: Swift-XRT afterglow detection
  18. GRB 220107A: Swift-XRT afterglow detection
  19. GRB 220107B: Fermi-LAT detection
  20. GRB 220107A: Fermi GBM observations
  21. GRB 220101A: continued 1.3m DFOT Optical Observations
  22. GRB 220104A: Fermi GBM Observation
  23. GRB 220101A: 2.2m CAHA (+CAFOS) first day optical detection
  24. GRB 220101A: iTelescope optical observations
  25. GRB 220101A: 1.3m DFOT observations
  26. GRB 211229B: Fermi GBM observation
  27. Alert from the HAWC Burst Monitor HAWC-220103A
  28. GRB 220101A: Swift-XRT refined Analysis
  29. GRB 220101A: Fermi-LAT detection
  30. GRB 211229A: Swift-XRT and UVOT observations
  31. GRB 211229A: Fermi GBM observation
  32. GRB 211227A: Swift-XRT refined Analysis
  33. GRB 211221A: Swift-XRT refined Analysis
  34. IceCube-211216B: No significant detection in HAWC
  35. IceCube-211216A: No significant detection in HAWC
  36. GRB 211216A: Fermi GBM observation
  37. GRB 211106A: XMM-Newton monitoring campaign detections
  38. Fermi-LAT Gamma-ray Observations of IceCube-211216B
  39. Fermi-LAT Gamma-ray Observations of IceCube-211216A
  40. IceCube-211216A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  41. GRB 211211A: HCT and GIT optical follow up observations
  42. GRB 211211A: Swift-XRT refined Analysis
  43. GRB 211211A: Fermi GBM observation
  44. IceCube-211208A: No significant detection in HAWC
  45. Fermi-LAT Gamma-ray Observations of IceCube-211208A
  46. IceCube-211208A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  47. Chandra observation of GW170817 at ~1573 days since merger (Epoch 1 of 4)
  48. GRB 211204C: Fermi GBM detection
  49. GRB 211207A: Swift-XRT refined Analysis
  50. GRB 211206A: AstroSat CZTI detection
  51. GRB 211124A: Fermi GBM Observation
  52. IceCube-211125A: No significant detection in HAWC
  53. GRB 211129A: Swift-XRT refined Analysis
  54. GRB 211129A: Fermi GBM observation
  55. IceCube-211125A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  56. GRB 211023A: Xinglong 2.16m optical observations
  57. Fermi-LAT Gamma-ray Observations of IceCube-211125A
  58. GRB 211120548: Fermi GBM observation
  59. Chandra observations of GRB 210905A
  60. GRB 211118A: Fermi GBM detection
  61. Fermi-LAT Gamma-ray Observations of IceCube-211123A
  62. HAWC-211123A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  63. Fermi-LAT Gamma-ray Observations of IceCube-211117A
  64. Fermi-LAT Gamma-ray Observations of IceCube-211116A
  65. Fermi trigger No 658755664: Global MASTER-Net observations report
  66. GRB 211023A: classification and SPI-ACS/INTEGRAL registration
  67. GRB 211106A: Swift/UVOT upper limits
  68. GRB 211107B: Swift-XRT afterglow detection
  69. GRB 211106A: Swift-XRT afterglow detection
  70. GRB 211023A: SAO RAS optical observations
  71. GRB 211107B: Swift-XRT observations
  72. GRB 211106A: Swift-XRT observations
  73. Swift Trigger 1082569 is probably not a GRB
  74. GRB 211023A: continued 1.3m DFOT Optical Observations and possible jet break
  75. GRB 211023A: 1.3m DFOT Optical Observations
  76. GRB 211024A: Swift-XRT source 4 is not an afterglow.
  77. GRB 211023B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  78. GRB 211024A: Possible afterglow candidate from GIT
  79. GRB 211024A: Swift-XRT observations
  80. GRB 211024A: Fermi GBM detection
  81. GRB 211018A: Swift-XRT observations
  82. GRB 211025A: Swift-XRT refined Analysis
  83. GRB 211024B: CAHA 2.2m Detection; ultra-long GRB?
  84. GRB 211024B: Swift-XRT refined Analysis
  85. GRB 210610B: Sintesz-Newton/CrAO optical observations
  86. GRB 211025A: Swift detection of a burst
  87. GRB 211023A: OAJ Bright Afterglow Confirmation
  88. Fermi-LAT Gamma-ray Observations of IceCube-211023A
  89. IceCube-211023A: No neutrino counterpart detected with ANTARES
  90. GRB 211023B: Swift-XRT refined Analysis
  91. GRB 211023A: Fermi-LAT detection
  92. GRB 211018A: Fermi GBM observation
  93. GRB 211018A: Fermi-LAT detection
  94. GRB 210928A: Kinder SLT-40cm optical limits
  95. GRB 210928A: Swift-XRT analysis (replaces GCN 30914)
  96. GRB 210928A: Swift-XRT refined Analysis
  97. GRB 210928A: Fermi GBM observation
  98. GRB 210928A: Fermi-LAT detection
  99. GRB 210930A: Swift-XRT refined Analysis
  100. Fermi-LAT Gamma-ray Observations of IceCubeCascade-210926A

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