100 likes | 311 Views
15. Sunrise, Sunset, Twilight, Star - Time. Presented By: Kelly Curtin, Asst. Professor. Course Outline. Navigational Astronomy Lecture 1 & 2 Mean Time / Apparent Time Lecture 3 Time Zones, Zone Description, Chronometer Time Lecture 4
E N D
15. Sunrise, Sunset, Twilight, Star - Time Presented By: Kelly Curtin, Asst. Professor
Course Outline • Navigational Astronomy Lecture 1 & 2 • Mean Time / Apparent Time Lecture 3 • Time Zones, Zone Description, Chronometer Time Lecture 4 • The Earth, Celestial, And Horizon Coordinate System Lecture 5 & 6 • The Spherical Triangle Lecture 7 • Circle of Equal Altitude Intercept Lecture 8 • Time Diagram, Right Ascension Lecture 9 • The Nautical Almanac, Finding GHA, LHA, and Dec. Lecture 10 & 11 • Instruments For Celestial Navigation Lecture 12 • Sight Reduction of the Sun, Stars, Planets, Moon Lecture 13 - 15 • Plotting and Advancing / Retarding the Assumed Position Lecture 16 • Calculating Time of Meridian Passage (LAN) Lecture 17 • Calculating Latitude at Meridian Passage Lecture 18 • Calculating Time of Sunrise/ Sunset/ Twilight Lecture 19 • Star Shooting Schedule / Pub. 249 Lecture 20 • Azimuth and Amplitudes Lecture 21 – 24 • Polaris – Azimuth and Latitude By Lecture 25 • Star – Finder – Stars, Planets, Selecting the 3 best Stars Lecture 26 • The Complete Day’s Work Lecture 27 & 28
The Pub 249 Air Almanac: Provides 7 Pre-selected Stars For Any Whole Degree Of Latitude At Any LHA Of Aries. May Be Used For Sight Reduction Of Stars, Although Not Quite As Accurate As Pub. 229 Method. Is Good For The Epoch Year Listed On The Cover. Corrections For Preceding Or Following Years Should Be Made Using The Pages In The Front Of The Pub. XV: Star Shooting Schedule, Pub. 249 Pub. 249
XV: Star Shooting Schedule, Pub. 249 Pub. 249 Latitude Zn Computed Altitude LHA of Aries
Pub. 249 XV: Star Shooting Schedule, Pub. 249 • Table 5. Corrections For Precession And Nutation
Pub. 249 XV: Star Shooting Schedule, Pub. 249
Example XV: Star Shooting Schedule, Pub. 249 The Date is 19 September 1981, your 0300 zone time position is Lat. 24° 35.0’N, Long. 088° 40’W. You are on course 288°T at a speed of 14 knots. 1. Pre-compute Star-Time and list the 7 selected stars from Pub. 249
#1: DR POS’N @ Civil Twilight 0525 DR POS’N L 24° 46’Nλ089° 14’W Sunrise Naut Civil 0455 -2 0501 -2 0459 -3 0456 0523 -1 0526 -1 0525 -3 0522 30° N 24° 46’ N 20° N 0547 -0 0548 0 0548 -3 0545 10° 6m 3m 1m 4° 46’ Correction for DLO = -3 min 46’ of Arc East of Central Meridian 90° 0509 0534
Star Time 0509 0534 Selected Stars ZT 0509 ZD +6 GMT 1109 GHA 163° 15.7’ Inc. 2° 15.4 GHA 165° 31.1 -wλ 089° 14.0 LHA 076° 17.1’ LHA 076° @ 0508 • TIME LHA STAR Hc Zn ∆ Hc • 0508 076 Cappella 68° 50’ 006° 7’ • 0512 077 Dubhe 22° 19’ 031° 27’ • 0516 078 Pollox 55° 38’ 076° 53’ • 0520 079 Procyon 50° 19’ 114° 50’ • 0524 080 Sirius 43° 23’ 151° 29’ • 0528 081 Rigel 56° 44’ 184° 4’ • 0532 082 Hamal 44° 31’ 279° 53’