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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"

28092 results found.

  1. GRB 210102B: Assy optical afterglow identification
  2. GRB 210104A: iTelescope optical upper limit
  3. GRB 210104B: Swift-BAT refined analysis
  4. GW170817: HST observations at 3.4 years from merger
  5. GRB 210104A: early ATLAS detections of the bright afterglow
  6. GRB 210104A: Swift-XRT refined Analysis
  7. GRB 210104B: Swift/UVOT Upper Limits
  8. GRB 210104B: Swift-XRT refined Analysis
  9. GRB 210104B: Assy optical upper limit
  10. GRB 210104A: DOAO optical afterglow observations
  11. GRB 210104B: Enhanced Swift-XRT position
  12. GRB 210104A: Nanshan/NEXT optical powerlaw decay
  13. GRB 210104A: Swift-BAT refined analysis
  14. GRB 210104B: Nanshan/NEXT optical upper limit
  15. GRB 210104A: Swift/UVOT Detection
  16. GRB 210104A: Fermi GBM detection
  17. GRB 210104A: Enhanced Swift-XRT position
  18. GRB 210104B: Swift detection of a burst
  19. GRB 210104A: MITSuME Ishigaki optical observation
  20. GRB 210104A: MITSuME Akeno optical observation
  21. GRB 210104A: BALROG localization (Fermi Trigger 631452424 / GRB 210104477)
  22. GRB 210104A: Swift detection of a burst with a bright optical counterpart
  23. GRB 210102C: Swift-BAT refined analysis
  24. GRB 210102B: Swift-XRT observations
  25. GRB 210102C: Fermi GBM detection
  26. MAXI GRB210102.38: Global MASTER-Net observations report
  27. GRB 210102B: MAXI/GSC detection
  28. INTEGRAL Weak #8913: AROMA-N Optical Observation
  29. Swift Trigger 1015615 is not a GRB
  30. Fermi trigger No 631119348: Global MASTER-Net observations report
  31. GRB 210101A: BALROG localization (Fermi Trigger 631205591 / GRB 210101620)
  32. GRB 210101A: Fermi GBM Final Real-time Localization
  33. GRB 201229A: Swift/UVOT Detection
  34. Fermi trigger No 631104264: Global MASTER-Net observations report
  35. GRB 201216C: TSHAO, Terskol, Mondy optical upper limits
  36. GRB 201227A: Chilescope optical observations, possible optical counterpart
  37. GRB 201227A: GRAWITA VST-ESO PARANAL observations
  38. GRB 201229A: AbAO optical afterglow detection, TSHAO optical upper limit
  39. GRB 201229A: SAO RAS optical observations
  40. GRB 201229A: Nanshan/NEXT optical upper limit
  41. GRB 201227A: Swift-XRT observations
  42. GRB 201229A: Swift-XRT refined Analysis
  43. GRB 201229A: Swift-BAT refined analysis
  44. GRB 201229B: BALROG localization (Fermi Trigger 630948017 / GRB 201229639)
  45. GRB 201229A: Enhanced Swift-XRT position
  46. GRB 201229A: Swift detection of a burst with a possible optical counterpart
  47. GRB 201227A: Insight-HXMT/HE detection
  48. GRB 201226A: Insight-HXMT/HE detection
  49. IPN triangulation of GRB 201227A (short)
  50. ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations
  51. GRB 201223A: AROMA-N Optical Observation
  52. GRB 201223A: Swift/UVOT Detection
  53. GRB 201223A: AbAO optical observations
  54. GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
  55. GRB 201223A: Swift-XRT refined Analysis
  56. GRB 201223A: Enhanced Swift-XRT position
  57. GRB 201223A: NOT optical upper limit and NEXT powerlaw decay
  58. GRB 201223A: GROWTH-India Telescope (GIT) photometric follow-up.
  59. GRB 201223A: Mondy and Kitab optical observations
  60. GRB 201223A: iTelescope optical afterglow observations
  61. GRB 201223A: MITSuME Akeno optical observation
  62. GRB 201223A: Swift-BAT refined analysis
  63. GRB 201223A: Fermi GBM Detection
  64. GRB 201223A: Nanshan/NEXT early optical afterglow detection
  65. GRB 201223A: Swift detection of a burst with a bright optical counterpart
  66. Swift GRB201223.75: Global MASTER-Net OT detection
  67. Swift-XRT observations of Icecube 201222A
  68. IceCube-201222A: Upper limits from a search for additional neutrino events in IceCube
  69. IceCube-201222A: No significant detection in HAWC
  70. IceCube-201221A: No significant detection in HAWC
  71. GRB 201221A: REM early-time afterglow detection
  72. GRB 201221D: 3.6m DOT optical observations
  73. GRB 201221B: Insight-HXMT/HE detection
  74. IceCube-201221A: Upper limits from Insight-HXMT/HE observations
  75. GRB 201221D: SMA submm observation
  76. GRB 201221D: LCOGT upper limits
  77. GRB 201221D: Swift-BAT refined analysis
  78. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  79. GRB 201216A - further Swift-XRT observations
  80. Fermi-LAT Gamma-ray Observations of IceCube-201222A
  81. Fermi-LAT Gamma-ray Observations of IceCube-201221A
  82. GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
  83. Short GRB201221D: High Redshift from OSIRIS/GTC
  84. IceCube-201222A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  85. Konus-Wind detection of GRB 201221D (short)
  86. GRB 201221D: Swift/UVOT Upper Limits
  87. GRB 201221D: Lowell Discovery Telescope afterglow observations
  88. GRB 201222B: BALROG localization (Fermi Trigger / GRB 201222461)
  89. GRB 201221D: FRAM-ORM optical limit
  90. GRB 201221D: Enhanced Swift-XRT position
  91. GRB 201221D: Nanshan/NEXT early optical upper limit
  92. GRB 201221D: candidate optical counterpart from the NOT
  93. GRB 201221A: Swift-BAT refined analysis
  94. GRB 201221D: Swift detection of a bright short burst
  95. correction to GCN 29110 - Fermi GBM Sub-Threshold Detection of GRB 201221A
  96. Fermi GBM Sub-Threshold Detection of GRB 201221A
  97. GRB 201221A: Swift/UVOT Upper Limits
  98. GRB 201221A: Swift-XRT refined Analysis
  99. Swift Trigger 1014012: possible GRB 201221C
  100. GRB 201221A: Enhanced Swift-XRT position

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