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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"

28722 results found.

  1. GRB 201229A: SAO RAS optical observations
  2. GRB 201229A: Nanshan/NEXT optical upper limit
  3. GRB 201227A: Swift-XRT observations
  4. GRB 201223A: SVOM-GWAC detected the optical counterpart during prompt emission phase
  5. GRB 201229A: Swift-XRT refined Analysis
  6. GRB 201229A: Swift-BAT refined analysis
  7. GRB 201104B: Maidanak and CrAO optical observations
  8. Fermi GRB 201229B: Global MASTER-Net observations report
  9. Konus-Wind observation of GRB 201227A
  10. GRB 201020B: Assy, Koshka, Mondy and Maidanak optical observations
  11. Fermi GRB 201228B: Global MASTER-Net observations report
  12. GRB 201227A: Insight-HXMT/HE detection
  13. GRB 201227A: Tiled Swift observations
  14. GRB 201227A: Swift ToO observations
  15. IPN triangulation of GRB 201227A (short)
  16. ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations
  17. GRB 201223A: AROMA-N Optical Observation
  18. GRB 201223A: Swift/UVOT Detection
  19. GRB 201223A: HCT optical upper limit
  20. GRB 201223A: AbAO optical observations
  21. GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
  22. IceCube-201222A: No Candidate Counterparts from the Zwicky Transient Facility
  23. GRB 201223A: Swift-XRT refined Analysis
  24. GRB 201223A: NOT optical upper limit and NEXT powerlaw decay
  25. GRB 201223A: GROWTH-India Telescope (GIT) photometric follow-up.
  26. GRB 201223A: Mondy and Kitab optical observations
  27. GRB 201223A: GWAC-F60A optical afterglow observations
  28. GRB 201223A: iTelescope optical afterglow observations
  29. GRB 201223A: MITSuME Akeno optical observation
  30. GRB 201223A: Swift-BAT refined analysis
  31. GRB 201223A: Fermi GBM Detection
  32. GRB 201223A: Nanshan/NEXT early optical afterglow detection
  33. Swift-XRT observations of Icecube 201222A
  34. IceCube-201222A: No significant detection in HAWC
  35. IceCube-201221A: No significant detection in HAWC
  36. GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  37. GRB 201221A: REM early-time afterglow detection
  38. GRB 201221D: 3.6m DOT optical observations
  39. GRB 201221B: Insight-HXMT/HE detection
  40. IceCube-201221A: Upper limits from Insight-HXMT/HE observations
  41. GRB 201221D: SMA submm observation
  42. Fermi GRB 201222B: Global MASTER-Net observations report
  43. GRB 201221D: MMT MMIRS detection of marginally extended source
  44. GRB 201221D: LCOGT upper limits
  45. GRB 201221D: Fermi GBM detection
  46. GRB 201221D: Swift-BAT refined analysis
  47. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  48. GRB 201216A - further Swift-XRT observations
  49. Fermi-LAT Gamma-ray Observations of IceCube-201222A
  50. Fermi-LAT Gamma-ray Observations of IceCube-201221A
  51. IceCube-201222A: not observable by Fermi-GBM
  52. GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
  53. Short GRB201221D: High Redshift from OSIRIS/GTC
  54. IceCube-201222A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  55. Konus-Wind detection of GRB 201221D (short)
  56. GRB 201221D: Swift/UVOT Upper Limits
  57. GRB 201221D: Lowell Discovery Telescope afterglow observations
  58. GRB 201221D: Swift-XRT refined Analysis
  59. Swift GRB 201221D: Global MASTER-Net observations report
  60. Fermi GRB 201221E: Global MASTER-Net observations report
  61. GRB 201221D: Nanshan/NEXT early optical upper limit
  62. GRB 201221D: candidate optical counterpart from the NOT
  63. GRB 201221A: Swift-BAT refined analysis
  64. correction to GCN 29110 - Fermi GBM Sub-Threshold Detection of GRB 201221A
  65. Fermi GBM Sub-Threshold Detection of GRB 201221A
  66. GRB 201221A: Swift/UVOT Upper Limits
  67. GRB 201221A: Swift-XRT refined Analysis
  68. IceCube-201221A: not observable by Fermi-GBM
  69. IceCube-201221A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  70. GRB 201221A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 5.7
  71. Swift GRB 201221A: Global MASTER-Net observations report
  72. Konus-Wind observation of GRB 201218A
  73. GRB 201209A: Mondy optical observations, afterglow confirmation
  74. GRB 201214A: TSHAO optical upper limit
  75. GRB 201214A: Swift-XRT afterglow detection
  76. GRB 201214A: 1.3m DFOT, optical upper limits
  77. IPN triangulation of GRB 201218A
  78. Fermi GRB 201218B: Global MASTER-Net observations report
  79. Fermi GRB 201218A: Global MASTER-Net observations report
  80. GRB201216C: No significant detection in HAWC
  81. GRB 201216C: Liverpool Telescope First Hour Observations
  82. Konus-Wind detection of GRB 201216C
  83. IceCube-201209A : MAXI/GSC upper limit
  84. GRB 201216C: Swift-BAT refined analysis
  85. Fermi GRB 201217A: Global MASTER-Net observations report
  86. GRB 201216C: VLT X-shooter spectroscopy and potential high redshift of a VHE-emitting GRB
  87. GRB 201216C: Fermi-LAT upper limit
  88. GRB 201216C: MAGIC detection in very high energy gamma rays
  89. GRB 201216C: AstroSat CZTI detection
  90. GRB 201216C: Fermi GBM detection
  91. GRB 201216A: Fermi GBM detection
  92. GRB 201216C: Swift/UVOT Upper Limits
  93. GRB 201216A: Swift-XRT observations
  94. GRB 201216C: VLT afterglow candidate discovery
  95. GRB 201216A: Swift ToO observations
  96. Fermi GRB 201216A: Global MASTER-Net observations report
  97. GRB 201216A: Swift/BAT-GUANO detection and arcminute localization
  98. GRB 201214B: MITSuME Akeno optical upper limits
  99. Chandra observations of GW170817 at ~3.3 years since merger (Full report)
  100. GRB 201214B: Lowell Discovery Telescope optical observations

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