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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"

20960 results found.

  1. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  2. GRB 250129a: Liverpool Telescope optical follow-up
  3. GRB 240129A: further SAO RAS optical observations
  4. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  5. GRB 250129A: SVOM/C-GFT optical observations
  6. Swift GRB250129A: MASTER 4 days observations report
  7. GRB 250201A: INTEGRAL SPI/ACS detection
  8. GRB 250129A: 1.3m DFOT Optical observations
  9. GRB 250129A: Liverpool Telescope observations suggest continued engine activity
  10. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  11. GRB 250129A: Skynet Continued Optical Observations
  12. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  13. GRB 250129A: SAO RAS optical observations
  14. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  15. GRB 250129A: optical photometry from Konkoly
  16. GRB 250129A: COLIBRÍ Optical Observations
  17. GRB 250128B: VLA possible radio detection
  18. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  19. GRB 250129A: NOT optical observations of continuining activity
  20. GRB 250129a: Liverpool Telescope optical follow-up
  21. GRB 250129A: AKO Optical Afterglow Detection
  22. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  23. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  24. GRB 250128B: VLA radio upper limit
  25. Ep250125A: 1.3m DFOT optical upper limit
  26. GRB 250129A: Skynet optical observations
  27. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  28. GRB 250128B: Gemini-North optical extended source detection
  29. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  30. GRB 250129A: Swift/UVOT Detection
  31. GRB 250128B: VLT/HAWKI near-infrared observations
  32. GRB 250127A: CrAO and Terskol optical upper limits
  33. GRB 250128B: VLT/FORS2 optical observations
  34. GRB 250129A: REM optical/NIR afterglow detection
  35. GRB 250129A: OHP/T193 optical and spectroscopy observations
  36. GRB 250129A: Early afterglow detection by LCO.
  37. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  38. GRB 250129A: LCO optical observations
  39. GRB 250129A: NOT optical observations and redshift confirmation
  40. GRB 250129A: GOTO optical observations show brightening afterglow
  41. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  42. Swift GRB 250129A: Global MASTER-Net observations report
  43. Fermi GRB 250128B: Global MASTER-Net observations report
  44. GRB 250128B: GOTO optical upper limit
  45. Swift GRB 250128B: Global MASTER-Net observations report
  46. GRB 250128B: LCO optical observations
  47. GRB 250127A: Swift-XRT observations
  48. GRB 250127B: DDOTI Upper Limit on the Afterglow
  49. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  50. Fermi GRB 250128A: Global MASTER-Net observations report
  51. Fermi GRB 250127B: Global MASTER-Net observations report
  52. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  53. GRB 250127A: SVOM/VT upper limit
  54. GRB 250127A: Swift ToO observations
  55. GRB 250127A: LCO optical upper limit
  56. EP250125A: Non-detection from Fermi-GBM Observations
  57. EP250125a: Optical upper limit with Kinder observations
  58. EP250125a: REM optical counterpart detection
  59. EP250125a: Swift/XRT detection of a fading counterpart
  60. EP250125a: a new X-ray transient detected by Einstein Probe
  61. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  62. EP250108a: AbAO, CMO and Terskol optical upper limits
  63. GRB 250121A: INTEGRAL/SPI-ACS detection
  64. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  65. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  66. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  67. ATCA detection of possible radio counterpart to GRB 250114A
  68. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  69. GRB 250119B: INTEGRAL/SPI-ACS detection
  70. EP 250108A: Late-time optical observation by LCO
  71. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  72. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  73. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  74. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  75. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  76. GRB 250117A: GECAM observation of a short burst
  77. EP250108a / AT2025kg: GMG Optical Observations
  78. EP250108a / AT2025kg: VLA radio upper limit
  79. GRB 241217A / EP241217B: radio detection with the VLA
  80. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  81. GRB 250114B: Swift-XRT afterglow detection
  82. GRB 250114B: SVOM/VT upper limit
  83. EP250108a: MeerKAT radio upper limit
  84. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  85. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  86. GRB 250114B: Liverpool Telescope optical upper limit
  87. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  88. GRB 250114B: Swift-XRT observations
  89. GRB 250114A: LCO optical counterpart detection.
  90. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  91. Integral GRB250114.55: Global MASTER-Net observations report
  92. GRB 250114A: LCOGT optical afterglow i-band detection
  93. GRB 250114B: Swift ToO observations
  94. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  95. GRB 250113A: INTEGRAL/SPI-ACS detection
  96. GRB 250114A: REM detection of the optical and NIR counterpart
  97. GRB 250114A: LCO optical observations
  98. GRB 250114A: TRT optical observations
  99. Swift GRB 250114A: Global MASTER-Net observations report
  100. GRB 250101A: Terskol Zeiss-2000 optical observations

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