SC starts with wrong gotocoord

[donboy]

When I open SC and use goto coord catalog the first object listed is the last one selected from a previous day with it's previous days altitude etc. To correct this I restart SC and that fixes it.

Don

[admin]

Hi Don,

I'm not seeing that one happening here - just tested with both leaving SharpCap open for a while then going to the 'Goto Co-ordinates' and also with closing, waiting a while, reopening and then trying. In both cases the altitude of the default target updates based on the time each time you open the 'Goto' window, and matches Stellarium values.

Note that if you leave the GOTO target window open for a long time then the altitude does not update as time passes - the calculations are done when that GOTO target window is opened, rather than being updated as time passes.

cheers,

Robin

PS - just to be sure ... you mean this, yes?

Screenshot 2024-09-14 152920.jpg (65.39 KiB) Viewed 725 times

[donboy]

Hi Robin,

Yes the red circled item.

Example: Recently I went to the Goto Catalog to load in my first object and the first item listed was M33 and it had it in the east at 53 deg which was the location for it the night before. The actual altitude was at 20 degrees at the time I opened this tool. And listed were objects that were not at the altitude listed for the current time but for later in the evening.

I atleast can restart SC and eliminate the error. Maybe it will work itself out in one of the future updates.

Don

[admin]

Hi Don,

OK, and closing/re-opening the GOTO window doesn't help? It should recalculate all the altitudes and directions when you open that window.

The only other thing I can think of is that somehow the Sidereal time being used is still from the previous day (if SharpCap has remained open and the mount is connected). SharpCap asks the mount for the sidereal time, but if that is reported wrongly in some situation then all the position calculations will be off.

If you run the SharpCap scripting (press Alt+F11), then enter the following line in the top script window and press enter

Code: Select all

print (SharpCap.SiderealTime)

You should get a number which is the local sidereal time for your longitude (provided the mount is connected in SharpCap). This can be checked against online web sites that can calculate the sidereal time for your lat/long position (ie https://aa.usno.navy.mil/data/siderealtime). A big disagreement might indicate the incorrect sidereal time is the issue.

cheers,

Robin

[donboy]

Hi Robin,

Here is what I got.

Screenshot 2024-09-16 122148.png (26.46 KiB) Viewed 714 times

Screenshot 2024-09-16 122103.png (43.07 KiB) Viewed 714 times

[admin]

Hi,

interesting - it certainly doesn't look like the sidereal time is correct in SharpCap from the screenshot above, so that could be part of it.

Did you have the camera open and mount connected when you tried the scripting in SharpCap? I did find an issue when investigating further that when no mount is connected, SharpCap calculates the sidereal time itself, but was reporting the Greenwich sidereal time, not the local sidereal time. However, if that was happening then SharpCap should have reported 15.9 or so, not 11...

cheers,

Robin

[donboy]

Hi Robin,

I did have no camera or mount connected when I ran the script. As soon as the weather clears I'll run the script again with all the equipment connected.

Don

[donboy]

Hi Robin,

The other night I fired up everything as normal. Opened SC and the mount, cameras and all accessories were connected and functioning. I opened Goto Catalog Coord and the locations listed were off by quite a lot, and were at a value that reflected the last time SC was used. I ran the test to compare Sideral time and they were equal. So I did what I normally do in this situation; I closed and reopened SC and as usual the second launch fixed the location values.

Some how the closing time of the last usage of SC is not being flushed the next time I image and open SC. And SC appears to be using those previous closing value(s). Maybe I should open and close and reopen SC before I use the Goto Catalog Coord tool.

Don

[admin]

Hi Don,

still puzzled by this one and the only thing making sense to me is odd sidereal time values coming from the ASCOM mount driver during the first run (perhaps the software on the PC has not fully synchronized with the mount?). What mount do you use and what ASCOM driver?

I already have code that checks the mount's reported time/date when connected and flags up if it is more than 1 minutes out from the system clock. I am going to add something that will also check the mount's sidereal time value at the same point and log the results (whether they match or not). If there is a problem in the sidereal time calculation then this extra logging should reveal it in a future version.

cheers,

Robin

[donboy]

Hi Robin,

The mount is an iOptron CEM60. And I use iCommander and it’s ASCOM diver for mount communication.

Regards,

Don