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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').

23918 results found.

  1. EP250207b: a new X-ray transient detected by Einstein Probe
  2. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  3. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  4. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  5. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  6. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  7. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  8. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  9. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  10. GRB 250207A: 1.3m DFOT Optical observations
  11. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  12. GRB 250206A: Swift-XRT observations
  13. GRB 250129A: GRANDMA Continued Afterglow Detection
  14. GRB 250207A: Swift-BAT refined analysis
  15. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  16. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  17. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  18. LIGO/Virgo/KAGRA S250206dm: GECKO coverage of S240206dm
  19. GRB 250205A: 1.3m DFOT optical upper limit
  20. LIGO/Virgo/KAGRA S250118az: Updated Sky localization
  21. LIGO/Virgo/KAGRA S250208ad: Updated Sky localization
  22. GRB 250206A: EIRSAT-1 GMOD Detection
  23. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  24. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  25. GRB 250207B: Swift-XRT observations
  26. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  27. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  28. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  29. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  30. GRB 250207A: Swift-XRT refined Analysis
  31. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  32. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  33. GRB 250207A: Enhanced Swift-XRT position
  34. 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%
  35. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  36. GRB 250207A: REM IR afterglow detection
  37. LIGO/Virgo/KAGRA S250206dm: ATLAS observations of the skymap
  38. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  39. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  40. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  41. IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
  42. GRB 250207A: REM optical afterglow detection
  43. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  45. GRB 250207A: Swift/UVOT Detection
  46. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
  47. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  48. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
  49. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  50. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  51. GRB 250129A: Continued AbAO and Mondy optical observations
  52. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  53. GRB 250207B: MAXI/GSC detection
  54. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  55. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  56. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  57. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  58. GRB 250207A: Swift detection of a burst with optical counterpart
  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 250205A: Fermi GBM Observation
  68. GRB 250205A: REM NIR upper limit
  69. GRB 250205A: Swift/UVOT Upper Limits
  70. LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
  71. EP250205a/GRB 250205A: Einstein Probe observation
  72. GRB 250127C: SVOM/GRM observation of a burst
  73. GRB 250204B: SVOM/GRM observation of a likely short burst
  74. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  75. GRB 250205A: Swift/XRT detection
  76. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  77. GRB250205A: SVOM/VT optical afterglow detection
  78. GRB 250205A: OHP/T193 optical counterpart candidate
  79. LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
  80. GRB 250205A: SVOM detection of a burst
  81. LIGO/Virgo/KAGRA S250205bk: NED Galaxies in the Localization Volume
  82. IPN triangulation of GRB 250201A
  83. LIGO/Virgo/KAGRA S250205bk: Updated Sky localization
  84. LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
  85. GRB 250129A: Swift-BAT refined analysis
  86. EP 250108A: Upper limits from Fermi-GBM Observations
  87. IPN triangulation of GRB 250204B (short/hard)
  88. IPN triangulation of GRB 250202B
  89. LIGO/Virgo/KAGRA S250204ax: Updated Sky localization
  90. GRB 250204B: AstroSat CZTI detection of a short burst
  91. GRB 250129A: LCO late afterglow detection
  92. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  93. LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
  94. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  95. GRB 250202B: NuSTAR detection of the prompt emission
  96. GRB 250202B: Fermi GBM Detection
  97. GRB 250129a: Liverpool Telescope optical follow-up
  98. GRB 240129A: further SAO RAS optical observations
  99. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  100. LIGO/Virgo/KAGRA S250202cu: Updated Sky localization

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