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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').
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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"

32490 results found.

  1. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  2. EP-WXT trigger 01709131361 / LIGO/Virgo/KAGRA S250206dm: FTW optical and NIR observations
  3. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  4. GRB 250207A: REM IR afterglow detection
  5. LIGO/Virgo/KAGRA S250206dm: ATLAS observations of the skymap
  6. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  7. GRB 250207A: FRAM-Auger optical detection
  8. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  9. GRB 250207B: Tiled Swift observations
  10. Konus-Wind detection of GRB 250204B
  11. IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
  12. GRB 250207A: REM optical afterglow detection
  13. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  14. LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  15. GRB 250207A: Swift/UVOT Detection
  16. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
  17. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  18. LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
  19. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
  20. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  21. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  22. GRB 250129A: Continued AbAO and Mondy optical observations
  23. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  24. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  25. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  26. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  27. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  28. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  29. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  30. LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
  31. GRB 250205A: Fermi GBM Observation
  32. GRB 250205A: REM NIR upper limit
  33. EP250205a/GRB 250205A: FTW optical and NIR observations of the counterpart
  34. GRB 250205A: Swift/UVOT Upper Limits
  35. LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
  36. EP250205a/GRB 250205A: correction to the source localization
  37. EP250205a/GRB 250205A: Einstein Probe observation
  38. GRB 250204B: SVOM/GRM observation of a likely short burst
  39. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  40. GRB 250205A: Swift/XRT detection
  41. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  42. GRB250205A: SVOM/VT optical afterglow detection
  43. GRB 250205A: GOTO optical upper limits
  44. GRB 250205A: OHP/T193 optical counterpart candidate
  45. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  46. LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
  47. Konus-Wind detection of GRB 250201A
  48. IPN triangulation of GRB 250201A
  49. LIGO/Virgo/KAGRA S250205bk: Updated Sky localization
  50. Konus-Wind detection of GRB 250202B
  51. LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
  52. GRB 250129A: Swift-BAT refined analysis
  53. EP 250108A: Upper limits from Fermi-GBM Observations
  54. IPN triangulation of GRB 250204B (short/hard)
  55. IPN triangulation of GRB 250202B
  56. LIGO/Virgo/KAGRA S250204ax: Updated Sky localization
  57. GRB 250204B: AstroSat CZTI detection of a short burst
  58. GRB 250129A: LCO late afterglow detection
  59. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  60. LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
  61. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  62. GRB 250202B: NuSTAR detection of the prompt emission
  63. GRB 250202C: GRBAlpha detection
  64. GRB 250129a: Liverpool Telescope optical follow-up
  65. GRB 240129A: further SAO RAS optical observations
  66. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  67. LIGO/Virgo/KAGRA S250202cu: Updated Sky localization
  68. LIGO/Virgo/KAGRA S250202cu: Identification of a GW compact binary merger candidate
  69. GRB 250129A: SVOM/C-GFT optical observations
  70. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  71. Swift GRB250129A: MASTER 4 days observations report
  72. GRB 250201A: INTEGRAL SPI/ACS detection
  73. Konus-Wind detection of GRB 250129A
  74. GRB 250129A: 1.3m DFOT Optical observations
  75. GRB 250129A: Liverpool Telescope observations suggest continued engine activity
  76. GRB 250129A: Skynet Continued Optical Observations
  77. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  78. EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
  79. GRB 250129A: SAO RAS optical observations
  80. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  81. GRB 250129A: optical photometry from Konkoly
  82. GRB 250129A: COLIBRÍ Optical Observations
  83. GRB 250128B: VLA possible radio detection
  84. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  85. GRB 250129A: iTelescope optical observation
  86. GRB 250129A: NOT optical observations of continuining activity
  87. GRB 250129a: Liverpool Telescope optical follow-up
  88. GRB 250129A: TNG NIR afterglow detection
  89. GRB 250129A: AKO Optical Afterglow Detection
  90. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  91. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  92. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  93. GRB 250128B: VLA radio upper limit
  94. Ep250125A: 1.3m DFOT optical upper limit
  95. GRB 250129A: Skynet optical observations
  96. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  97. GRB 250128B: Gemini-North optical extended source detection
  98. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  99. GRB 250128B: TNG optical upper limit
  100. GRB 250129A: Swift/UVOT Detection

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