Posts Made By: Mike Shade

I have a 16X16 foot roll-off roof and I love it. My understanding is that domes can (but not always will) have seeing problems. My building in Sonoita AZ (about 2 miles from Herb) cools of quickly after the roof is opened. It was designed for a 22" f/5 Newtonian but that scope had some problems so now have a C-14 on older AP1200 on a pier in center of floor (will eventually have a 17" RC in it). There are a few problems or issues: since AZ can get some wind, if it is windy I can't open the roof (I don't want to have to retrieve it from the next county). Also, I had to get a permit and engineer's stamp for the roof hold down system. Thus far it has lived through a 72mph wind gust (it is designed to stand 80mph winds). Depending on neighbors and such, a dome might not fit into the neighborhood very well. Also, at least in theory, a roll off might be cheaper than a dome.

Mike

Whoops, excuse earlier error....Herb was over at the observatory and suggested I shoot M51 with my old ST7 through the C-14 at f/7. I of course told him it wouldn't fit but here is the result. One 30 minute shot, flat/bias/dark, some processing in Maxim and AIP4Win, Sonoita Hills Observatory, Sonoita AZ.

Mike

You might consider trying different processing programs-I like AIP4win. I will play in Photoshop a bit but I think that AIP4 is better for straight CCd work. Maxim does OK but does not have as many options. Since I have begun using this program, I have been able to get better results. Something else I have done is to take a real short exposure of something and take longer ones. I will then subtract the longer from the shorter (or is it shorter from the longer; it has been some time since I have done this) but you can preserve some of the detail in easily burned out areas like galaxy cores. I tried this with Hubbles Variable Nebula and it worked pretty well. Of course, I don't think that it is possible to preserve all the information contained in the core of brighter objects but some of it can indeed be preserved/enhanced. Hope this helps.

Mike

I think that this is a very good image, there are a few things that you might do to make it better. You might try some sort of "digital development" routine on it or a deconvolution procedure such as in AIP4Win. This might bring out some more of the information contained in the spiral arms. Perhaps one single exposure instead of combined exposures? Is your location dark enough to go 20 or 30 minutes? If so try it. this of course assumes that you mount can track that well for that long, also assumes that you have a pretty good polar alignment. Might also consider a coma corrector such as the one from Lumicon (there are others out there as well). What a camera are you using?

Mike

Hey, this is very nice. What camera did you use? How do you like that STV autoguider? How would you rate it compared to the old ST4? What sort of guide scope do you use? Is it a good value for the money? Accurate enough? Easy to use?

As you might guess, I am pondering the purchase of one in the near future.

Thanks,

Mike

I have always liked the "fluffy" texture of this object. I can't seem to remember...what is the Mewlon again?

Mike

If you already have a cement floor, addinga pier is going to be something of a problem as you are going to have to do some drilling. However, if you do not havea cement floor you will be able to do pretty much whatever you want. When I built the observatory here, I used a 36" diameter piece of Sonotube (the cardboard like tube they use to make concrete piers with) sunk about 6' in the ground. Inside of this I placed a rebar reinforcing cage with additional piece of rebar "floated" vertically. When the concrete was setting I placed the four 1" "J" bolts 16" into the concrete. I had a form that matched the pier base so the bolts would line up correctly. Around the pier top, prior to the floor being poured I rolled some "sill sealer" that you use between the bottom plate of framing and the floor. This isolates the pier from vibrations from the floor. I used to have a 22" f/5 Newtonian in there but the telescope was useless so now have a pier with an AP1200/C-14 on it. The actual telescope pier is a 10" diameter piece of pipe welded to a 3/4" thick piece of flat steel, which bolts to the floor. There are braces and such on this bottom piece. The pier is filled with about 250# of sand and is VERY stable. Top of pier has the AP adapter plate and the mount attaches to this.

Mike

Get the best mirror you can, smooth and accurate. Don't settle for a substandard mirror.

Mike

I use an old ST7 in my C-14 at f/7 or so. This allows me to pick on things like the NGC, IC, and Arp lists. Does not allow me to take a full frame M51 for example but I get bored with the usual objects. I will be upgrading to an ST8E soon so that should give me a little more real estate.

If you browse back a few weeks you will see some of my work posted on this discussion group.

Have a new 1200GTO that the C-14 now resides on and the mount seems more than capable.

Mike

For precise polar alignmentyou need to do a drift alignment. Also something that you might think of is what is you mean photographic declination? For me here in SE Arizona, it is about +22, for somewhere further north, it will be higher. Basically what this does if average out your drift for most of the sky. You will not be shoooting pictures at -50 declination and probably not a +80 either so you need to find your "average" which is partially based on your latitude.

So, assuming that you are aligned reasonably well north, point the scope to your mean photographic declination and the meridian. you will need a high power guiding eyepiece with illuminated crosshairs. Align it so that when you move in Dec it moves on on line and RA moved the other line. Also note which way is north and south IN THE EYEPIECE. find a star and set in on the N/S line and watch it drift in declination only and note its direction of drift. If the star moves north, move the scope toward the east, if the star moves south, move to the west. hopefully your mount will allow you to make small adjustments. Adjust untill there is no drift for 10 minutes. Now point the scope over low in the east, keeping it at your mean photographic declination (only move in RA). Again figure out which way is north/south in the eyepiece, center a star on the N/S line and watch drift. If it drift north, adjust polar axis down, if it drift south move polar axis up. Again there should be no drift in 10 minutes. Now go back to the meridian and do it again but shoot for 20 minutes with no drift, then go back to the east.

Also keep in mind that if you need to move the scope a bit to find a bright star that is OK but no more than like 1/2 degree, less if possible. Also when you are drifting keep in mind your starting position and don't get too far from it. You might need to move east and find another star. Also, keep in mind that this procedure can take a bit of time but when done you will have a very accurate polar alignment.

Mike