Ahh.... I see from the error message that you use menu->group->match and will try to do the entire group (and for now it has a small bug I am fixing it). Try to use instead the button from the tool bar which looks like a check mark with the label "Match Stars". See bellow imaeg more info.
First to explain the steps of image/plate solving:
- Detection = searches the image and find the star like light source and extracts the image coordinates/relative magnitude
- Setting Hint = is used to speed up the search for images shot at a high focal length – anything higher the 100mm should have a hint for position/focal. You can provide as a hint a constellation, common names for stars or deep sky object, messier/ngc/ic objects, sao catalog number or the numeric value for right accession/declination. Also to provide a hint for the field size most times I use the numeric entry for focal length but you can also use the select optical system button.
- Catalogs = there are several types of catalogs – the main used in the matching is the stars catalog. It’s important to chose the right catalog for the image – for example it might be ok to use SAO for a wide field image – but for an image like this one sao has to few stars in the region to be used to match. In this case you need to use tycho2 or a bigger catalog. Catalogs can be used from local source (if you decide to download them in case you want to work offline) or better, from remote sources.
- Matching = is process where the detected light dots are matched with the star catalogs
And these are the steps to solve this image:
1. After the image was loaded press the “check mark” button (match stars) from the toolbar. If the image was previously detected it will ask you if you want to re-detect the light sources.
2. A window will popup asking you to select the catalog – for this image use SAO but for images at a focal >200mm use a bigger catalog like tycho2 (the same I used for this image), usnob1.0 or nomad, etc
3. Then the application will ask you if you want to provide a hint – in case when the image was taken with an instrument (telescope/lens) with a higher focal length then 100mm you might want to say yes and set a hint – in this case you can just skip over point 4.
4. If you got for Hint In the Hint window you chose hint type: custom, select origin hint by messier and set to messier 23 (for example which is almost in the center), or you can enter the coordinates by hand. The in the second part specify an approximate focal used to shot the image put in 35mm
5. after providing the hint the matching/searching window will show and it should solve
Alternatively you can do the steps manually from the main menu in this order:
- There is a detection threshold which you can use to detect more or less objects in the image Menu->Options->”Detection Threshold” - the lower you set that value the more finer the detection will be and find more stars.
- You can increase number of zoom steps from Menu->Options->Matching->”Search Zoom Steps”
- if you have earth objects (trees, hills, power polls, etc) you can block them using the “Add Area” button from the tool bar (the drag/draw with your mouse the area in the image) – that will block detection in the rectangle area. You can adjust the area with right-click->Areas functions
Any questions please ask