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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"

6797 results found.

  1. GRB 210211A: Fermi GBM observation
  2. Swift-XRT observations of IceCube-210210A
  3. Fermi-LAT Gamma-ray Observations of IceCube-210210A
  4. IceCube-210210A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  5. GRB 210210A: Swift-XRT refined Analysis
  6. GRB 210208A: GIT optical upper limit
  7. GRB 210209A: Swift-XRT refined Analysis
  8. GRB 210207B: Swift-XRT refined Analysis
  9. Konus-Wind detection of GRB 210204A (correction to GCN 29415)
  10. Konus-Wind detection of GRB 210204A / ZTF21aagwbjr
  11. GRB 210204A: Optical Observations from HCT
  12. GRB 210204A / ZTF21aagwbjr: Swift-XRT observations
  13. GRB 210205A: Swift-XRT refined Analysis
  14. GRB 210204: Fermi GBM observation
  15. GRB 210202A: Fermi GBM detection
  16. GRB 210202A: Fermi-LAT detection
  17. Continued Chandra observations of GW170817 at ~3.3 years since merger
  18. GRB 140330A: Swift-XRT refined Analysis
  19. GRB 140320B: Swift-XRT refined Analysis
  20. GRB 140402A: Swift-XRT refined Analysis
  21. GRB 140104B: Swift-XRT refined Analysis
  22. ZTF21aaeyldq: Observations with the 3.6m DOT
  23. GRB 210120A: Fermi GBM detection
  24. IPN triangulation of GRB 210124B (short)
  25. GRB 210120A : 1.3m DFOT optical observations
  26. GRB 210112A: 3.6m DOT optical detection
  27. GRB 210119A: Fermi GBM observation
  28. Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
  29. GRB 201221D: near-infrared observation with LBT
  30. ZTF21aaeyldq: observations with the 3.6m Devasthal Optical Telescope
  31. GRB 210112A: Swift-XRT refined Analysis
  32. NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  33. Correction to GCN 29278: GRB 201216C XRT refined analysis
  34. GRB 201216C: Swift-XRT refined Analysis
  35. GRB 210102B: further Swift-XRT observations
  36. GRB 210104A: iTelescope optical upper limit
  37. GW170817: HST observations at 3.4 years from merger
  38. GRB 210104A: Swift-XRT refined Analysis
  39. GRB 210104B: Swift-XRT refined Analysis
  40. GRB 210104A: DOAO optical afterglow observations
  41. GRB 210104A: Nanshan/NEXT optical powerlaw decay
  42. GRB 210104A: Fermi GBM detection
  43. GRB 210102B: Swift-XRT observations
  44. GRB 210102C: Fermi GBM detection
  45. GRB 201227A: Chilescope optical observations, possible optical counterpart
  46. GRB 201227A: GRAWITA VST-ESO PARANAL observations
  47. GRB 201227A: Fermi GBM observation
  48. GRB 201229A: SAO RAS optical observations
  49. GRB 201227A: Swift-XRT observations
  50. GRB 201229A: Swift-XRT refined Analysis
  51. GRB 201104B: Maidanak and CrAO optical observations
  52. GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
  53. GRB 201223A: Swift-XRT refined Analysis
  54. GRB 201223A: GROWTH-India Telescope (GIT) photometric follow-up.
  55. GRB 201223A: iTelescope optical afterglow observations
  56. GRB 201223A: Fermi GBM Detection
  57. Swift-XRT observations of Icecube 201222A
  58. IceCube-201222A: No significant detection in HAWC
  59. IceCube-201221A: No significant detection in HAWC
  60. GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  61. GRB 201221D: Fermi GBM detection
  62. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  63. GRB 201216A - further Swift-XRT observations
  64. Fermi-LAT Gamma-ray Observations of IceCube-201222A
  65. Fermi-LAT Gamma-ray Observations of IceCube-201221A
  66. IceCube-201222A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  67. GRB 201221D: Swift-XRT refined Analysis
  68. GRB 201221A: Swift/UVOT Upper Limits
  69. GRB 201221A: Swift-XRT refined Analysis
  70. IceCube-201221A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  71. GRB 201214A: Swift-XRT afterglow detection
  72. GRB 201214A: 1.3m DFOT, optical upper limits
  73. GRB201216C: No significant detection in HAWC
  74. GRB 201216C: Fermi-LAT upper limit
  75. GRB 201216C: Fermi GBM detection
  76. GRB 201216A: Fermi GBM detection
  77. GRB 201216A: Swift-XRT observations
  78. Chandra observations of GW170817 at ~3.3 years since merger (Full report)
  79. GRB 201214B: Swift-XRT observations
  80. GRB 201214A: Swift-XRT observations
  81. IceCube-201209: No significant detection in HAWC
  82. Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
  83. Long-lasting X-ray emission from GW170817 detected by Chandra
  84. GRB 201203A: 1.3m DFOT, optical upper limits
  85. Fermi-LAT Gamma-ray Observations of IceCube-201209A
  86. Chandra observations of GW170817 at ~3.3 years since merger (Observation 1 of 4)
  87. GRB 201208A: Swift-XRT afterglow detection
  88. GRB 201208A: Fermi GBM observation
  89. IceCube-201209A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  90. GRB 201209A: Swift-XRT refined Analysis
  91. GRB 201208A: Fermi-LAT detection
  92. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  93. GRB 201203A: GROWTH-India Telescope optical upper limit.
  94. GRB 201203A: Swift-XRT afterglow detection
  95. IceCube-201130A: No significant detection in HAWC
  96. IceCube-201130A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  97. GRB 201128B: Swift-XRT observations
  98. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  99. Fermi-LAT Gamma-ray Observations of IceCube-201130A
  100. Swift-XRT observations of IceCube 201130A

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