#1  
Old 30-07-2019, 08:32 PM
poider (Peter)
Registered User

poider is offline
 
Join Date: Apr 2012
Location: Adelaide, Australia
Posts: 178
Compass

So when going for polar alignment with a compass, is a compass app on a smart phone accurate enough or should I just go and buy a compass, I can not see the octans stars from my light polluted location?
Reply With Quote
  #2  
Old 30-07-2019, 09:59 PM
Ukastronomer's Avatar
Ukastronomer (Jeremy)
Feel free to edit my imag

Ukastronomer is offline
 
Join Date: Jan 2019
Location: Llandysul, WALES, UK
Posts: 1,221
Personally I think the multi billion $ GPS system may be more accurate than a $10 compass
Reply With Quote
  #3  
Old 30-07-2019, 10:59 PM
xelasnave's Avatar
xelasnave
Gravity does not Suck

xelasnave is offline
 
Join Date: Mar 2005
Location: Tabulam
Posts: 12,789
I tried out a compass app today..CSP was about 20 degrees away from where I have placed it with star trails...so not impressed..if you can take a long exposure so you get star trails and that gives one a pretty good idea. CSP is what all those semi circles the star make have as their center as we all know.
Before I got pole master I would site the camera (with scope preferably) to see the same as the view thru the polar scopeduring the day so later with star trails I would get pretty decent alignment.
Alex
Reply With Quote
  #4  
Old 30-07-2019, 11:02 PM
xelasnave's Avatar
xelasnave
Gravity does not Suck

xelasnave is offline
 
Join Date: Mar 2005
Location: Tabulam
Posts: 12,789
I am going out right now to see how a new planetarium app may assist to get a ruff idea...I am working out which trees need to come down...well confirming my selection.
Alex
Reply With Quote
  #5  
Old 30-07-2019, 11:11 PM
xelasnave's Avatar
xelasnave
Gravity does not Suck

xelasnave is offline
 
Join Date: Mar 2005
Location: Tabulam
Posts: 12,789
Well that didn't go well...pointed at Jupiter and at first it was seemingly spot on ..then tried to find CSP...didn't seem to be marked on the app..but when I tried it on Jupiter again I had to point 15 degrees away from it for it to show on the app.
I like the star trails still.
Alex
Reply With Quote
  #6  
Old 30-07-2019, 11:15 PM
Hemi
Registered User

Hemi is online now
 
Join Date: Dec 2010
Location: Darwin
Posts: 261
Hi Poider,

The compass on my iPhone worked for me, as did the inclinometer.
It got me in the ball park, from there I run the polar alignment routine on the mount to get it spot on (relative to my needs: visual and short exposure imaging). If you have a fully manual mount then Iím not sure. Most posts say getting a dedicated compass to avoid interference. There is a thread on here with instructions on creating sun dial of sorts to get accurate PA using the suns shadow:
http://www.iceinspace.com.au/forum/s...ght=Solar+noon

Regards

Hemi
Reply With Quote
  #7  
Old 30-07-2019, 11:19 PM
Hemi
Registered User

Hemi is online now
 
Join Date: Dec 2010
Location: Darwin
Posts: 261
Quote:
Originally Posted by xelasnave View Post
Well that didn't go well...pointed at Jupiter and at first it was seemingly spot on ..then tried to find CSP...didn't seem to be marked on the app..but when I tried it on Jupiter again I had to point 15 degrees away from it for it to show on the app.
I like the star trails still.
Alex
Hi Alex, Iím not sure what app your using, but the gyrometer in your device might need recalibrating. I use sky safari and find its pretty accurate.

Cheers

Hemi
Reply With Quote
  #8  
Old 31-07-2019, 06:43 AM
xelasnave's Avatar
xelasnave
Gravity does not Suck

xelasnave is offline
 
Join Date: Mar 2005
Location: Tabulam
Posts: 12,789
Quote:
Originally Posted by Hemi View Post
Hi Alex, Iím not sure what app your using, but the gyrometer in your device might need recalibrating. I use sky safari and find its pretty accurate.

Cheers

Hemi
Thanks Hemi. I expect you may be correct...I was not prepared to get cold sorting it out ...I expect the compass problem is for the same reason. I was not happy last night ...it was cloudy at Sunset with some sprinkles so being still cloudy around eight I lite a fire to burn off some excess wood. I went out a little time before my post to check the fire after a rain front passed ..I wanted to make sure it was out before I went to bed...and wouldn't you know it..the sky was nice and clear..and I had not set up.
The phone I have is only a couple of days old and we are still getting to know each other.
Mind you what I have noticed is the camera is , by my phone standards, extraordinary.
Alex
Reply With Quote
  #9  
Old 31-07-2019, 07:08 AM
Startrek (Martin)
Registered User

Startrek is offline
 
Join Date: Dec 2017
Location: Sydney
Posts: 1,461
Solar noon meridian method gets me under a degree
All you need is a timber dowel , some string , a good float level and a sunny day

I gave my Silver compass away to a bushwalking friend as it was a waste of time , needle keeps moving as thereís to much iron around and forget using your iPhone itís way off

Let me know if you want a procedure
Reply With Quote
  #10  
Old 31-07-2019, 07:09 AM
Startrek (Martin)
Registered User

