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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

36326 results found.

  1. GRB 250129A: optical photometry from Konkoly
  2. GRB 250129A: COLIBRÍ Optical Observations
  3. GRB 250128B: VLA possible radio detection
  4. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  5. GRB 250129A: iTelescope optical observation
  6. GRB 250129A: NOT optical observations of continuining activity
  7. GRB 250129a: Liverpool Telescope optical follow-up
  8. GRB 250129A: TNG NIR afterglow detection
  9. GRB 250129A: AKO Optical Afterglow Detection
  10. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  11. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  12. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  13. GRB 250128B: VLA radio upper limit
  14. GRB 250129A: Skynet optical observations
  15. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  16. GRB 250129A: Swift-XRT refined Analysis
  17. GRB 250128B: Gemini-North optical extended source detection
  18. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  19. GRB 250128B: TNG optical upper limit
  20. GRB 250129A: Swift/UVOT Detection
  21. GRB 250128B: VLT/HAWKI near-infrared observations
  22. GRB 250127A: CrAO and Terskol optical upper limits
  23. GRB 250129A: Enhanced Swift-XRT position
  24. GRB 250128B: NOT optical upper limit
  25. GRB 250128B: VLT/FORS2 optical observations
  26. GRB 250129A: REM optical/NIR afterglow detection
  27. GRB 250129A: OHP/T193 optical and spectroscopy observations
  28. GRB 250129A: Early afterglow detection by LCO.
  29. GRB 250128B: OHP/T193 optical upper limit
  30. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  31. GRB 250129A: LCO optical observations
  32. GRB 250129A: NOT optical observations and redshift confirmation
  33. GRB 250129A: GOTO optical observations show brightening afterglow
  34. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  35. Swift GRB 250129A: Global MASTER-Net observations report
  36. GRB 250128B: Enhanced Swift-XRT position
  37. Fermi GRB 250128B: Global MASTER-Net observations report
  38. GRB 250129A: Swift detection of a burst with an optical counterpart
  39. Swift GRB 250129A: Global MASTER-Net OT detection
  40. GRB 250128B: Swift-XRT refined Analysis
  41. GRB 250128B: Fermi GBM Observation
  42. GRB 250128B: GOTO optical upper limit
  43. Swift GRB 250128B: Global MASTER-Net observations report
  44. EP250125a: Upper limits from Swift/BAT-GUANO
  45. GRB 250128B: LCO optical observations
  46. GRB 250128B: Swift detection of a short burst
  47. GRB 250128B: Fermi GBM Final Real-time Localization
  48. GRB 250127A: Swift-XRT observations
  49. GRB 250127B: DDOTI Upper Limit on the Afterglow
  50. GRB 250127A: EP-FXT afterglow detection
  51. Fermi GRB 250128A: Global MASTER-Net observations report
  52. GRB 250128A: Fermi GBM Final Real-time Localization
  53. GRB 250117A: Fermi GBM Observation
  54. Fermi GRB 250127B: Global MASTER-Net observations report
  55. GRB 250127A: SVOM/VT upper limit
  56. GRB 250127B: Fermi GBM Final Real-time Localization
  57. IPN triangulation of GRB 250119C
  58. GRB 250127A: Swift ToO observations
  59. GRB 250127A: LCO optical upper limit
  60. GRB 241223A: cubesat Avion detection
  61. GRB 250127A: SVOM detection of a long burst
  62. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  63. EP250125A: Non-detection from Fermi-GBM Observations
  64. GRB 250126A: MAXI/GSC detection
  65. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  66. GRB 250126A: Fermi GBM Final Real-time Localization
  67. GRB 250118A: Fermi GBM Observation
  68. GRB 250119C: Fermi GBM Observation
  69. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  70. IPN triangulation of a bright burst from SGR 1E1841-045
  71. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  72. EP250108a: AbAO, CMO and Terskol optical upper limits
  73. Konus-Wind detection of GRB 250118B
  74. GRB 250121A: Fermi GBM Observation
  75. IPN triangulation of GRB 250118B
  76. Konus-Wind detection of GRB 250119B
  77. IPN triangulation of GRB 250119B
  78. GRB 250122A: Fermi GBM Final Real-time Localization
  79. Improved IPN triangulation of GRB 250107C
  80. GRB 250114A: Swift-BAT refined analysis
  81. GRB 250121A: INTEGRAL/SPI-ACS detection
  82. GRB 250121A: Fermi-LAT detection
  83. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  84. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  85. GRB 250121A: Fermi GBM Final Real-time Localization
  86. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  87. GRB 250119B: Fermi GBM Observation
  88. Konus-Wind detection of GRB 250117A
  89. IPN triangulation of GRB 250117A (short)
  90. ATCA detection of possible radio counterpart to GRB 250114A
  91. GRB 250119B: INTEGRAL/SPI-ACS detection
  92. EP 250108A: Late-time optical observation by LCO
  93. GRB 250117A: SVOM/GRM observation of a short burst
  94. GRB 250119C: Fermi GBM Final Real-time Localization
  95. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  96. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  97. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  98. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  99. GRB 250117A: GECAM observation of a short burst
  100. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)

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