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  #21  
Old 07-08-2018, 12:05 PM
bluesilver (Peter)
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Sorry again for this basic question,
I was just re reading over all this and see that a comment was made about Zenith.
( Antares may have been close to zenith, and in my experience dobs don't align or track all that well choosing stars close to zenith )
Sorry for the basic questions, but what actually is Zenith or what is meant by Zenith?
I have looked it up, but still not sure what is meant by it.
This could be part of my problems, only a small part, the most is myself still learning sorry.
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  #22  
Old 07-08-2018, 12:24 PM
TwistedRider (Drew)
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I think when I do my DOB, I use alpha Centauri and Arcturus(sp?)

Only mildly off centre on the 2nd slew.
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  #23  
Old 07-08-2018, 02:45 PM
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Quote:
Originally Posted by bluesilver View Post
… Sorry for the basic questions, but what actually is Zenith or what is meant by Zenith?
Zenith is a term that means directly overhead, that is, Altitude 90 degrees.
This means your DOB would be pointing straight up.
Not good for alignment.
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  #24  
Old 07-08-2018, 02:52 PM
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Rules for choosing alignment stars

Rules from Skywatcher :

Rules for choosing alignment stars:
• It is recommended that the altitude (angle of elevation above a theoretical flat horizon) of the two alignment stars are between 15 and 60 degrees and the difference in altitude between them is between 10 and 30 degrees.
• The azimuth (Compass direction) difference between the two alignment stars can be between 45 and 135 degrees, BUT it is best to be close to 90 degrees.
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  #25  
Old 07-08-2018, 03:54 PM
bluesilver (Peter)
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Thanks for the reply,
That makes sense now that it is said that way.
My biggest issue is my stars are not the stars that i think they are.
Will have to have a look at getting one of those apps,
Have heard good things about SkySafari 5 or 6
For those that are using Skysafari 5 or 6, is there much difference between the plus and pro versions?
From what i can see, you should be able to basically hold the phone up to the sky and it will show you what stars are there, as in names.
Do both versions do this?
Thanks.

Last edited by bluesilver; 07-08-2018 at 04:14 PM.
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  #26  
Old 07-08-2018, 04:44 PM
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gaseous (Patrick)
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I've got the 5 plus version, and it does more than enough for the casual observer - it's got everything you'd need (including showing the zenith!) You can create your own observing lists, and if you decide to get a wifi adapter you can use skysafari to control your scope, so you can run through your observing list and pick goto from there. Not sure what other stuff the 6/pro offers, but I can't imagine it's anything too essential.
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  #27  
Old 17-08-2018, 08:55 PM
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MPS (Mathew)
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Hi Peter
I am also very new to stargazing. I also have the SkyWatcher 10' goto dob. I do use the app stellarium which ive found to be vital. Ive also found with the dob that you need to have it pretty much perfectly flat.....to help with this i purchased a concrete square 60cm x 60cm and placed it perfectly level on the area i view from. This solved all goto accuracy issues. And finally i also use the wifi module for the goto. It syncs to my phone withbthe synscan app. I have found this to be very very accurate and easy to use. Very easy look and press icons for noobs like myself. It also automatically detects location and altitude etc. Ive had my dob for only 2 months now ans seriously cannot fault it. And i do collimate it every time before use as it seems to go out a bit.
Cheers
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  #28  
Old 18-08-2018, 08:20 AM
bluesilver (Peter)
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Hi Mathew,
I got myself the SkyScan app and looks to be pretty easy to use and help with my star alignment errors.
Only thing is that now i haven't been able to get outside to actually use the Dob for a few weeks due to either cloud cover or work,
Hoping this week will be better.
I have got a good level setup all ready to go and was looking to actually give the auto tracking a go as well when the weather clears up.
Cheers.
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  #29  
Old 25-08-2018, 08:09 PM
bluesilver (Peter)
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Hi again, sorry for bringing this post back up again, Apologizes.
Go my Dobsonian out again tonight, being a good clear night apart from the near full moon.
I tried to to the two star alignment again, but failed miserably, something i am doing must obviously be wrong or is it possible that i have a faulty unit?
Got everything spot on this time round, base is perfectly flat and level, have Synscanlnit 2.1 to tell me the correct details to enter into the GOTO hand held unit and SkySafari 5 Plus to tell me what stars are what.
So i set the Dobsonian up so it was facing North and the tube flat so it was reading 0 on the side scale.
Entered the details exactly as it was on Synscanlnit 2.1
Then selected a two star alignment, I went with Fomalhaut as the first and and Altair as the second, as they were up at about the same height in the sky and roughly close to 90 degrees apart.
Lined up the first star and centred it, then scope slew around for the second star, it got the height about right but was about almost 120 degrees off.
So i decided to turn it all off and start of with the scope facing South this time, same thing except this time is ended up about 90 - 120 degrees off.

