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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"

31633 results found.

  1. GRB 250129A: LCO late afterglow detection
  2. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  3. LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
  4. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  5. GRB 250202B: NuSTAR detection of the prompt emission
  6. GRB 250202C: GRBAlpha detection
  7. GRB 250129a: Liverpool Telescope optical follow-up
  8. GRB 240129A: further SAO RAS optical observations
  9. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  10. LIGO/Virgo/KAGRA S250202cu: Updated Sky localization
  11. LIGO/Virgo/KAGRA S250202cu: Identification of a GW compact binary merger candidate
  12. GRB 250129A: SVOM/C-GFT optical observations
  13. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  14. Swift GRB250129A: MASTER 4 days observations report
  15. GRB 250201A: INTEGRAL SPI/ACS detection
  16. Konus-Wind detection of GRB 250129A
  17. GRB 250129A: 1.3m DFOT Optical observations
  18. GRB 250129A: Liverpool Telescope observations suggest continued engine activity
  19. GRB 250129A: Skynet Continued Optical Observations
  20. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  21. EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
  22. GRB 250129A: SAO RAS optical observations
  23. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  24. GRB 250129A: optical photometry from Konkoly
  25. GRB 250129A: COLIBRÍ Optical Observations
  26. GRB 250128B: VLA possible radio detection
  27. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  28. GRB 250129A: iTelescope optical observation
  29. GRB 250129A: NOT optical observations of continuining activity
  30. GRB 250129a: Liverpool Telescope optical follow-up
  31. GRB 250129A: TNG NIR afterglow detection
  32. GRB 250129A: AKO Optical Afterglow Detection
  33. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  34. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  35. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  36. GRB 250128B: VLA radio upper limit
  37. Ep250125A: 1.3m DFOT optical upper limit
  38. GRB 250129A: Skynet optical observations
  39. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  40. GRB 250128B: Gemini-North optical extended source detection
  41. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  42. GRB 250128B: TNG optical upper limit
  43. GRB 250129A: Swift/UVOT Detection
  44. GRB 250128B: VLT/HAWKI near-infrared observations
  45. GRB 250127A: CrAO and Terskol optical upper limits
  46. GRB 250128B: NOT optical upper limit
  47. GRB 250128B: VLT/FORS2 optical observations
  48. GRB 250129A: REM optical/NIR afterglow detection
  49. GRB 250129A: OHP/T193 optical and spectroscopy observations
  50. GRB 250129A: Early afterglow detection by LCO.
  51. GRB 250128B: OHP/T193 optical upper limit
  52. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  53. GRB 250129A: LCO optical observations
  54. GRB 250129A: NOT optical observations and redshift confirmation
  55. GRB 250129A: GOTO optical observations show brightening afterglow
  56. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  57. Swift GRB 250129A: Global MASTER-Net observations report
  58. Fermi GRB 250128B: Global MASTER-Net observations report
  59. GRB 250128B: Fermi GBM Observation
  60. GRB 250128B: GOTO optical upper limit
  61. Swift GRB 250128B: Global MASTER-Net observations report
  62. EP250125a: Upper limits from Swift/BAT-GUANO
  63. GRB 250128B: LCO optical observations
  64. GRB 250127A: Swift-XRT observations
  65. GRB 250127B: DDOTI Upper Limit on the Afterglow
  66. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  67. GRB 250127A: EP-FXT afterglow detection
  68. Fermi GRB 250128A: Global MASTER-Net observations report
  69. GRB 250117A: Fermi GBM Observation
  70. Fermi GRB 250127B: Global MASTER-Net observations report
  71. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  72. GRB 250127A: SVOM/VT upper limit
  73. IPN triangulation of GRB 250119C
  74. GRB 250127A: Swift ToO observations
  75. GRB 250127A: LCO optical upper limit
  76. GRB 241223A: cubesat Avion detection
  77. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  78. EP250125A: Non-detection from Fermi-GBM Observations
  79. GRB 250126A: MAXI/GSC detection
  80. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  81. GECAM-A detection of a bright burst from SGR 1E1841-045
  82. GRB 250118A: Fermi GBM Observation
  83. EP250125a: Optical upper limit with Kinder observations
  84. EP250125a: REM optical counterpart detection
  85. GRB 250119C: Fermi GBM Observation
  86. EP250125a: Swift/XRT detection of a fading counterpart
  87. EP250125a: a new X-ray transient detected by Einstein Probe
  88. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  89. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  90. IPN triangulation of a bright burst from SGR 1E1841-045
  91. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  92. EP250108a: AbAO, CMO and Terskol optical upper limits
  93. Konus-Wind detection of GRB 250118B
  94. GRB 250121A: Fermi GBM Observation
  95. IPN triangulation of GRB 250118B
  96. Konus-Wind detection of GRB 250119B
  97. IPN triangulation of GRB 250119B
  98. Improved IPN triangulation of GRB 250107C
  99. GRB 250114A: Swift-BAT refined analysis
  100. GRB 250121A: INTEGRAL/SPI-ACS detection

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