Slew to target after Polar Align

[CarlGreen]

Hi All,
Sorry if this is a basic question, but trying to learn all this astrophotography and Sharpcap and is it proving quite difficult, even with all the You Tube information out there!

A few nights ago (On one of the rare occasion that it was clear!) I set up my gear (EQ8 Mount, Altair 155 EDT Main Scope, ZWO 294MC Pro, .8 Flattener, - There is also Guiding stuff but not applicable to this question (I think))

I did my first ever Polar Alignment using Sharpcap (In fact my first Polar Alignment full stop!) and the Program gave an "Excellent" alignment report.

Here is EXACTLY what I did.............

After getting Excellent Polar Alignment, my scope is pointing to Polaris.........

I then opened the Tools/Go To Catalog Target/Co Ordinates and selected GOTO a target from the catalog (I then typed in Jupiter to set Jupiter as a Target).
I pressed Start and the mount started to Slew...(So far so good!)
(I was looking at Jupiter from my garden so knew roughly where the scope should be pointing once it had finished)
However, it skewed to a completely different point in the sky than where Jupiter was! (It was nearly 180 degrees away from where it should have been pointing (180 is a guess!))
Have I missed something? Is there a step I have not done?

Any advice greatly accepted.

Thanks all

Carl

[Fir Chlis]

I had something similar when I first started using SharpCap, but it was when I parked the mount at the end of the evening, it went horizontal rather than to the home position. It was caused by my mount (HEQ5Pro) not being in sync with EQMOD.

With the mount in the home position, on the EQMOD main page, press the >>> to open the larger page and then press on the symbol highlighted to sync EQMOD With the mount. I usually do this (when I remember) each time I set up.

EQMOD.png (199.61 KiB) Viewed 4736 times

The only other thing I can think of is, do you have your Latitude and Longitude set correctly in EQMOD?

You can check all this in the daytime. If you set your scope pointing North, use something like the Stellarium app on a smartphone to find a target and get Sharpcap to GoTo the target, but not to platesolve, you should be able to see if the scope is pointing in roughly the correct direction.


Geoff

[admin]

Hi,

Geoff has pretty much covered the most likely causes - ie

* Wrong latitude/longitude setup for the mount in the ASCOM driver
* Wrong home position (should read Dec=+90 and HA=6 when in the home position of scope up, weights down, pointing north)
* Also potentially - incorrect time

Did you remember to return the mount to the original position after completing the polar align?

cheers,

Robin

[CarlGreen]

Thanks to both of you for your answers.
I did NOT return the scope to its original position (Weights pointing North and scope pointing north "on top" of Mount (It was at 90 degrees as I did not know you had to put it back to start position?) and how can I check the Lat / Long in Ascom?

Thanks

[CarlGreen]

Thanks to both of you for your answers.
I did NOT return the scope to its original position (Weights pointing North and scope pointing north "on top" of Mount (It was at 90 degrees as I did not know you had to put it back to start position?) and how can I check the Lat / Long in Ascom?

Thanks

The settings in my GS Server settings are showing Observatory Location as (N 52 15 36 and W 0 40 33) - In Google Maps, my location shows as 52.260073576125, -0.675898561889992
Which using a Lat/Lon converter gave me the Hours /Min/Sec figures which I put into the settings. Could someone confirm if these are correct please?

[Fir Chlis]

If you have an iPhone, the Compass app will give your Lat/Long in the hh:mm:ss/dd:mm:ss format. I guess Androids may have a similar function.

Geoff

[CarlGreen]

If you have an iPhone, the Compass app will give your Lat/Long in the hh:mm:ss/dd:mm:ss format. I guess Androids may have a similar function.

Geoff

Thanks, did that and they do match.

[CarlGreen]

Hi,

Geoff has pretty much covered the most likely causes - ie

* Wrong latitude/longitude setup for the mount in the ASCOM driver
* Wrong home position (should read Dec=+90 and HA=6 when in the home position of scope up, weights down, pointing north)
* Also potentially - incorrect time

Did you remember to return the mount to the original position after completing the polar align?

cheers,

Robin

Thanks Robin, my coordinates seem correct so I guess it was probably because I had not returned the scope to the Home position.
(How do I check that?) I use GS Server as my software to connect the mount (I think! - Select Ascom GS Server in hardware settings - Open GS and that's where I saw the Lat/Long details)

Carl

[Jean-Francois]

Hello Carl,

Note the difference between the "polar alignment" of the mount with SharpCap and the "alignment" of the mount (with what you use).

With SharpCap you perform the mechanical alignment of the mount rotation axis with the sky rotation axis.
At the end of the process, you have only that (RA-axis of the mount pointing to the sky rotation axis).
For this, you do not need to know the location (precisely) or the time (at all).

For the use of the mount, you need in addition to set the correct parameters (time and location).
For that you can use the 1 or 2 stars alignment process of the SynScan software.
Or you do a plate solve/sync so that the mount will know where it is pointing.
Generally you start from the home position (or you use the automatic homing of the EQ8 + SynScan).

For the coordinates of the mount:
DEC is between -90° and +90° (with + = north and - = south).
The decimal calculation: the decimal part multiplicated by 60, then again the decimal part multiplicated by 60.
52.26007357612: means 0.26007357612*60 = 15.604414566 and 0.604414566*60 = 36.26487396 ... so N 52°15' 36''

And if you have N 52°15' 36' ... so ((36/60 + 15)/60 + 52 = 52.26°

RA is between 0h and 24h, or 0°and 360° or ... in "hours/minutes/seconds of time" or "degree/minutes/seconds of arc".

The Hours/Min/Sec are for the "time" of the RA coordinate with maximum 23h 59m 59s.
The Degrees/Min/Sec are for the "angle" of the DEC with maximum 89° 59' 59'' and the latitude and the longitude coordinate on earth.

But the longitude coordinate on earth can be in degree from 0° to 360° or from -180° to +180° or a positive number between 0 and 180 and the West or East side.

Regards,
Jean-Francois