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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"

26037 results found.

  1. GRB 250207A: Swift detection of a burst with optical counterpart
  2. GRB 250205A: Fermi GBM Observation
  3. GRB 250205A: REM NIR upper limit
  4. GRB 250205A: Swift/UVOT Upper Limits
  5. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  6. GRB 250205A: Swift/XRT detection
  7. GRB250205A: SVOM/VT optical afterglow detection
  8. IPN triangulation of GRB 250201A
  9. GRB 250129A: Swift-BAT refined analysis
  10. IPN triangulation of GRB 250204B (short/hard)
  11. IPN triangulation of GRB 250202B
  12. GRB 250129A: LCO late afterglow detection
  13. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  14. GRB 250129a: Liverpool Telescope optical follow-up
  15. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  16. GRB 250129A: SVOM/C-GFT optical observations
  17. Swift GRB250129A: MASTER 4 days observations report
  18. Konus-Wind detection of GRB 250129A
  19. GRB 250129A: 1.3m DFOT Optical observations
  20. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  21. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  22. GRB 250129A: optical photometry from Konkoly
  23. GRB 250129A: COLIBRÍ Optical Observations
  24. GRB 250128B: VLA possible radio detection
  25. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  26. GRB 250129A: iTelescope optical observation
  27. GRB 250129A: NOT optical observations of continuining activity
  28. GRB 250129a: Liverpool Telescope optical follow-up
  29. GRB 250129A: TNG NIR afterglow detection
  30. GRB 250129A: AKO Optical Afterglow Detection
  31. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  32. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  33. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  34. GRB 250128B: VLA radio upper limit
  35. Ep250125A: 1.3m DFOT optical upper limit
  36. GRB 250129A: Skynet optical observations
  37. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  38. GRB 250129A: Swift-XRT refined Analysis
  39. GRB 250128B: Gemini-North optical extended source detection
  40. GRB 250128B: TNG optical upper limit
  41. GRB 250129A: Swift/UVOT Detection
  42. GRB 250128B: VLT/HAWKI near-infrared observations
  43. GRB 250127A: CrAO and Terskol optical upper limits
  44. GRB 250129A: Enhanced Swift-XRT position
  45. GRB 250128B: NOT optical upper limit
  46. GRB 250128B: VLT/FORS2 optical observations
  47. GRB 250129A: REM optical/NIR afterglow detection
  48. GRB 250129A: OHP/T193 optical and spectroscopy observations
  49. GRB 250129A: Early afterglow detection by LCO.
  50. GRB 250128B: OHP/T193 optical upper limit
  51. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  52. GRB 250129A: LCO optical observations
  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. GRB 250129A: Swift detection of a burst with an optical counterpart
  58. Swift GRB 250129A: Global MASTER-Net OT detection
  59. GRB 250128B: Swift-XRT refined Analysis
  60. GRB 250128B: Fermi GBM Observation
  61. GRB 250128B: GOTO optical upper limit
  62. Swift GRB 250128B: Global MASTER-Net observations report
  63. EP250125a: Upper limits from Swift/BAT-GUANO
  64. GRB 250128B: LCO optical observations
  65. GRB 250128B: Swift detection of a short burst
  66. GRB 250127A: Swift-XRT observations
  67. GRB 250127B: DDOTI Upper Limit on the Afterglow
  68. GRB 250127A: EP-FXT afterglow detection
  69. GRB 250117A: Fermi GBM Observation
  70. GRB 250127A: SVOM/VT upper limit
  71. IPN triangulation of GRB 250119C
  72. GRB 250127A: Swift ToO observations
  73. GRB 250118A: Fermi GBM Observation
  74. EP250125a: REM optical counterpart detection
  75. GRB 250119C: Fermi GBM Observation
  76. EP250125a: Swift/XRT detection of a fading counterpart
  77. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  78. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  79. IPN triangulation of GRB 250118B
  80. Konus-Wind detection of GRB 250119B
  81. IPN triangulation of GRB 250119B
  82. Improved IPN triangulation of GRB 250107C
  83. GRB 250114A: Swift-BAT refined analysis
  84. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  85. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  86. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  87. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  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 250117A: SVOM/GRM observation of a short burst
  92. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  93. EP250108a / AT2025kg: VLA radio upper limit
  94. Swift Trigger 1282245 is not a GRB
  95. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  96. GRB 250114B: Swift-XRT afterglow detection
  97. GRB 250114B: SVOM/VT upper limit
  98. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  99. IPN triangulation of GRB 250113A
  100. GRB 250114B: Liverpool Telescope optical upper limit

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