Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Re: Short Term Proper Motion
    From: Bill Bertrand
    Date: 2019 Mar 11, 08:54 -0700

    Thanks Paul.  I negelected to include the Hipparcos fragments at the bottom of my firs post.  I am including the complete post to avoid neeing to jump between them.  In answer to your comments

    • The header notes indicate that the j2000 values are extrapolated.  (In BOLD)
    • The j1991.25 Dec value is listed (it differs ~3x10^-5) degrees for the 9 year difference
    • I used BOLD font for important parts
    • I assumed that I could multiply mas/year * years to get the delta declination (mas) for this simple short term declination change.  (Is that incorrect?)
    • As you noted, I fear I am using the catalog data incorrectly.

    I am having a problem calculating simple short term proper motion.  Since I am off by orders of magnitude, it's certain I missed a point obvious to others.

    To use the simplest case, I am confining my example on proper motion in declination, to avoid RA's need to be a function of the cos(declination).
    The example:  Bellatrix on Date: 2016/12/28 T 23:14:15 UTC
    • (Stellarium output for the date is listed below and the Bellatrix fragment of Hipparcos below that)
    • Dec J2000            (Stellarium &  Hipparcos): 6°20'58.7" or 6°20.98'
    • Declination on that date (USNO, Stellarium): 6°21'41.0" or 6°21.68'
    • The Declination on the 2 dates differ by 0.7 minutes of arc!
    • I calculate 16.99 Julian years between J2000 and the date above at 365.25 JDays/JYear
    • Stellarium pmDec =-13.6 (mas/yr), Hipparcos pmDec = -12.88 (mas/yr) milliarcseconds/year
    • @-12.88 mas/yr  I get -218.86 mas in 16.99 years or -0.218 arcseconds
    Where did I go wrong?
    Thank you in advance,
    Bill Bertrand

    What follows is the Hipparcos catalog fragment (supplied by VizieR) for Belletrix that I used:

    #
    #   VizieR Astronomical Server vizier.u-strasbg.fr
    #    Date: 2018-07-31T21:42:33 [V1.99+ (14-Oct-2013)]
    #   In case of problem, please report to:    cds-question@unistra.fr
    #
    #
    #Coosys    J2000:    eq_FK5 J2000
    #INFO    votable-version=1.99+ (14-Oct-2013)   
    #INFO    -ref=VIZ5b60d1c7543c   
    #INFO    -out.max=99999   
    #INFO    queryParameters=26   
    #-oc.form=dec
    #-out.max=99999
    #-out.add=_RAJ,_DEJ
    #-nav=cat:I/311&tab:{I/311/

    hip2}&key:source=I/311/hip2&HTTPPRM:&&-ref=VIZ5b60d1c7543c&-out.src=I/311/hip2&Clear= Clear&-c.r=  2&-out=HIP&-out=n_HIP&-out=Sn&-out=So&-out=RArad&-out=DErad&-out=Plx&-out=e_Plx&-out=pmRA&-out=pmDE&-out=Hpmag&Hpmag=<2.0&-out=B-V&-out=HIP1&-meta.ucd=2&-meta=1&-meta.foot=1&-usenav=1&-bmark=POST&-out.add=_RAJ,_DEJ&-order=I&-oc.form=dec&-c.geom=r&-out.max=10&-out.form=| -Separated-Values&undefined=CDS, France&-c.eq=J2000&-c.u=arcmin&
    #-c.eq=J2000
    #-c.r=  2
    #-c.u=arcmin
    #-c.geom=r
    #-source=I/311/hip2
    #-order=I
    #-out=HIP
    #-out=n_HIP
    #-out=Sn
    #-out=So
    #-out=RArad
    #-out=DErad
    #-out=Plx
    #-out=e_Plx
    #-out=pmRA
    #-out=pmDE
    #-out=Hpmag
    #Hpmag=<7
    #-out=B-V
    #-out=HIP1
    #HIP1=HIP1
    #Phot=Phot
    #

    #RESOURCE=yCat_1311
    #Name: I/311
    #Title: Hipparcos, the New Reduction (van Leeuwen, 2007)
    #Coosys    J2000_1991.250:    eq_FK5 J2000
    #Table    I_311_hip2:
    #Name: I/311/hip2
    #Title: The Astrometric Catalogue
    #Column    _RAJ2000    (F14.10)    Right ascension (FK5, Equinox=J2000.0) at Epoch=J2000, proper motions taken into account     [ucd=pos.eq.ra]
    #Column    _DEJ2000    (F14.10)    Declination (FK5, Equinox=J2000.0) at Epoch=J2000, proper motions taken into account     [ucd=pos.eq.dec]

