Setting up an EQ mount (latitude)

[Swoop1]

I have read the manual for setting up the EQ3-2 mount for my scope and it mentions latitude setting for the observation location. I have checked online for the lat of my home town (Marlow, Bucks) and the answer as a coordinate is 51.5719N 0.7769W.

This is confusing me. Back in the day when I was in the army and responsible for getting soldiers lost in Northern Irish fields, I was taught that grid references were "Along the corridor and up the stairs" or coordinates from the bottom/ top of the map followed by coordinates from the side of the map.

Now, knowing that Greenwich is on the 0 meridian, I know that the 0.7769W coordinate relates to how far west of Greenwich I am but, shouldn't that number be given first?

Please help this old and confused veteran get it right.

Carry on.

[Moonshane]

Hi there

your latitude is 51 degrees so this is what you should set your mount to initially. You then align properly with your polar scope if you have one. assuming visual only then setting to 51 and then pointing the leg with the N on it towards Polaris (or north on a compass) is good enough.

[Cornelius Varley]

4 minutes ago, Swoop1 said:

I have read the manual for setting up the EQ3-2 mount for my scope and it mentions latitude setting for the observation location. I have checked online for the lat of my home town (Marlow, Bucks) and the answer as a coordinate is 51.5719N 0.7769W.

This is confusing me. Back in the day when I was in the army and responsible for getting soldiers lost in Northern Irish fields, I was taught that grid references were "Along the corridor and up the stairs" or coordinates from the bottom/ top of the map followed by coordinates from the side of the map.

Now, knowing that Greenwich is on the 0 meridian, I know that the 0.7769W coordinate relates to how far west of Greenwich I am but, shouldn't that number be given first?

Please help this old and confused veteran get it right.

Carry on.

Your knowledge of map coordinates is correct, everybody else gets it wrong.

[Moonshane]

ps what you are doing is pointing the axis of your right ascension at Polaris, the north star. your latitude (51) means that Polaris is 39 degrees down from the zenith (i.e. straight up) as combined they make 90 degrees. if you lived at the north pole, your latitude would be 90 degrees and Polaris would be right overhead. if you lived on the equator, your latitude would be 0 and Polaris would be 90 degrees down from the zenith - i.e. on the horizon.

[Astro Imp]

For visual what Moonshane said is correct but be aware that the scale on the scope is not 100% accurate.

Until very recently I owned this mount. My method was to assemble the tripod, use a compass to point the peg on the tripod north. Now attach the mount and set the scale (in your case 51 degrees), mount the OTA and then make fine adjustments to get Polaris in the centre of my highest power eyepiece. Providing you are always observing from the same location this only needs to be done once. On subsequent observing sessions you only need to point the peg on the tripod north and you are good to go.

With this method I found it was only necessary to make occasional tweaks to the declination slow motion control when observing objects for extended periods of time.

HTH and good luck.

 

[D4N]

Geographical positions in the form of latitude and longitude are given latitude first then longitude.

Grid positions like you would get on an OS or military map are given in Eastings and Northings with the Easting first.  Direction is denoted by positive or negative with a negative Easting being West and a negative Northing being South.

Grid positions only work regionally due to the curvature of the Earth whereas geographic positions work world wide.

[Swoop1]

Thanks all for your info and advice.

 

[LukeSkywatcher]

IIRC from my days of using an EQ mount, the knob you need to set to 51 degrees north is circled (if you can call it a circle) in red in the image below. I think its called the declination axis (turn it one way and the scope moves to point upwards.Turn it the other way and the scope moves to point downwards). Once thats done, just align the polar axis leg of the mount (on the right here) to north and you are good to go as far as visual observing is concerned. 

 

[skfboiler]

3 hours ago, LukeSkywatcher said:

IIRC from my days of using an EQ mount, the knob you need to set to 51 degrees north is circled (if you can call it a circle) in red in the image below. I think its called the declination axis (turn it one way and the scope moves to point upwards.Turn it the other way and the scope moves to point downwards). Once thats done, just align the polar axis leg of the mount (on the right here) to north and you are good to go as far as visual observing is concerned. 

 

That mount looks familiar.  Anyhow just one correction, the knob you circled is actually called the "Latitude adjustment knob".  There one in the back, like the one you circled and one in the front.  In addition, in the front of the mount under the front "Latitude adjustment knob", there are 2 round knobs called the "Azimuth Adjustment Knobs".  After I set the scope on the ground I point the leg with the label "N" towards the star Polaris, eyeballed the best I can.  Then I adjust these knobs until Polaris is centered in the eyepiece.  To adjust the knobs you loosen one and the tighten the other, then tighten the one, then loosen the other.