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Homework Help: Archived Calculating the optimal day to observe an object given the RA and dec

  1. Aug 20, 2014 #1
    1. The problem statement, all variables and given/known data

    OmegaCen is a Globular Cluster which lies at coordinates: R.A. = 13h26m45.89s,
    Dec = −47°28′36.7′′ (J2000.0) estimate the optimal day on which to observe
    this object.

    2. Relevant equations

    3. The attempt at a solution

    We are to interpret optimal as 12 am midnight directly overhead

    since this is 12 hrs after noon you subtract 12hrs RA = 1hr26m45.89sec
    which is ≈ 1.446 hrs RA and this is due to the monthly RA shift
    2 hrs of RA shift per month so, 30/1.446 ≈ 20.75 days
    so 20.75 days after the vernal equinox, which is april the 10.75 th
    im not quite sure how to interpret the 10.75, do i say its on the 10th of april or the 11th ? and the observation is meant to be at 12 am midnight so would you say its on the 11th april? (at the very beginning). Thank you!
  2. jcsd
  3. Feb 4, 2016 #2


    User Avatar
    2017 Award

    Staff: Mentor

    The vernal equinox probably won't happen exactly at midnight, but that depends on the time zone... April 11th should be fine.

    (see the readme why you suddenly get an answer for an old thread)
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