    #Column    HIP    (I6)    Hipparcos identifier    [ucd=meta.id;meta.main]
    #Column    n_HIP    (A1)    Simbad column added by the CDS    [ucd=meta.note]
    #Column    Sn    (I3)    [0,159] Solution type new reduction (1)    [ucd=meta.id;stat.fit]
    #Column    So    (I1)    [0,5] Solution type old reduction (2)    [ucd=meta.id;stat.fit]
    #Column    RArad    (F12.8)    Right Ascension in ICRS, Ep=1991.25    [ucd=pos.eq.ra;meta.main]
    #Column    DErad    (F12.8)    Declination in ICRS, Ep=1991.25    [ucd=pos.eq.dec;meta.main]
    #Column    Plx    (F7.2)    Parallax    [ucd=pos.parallax]
    #Column    e_Plx    (F6.2)    Formal error on Plx    [ucd=stat.error;pos.parallax]
    #Column    pmRA    (F8.2)    Proper motion in Right Ascension    [ucd=pos.pm;pos.eq.ra]
    #Column    pmDE    (F8.2)    Proper motion in Declination    [ucd=pos.pm;pos.eq.dec]
    #Column    Hpmag    (F7.4)    Hipparcos magnitude    [ucd=phot.mag;em.opt.V]
    #Column    B-V    (F6.3)    Colour index    [ucd=phot.color;em.opt.B;em.opt.V]
    #Column    HIP1    (A4)    Data from the first edition of the Hipparcos Catalog (1997, Cat. I/239)    [ucd=meta.ref.url]
    _RAJ2000         |_DEJ2000           |HIP    |n_HIP|Sn|So|RArad             |DErad              |Plx      |e_Plx |pmRA |pmDE  |Hpmag|B-V   |HIP1
    deg                    |deg                     |      | |   |                   |deg                 |deg                  |mas    |mas   |mas/yr|mas/yr |mag     |mag   |
    ----------------------|-----------------------|------|-|---|-                |-------------------|--------------------|---------|--------|---------|----------|----------|--------|----
    081.2827635599|+06.3497032659| 25336| |  7|0           |081.28278339|+06.34973457|  12.92|  0.52|   -8.11|  -12.88| 1.5493|-0.224|HIP1




    #Table: IV/27A/catalog.dat (cdsarc.u-strasbg.fr)
    ---------------------------------------------------------------------------------
          |            |     |    |      | R  R         D  D     |     |   |     |
        HD|DM          |   GC|  HR|   HIP|Ah Am   RAs  Ed Em  DEs| Vmag| Fl|Bayer|Cst
    ------|------------|-----|----|------|-----------------------|-----|---|-----|---
     35468|BD+06   919 | 6668|1790| 25336|05 25 07.87 +06 20 59.0| 1.64| 24|gam  |Ori
     
     
     
     
     
     #Table: IV/27A/table3.dat (cdsarc.u-strasbg.fr)
    ----------------------------------------------------------------------------------------------------
        HD|BFD          |Name                                                   |r_
    ------|-------------|-------------------------------------------------------|-----------------------
     35468| 24 gam   Ori|Bellatrix                                              | 2,15,17,19,22
    Stellarium Output Bellatrix 2016/12/28 T 23:14:15 UTC:
    Bellatrix
    γ Ori - 24 Ori - HIP 25336 - SAO 112740 - HD 35468 - HR 1790 - WDS J05251+0621AB
    Type: double star
    Magnitude: 1.60 (extincted to: 2.06)
    Absolute Magnitude: -2.84
    Color Index (B-V): -0.22
    RA/Dec (J2000.0): 5h25m07.86s/+6°20'58.7"
    RA/Dec (on date): 5h26m03.06s/+6°21'41.0"

    HA/Dec: 18h59m30.86s/+6°23'10.8" (apparent)
    Az./Alt.: +90°59'13.0"/+16°08'00.3" (apparent)
    Gal. long./lat.: -163°04'19.7"/-15°57'11.8"
    Supergal. long./lat.: -20°28'43.1"/-58°39'59.6"
    Ecl. long./lat. (J2000.0): +80°56'47.1"/-16°48'57.9"
    Ecl. long./lat. (on date): +81°11'08.7"/-16°48'50.0"
    Ecliptic obliquity (on date): +23°26'04.3"
    Mean Sidereal Time: 0h25m22.1s
    Apparent Sidereal Time: 0h25m21.7s
    IAU Constellation: Ori
    Distance: 252.44 ly
    Spectral Type: B2III
    Parallax: 0.01292"
    Position angle (2009): 144.00°
    Separation (2009): 178.000" (+0°02'58")
    Proper motions by axes: -9.1 -13.6 (mas/yr)
    Position angle of the proper motion: 213.8°
    Angular speed of the proper motion: 16.4 (mas/yr)
       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    NavList is a community devoted to the preservation and practice of celestial navigation and other methods of traditional position-finding. We're a group of navigators, navigation enthusiasts and hobbyists, mathematicians and physicists, and historians interested in all aspects of navigation but primarily those techniques which are non-electronic.

    To post a message, if you are already signed up as a NavList member, start a new discussion or reply to any posted message and use your posting code (this is a simple low-security password assigned when you join). You may also join by posting. Your first on-topic messsage automatically makes you a member, and a posting code will be assigned and emailed to you for future posts.

    Uniquely, the NavList message boards also permit full interaction entirely by email. You can optionally receive individual posts or daily digests by email, and any member can post messages by email (bypassing the web site) by sending to our posting address which is "NavList@NavList.net". This functionality is similar to a traditional Internet mailing list: post by email, read by email, reply by email. Most members will prefer the web interface here for posting and replying to messages.

    NavList is more than an online community... more about that another day.

    © Copyright notice: please note that the rights to all messages and posts in this discussion group are held by their respective authors. No messages or text or images extracted from messages may be reproduced without the explicit consent of the message author. Email me, Frank Reed, if you have any questions.

    Join / Get NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site