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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 210208A: GIT optical upper limit
  2. GRB 210209A: Swift-XRT refined Analysis
  3. GRB 210207B: Swift-XRT refined Analysis
  4. Konus-Wind detection of GRB 210204A (correction to GCN 29415)
  5. Konus-Wind detection of GRB 210204A / ZTF21aagwbjr
  6. GRB 210204A: Optical Observations from HCT
  7. GRB 210204A / ZTF21aagwbjr: Swift-XRT observations
  8. GRB 210205A: Swift-XRT refined Analysis
  9. GRB 210204: Fermi GBM observation
  10. GRB 210202A: Fermi GBM detection
  11. GRB 210202A: Fermi-LAT detection
  12. Continued Chandra observations of GW170817 at ~3.3 years since merger
  13. GRB 140330A: Swift-XRT refined Analysis
  14. GRB 140320B: Swift-XRT refined Analysis
  15. GRB 140402A: Swift-XRT refined Analysis
  16. GRB 140104B: Swift-XRT refined Analysis
  17. ZTF21aaeyldq: Observations with the 3.6m DOT
  18. GRB 210120A: Fermi GBM detection
  19. IPN triangulation of GRB 210124B (short)
  20. GRB 210120A : 1.3m DFOT optical observations
  21. GRB 210112A: 3.6m DOT optical detection
  22. GRB 210119A: Fermi GBM observation
  23. Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
  24. GRB 201221D: near-infrared observation with LBT
  25. ZTF21aaeyldq: observations with the 3.6m Devasthal Optical Telescope
  26. GRB 210112A: Swift-XRT refined Analysis
  27. NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  28. Correction to GCN 29278: GRB 201216C XRT refined analysis
  29. GRB 201216C: Swift-XRT refined Analysis
  30. GRB 210102B: further Swift-XRT observations
  31. GRB 210104A: iTelescope optical upper limit
  32. GW170817: HST observations at 3.4 years from merger
  33. GRB 210104A: Swift-XRT refined Analysis
  34. GRB 210104B: Swift-XRT refined Analysis
  35. GRB 210104A: DOAO optical afterglow observations
  36. GRB 210104A: Nanshan/NEXT optical powerlaw decay
  37. GRB 210104A: Fermi GBM detection
  38. GRB 210102B: Swift-XRT observations
  39. GRB 210102C: Fermi GBM detection
  40. GRB 201227A: Chilescope optical observations, possible optical counterpart
  41. GRB 201227A: GRAWITA VST-ESO PARANAL observations
  42. GRB 201227A: Fermi GBM observation
  43. GRB 201229A: SAO RAS optical observations
  44. GRB 201227A: Swift-XRT observations
  45. GRB 201229A: Swift-XRT refined Analysis
  46. GRB 201104B: Maidanak and CrAO optical observations
  47. GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
  48. GRB 201223A: Swift-XRT refined Analysis
  49. GRB 201223A: GROWTH-India Telescope (GIT) photometric follow-up.
  50. GRB 201223A: iTelescope optical afterglow observations
  51. GRB 201223A: Fermi GBM Detection
  52. Swift-XRT observations of Icecube 201222A
  53. IceCube-201222A: No significant detection in HAWC
  54. IceCube-201221A: No significant detection in HAWC
  55. GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  56. GRB 201221D: Fermi GBM detection
  57. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  58. GRB 201216A - further Swift-XRT observations
  59. Fermi-LAT Gamma-ray Observations of IceCube-201222A
  60. Fermi-LAT Gamma-ray Observations of IceCube-201221A
  61. IceCube-201222A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  62. GRB 201221D: Swift-XRT refined Analysis
  63. GRB 201221A: Swift/UVOT Upper Limits
  64. GRB 201221A: Swift-XRT refined Analysis
  65. IceCube-201221A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  66. GRB 201214A: Swift-XRT afterglow detection
  67. GRB 201214A: 1.3m DFOT, optical upper limits
  68. GRB201216C: No significant detection in HAWC
  69. GRB 201216C: Fermi-LAT upper limit
  70. GRB 201216C: Fermi GBM detection
  71. GRB 201216A: Fermi GBM detection
  72. GRB 201216A: Swift-XRT observations
  73. Chandra observations of GW170817 at ~3.3 years since merger (Full report)
  74. GRB 201214B: Swift-XRT observations
  75. GRB 201214A: Swift-XRT observations
  76. IceCube-201209: No significant detection in HAWC
  77. Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
  78. Long-lasting X-ray emission from GW170817 detected by Chandra
  79. GRB 201203A: 1.3m DFOT, optical upper limits
  80. Fermi-LAT Gamma-ray Observations of IceCube-201209A
  81. Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
  82. GRB 201208A: Swift-XRT afterglow detection
  83. GRB 201208A: Fermi GBM observation
  84. IceCube-201209A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  85. GRB 201209A: Swift-XRT refined Analysis
  86. GRB 201208A: Fermi-LAT detection
  87. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  88. GRB 201203A: GROWTH-India Telescope optical upper limit.
  89. GRB 201203A: Swift-XRT afterglow detection
  90. IceCube-201130A: No significant detection in HAWC
  91. IceCube-201130A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  92. GRB 201128B: Swift-XRT observations
  93. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  94. Fermi-LAT Gamma-ray Observations of IceCube-201130A
  95. Swift-XRT observations of IceCube 201130A
  96. GRB 201128A: Swift-XRT refined Analysis
  97. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
  98. Fermi-LAT Gamma-ray Observations of IceCube-201120A
  99. IceCube-201120A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  100. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e

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