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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"

28692 results found.

  1. GRB 201223A: Fermi GBM Detection
  2. GRB 201223A: Nanshan/NEXT early optical afterglow detection
  3. Swift-XRT observations of Icecube 201222A
  4. IceCube-201222A: No significant detection in HAWC
  5. IceCube-201221A: No significant detection in HAWC
  6. GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  7. GRB 201221A: REM early-time afterglow detection
  8. GRB 201221D: 3.6m DOT optical observations
  9. GRB 201221B: Insight-HXMT/HE detection
  10. IceCube-201221A: Upper limits from Insight-HXMT/HE observations
  11. GRB 201221D: SMA submm observation
  12. Fermi GRB 201222B: Global MASTER-Net observations report
  13. GRB 201221D: MMT MMIRS detection of marginally extended source
  14. GRB 201221D: LCOGT upper limits
  15. GRB 201221D: Fermi GBM detection
  16. GRB 201221D: Swift-BAT refined analysis
  17. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  18. GRB 201216A - further Swift-XRT observations
  19. Fermi-LAT Gamma-ray Observations of IceCube-201222A
  20. Fermi-LAT Gamma-ray Observations of IceCube-201221A
  21. IceCube-201222A: not observable by Fermi-GBM
  22. GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
  23. Short GRB201221D: High Redshift from OSIRIS/GTC
  24. IceCube-201222A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  25. Konus-Wind detection of GRB 201221D (short)
  26. GRB 201221D: Swift/UVOT Upper Limits
  27. GRB 201221D: Lowell Discovery Telescope afterglow observations
  28. GRB 201221D: Swift-XRT refined Analysis
  29. Swift GRB 201221D: Global MASTER-Net observations report
  30. Fermi GRB 201221E: Global MASTER-Net observations report
  31. GRB 201221D: Nanshan/NEXT early optical upper limit
  32. GRB 201221D: candidate optical counterpart from the NOT
  33. GRB 201221A: Swift-BAT refined analysis
  34. correction to GCN 29110 - Fermi GBM Sub-Threshold Detection of GRB 201221A
  35. Fermi GBM Sub-Threshold Detection of GRB 201221A
  36. GRB 201221A: Swift/UVOT Upper Limits
  37. GRB 201221A: Swift-XRT refined Analysis
  38. IceCube-201221A: not observable by Fermi-GBM
  39. IceCube-201221A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  40. GRB 201221A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 5.7
  41. Swift GRB 201221A: Global MASTER-Net observations report
  42. Konus-Wind observation of GRB 201218A
  43. GRB 201209A: Mondy optical observations, afterglow confirmation
  44. GRB 201214A: TSHAO optical upper limit
  45. GRB 201214A: Swift-XRT afterglow detection
  46. GRB 201214A: 1.3m DFOT, optical upper limits
  47. IPN triangulation of GRB 201218A
  48. Fermi GRB 201218B: Global MASTER-Net observations report
  49. Fermi GRB 201218A: Global MASTER-Net observations report
  50. GRB201216C: No significant detection in HAWC
  51. GRB 201216C: Liverpool Telescope First Hour Observations
  52. Konus-Wind detection of GRB 201216C
  53. IceCube-201209A : MAXI/GSC upper limit
  54. GRB 201216C: Swift-BAT refined analysis
  55. Fermi GRB 201217A: Global MASTER-Net observations report
  56. GRB 201216C: VLT X-shooter spectroscopy and potential high redshift of a VHE-emitting GRB
  57. GRB 201216C: Fermi-LAT upper limit
  58. GRB 201216C: MAGIC detection in very high energy gamma rays
  59. GRB 201216C: AstroSat CZTI detection
  60. GRB 201216C: Fermi GBM detection
  61. GRB 201216A: Fermi GBM detection
  62. GRB 201216C: Swift/UVOT Upper Limits
  63. GRB 201216A: Swift-XRT observations
  64. GRB 201216C: VLT afterglow candidate discovery
  65. GRB 201216A: Swift ToO observations
  66. Fermi GRB 201216A: Global MASTER-Net observations report
  67. GRB 201216A: Swift/BAT-GUANO detection and arcminute localization
  68. GRB 201214B: MITSuME Akeno optical upper limits
  69. Chandra observations of GW170817 at ~3.3 years since merger (Full report)
  70. GRB 201214B: Lowell Discovery Telescope optical observations
  71. VLA observations of GW170817 at ~3.3 years post-merger
  72. Fermi GRB 201215A: Global MASTER-Net observations report
  73. GRB 201209A: Insight-HXMT/HE detection
  74. IceCube-201209A: Upper limits from Insight-HXMT/HE observations
  75. GRB 201214A: Swift-XRT observations
  76. GRB 201214B: Swift BAT location of short burst
  77. Fermi GRB 201214B: Global MASTER-Net observations report
  78. GRB 201214B: Swift ToO observations
  79. IceCube-201209: No significant detection in HAWC
  80. Potential X-ray KN afterglow from Chandra observations of GW170817 ~3.3 years since merger (3 Epochs of 4)
  81. GRB 201214A: Swift ToO observations
  82. GRB 201015A: optical observations and supernova identification
  83. GRB 201203A: Zeiss-1000 (Koshka observatory) optical upper limit
  84. IceCube-201209A: No Candidate Counterparts from the Zwicky Transient Facility
  85. GRB 201203A: 1.3m DFOT, optical upper limits
  86. GRB 200826A: GMOS-N detected source magnitude (Correction)
  87. GRB 201015A: 5-GHz radio afterglow detection with the EVN
  88. GRB 201209A: Swift/UVOT Upper Limits
  89. IceCube-201209A: Upper limits from Fermi-GBM Observations
  90. Fermi-LAT Gamma-ray Observations of IceCube-201209A
  91. IceCube-201209A: No neutrino counterpart candidates in ANTARES search
  92. GRB 201209A: Swift-BAT refined analysis
  93. IPN triangulation of GRB 201207A
  94. GRB 201208A: Swift-XRT afterglow detection
  95. GRB 201208A: Fermi GBM observation
  96. IceCube-201209A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  97. GRB 201208A: LCO observations
  98. GRB 201209A: Swift-XRT refined Analysis
  99. GRB 201209A: Xinglong-2.16m likely optical afterglow detection
  100. GRB 201209A: AstroSat CZTI detection

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