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Re: Sun Moon Lunars to 155 degrees
From: Brad Morris
Date: 2010 Mar 30, 20:47 -0400
From: Brad Morris
Date: 2010 Mar 30, 20:47 -0400
Hi George You wrote: Where has equation of time got to? It went missing through that hole in my head. The Nautical Almanac 1773, states that the Equation of Time for 4 August 1773 is ADD 5 minutes 36.4 seconds Additionally, we have 5.8 seconds from noon to noon at Greenwich, this being 15-48-17 GMT, we must add 0.914 seconds 06-54-00 (LAT) 00-05-36.4 (EoT) 00-00-00.914 (EoT adjustment) Thus we have 06-59-37.3 seconds, which I will round off to an even 37 seconds 15-48-17 (GMT from Frank's Online Calculator, using given altitudes) 06-59-37 (LMT From LAT using given sun altitude, sun semi-diameter and EoT) -- -- -- -- - 08-48-40(time difference from Greenwich) Convert to Arc 132d 10m 0s West Check by adding it to Cook's given longitude 227d 40m 30s East, yields 359d 50m 30s There still is a missing 9 minutes and 30 seconds of longitude. --------------------------------------------------------------------- Instead of using the altitude directly, I will correct it here for DIP and by the 2010 Nautical Alamanc using the 0-10degree altitude correction tables. Sun's altitude given by Cook as 5d 41m 45s (actually, 5d 41 3/4m) Dip correction for 24 feet is -4.8 minutes Altitude correction for 5d 41m 45s is +7.2 minutes So the altitude of the sun might be 5d 44m 19s Using 5d 44m 19s, sun's declination of N17d 8m 8s and Cook's latitude of S20d 49m, we get LAT of 06-52-59, to which we will add the same EoT adjustments 06-52-59 (LAT) 00-05-36.4 (EoT) 00-00-00.914 (EoT adjustment) -------------- 06-57-36.3 (LMT) Before we can jump to the time difference, we must calculate the GMT using the corrected sun's altitude and a corrected moon's altitude. Again, using the modern correction tables, 10d 31m 52s Moon's apparent altitude, dip correction of -4m48s, moon's HP of 58.9 yields an altitude correction of +6.4m, all in turn yielding a Moon's corrected altitude of 10d 33m 28s. Of course we could have used the 1773 NA Horizontal Parallax of 57' 09", yielding a slightly different alt corr'n +4.1m Injecting this into Frank's online calculator with the parameters Date 4-Aug-1773 Time 15-48-22 (NOTE: this bumped by 5 seconds since last time ) Sun's alt 5 degrees 44.3 minutes Moon's alt 10 degrees 33.48minutes DR Long 227 degrees 40.5 minutes EAST DR Lat 20 degrees 49 minutes SOUTH Temperature 76 degrees F IC 0 HoE 24 feet, in deference to the consensus of opinion Yields 0 error in lunar and 0.5 minutes of error in longitude 15-48-22 (GMT from Frank's Online Calculator, using given altitudes) 06-57-36 (LMT From LAT using given sun altitude, dip & alt correction) ----------- 08-50-46 (time difference from Greenwich) Convert to Arc 132d 41m 30s WEST As a check, add to Cook's given value of 227d 40m 30s EAST yields 360 degrees 22 minutes 0 seconds. This is 22 minutes too much. --------------------------------------------- Of course we could have used the 1773 NA Horizontal Parallax of 57' 09", yielding a slightly different alt corr'n +4.1m yielding a final Moon Alt of 10d 31.2m. Injecting that into Frank's online calculator requires that we revert to 15-48-17 for time. 15-48-17 (GMT) 06-57-36 (LMT From LAT using given sun altitude, dip & alt correction) ---------- 08-50-41 (time difference from Greenwich) Convert to arc 132d 40m 15s WEST adding to 227d 40m 30s EAST, yields360d 20m 45s. This is still 20minutes 45seconds too much. ------------------------------------------------------------------------- Still no joy in the land of lunars! Could it be that the altitudes given are actually in error? Or am I still missing something! Best Regards Brad "Confidentiality and Privilege Notice The information transmitted by this electronic mail (and any attachments) is being sent by or on behalf of Tactronics; it is intended for the exclusive use of the addressee named above and may constitute information that is privileged or confidential or otherwise legally exempt from disclosure. If you are not the addressee or an employee or agent responsible for delivering this message to same, you are not authorized to retain, read, copy or disseminate this electronic mail (or any attachments) or any part thereof. If you have received this electronic mail (and any attachments) in error, please call us immediately and send written confirmation that same has been deleted from your system. Thank you."
