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RA/DEC J2000 of stars

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VReijs
2013-02-06
2013-02-12
  • VReijs
    VReijs
    2013-02-06

    Hello, I have a query about the RA/DEC coordinates of stars in Stellarium (0.12.0).

    For Arcturus I get a RA/DEC (J2000) of 14h22m2.1s/+22deg30'29.7"
    What star catalogue is this: I think it is NOMAD, correct?

    If I check Tycho2 (like used in SkyMap Pro 9), I get a RA/DEC (J2000) of 14h15m39.673s/+19deg10'56.688"

    SimBAD database gives: 14 15 39.67207 +19 10 56.6730
    (http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=arcturus&submit=SIMBAD+search )

    Hipparcus give (J2000):
    _RAJ2000 14 15 39.672 and _DEJ2000 +19 10 56.67
    (http://vizier.u-strasbg.fr/viz-bin/VizieR-S?HIP%2069673 )

    Why this difference in Stellarium? It can't be proper motion (as we use the reference data J2000 in all cases).
    I see similar difference for other stars...

    Le me know if I understand the coordinates properly. Thanks.

    All the best,

    Victor

     
  • barrykgerdes
    barrykgerdes
    2013-02-06

    My Stellarium shows Arcturus as
    14h15m35.5s/+19d10'45.3" for j2000

    Barry

     
    • VReijs
      VReijs
      2013-02-06

      Hello Barry,

      What Stellarium version do you have? Your RA/DEC values look much better.
      I am looking at the data that is show if I left click the star.
      Thanks for your help.

      On 6 February 2013 21:05, barrykgerdes barrykgerdes@users.sf.net wrote:

      My Stellarium shows Arcturus as
      14h15m35.5s/+19d10'45.3" for j2000

       
  • Alexander Wolf
    Alexander Wolf
    2013-02-07

    Info from my Stellarium for current date:

    Arcturus (α Boo) - HIP 69673 A
    Type: double star
    Magnitude: 0.15 (extincted to: 0.44. B-V: 0.82)
    Absolute Magnitude: -0.11
    RA/DE (J2000): 14h15m39.5s/+19°10'45.3"
    RA/DE (of date): 14h16m16s/+19°07'08"
    Galactic longitude/latitude (J2000): +15°02'27.7"/+69°06'38.5"
    Hour angle/DE: 3h08m53s/+19°07'08" (geometric)
    Hour angle/DE: 3h08m51s/+19°07'45" (apparent)
    Az/Alt: +244°59'15"/+40°22'54" (geometric)
    Az/Alt: +244°59'15"/+40°23'38" (apparent)
    Spectral Type: K2IIIp
    Distance: 36.71 Light Years
    Parallax: 0.08885"

    Your coordinates - RA/DEC (J2000) of 14h22m2.1s/+22deg30'29.7" - was correct for Feb of -3335 :)

     
    • VReijs
      VReijs
      2013-02-07

      Hello Alexander,

      RA/DE (J2000): 14h15m39.5s/+19°10'45.3"

      Your coordinates - RA/DEC (J2000) of 14h22m2.1s/+22deg30'29.7" - was
      correct for Feb of -3335 :)

      For me 9and I think in general) the RA/DEC(J2000.0) is a constance: as I
      think in is the definition of where the star is on date J2000.0 So these
      values don't change regardless of the date/location one is on/in.
      See for instance Skymap and other programs where the reference RA/DEC is
      constant.

      So what is you definition of RA/DE(J2000)?

      All the best,

      Victor

       
  • barrykgerdes
    barrykgerdes
    2013-02-07

    All versions fro 0.10.3 to 0.12.1
    The only way those coords could show this is the date was milleniums out

    Barry

     


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