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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"

26353 results found.

  1. GRB 210323B: Fermi GBM observation
  2. GRB 210610B: REM optical/NIR observations of the afterglow
  3. Follow-up on HAWC Transient Monitoring Alert J0020+3108
  4. Swift ToO Observations of HAWC transient J0020+3108
  5. GRB 210605B: Swift-XRT afterglow detection
  6. GRB 210610A: Fermi GBM observations
  7. GRB 210610B: Further SAO RAS optical observations
  8. GRB 210610A: SAO RAS optical observations
  9. GRB 210610B: optical photometry of afterglow at INASAN/Simeiz
  10. GRB 210421B: Fermi GBM detection
  11. GRB 210607C: AstroSat CZTI detection
  12. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  13. GRB210610B: SARA-KP 0.9m Optical Afterglow Detection
  14. GRB 210610B: MITSuME Akeno optical observation
  15. GRB 201228B: Fermi GBM observation
  16. GRB 210610B: Liverpool Telescope optical photometry
  17. GRB 210610A: CrAO/ZTSH optical observations
  18. GRB 210610B: CrAO/ZTSH optical observations (correction to the GCN circ. 30212)
  19. GRB 210610A: CrAO/ZTSH optical observations
  20. GRB 210606A: Fermi GBM detection
  21. GRB 210605B: Fermi GBM detection
  22. GRB 210610B: Swift-XRT refined Analysis
  23. GRB 210610B: Swift-BAT refined analysis
  24. GRB 210610B: Zwicky Transient Facility afterglow detection
  25. GRB 210610B: optical afterglow observations
  26. GRB 210607C: Insight-HXMT/HE detection
  27. GRB 210610B: Fermi GBM detection
  28. GRB 210610B: University of Siena Observatory optical photometry of the afterglow
  29. GRB 210610B: GOTO confirmation of afterglow detection
  30. GRB 210610A: Swift-XRT refined Analysis
  31. GRB 210610A: RATIR Optical and NIR Detection
  32. GRB 210610B: RATIR Optical and NIR Observations
  33. GRB 210610B: Enhanced Swift-XRT position
  34. GRB 210610B: SAO RAS optical observations
  35. GRB 210610A: Swift-BAT refined analysis
  36. GRB 210610B: correction to GCN 30181
  37. HAWC Transient Monitoring Alert: Significant Spot after 3 transits
  38. GRB 210610B: iTelescope optical afterglow observations
  39. GRB210610B: MeerLICHT multi-colour photometry
  40. GRB 210610B: CrAO/ZTSh optical afterglow photometry
  41. GRB 210610B: GIT optical detection
  42. Swift GRB210610.83: Global MASTER-Net OT detection
  43. GRB 210606A: Swift-XRT afterglow detection
  44. GRB 210610B: BALROG localization (Fermi Trigger 645047470 / GRB 210610827)
  45. GRB 210610B: Swift detection of a burst with bright optical afterglow
  46. GRB 210610A: MITSuME Ishigaki optical observation
  47. GRB210610A: MeerLICHT multi-colour photometry
  48. GRB 210610A: Enhanced Swift-XRT position
  49. GRB 210610A: GIT optical detection
  50. GRB 210610A: Xinglong-2.16m optical afterglow observations
  51. GRB 210610A: MITSuME Akeno optical observation
  52. GRB 210610A: Swift detection of a burst with an optical counterpart
  53. GRB 210607B: Insight-HXMT/HE detection
  54. Fermi-LAT Gamma-ray Observations of IceCube-210608A
  55. IPN triangulation of GRB 210606B
  56. GRB 210607A/MAXI J1733-222: MAXI/GSC detection
  57. MAXI GRB210607.82: Global MASTER-Net observations report
  58. Fermi trigger No 644793834: Global MASTER-Net observations report
  59. GRB 210606B: Fermi GBM detection
  60. GRB 210605B: Swift-XRT observations
  61. IPN triangulation of GRB 210605A (short)
  62. GRB 210606B: BALROG localization (Fermi Trigger 644712030 / GRB 210606945)
  63. GRB 210606B: GECAM detection
  64. Fermi GRB 210606A: DDOTI Upper Limits on the Afterglow
  65. GRB 210606A: Swift/BAT-GUANO detection and arcminute localization
  66. GRB 210605B: Swift/BAT-GUANO detection and arcminute localization
  67. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
  68. Fermi GBM Sub-Threshold Detection of new Swift SGR J1555.2-5402
  69. SGR J1555.2-5402: Swift-BAT refined analysis
  70. NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
  71. Swift Detection of probable new Swift SGR J1555.2-5402
  72. MAXI GRB210602.50: Global MASTER-Net observations report
  73. Swift GRB210603.41: Global MASTER-Net observations report
  74. GRB 210602B: GECAM detection
  75. GRB 210529A: GECAM detection
  76. GRB 210602A: MAXI/GSC detection
  77. GRB 210601A: Fermi GBM Final Real-time Localization
  78. IPN triangulation of GRB 210531A
  79. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  80. GRB 210531A: AstroSat CZTI detection
  81. Fermi trigger No 644155206: Global MASTER-Net observations report
  82. GRB 210531A: BALROG localization (Fermi Trigger 644155206 / GRB 210531500)
  83. GRB 210529B: DDOTI Upper Limits on the Afterglow
  84. GRB 210528A: Fermi GBM detection
  85. GRB 210528A: AstroSat CZTI detection
  86. GRB 210528B: DDOTI Upper Limits on the Afterglow
  87. GRB 210528B: MITSuME Akeno optical upper limits
  88. MAXI GRB210528.95: Global MASTER-Net observations report
  89. GRB 210528B: MAXI/GSC detection
  90. GRB 210527A: Swift-BAT refined analysis
  91. GRB 210528A: BALROG localization (Fermi Trigger 643903431 / GRB 210528586)
  92. GRB 210527A: Swift/UVOT Observations
  93. GRB 210527A: GIT optical upper limit
  94. GRB 210527A: MITSuME Akeno optical upper limits
  95. GRB 210527A: Swift-XRT refined Analysis
  96. GRB 210527A: RATIR Optical and NIR Observations
  97. GRB 210527A: Enhanced Swift-XRT position
  98. GRB 210527A: Swift-XRT observations
  99. GRB 210306A: LBT observations of the likely host galaxy
  100. ZTF21aayokph (AT2021lfa): LBT optical observations

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