Not sure what is going on now as the stars are correct, should i be doing a factory reset? or is it possible that there might be a faulty unit?
I am guessing it is just me, but a little stumped right now,
I can tell you what the coordinates i am putting in right at the start from Synscanlnit 2.1 if that might help at all?

Just a little frustrating at the moment, everything is setup spot on level wise at least.
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  #30  
Old 25-08-2018, 09:00 PM
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gaseous (Patrick)
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List your coordinates Peter and we'll see what can be done. It's either a faulty unit, or a simple to fix input error (hopefully).
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  #31  
Old 26-08-2018, 07:31 AM
bluesilver (Peter)
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Thanks for the reply,
Here is exactly what i put in yesterday
Set Longitude, E 146° 23'
Set Latitude, S 41° 15'
Set Time, + 10:00
Set Elevation, + 0032 m (also used 0000 m but made no difference)
Date, 08/24/2018
Enter time, 19:45
Daylight Saving NO

It all looks correct to me, but hopefully someone can find an error i have made.
Not sure if selecting a factory reset will fix anything? or the other option is a faulty unit possibly?
Any help is greatly appreciated.
Thanks.

Last edited by bluesilver; 26-08-2018 at 07:43 AM.
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  #32  
Old 26-08-2018, 08:30 AM
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Sounds to me like your setup was perfect.
I cannot think of any reason it could be that far out, providing you aligned on the first alignment star correctly. So if you are sure you pointed to Fomalhaut, it sounds like a faulty unit.

So to confirm, you move the scope to Fomalhaut, which is roughly ESE (114* at 19:45).
And select Altair as second.
And it slews to where?
It should move about 63* anti-clockwise (to NE 51*)

You said it was about 120* out. So did it move 180* anti-clockwise, or 60* the wrong way (clockwise).

Looking at your sky for last night (using Stellarium), there are a couple of stars that you may have mistaken for Fomalhaut. (like Arcturus or even Canopus) that may have given you that sort of result.

Just saying....!

otherwise the unit must be crook.
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  #33  
Old 26-08-2018, 09:55 AM
bluesilver (Peter)
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Hi, Thanks again for the reply, appreciated.
Yes, pretty sure i was 100% spot on for the stars, It was near close to a full moon so most of the stars wasn't as bright here which made selecting them a tad easier to compared to no moon.

I am pretty sure it was in that location, i can't say for 100% sure on the exact location though.
It then did as you mentioned, went anti clockwise, and went right past the star Altair and ended up roughly a few degrees before Jupiter, a bit rough i know, but this is roughly where it ended up.

I have had other nights when the unit has slewed over 360 degrees, the worst being once it went about 450 degrees.

I could try it again tonight if it is clear enough, using the same stars and see if i can get more accurate details on how far it slewed?

It is odd that it ended up in two different positions, one position when i set it up facing North and and other location when it was setup facing South.

Thanks again, it is appreciated.
Peter.

