Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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"

39184 results found.

  1. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  2. GRB 250430A: AKO Optical Afterglow Detection
  3. GRB 250430A: Kanata optical upper limit
  4. EP 250427A: Optical counterpart detection by LCO.
  5. GRB 250430A: Swift detection of a burst with optical counterpart
  6. Swift GRB250430.73: Global MASTER-Net observations report
  7. EP250427a / GRB 250427A: OHP/T193 continued photometric observations
  8. SVOM/sb25043004: SVOM detection of a X-ray transient
  9. Fermi trigger No 767623859: Global MASTER-Net observations report
  10. EP250428b: GROWTH-India telescope optical upper limit
  11. EP250428b: SAO RAS optical upper limit
  12. IceCube-250429A - IceCube observation of a high-energy neutrino candidate track-like event
  13. GRB 250427A: Swift/UVOT Detection
  14. EP250428b: Global MASTER-Net observations report
  15. EP250427a / GRB 250427A: OHP/T193 photometric observations
  16. EP250427a: EP-FXT follow-up observations
  17. EP250427a/GRB 250427A: FTW optical and NIR observations of the counterpart
  18. EP250427a: Lesedi optical counterpart detection
  19. GRB250427A/EP250427a GIT optical afterglow detection:
  20. EP250427a: LT optical counterpart detection
  21. GRB 250427A: Swift-XRT refined Analysis
  22. EP250427a / GRB 250427A: LCO optical counterpart detection
  23. EP250427a / GRB 250427A: VLT/X-shooter redshift confirmation z = 1.520
  24. EP250427A/GRB250427A: Keck/LRIS redshift
  25. EP250427a: REM optical/NIR afterglow detection
  26. GRB 250424A: LCO optical observation
  27. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  28. EP250427a: TRT optical counterpart detection
  29. EP250427a: Global MASTER-Net observations report
  30. IceCube Alert 250426.74: Global MASTER-Net observations report
  31. GRB 250424A: Swift-BAT refined analysis
  32. IceCube-250426A - IceCube observation of a high-energy neutrino candidate track-like event
  33. GRB 250424A: SVOM/GRM observation of a long burst
  34. GRB 250424A: PRIME near-infrared detection
  35. GRB 250424A: WINTER J-band detection
  36. GRB 250424A: EIRSAT-1 GMOD Detection
  37. GRB 250424A: SVOM/VT optical observation
  38. GRB 250419A: Mondy Optical Observations
  39. GRB 250424A: Swift/UVOT Detection
  40. Konus-Wind detection of GRB 250424A
  41. Fermi-LAT gamma-ray observations of IceCube-250421A
  42. GRB 250424A: Skynet Optical Observations
  43. GRB 250424A: Kilonova-Catcher optical afterglow detection
  44. GRB 250419a: Continued Liverpool Telescope observations
  45. GRB 250419A: Liverpool Telescope optical upper limit
  46. GRB 250407A: GRBAlpha detection
  47. GRB 250404A / EP250404a: GRBAlpha detection
  48. GRB 250330B: GRBAlpha detection
  49. GRB 250419A: SVOM/ECLAIRs refined analysis
  50. GRB 250424A: Swift-XRT refined Analysis
  51. GRB 250424A: Enhanced Swift-XRT position
  52. GRB 250424A: AstroSat CZTI detection of a bright long burst
  53. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  54. GRB 250424A: BlackGEM optical afterglow detection
  55. GRB 250424A: VLT/X-shooter spectroscopic redshift z = 0.310
  56. GRB 250424A: likely host galaxy
  57. GRB 250424A: DDOTI Afterglow Detection
  58. GRB 250424A: REM optical/NIR afterglow detection
  59. GRB 250424A: Swift detection of a burst with an optical counterpart
  60. Swift GRB 250424A: Global MASTER-Net observations report
  61. Swift GRB 250424A: Global MASTER-Net OT detection
  62. EP250421a: Nickel optical upper limit
  63. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  64. EP250421a: Upper limits from Fermi-GBM Observations
  65. SVOM/sb25042207: GOTO optical upper limits
  66. GRB 250421A: AstroSat CZTI detection
  67. GRB250419A: VLA radio detection
  68. GRB 250419A: Mephisto Multi-band Optical Detection
  69. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  70. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  71. GRB 250419A: Optical Observations via Virtual Telescope Project
  72. EP250421a: REM optical upper limit
  73. GRB 250419A: Mondy Continued Optical Observations
  74. Fermi GRB 250421A: Global MASTER-Net observations report
  75. EP250421a: Global MASTER-Net observations report
  76. GRB 250421B: AstroSat CZTI detection of a bright long burst
  77. EP250421a: Mephisto optical counterpart confirmation
  78. IceCube Alert 250421.71: Global MASTER-Net observations report
  79. EP250421a: JinShan likely optical counterpart
  80. GRB 250421A: Fermi GBM Final Real-time Localization
  81. GRB 250419A: Liverpool Telescope observations
  82. GRB 250419A: LCO optical observation
  83. GRB 250419A: JinShan optical observations
  84. GRB 250419A: SVOM/VT optical continuous observations
  85. GRB 250419A: SVOM/C-GFT optical observations
  86. GRB 250419A: Swift/UVOT Follow up
  87. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  88. GRB 250419A: LCO optical afterglow multi-band observations
  89. GRB 250419A: Mondy and AbAO Optical Observations
  90. GRB 250419A: Liverpool Telescope observations
  91. GRB 250419A: AKO Optical Afterglow Detection
  92. GRB 250419A: MASTER optical afterglow observation
  93. GRB 250407A: rest-frame energetics from Konus-Wind observation
  94. GRB 250419A: Swift-XRT localisation
  95. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  96. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  97. GRB 250419A: Swift-XRT refined Analysis
  98. GRB 250419A: GOTO optical counterpart detection
  99. GRB 250419A: KAIT optical afterglow observations
  100. GRB 250419A: SVOM/VT optical bright counterpart confirmation

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov