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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"

43117 results found.

  1. LIGO/Virgo/KAGRA S250118az: Updated Sky localization
  2. LIGO/Virgo/KAGRA S250208ad: Updated Sky localization
  3. GRB 250206A: EIRSAT-1 GMOD Detection
  4. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  5. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  6. GRB 250206A: Fermi-LAT detection
  7. GRB 250207B: Swift-XRT observations
  8. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  9. IceCube-250203A: No transient candidates from the Zwicky Transient Facility
  10. LIGO/Virgo/KAGRA S250206dm: Spectroscopic Classification of AT2025bay and AT2025baz with Keck I/LRIS
  11. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  12. LIGO/Virgo/KAGRA S250206dm: ePESSTO+ classification of AT2025bar
  13. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  14. GRB 250208A: Fermi GBM Final Real-time Localization
  15. EP250207a: EP-WXT detection and XRT follow-up observation
  16. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  18. GRB 250207A: Swift-XRT refined Analysis
  19. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  20. EP-WXT trigger 01709131361: correction to GCN 39214
  21. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  22. GRB 250207A: Enhanced Swift-XRT position
  23. CHIME/FRB source FRB 20250206A detected less than 1 minute after LIGO-Virgo-Kagra (LVK) S250206dm, however the probability of spatial coincidence is order 0.1%
  24. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  25. EP-WXT trigger 01709131361 / LIGO/Virgo/KAGRA S250206dm: FTW optical and NIR observations
  26. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  27. GRB 250207A: REM IR afterglow detection
  28. LIGO/Virgo/KAGRA S250206dm: ATLAS observations of the skymap
  29. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  30. GRB 250207A: FRAM-Auger optical detection
  31. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  32. GRB 250207B: Tiled Swift observations
  33. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  34. Konus-Wind detection of GRB 250204B
  35. IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
  36. IceCube-250207A - IceCube observation of a high-energy neutrino candidate track-like event
  37. GRB 250207A: REM optical afterglow detection
  38. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  39. LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  40. GRB 250207A: Swift/UVOT Detection
  41. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
  42. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  43. LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
  44. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
  45. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  46. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  47. GRB 250129A: Continued AbAO and Mondy optical observations
  48. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  49. GRB 250207B: MAXI/GSC detection
  50. The EP-WXT trigger 01709131347 is likely a flaring star
  51. The EP-WXT trigger 01709131332 is likely a flaring star
  52. The EP-WXT trigger 01709131290 is likely a flaring star
  53. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  54. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  55. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  56. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  57. GRB 250207A: Swift detection of a burst with optical counterpart
  58. GRB 250207A: Fermi GBM Final Real-time Localization
  59. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  60. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  61. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  62. LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
  63. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  64. LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
  65. LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
  66. GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
  67. GRB 250206A: Fermi GBM Final Real-time Localization
  68. GRB 250205A: Fermi GBM Observation
  69. GRB 250205A: REM NIR upper limit
  70. EP250205a/GRB 250205A: FTW optical and NIR observations of the counterpart
  71. GRB 250205A: Swift/UVOT Upper Limits
  72. LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
  73. EP250205a/GRB 250205A: correction to the source localization
  74. EP250205a/GRB 250205A: Einstein Probe observation
  75. GRB 250127C: SVOM/GRM observation of a burst
  76. GRB 250204B: SVOM/GRM observation of a likely short burst
  77. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  78. GRB 250205A: Swift/XRT detection
  79. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  80. GRB250205A: SVOM/VT optical afterglow detection
  81. GRB 250205A: GOTO optical upper limits
  82. GRB 250205A: OHP/T193 optical counterpart candidate
  83. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  84. LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
  85. GRB 250205A: SVOM detection of a burst
  86. LIGO/Virgo/KAGRA S250205bk: NED Galaxies in the Localization Volume
  87. Konus-Wind detection of GRB 250201A
  88. IPN triangulation of GRB 250201A
  89. LIGO/Virgo/KAGRA S250205bk: Updated Sky localization
  90. Konus-Wind detection of GRB 250202B
  91. LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
  92. GRB 250129A: Swift-BAT refined analysis
  93. EP 250108A: Upper limits from Fermi-GBM Observations
  94. IPN triangulation of GRB 250204B (short/hard)
  95. IPN triangulation of GRB 250202B
  96. LIGO/Virgo/KAGRA S250204ax: Updated Sky localization
  97. GRB 250204B: AstroSat CZTI detection of a short burst
  98. GRB 250204B: Fermi GBM Final Localization
  99. GRB 250129A: LCO late afterglow detection
  100. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations

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