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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

24436 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: DDOTI Upper Limits
  6. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  7. Konus-Wind detection of GRB 250204B
  8. IceCube-250207A - IceCube observation of a high-energy neutrino candidate track-like event
  9. GRB 250207A: REM optical afterglow detection
  10. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  11. LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  12. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  13. LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
  14. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
  15. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  16. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  17. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  18. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  19. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  20. GRB 250207A: Fermi GBM Final Real-time Localization
  21. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  22. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  23. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  24. LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
  25. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  26. LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
  27. LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
  28. GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
  29. GRB 250206A: Fermi GBM Final Real-time Localization
  30. GRB 250205A: Fermi GBM Observation
  31. GRB 250205A: REM NIR upper limit
  32. LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
  33. EP250205a/GRB 250205A: correction to the source localization
  34. EP250205a/GRB 250205A: Einstein Probe observation
  35. GRB 250127C: SVOM/GRM observation of a burst
  36. GRB250205A: SVOM/VT optical afterglow detection
  37. GRB 250205A: GOTO optical upper limits
  38. LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
  39. GRB 250205A: SVOM detection of a burst
  40. LIGO/Virgo/KAGRA S250205bk: NED Galaxies in the Localization Volume
  41. Konus-Wind detection of GRB 250201A
  42. IPN triangulation of GRB 250201A
  43. LIGO/Virgo/KAGRA S250205bk: Updated Sky localization
  44. Konus-Wind detection of GRB 250202B
  45. LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
  46. GRB 250129A: Swift-BAT refined analysis
  47. EP 250108A: Upper limits from Fermi-GBM Observations
  48. IPN triangulation of GRB 250204B (short/hard)
  49. IPN triangulation of GRB 250202B
  50. LIGO/Virgo/KAGRA S250204ax: Updated Sky localization
  51. GRB 250204B: Fermi GBM Final Localization
  52. GRB 250129A: LCO late afterglow detection
  53. GRB 250204A: Fermi GBM Final Real-time Localization
  54. LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
  55. GRB 250202B: NuSTAR detection of the prompt emission
  56. GRB 250202C: GRBAlpha detection
  57. GRB 250202B: Fermi GBM Detection
  58. IceCube-250203A - IceCube observation of a high-energy neutrino candidate track-like event
  59. GRB 250129a: Liverpool Telescope optical follow-up
  60. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  61. LIGO/Virgo/KAGRA S250202cu: Updated Sky localization
  62. GRB 250202C: Fermi GBM Final Real-time Localization
  63. LIGO/Virgo/KAGRA S250202cu: Identification of a GW compact binary merger candidate
  64. GRB 250129A: SVOM/C-GFT optical observations
  65. The EP-WXT trigger 01709131153 is not a real source
  66. LIGO/Virgo/KAGRA S250202ad: Retraction of GW compact binary merger candidate
  67. GRB 250202B: Fermi GBM Final Real-time Localization
  68. Swift GRB250129A: MASTER 4 days observations report
  69. GRB 250202A: Fermi GBM Final Real-time Localization
  70. Konus-Wind detection of GRB 250129A
  71. GRB 250129A: 1.3m DFOT Optical observations
  72. GRB 250201A: BALROG localization (Fermi Trigger 760096791 / GRB 250201417)
  73. GRB 250201A: Fermi GBM Final Real-time Localization
  74. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  75. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  76. EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
  77. GRB 250129A: iTelescope optical observation
  78. GRB 250129A: NOT optical observations of continuining activity
  79. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  80. GRB 250128B: VLA radio upper limit
  81. Ep250125A: 1.3m DFOT optical upper limit
  82. GRB 250128B: Gemini-North optical extended source detection
  83. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  84. GRB 250128B: TNG optical upper limit
  85. GRB 250128B: VLT/FORS2 optical observations
  86. GRB 250129A: REM optical/NIR afterglow detection
  87. GRB 250128B: OHP/T193 optical upper limit
  88. GRB 250129A: NOT optical observations and redshift confirmation
  89. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  90. Swift GRB 250129A: Global MASTER-Net observations report
  91. Fermi GRB 250128B: Global MASTER-Net observations report
  92. GRB 250129A: Swift detection of a burst with an optical counterpart
  93. Swift GRB 250129A: Global MASTER-Net OT detection
  94. GRB 250128B: Fermi GBM Observation
  95. Swift GRB 250128B: Global MASTER-Net observations report
  96. EP250125a: Upper limits from Swift/BAT-GUANO
  97. GRB 250128B: Swift detection of a short burst
  98. GRB 250128B: Fermi GBM Final Real-time Localization
  99. GRB 250127A: Swift-XRT observations
  100. Fermi-LAT Gamma-ray Observations of IceCube-250102A

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