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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

19093 results found.

  1. Konus-Wind detection of GRB 250202B
  2. IPN triangulation of GRB 250202B
  3. GRB 250204B: AstroSat CZTI detection of a short burst
  4. GRB 250129A: LCO late afterglow detection
  5. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  6. LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
  7. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  8. GRB 250129a: Liverpool Telescope optical follow-up
  9. GRB 240129A: further SAO RAS optical observations
  10. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  11. GRB 250129A: SVOM/C-GFT optical observations
  12. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  13. Swift GRB250129A: MASTER 4 days observations report
  14. Konus-Wind detection of GRB 250129A
  15. GRB 250129A: 1.3m DFOT Optical observations
  16. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  17. GRB 250129A: SAO RAS optical observations
  18. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  19. GRB 250129A: COLIBRÍ Optical Observations
  20. GRB 250129A: iTelescope optical observation
  21. GRB 250129a: Liverpool Telescope optical follow-up
  22. GRB 250129A: TNG NIR afterglow detection
  23. GRB 250129A: AKO Optical Afterglow Detection
  24. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  25. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  26. GRB 250128B: VLA radio upper limit
  27. Ep250125A: 1.3m DFOT optical upper limit
  28. GRB 250129A: Skynet optical observations
  29. GRB 250128B: TNG optical upper limit
  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 250129A: Enhanced Swift-XRT position
  34. GRB 250128B: NOT optical upper limit
  35. GRB 250128B: VLT/FORS2 optical observations
  36. GRB 250129A: REM optical/NIR afterglow detection
  37. GRB 250129A: OHP/T193 optical and spectroscopy observations
  38. GRB 250129A: Early afterglow detection by LCO.
  39. GRB 250128B: OHP/T193 optical upper limit
  40. GRB 250129A: LCO optical observations
  41. GRB 250128B: Enhanced Swift-XRT position
  42. GRB 250129A: Swift detection of a burst with an optical counterpart
  43. GRB 250128B: Swift-XRT refined Analysis
  44. GRB 250128B: GOTO optical upper limit
  45. EP250125a: Upper limits from Swift/BAT-GUANO
  46. GRB 250128B: LCO optical observations
  47. GRB 250128B: Swift detection of a short burst
  48. GRB 250127A: Swift-XRT observations
  49. GRB 250127B: DDOTI Upper Limit on the Afterglow
  50. IPN triangulation of GRB 250119C
  51. GRB 250127A: Swift ToO observations
  52. GRB 250127A: LCO optical upper limit
  53. GRB 241223A: cubesat Avion detection
  54. GRB 250127A: SVOM detection of a long burst
  55. EP250125a: Optical upper limit with Kinder observations
  56. EP250125a: REM optical counterpart detection
  57. EP250125a: a new X-ray transient detected by Einstein Probe
  58. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  59. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  60. EP250108a: AbAO, CMO and Terskol optical upper limits
  61. IPN triangulation of GRB 250118B
  62. IPN triangulation of GRB 250119B
  63. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  64. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  65. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  66. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  67. IPN triangulation of GRB 250117A (short)
  68. EP 250108A: Late-time optical observation by LCO
  69. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  70. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  73. EP250108a / AT2025kg: GMG Optical Observations
  74. GRB 241217A / EP241217B: radio detection with the VLA
  75. GRB 250114B: Swift-XRT afterglow detection
  76. EP250108a: MeerKAT radio upper limit
  77. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  78. IPN triangulation of GRB 250113A
  79. GRB 250114B: Liverpool Telescope optical upper limit
  80. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  81. GRB 250114A: LCO optical counterpart detection.
  82. GRB 250114B: OHP/T193 optical upper limit
  83. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  84. GRB 250114A: LCOGT optical afterglow i-band detection
  85. GRB 250114B : GIT optical upper limit
  86. GRB 250114B: Swift ToO observations
  87. EP250111a: SAO RAS optical upper limit
  88. GRB 250114A: Enhanced Swift-XRT position
  89. GRB 250114A: REM detection of the optical and NIR counterpart
  90. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  91. GRB 250114A: LCO optical observations
  92. GRB 250114A: TRT optical observations
  93. GRB 250114A: Swift detection of a burst with an optical counterpart
  94. GRB 250101A: Terskol Zeiss-2000 optical observations
  95. EP250108a / AT 2025kg: SAO RAS optical observations
  96. EP241021a: SMA radio observation
  97. GRB 250113A: SVOM/GRM observation of a long burst
  98. EP250109b: optical upper limits with the Liverpool Telescope
  99. GRB 250106A: Swift-XRT afterglow detection
  100. EP250111a: KAIT optical observations

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