Deviation of the homeposition after a new start.

[rharter]

Hi all,

following the Autoslew manual I have done all the mentioned adjustments for a stationary mount to start again only with the Homefind referencing and the corresponding pointing file.

After a new start I always have a deviation of about 15 arcsec in RA of the former synchronized and centralized star with the "Set new Homepostion" and saving procedure. I will not again synchronize following the manual.

Where is my fault or has anyone else the same experience and what possible solution did you find?

Right now I must always following the whole procedure after a new start of synchronization and "Set new Homeposition" to have a star centalized without deviation from the beginning. By the way,certainly nothing was changed during the stop at the system.

Thanks

 

Kind regards

Ralph

[GeorgeCarey]

Have checked the accuracy of your computer's clock?

[rharter]

Hi,

 

oops, sorry wrong unit.The deviation is about 15 arcmin in RA !

 

Ralph

[GeorgeCarey]

Are you using the same epoch in Autoslew and your planetarium software?

[rharter]

Hi George,

 

good point, I will check this comming weekend at the location. I have changed the local computer a view weeks ago...

 

Did I forget a adjustment ?

 

Autoslew:

Main frame: Ep. ; real

Control/ASCOM ACL: Used Epoch=0.0

 

Sky X:

Navigate / Enter Coordinates, Apparent Equinox: Current

Mount Setup: ASCOM Poth Hub, Setup advanced : Coordinate Management: Local

 

Maxim DL:

Setup/Telescope Poth Hub, Setup advanced: Coordinate Management: Local

Observatory/Telescope: Target Coordinates: JNOW

 

Ralph

[Robert-Poelzl]

Hallo Ralph

Which telescope you are using?

 

Robert

[rharter]

Hi,

 

at first I checked the epoch adjustments. In Maxcim DL I have found a J2000 instead JNOW. It could have an influence via the poth hub...?

But I could not verify it, clouds, clouds, clouds, mayby next weekend....

to Robert:

my telescope is an ODK 14" piggypacking with a APO 80. But shouldn´t be a collimation error of the main telescope calculated and therefore already considered?

 

Ralph

[rharter]

Hi again,

 

this weekend I had luck for 1 hour without clouds...  and I could verify that it had no effect with the wrong epoch in MaximDL. The deviation of about 15 arcmin in west

is still there after a new start. Itself after a new synchtonization and new home position with save and followed powercycle the deviation is present. I took an image with the position deviation of 300s and tracking is ok.

Any ideas what can cause this ?

 

Kind regards

Ralph

[rharter]

Hi,

 

still on the search of my deviation, I have found a difference in time between Autoslew/time Settings from GPS ( in UTC) and The Sky time (from computer). see pic. All in all 2hours! Could this be the reason? How are your adjustments to avoid this?

 

 

Ralph

[GeorgeCarey]

But two hours would mean your error should  be enormous, not 15 arc minutes.

There is a reading of -104 seconds under DIFF which is perhaps the reason.

I don't use gps so I am not an expert on this...

[robertp]

Hi Ralph,

 

from the screenshot you posted, it looks like you are using the query-timer. I had to use it several years ago when I had a PC with a very bad internal clock. I'm not sure, but your query timer deviation seems to be rather big. Haver you calibrated the timer recently? Have you checked what happens if you disable the query-timer?

 

One other question: In your original post, you said:

"After a new start I always have a deviation of about 15 arcsec in RA of the former synchronized and centralized star with the "Set new Homepostion" and saving procedure. I will not again synchronize following the manual."

To my understanding, it is not a problem to do another sync. This should not render your pointing file invalid. Have you tried that?

 

Robert

[rharter]

Hi Robert,

 

when I disable the checkbox of "synch query" in Time Settings the other checkbox "synch PC-Tim" seems to be linked and is disabled as well.

Or do you mean something different?

 

 

the other point:

 

In the manual is said in "Mount/New Home Position":" never synchronize with the planetarium software again"after saving  "set new homeposition"!.....? So this is why I do not want to sych again.

I do not know what will happen when synchronizing again in contradiction to  the instruction manual.

 

Ralph

[rharter]

Hi,

 

after a long search for the deviation I guess I have found the source. A time problem was the right path to the source.

In the planetarium program The Sky X under Input/Location in the custom adjustment is an aditional field for time zone.

Here should be the correct difference to UTC time. Unfortunatley I entered here the MEZ and not the right MESZ.

With the correct difference now the deviation fade away.

 

Ralph

[GeorgeCarey]

Good to hear that you fixed the problem!

George

[prefetch]

it's always nice to hear it when people find solutions to these gremlins.  thanks for posting.

 

[rharter]

Hi again,

 

during my extended search for time deviations I came across a very interesting point, which effects a lot of phenomena and of course tracking as well. The internal “Windows” clock and its time server is far from being precise. I notice a deviation on my laptop of around 8sec which is resulting in a deviation in RA especially when a planetarium program is synchronized with the internal pc clock!
I guess I have found a good solution to fix this problem.:

 

1. The deviation of your internal pc timer to standard can be shown with: www.time.is
2. I have changed the Internet time server to pool.ntp.org (it is said that this time server is more precise) in date and time settings / internet time,
3. Change the time synchronization interval from 1 week (default) to daily or hourly with this mentioned tool:
http://www.thewindowsclub.com/change-internet-time-update-interval-windows

 

I hope this will help to minimize our multiple source of errors.

 

Ralph

[Jay]

Internal PC time will never be very accurate if using only Windows. I've been using an additional (free) programs (like Network time) when more accurate time is needed for the PC. Refresh time has usually been 15 min and adjustment tolerance 100 ms

 

Jay