compass alignment?

[neil groves]

I just been mulling over polar alignment and came up with a theory, if I polar align my mount in one position in the garden where I can see Polaris, then fix my compass to the top of the mount securely, I should then be able to move my mount to a different position in the garden and making sure the compass gives me the same readings I should still be aligned even though I can't see Polaris right?

the reason I ask is that I need to go onto my front porch to compose Scorpio, in particular I want to have a go at the nebulous area around Antares as I have seen some beautiful colours from around that area, however I can't see Polaris from the front porch and still need to be polar aligned for imaging......is this a viable idea?

Neil.

[Owmuchonomy]

Hi Neil I guess you'll run into a couple of issues. Firstly, in my experience compasses aren't that accurate and secondly your metal mount will interfere terribly with the reading. Can you not use a polar routine using a two star alignment? Then you don't need Polaris at all.

[neil groves]

i'll get my instructions out, I don't know how to do that.

thanks.

Neil.

[Owmuchonomy]

I'm not familiar with the CGEM mount but on the HEQ5 Synscan software what you can do is point roughly north then do a two star alignment. Move to the Polar alignment routine and do that. Repeat the whole cycle until you are happy with the errors quoted by the software. For imaging I aim for less than 30".

[carastro]

You would need to learn to drift align which is not that simple for a learner.  As soon as you move the mount you need to polar align again, the ground could be more level in one location than another.  You only need to be a small amount out and it's not polar aligned.  

I am currently trying to image the Antares region and cannot get it from my house at all, so I am having to wait until i go to Astro camps.  

I honestly don't think what you are suggesting will work except by pure luck.

Carole 

[davedownsouth]

Each evening I get my scope polar aligned and when I take it down and put it back out in exactly the same position the next night, with the tripod legs length untouched, I always have to shift the mount a small amount to get it polar aligned properly.  If I was to move it one foot in either direction, my bet is I would not get Polaris in the view of the polar scope, let alone aligned properly.

[neil groves]

im going to try, i'll report back when I have had a chance and tell you how miserably it failed ha ha

Neil.

[Psychobilly]

I used the Shadow method to mark a true north line on the factory carpark  so that I could do some solar imaging during breaktimes...

http://www.armystudyguide.com/content/army_board_study_guide_topics/land_navigation_map_reading/field-expedient-methods-of-determining-direction.shtml

Peter...

[Frankwc]

Hi Neil

           If you have a smartphone then download an application called GPS Essentials the compass on the app relies  on the GPS sattelite constellation and the Earths magnetic field. I've used it time and agiain and find accurate enough to set things up. It also gives an accurate UTC time derived from the GPS.  I hope I given you some ideas.

                                                                                   Frank

[neil groves]

I just found an app called clineometer which acts like a bubble level with digital read out.....will post updates as and when i get a chance to try them out......Antares here we come  

Neil.

[neil groves]

_{Just been giving some more thought to this, suppose I found out the exact coordinates for Polaris, then set my digital bubble level on the mount and aligned said mount to said coordinates according to my said digital readout bubble level, that would get me close enough me thinks?......ok I gotta go check of said bubble level measures in degrees.........}

_Neil.

[neil groves]

I it appears that it does read in degrees, I wish though that I could plot on the coordinates for the north celestrial pole and then the screen let me know when I am there.....oh well, i'm still hopeful

Neil.

[neil groves]

Tonight I am thinking maybe I will have a go at the Antares area, I can't get it from the back garden so I am going to align my mount in the driveway, take my readings from my clinometer app then move the tripod to the front porch and set it up so the readings are the same,  I can't use the driveway since there is a streetlight to the left of where I need to be, so watch this space

Neil.

[neil groves]

It failed miserably, the trouble is there are too many variables, the ground isn't the same level even,it's too much of a longshot, i'm going with what you guys are telling me. once aligned for the night, leave well alone lol.

Neil.

[neil groves]

^{ok I think I've come up with a solution to polar alignment, I have downloaded a clinometer and a compass to my android, I am going to roughly align my mount to Polaris using the polar align scope, I will then set the ALT such that my clinometer reads 37 degrees incline when clamped into the top of the mount where the OTA goes, then switching from the clinometer to the compass on the android which will remain clamped in the OTA holder, I will center Polaris on the vertical line of the polar finder scope and rotate  the mount .7 degrees towards the last star in the handle of the little dipper using the compass, and sorted!}

^{I'll be back tomorrow whining that it didn't work probably though it does sound like a plan right?}

^Neil.

[Joseki]

Just thinking about this myself as I can't see polaris from my garden. When I have the time to figure it out I'm going to try with a rough basic allign (wooden frame & compass and inclinometer) then one of the software assisted drift alignment.

Sent from my GT-I9300 using Tapatalk

[Gina]

I used the sun to mark my pier adapter for the approximate N.  Like a sundial in reverse.  A vertical post in the centre and mark the shadow at 1pm in summer or noon in winter, an allowance for longitude and there you are.  Within 5 degrees is adequate for the position of the azimuth post as there is something like 10 degrees lattitude in the PA azimuth adjustment.  If you can't manage noon, any other hour with the sun up will do with the appropriate correction of 15 degrees per hour.

You don't need Polaris if you use drift alignment or one of the many software apps that use imaging on a couple of stars to determine PA.  I use AstroTortilla as my choice.

[neil groves]

Well that idea didn't work lol, back to the drawing board.

Neil.

[carastro]

Neil, it is difficult if you can't see polaris.  You will need to learn to drift align.  there are also softwares out there that will do it such as Alignmaster, but I feel this is probably too far down to line for you just yet as you need to control your mount by the laptop and Ascom for it to work.

I think drift aligning is your best bet.  APT has a DARV drift aligning facility which if you're using a Canon camera you might want to get anyway as it's great for capture, but I have not used it so can't comment.  

Carole 

[ollypenrice]

Yup, drift aligning is just something you need to learn. This guy is great; http://www.andysshotglass.com/DriftAlignment.html

Olly

[neil groves]

^{What is APT?}

^Neil.

[neil groves]

 I actually had an alignment on Polaris last night that was good for 60 sec subs, just judging by where I placed Polaris in the polar scope, I was impressed lol.

Neil.

[Gina]

APT = Astro Photography Tool.  It's very low cost software originally written for DSLR cameras but now covers astro CCD cameras as well.  It is used to capture images.  HTH.

[neil groves]

I just went and checked out APT and it looks like it only works with windows, is there an alignment APP that works with android do you know?

i'm trying to limit the amount of stuff I have to carry into and out of the garden every session.

Neil.

[stargazerlily]

This is a very interesting thread ... and I have learned a lot.  However, with all this info I'm beginning to wonder if I'm doing things wrong. This is what I do ...

i) Set up the tripod for my HEQ5 mount and use a hand held compass to align the N leg roughly towards north.

ii) Use a digital spirit level to ensure the mounting plate is horizontal (to within 1/2 degree or so) by measuring across each pair of legs in turn.

iii) Fit the HEQ5 mount.

iv) Check time of day and location of Polaris using Polar Finder and use the polar scope in the mount to align the mount onto Polaris (as a side ... I've often wondered why the little circle in the polar scope doesn't have a cross hair so that you can see when Polaris is in the dead centre).

v) Fit scope etc, etc.

I'm hoping that I've been doing things correctly ... 

Cheers

Pete