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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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32715 results found.

  1. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  2. GRB 250129A: GRANDMA Continued Afterglow Detection
  3. GRB 250207A: Swift-BAT refined analysis
  4. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  5. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  6. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  7. GRB 250205A: 1.3m DFOT optical upper limit
  8. GRB 250206A: Tiled Swift observations
  9. LIGO/Virgo/KAGRA S250118az: Updated Sky localization
  10. LIGO/Virgo/KAGRA S250208ad: Updated Sky localization
  11. GRB 250206A: EIRSAT-1 GMOD Detection
  12. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  13. GRB 250206A: Fermi-LAT detection
  14. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  15. IceCube-250203A: No transient candidates from the Zwicky Transient Facility
  16. LIGO/Virgo/KAGRA S250206dm: Spectroscopic Classification of AT2025bay and AT2025baz with Keck I/LRIS
  17. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  18. LIGO/Virgo/KAGRA S250206dm: ePESSTO+ classification of AT2025bar
  19. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  20. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  21. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  22. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  23. EP-WXT trigger 01709131361: correction to GCN 39214
  24. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  25. 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%
  26. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  27. EP-WXT trigger 01709131361 / LIGO/Virgo/KAGRA S250206dm: FTW optical and NIR observations
  28. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  29. GRB 250207A: REM IR afterglow detection
  30. LIGO/Virgo/KAGRA S250206dm: ATLAS observations of the skymap
  31. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  32. GRB 250207A: FRAM-Auger optical detection
  33. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  34. GRB 250207B: Tiled Swift observations
  35. Konus-Wind detection of GRB 250204B
  36. IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
  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 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  50. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  51. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  52. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  53. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  54. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  55. LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
  56. GRB 250205A: Fermi GBM Observation
  57. GRB 250205A: REM NIR upper limit
  58. EP250205a/GRB 250205A: FTW optical and NIR observations of the counterpart
  59. GRB 250205A: Swift/UVOT Upper Limits
  60. LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
  61. EP250205a/GRB 250205A: correction to the source localization
  62. EP250205a/GRB 250205A: Einstein Probe observation
  63. GRB 250204B: SVOM/GRM observation of a likely short burst
  64. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  65. GRB 250205A: Swift/XRT detection
  66. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  67. GRB250205A: SVOM/VT optical afterglow detection
  68. GRB 250205A: GOTO optical upper limits
  69. GRB 250205A: OHP/T193 optical counterpart candidate
  70. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  71. LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
  72. Konus-Wind detection of GRB 250201A
  73. IPN triangulation of GRB 250201A
  74. LIGO/Virgo/KAGRA S250205bk: Updated Sky localization
  75. Konus-Wind detection of GRB 250202B
  76. LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
  77. GRB 250129A: Swift-BAT refined analysis
  78. EP 250108A: Upper limits from Fermi-GBM Observations
  79. IPN triangulation of GRB 250204B (short/hard)
  80. IPN triangulation of GRB 250202B
  81. LIGO/Virgo/KAGRA S250204ax: Updated Sky localization
  82. GRB 250204B: AstroSat CZTI detection of a short burst
  83. GRB 250129A: LCO late afterglow detection
  84. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  85. LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
  86. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  87. GRB 250202B: NuSTAR detection of the prompt emission
  88. GRB 250202C: GRBAlpha detection
  89. GRB 250129a: Liverpool Telescope optical follow-up
  90. GRB 240129A: further SAO RAS optical observations
  91. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  92. LIGO/Virgo/KAGRA S250202cu: Updated Sky localization
  93. LIGO/Virgo/KAGRA S250202cu: Identification of a GW compact binary merger candidate
  94. GRB 250129A: SVOM/C-GFT optical observations
  95. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  96. Swift GRB250129A: MASTER 4 days observations report
  97. GRB 250201A: INTEGRAL SPI/ACS detection
  98. Konus-Wind detection of GRB 250129A
  99. GRB 250129A: 1.3m DFOT Optical observations
  100. GRB 250129A: Liverpool Telescope observations suggest continued engine activity

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