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It seems occuring when the map is centered near one of the margins of the DSS image. |
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I cannot reproduce the problem. I set the fov to 5deg, center on ic410, set the DSS source to "Skyview DSS", click the DSS button and the image is perfectly aligned. What is the source for your dss image? Can you zip and upload the file $temp.fits here if it is not too big. |
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I'm using the 102CD mode, stored locally. |
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1.png (439,868 bytes) |
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I see online DSS plates are not usable @ FOV=5°. Anyway I also found a change in FOV, as you can see in the attached png - I was at 5° but after the DSS click SkyChart switched to a larger FOV (greater than 6°). |
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Yes, if you select "Skyview DSS" the online DSS can show wide FOV by making mosaic of the DSS images. This is probably the best option. And I can reproduce the problem with the 102CD. The WCS is wrong in the FITS file, I will take a look at libgetdss if I can fix it. |
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I have noticed similar with 4.1 SVN and pictures installed from https://www.ap-i.net/skychart/en/download (skychart-data-pictures_4.0-3421_all.deb). Search and lock on NGC 1101 and zoom in to about 10". The picture is shifted left of the center of the screen. If compare parametric shape and actual picture, picture is shifted left in about half of the actual size... Upper happens with SAC catalog. If perform the same with Open NGC, all seems to be aligned properly. As well, when switch between catalogs, be sure to perform Search and lock - otherwise catalogs seems to not being switched, as on changing time position of picture is not changed accordingly. |
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The issue is in the DSS 102 CD extraction software when the FOV is out of a plate boundary. I cannot find the issue for now and a real solution will be to merge data from adjacent plate, something this software is not intended for. The solution for large DSS FOV is really to use Skyview online as it merge many plate nicely. Sasa, your problem with NGC 1101 is different. The offset you see is because the SAC coordinates are sometime imprecise, so the picture is at the right place but the symbol and search position from SAC are wrong. OpenNGC contain much better coordinates and since last week version it also include the IC. It is now a much better choice than SAC and I will probably switch the default catalog after a few more testing. |
- Anonymous
