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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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28286 results found.

  1. GRB 250207A: Enhanced Swift-XRT position
  2. 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%
  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. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  8. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  9. IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
  10. GRB 250207A: REM optical afterglow detection
  11. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  12. LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  13. GRB 250207A: Swift/UVOT Detection
  14. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
  15. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  16. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
  17. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  18. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  19. GRB 250129A: Continued AbAO and Mondy optical observations
  20. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  21. GRB 250207B: MAXI/GSC detection
  22. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  23. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  24. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  25. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  26. GRB 250207A: Swift detection of a burst with optical counterpart
  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: Updated NED Galaxies in the Localization Volume
  31. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  32. LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
  33. LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
  34. GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
  35. GRB 250205A: Fermi GBM Observation
  36. GRB 250205A: REM NIR upper limit
  37. GRB 250205A: Swift/UVOT Upper Limits
  38. LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
  39. EP250205a/GRB 250205A: Einstein Probe observation
  40. GRB 250127C: SVOM/GRM observation of a burst
  41. GRB 250204B: SVOM/GRM observation of a likely short burst
  42. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  43. GRB 250205A: Swift/XRT detection
  44. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  45. GRB250205A: SVOM/VT optical afterglow detection
  46. GRB 250205A: OHP/T193 optical counterpart candidate
  47. LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
  48. GRB 250205A: SVOM detection of a burst
  49. LIGO/Virgo/KAGRA S250205bk: NED Galaxies in the Localization Volume
  50. IPN triangulation of GRB 250201A
  51. LIGO/Virgo/KAGRA S250205bk: Updated Sky localization
  52. LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
  53. GRB 250129A: Swift-BAT refined analysis
  54. EP 250108A: Upper limits from Fermi-GBM Observations
  55. IPN triangulation of GRB 250204B (short/hard)
  56. IPN triangulation of GRB 250202B
  57. LIGO/Virgo/KAGRA S250204ax: Updated Sky localization
  58. GRB 250204B: AstroSat CZTI detection of a short burst
  59. GRB 250129A: LCO late afterglow detection
  60. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  61. LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
  62. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  63. GRB 250202B: NuSTAR detection of the prompt emission
  64. GRB 250202B: Fermi GBM Detection
  65. GRB 250129a: Liverpool Telescope optical follow-up
  66. GRB 240129A: further SAO RAS optical observations
  67. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  68. LIGO/Virgo/KAGRA S250202cu: Updated Sky localization
  69. LIGO/Virgo/KAGRA S250202cu: Identification of a GW compact binary merger candidate
  70. GRB 250129A: SVOM/C-GFT optical observations
  71. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  72. Swift GRB250129A: MASTER 4 days observations report
  73. GRB 250129A: 1.3m DFOT Optical observations
  74. GRB 250201A: BALROG localization (Fermi Trigger 760096791 / GRB 250201417)
  75. GRB 250201A: Fermi GBM Final Real-time Localization
  76. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC 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: COLIBRÍ Optical Observations
  82. GRB 250129A: iTelescope optical observation
  83. GRB 250129a: Liverpool Telescope optical follow-up
  84. GRB 250129A: TNG NIR afterglow detection
  85. GRB 250129A: AKO Optical Afterglow Detection
  86. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  87. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  88. GRB 250128B: VLA radio upper limit
  89. Ep250125A: 1.3m DFOT optical upper limit
  90. GRB 250129A: Skynet optical observations
  91. GRB 250129A: Swift-XRT refined Analysis
  92. GRB 250128B: Gemini-North optical extended source detection
  93. GRB 250128B: TNG optical upper limit
  94. GRB 250129A: Swift/UVOT Detection
  95. GRB 250128B: VLT/HAWKI near-infrared observations
  96. GRB 250127A: CrAO and Terskol optical upper limits
  97. GRB 250129A: Enhanced Swift-XRT position
  98. GRB 250128B: NOT optical upper limit
  99. GRB 250128B: VLT/FORS2 optical observations
  100. GRB 250129A: REM optical/NIR afterglow detection

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