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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"

38304 results found.

  1. GRB 250129a: Liverpool Telescope optical follow-up
  2. GRB 240129A: further SAO RAS optical observations
  3. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  4. GRB 250202C: Fermi GBM Final Real-time Localization
  5. GRB 250129A: SVOM/C-GFT optical observations
  6. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  7. GRB 250202B: Fermi GBM Final Real-time Localization
  8. Swift GRB250129A: MASTER 4 days observations report
  9. GRB 250202A: Fermi GBM Final Real-time Localization
  10. GRB 250201A: INTEGRAL SPI/ACS detection
  11. Konus-Wind detection of GRB 250129A
  12. GRB 250129A: 1.3m DFOT Optical observations
  13. GRB 250129A: Liverpool Telescope observations suggest continued engine activity
  14. GRB 250201A: BALROG localization (Fermi Trigger 760096791 / GRB 250201417)
  15. GRB 250201A: Fermi GBM Final Real-time Localization
  16. GRB 250129A: Skynet Continued Optical Observations
  17. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  18. GRB 250129A: SAO RAS optical observations
  19. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  20. GRB 250129A: optical photometry from Konkoly
  21. GRB 250129A: COLIBRÍ Optical Observations
  22. GRB 250128B: VLA possible radio detection
  23. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  24. GRB 250129A: iTelescope optical observation
  25. GRB 250129A: NOT optical observations of continuining activity
  26. GRB 250129a: Liverpool Telescope optical follow-up
  27. GRB 250129A: TNG NIR afterglow detection
  28. GRB 250129A: AKO Optical Afterglow Detection
  29. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  30. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  31. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  32. GRB 250128B: VLA radio upper limit
  33. Ep250125A: 1.3m DFOT optical upper limit
  34. GRB 250129A: Skynet optical observations
  35. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  36. GRB 250129A: Swift-XRT refined Analysis
  37. GRB 250128B: Gemini-North optical extended source detection
  38. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  39. GRB 250128B: TNG optical upper limit
  40. GRB 250129A: Swift/UVOT Detection
  41. GRB 250128B: VLT/HAWKI near-infrared observations
  42. GRB 250127A: CrAO and Terskol optical upper limits
  43. GRB 250129A: Enhanced Swift-XRT position
  44. GRB 250128B: NOT optical upper limit
  45. GRB 250128B: VLT/FORS2 optical observations
  46. GRB 250129A: REM optical/NIR afterglow detection
  47. GRB 250129A: OHP/T193 optical and spectroscopy observations
  48. GRB 250129A: Early afterglow detection by LCO.
  49. GRB 250128B: OHP/T193 optical upper limit
  50. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  51. GRB 250129A: LCO optical observations
  52. GRB 250129A: NOT optical observations and redshift confirmation
  53. GRB 250129A: GOTO optical observations show brightening afterglow
  54. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  55. Swift GRB 250129A: Global MASTER-Net observations report
  56. GRB 250128B: Enhanced Swift-XRT position
  57. Fermi GRB 250128B: Global MASTER-Net observations report
  58. GRB 250129A: Swift detection of a burst with an optical counterpart
  59. Swift GRB 250129A: Global MASTER-Net OT detection
  60. GRB 250128B: Swift-XRT refined Analysis
  61. GRB 250128B: Fermi GBM Observation
  62. GRB 250128B: GOTO optical upper limit
  63. Swift GRB 250128B: Global MASTER-Net observations report
  64. EP250125a: Upper limits from Swift/BAT-GUANO
  65. GRB 250128B: LCO optical observations
  66. GRB 250128B: Swift detection of a short burst
  67. GRB 250128B: Fermi GBM Final Real-time Localization
  68. GRB 250127A: Swift-XRT observations
  69. GRB 250127B: DDOTI Upper Limit on the Afterglow
  70. GRB 250127A: EP-FXT afterglow detection
  71. Fermi GRB 250128A: Global MASTER-Net observations report
  72. GRB 250128A: Fermi GBM Final Real-time Localization
  73. GRB 250117A: Fermi GBM Observation
  74. Fermi GRB 250127B: Global MASTER-Net observations report
  75. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  76. GRB 250127A: SVOM/VT upper limit
  77. GRB 250127B: Fermi GBM Final Real-time Localization
  78. IPN triangulation of GRB 250119C
  79. GRB 250127A: Swift ToO observations
  80. GRB 250127A: LCO optical upper limit
  81. GRB 241223A: cubesat Avion detection
  82. GRB 250127A: SVOM detection of a long burst
  83. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  84. EP250125A: Non-detection from Fermi-GBM Observations
  85. GRB 250126A: MAXI/GSC detection
  86. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  87. GRB 250126A: Fermi GBM Final Real-time Localization
  88. GRB 250118A: Fermi GBM Observation
  89. EP250125a: REM optical counterpart detection
  90. GRB 250119C: Fermi GBM Observation
  91. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  92. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  93. EP250108a: AbAO, CMO and Terskol optical upper limits
  94. Konus-Wind detection of GRB 250118B
  95. GRB 250121A: Fermi GBM Observation
  96. IPN triangulation of GRB 250118B
  97. Konus-Wind detection of GRB 250119B
  98. IPN triangulation of GRB 250119B
  99. GRB 250122A: Fermi GBM Final Real-time Localization
  100. Improved IPN triangulation of GRB 250107C

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