Startrek is offline
 
Join Date: Dec 2017
Location: Sydney
Posts: 1,461
The good old Sun never fails spot on every time !!
Reply With Quote
  #11  
Old 31-07-2019, 10:29 AM
poider (Peter)
Registered User

poider is offline
 
Join Date: Apr 2012
Location: Adelaide, Australia
Posts: 178
Quote:
Originally Posted by Startrek View Post
Solar noon meridian method gets me under a degree
All you need is a timber dowel , some string , a good float level and a sunny day

I gave my Silver compass away to a bushwalking friend as it was a waste of time , needle keeps moving as thereís to much iron around and forget using your iPhone itís way off

Let me know if you want a procedure
Thank you startrek I have seen your tutorial, a friend told me to use the sun and a stick, I did and it was fairly close, but I now want to do a permanent mark of some sort and only have a grassy backyard, I will try again on the weekend if the sun allows me to, last weekend I had about two seconds of sunlight within a minute of the high noon so wasnít as spot on as I wanted
Reply With Quote
  #12  
Old 31-07-2019, 11:48 AM
Wavytone (Nick)
BigBanger

Wavytone is offline
 
Join Date: Jul 2008
Location: Killara, Sydney
Posts: 3,995
The apps in iPhones are ok if they are calibrated.

No idea about androids...
Reply With Quote
  #13  
Old 31-07-2019, 11:57 AM
bojan's Avatar
bojan
amateur

bojan is offline
 
Join Date: Jul 2006
Location: Mt Waverley, VIC
Posts: 5,884
This is how I do it
http://www.iceinspace.com.au/forum/s...6&postcount=23
Reply With Quote
  #14  
Old 31-07-2019, 12:27 PM
poider (Peter)
Registered User

poider is offline
 
Join Date: Apr 2012
Location: Adelaide, Australia
Posts: 178
If I stand facing south my compass reading is 180 degrees, my magnetic declination is 7.5 east positive, does this mean that if I stand with my compass reading 172.5 I will be facing true south
Reply With Quote
  #15  
Old 31-07-2019, 12:41 PM
bojan's Avatar
bojan
amateur

bojan is offline
 
Join Date: Jul 2006
Location: Mt Waverley, VIC
Posts: 5,884
Your true south will be 7.56į to the East (left) side of where magnetic needle points at.

Mine (Melbourne) is ~11į.. see picture and/or map: https://www.victorianseekersclub.org.au/navigation

Last edited by bojan; 31-07-2019 at 12:53 PM.
Reply With Quote
  #16  
Old 31-07-2019, 12:58 PM
Startrek (Martin)
Registered User

Startrek is offline
 
Join Date: Dec 2017
Location: Sydney
Posts: 1,461
Peter
If your plonking your tripod down on grass I would recommend to find 3 pavers or bricks and set them into the ground reasonably level on some gravel or blue metal so your tripod legs have something solid to sit on otherwise your tripod and mount will sink at various times according to the weather especially in wet weather
In regard to your true south line ( SCP ) just buy a 300 x 300 or 450 x 450 concrete pad from Bunnings and sit it level on the ground centred below your tripod and you can use the solar noon meridian method to score a permanent line on it for your true south direction
You can mow over the bricks and pavers if they installed level just below the grass finished cut level
Get the idea ?
Reply With Quote
  #17  
Old 31-07-2019, 01:23 PM
poider (Peter)
Registered User

poider is offline
 
Join Date: Apr 2012
Location: Adelaide, Australia
Posts: 178
Thank you all for your assistance, I have been thinking of putting down three pavers for some time now so I am on the right track
Reply With Quote
  #18  
Old 02-08-2019, 08:31 PM
Wavytone (Nick)
BigBanger

Wavytone is offline
 
Join Date: Jul 2008
Location: Killara, Sydney
Posts: 3,995
Quote:
Originally Posted by poider View Post
magnetic declination
By the way please use the correct term - which is "magnetic variation".

Declination refers to the position (geocentric latitude) of astronomical objects, it has nothing to do with magnetism.
Reply With Quote
  #19  
Old 02-08-2019, 08:45 PM
gjr80 (Gary)
Registered User

gjr80 is offline
 
Join Date: Aug 2017
Location: Brisbane
Posts: 25
Hmm, maybe a few others need educating too.....

Gary
Quote:
Originally Posted by Wavytone View Post
By the way please use the correct term - which is "magnetic variation".

Declination refers to the position (geocentric latitude) of astronomical objects, it has nothing to do with magnetism.
Reply With Quote
  #20  
Old 02-08-2019, 09:20 PM
raymo
Registered User

raymo is offline
 
Join Date: Sep 2011
Location: margaret river, western australia
Posts: 4,927
Sorry Wavey, but magnetic declination is correct, as is magnetic variation. Either term can be used, unless The Oxford Dictionary is mistaken, which
I think unlikely.
raymo
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 12:50 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
Celestron Australia
Advertisement
Bintel
Advertisement
NexDome Observatories
Advertisement
Lunatico Astronomical
Advertisement
OzScopes Authorised Dealer
Advertisement
Meade Australia
Advertisement
SkyWatcher Australia
Advertisement
Astronomy and Electronics Centre
Advertisement