Last edited by bluesilver; 26-08-2018 at 10:12 AM.
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  #34  
Old 26-08-2018, 10:38 AM
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gaseous (Patrick)
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As Allan said, your setup sounds spot on. A dob will occasionally slew almost a full circle rather than a handful of degrees, but I think this is an inbuilt function to avoid wrapping your scope in power cables.


The fact that you said it once slewed 450° suggests to me that there is something a bit fishy with the unit itself. If you're certain the input data is correct and the stars are correct, then something is very amiss.
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  #35  
Old 26-08-2018, 10:49 AM
bluesilver (Peter)
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Yes, it does seam a tad strange to me, but thought best to ask all the questions first being still new to it all.
I go the unit from Andrews, so nothing odd there, haven't called or talked to them yet about it, was trying to find out of i have got something setup wrong first as i am sure a warranty or something on this unit will be a pain if it is faulty and very time consuming process.

I might go through it all again tonight if it is fine and see if i can write down exactly where i start and where the scope slews to, using the same stars.
Will do it setup for both North ans South, hopefully this will help narrowing down if it is the unit or just myself.
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  #36  
Old 26-08-2018, 11:14 AM
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Maybe before you do the alignment, just use the direction arrows to see if it's actually slewing/stopping in accordance with your manual button input.
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  #37  
Old 26-08-2018, 12:09 PM
bluesilver (Peter)
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I am not quiet sure what you mean by that?
Are you saying, just turn the unit on, don't do anything, then just see if the unit moves by using the directional arrow keys, up / down. left / right ?
If so, it does, this is how i have been using it most nights.
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  #38  
Old 26-08-2018, 12:25 PM
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When you have it on fast slew rate,
does pushing the up button lift the scope.
Does left button slew it anti clockwise.?

Also, after doing an initial alignment, do a goto the first named star (Fomalhaut from what you said) and see if it returns to the eyepiece.

Then try the other.

looking more like "This R2 unit has a bad motivator" .
sorry to say.
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  #39  
Old 26-08-2018, 12:39 PM
bluesilver (Peter)
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Hi, yes, on rate 9, the fastest slew rate, up makes the scope go up, down makes it go down, left makes it go left and right makes it go right, so everything goes in the right direction it is suppose to go.

I didn't try to see if it goes back to the first star after the alignment, i will also check that out next time as well.

So it could actually be the SynScan hand controller unit that is faulty, not so much the two motor drivers?.
It is version 04.37.03 I haven't downloaded any software or firmware or the like to it,
I am thinking it should of been already to go when it was delivered,
( no software / firmware to be downloaded) is this an area also to look at,
Am i correct in saying i shouldn't have to load anything into it?
Just thinking if there is anything else that i have missed.

Last edited by bluesilver; 26-08-2018 at 03:20 PM.
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  #40  
Old 26-08-2018, 07:28 PM
bluesilver (Peter)
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Hi again, so i have just been out trying a few things tonight, sadly to say the same results, and never the same twice.
So here is what i got, using the same two stars to keep things the same.

Setup facing North, tube level on 0 time is 7pm
Chose Fomalhaut as the first star and coordinates were
112° 25.1 E + 19°48.3
Second star Altair, coordinates were 48 NE + 27
Slew went off anti clockwise, past Altair and final resting spot was about 297 NW, so roughly around 111 degrees off.
I then as suggested, selected it to view Fomalhaut, ended up going roughly 15 degrees right of it, although the height was about right.
Tried all this again, this time when it came to rest instead of selecting ok, i slew it back to where Altair was and oked it, Still was way off when i selected it to view Fomalhaut.

This time setup facing South, results were slightly better with the end slew being around 78 degrees right of Altair.
Tried both of these a few time tonight and the results varied greatly where it stopped ( second star) worst being almost as far around as the southern cross.

I hope these figures and write up makes a little sense.

So all up dose this kind of point to the SynScan hand held unit being faulty?
Not sure what else to do or test now, any thought or inputs are appreciated, really at a loss now.
Thanks.
Peter.
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