One of the biggest challenges of owning a 20" F/5 dob is transporting it. Well, for me it is. The trusses especially pose a challenge because of their length. I load them in the back of my car, which actually is large enough to contain the entire telescope (that's why I bought it in the first place), but then they reach over the front passenger seat. When I break, or go down hill, they slide forward and I am afraid they will some day crash through the front window.
So I decided to buy new trusses and make them such that the telescope contains two sets with a wood ring in between for stability.
Sorry for the rotated view, but I guess you get the point. The ring I cut with a cutting tool from a slab of wood. Then I spent several days cutting the trusses to the right length so all my eye pieces reach focus. This took several nights last week, but on Thursday night finally I was done!
So I took my telescope to my regular observing location near the ESA satellite tracking station near Cebreros, west of Madrid in Spain. The SQM got stuck at 20.9, whereas 21.1 is more common. Still, I didn't want to waste another night and I decided to track down several Abell planetary nebulae:
Abell 40: At 256x with OIII visible occasionally. A bright star with a fainter one south of it. West of it lie two faint stars with another, fainter, one east of it. East of that faint star I see about 10% of the time a faint glow.
Abell 41: At 256x visible without a filter as a tiny disk. UHC gives a beautiful view of a disk in a rich star field. It forms a triangle with a faint double star and a single star of about m=12. OIII dims the stars too much. H-Beta makes the disk disappear.
Abell 42: At 83x, 151x and 256x without and with UHC, OIII or H-Beta shows no nebula. I'll try again under darker skies.
Abell 43: At 83x and 151x very faintly visible without a filter. OIII makes visible a nice disk. According to images it is a ring, but I don't see that. One star lies at the eastern rim of the nebula and it is about as bright as the central star. According to images there is another star to the southern rim but I don't see it.
Abell 44: At 83x without a filter I only see the central star. To the north east I see a triangle of faint stars, of which the two northern most ones point toward the central star. To the south I see another faint star with an even fainter double star just north of it. North of the double star lies the central star of the nebula. OIII reveals a small disk around the central star which is invisible with H-Beta.
Abell 45: At 83x I am sure to be at the right location, but I don't see the nebula even when I use an OIII filter. I'll try again under darker skies.
So far I managed to see 20 Abell planetaries but I am sure I can see many more with my telescope.
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