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Old 13-03-2008, 12:49 AM
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goober (Doug)
No obs, raising Harrison

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Join Date: Nov 2007
Location: Melbourne, Australia
Posts: 795
Two Hours with an Argo Navis

Last November I ordered an Argo Navis for my refractor. I was getting frustrated at the lack of reference stars for starhopping from my light polluted back yard. I was going to order another "push to" product, but the Argo is home grown, and would grow with me if I went up in aperture again.

Anyways, this morning it arrived. The delay was due to the unusual encoders my mount required. I went over all the pieces this morning before work and was alarmed to find I had nuts, screws and other assorted pieces I didn't now what to do with. An email to Gary at Wildcard during the day put me at ease - I didn't need a lot of it for my rig, it's just part of the package.

I installed the encoders when I got home, quite straightforward, although the altitude encoder was very snug in it's "housing". I plugged the huge hand unit into the encoders, and went through the setup process. The two buttons and wheel system works very well - intuitive and easy.

I went the whole hog in setup, plugging in precise location, my guess at the FIX ALT REF value (-12.670 degrees, thanks to Tom Trussock, who's been through this before). I pretended to align on Sirius during the day to test the polarity of the encoders and found them reversed, so switched them around. RA and Dec track in the correct directions now.

Gary from Wildcard had put a post up recommending a daytime encoder check against a fixed point (e.g. distant power pole insulator). I tried this, and did the 360 degree azimuth swing and found it fell exactly back on 0, same with altitude.... encoders working, no slipping, good.

Night falls and I head outside. Put the scope at -12.670 degrees, FIX ALT REF check, and align on my two stars. I choose Archerner and Regulus, which gives me a Warp of zero ... huh? Oh, I have AUTO ADJUST ON, which will give me zero Warp.

Time to play...

MODE CATALOGUE - take me to Betelguese, Procyon, Spica... all hit the target more or less. Some are just at the edge of the field of view. I then go for Saturn, which should be a good test of location coordinates. It's not in the eyepiece. I realise then that I still have my 30'/154x eyepiece in from the two star alignment. I pop in the 1.7 degree/49x and Saturn's there.

I then proceed to sweep the skies, covering all points of the compass. The Argo Navis handled it really well. After a criss cross or two of the sky the pointing was beginning to drift. Not by much, perhaps half a field of view. Each time I noticed it drifting, I'd plug the current object back into MODE ALIGN, and that seemed to resynchronize it.

I entered TOUR mode and tried a few out...

ANY OBJECT IN CRUX ... basically took me to the Jewel Box and the various stars.

OPEN CLUSTERS IN CARINA > MAG. 7 ... lots of things to look at here, NGC, Cr, Tr, Hogg, etc. The ones I could recognize were in the eyepiece, so I assume the ones I couldn't were there as well. A great feature is you can press ENTER again, and get a scrolling ticker tape message about the object - size, mag., notes, atlas map reference. Great feature.

MESSIERS IN 360 degrees - this basically took me to every one. Once I was in Draco I thought this is getting a bit silly, so rejigged the tour to...

MESSIERS IN 180 degrees - okay, this would give me visible Messiers, or so I thought. After touring the Virgo/Coma Bernices galaxies (didn't see one!), I was suddenly in Scorpius, below the horizon again. I could see Orion over there, so where was M78, M42, M43 in my tour? Obviously the 180 degrees is within 180 degrees of your launch point, and I launched from near Corvus. Is there a "above the horizon" option?

GLOBULARS IN CENTAURUS - Omega, 5286, both in the centre of the eyepiece.

GALAXIES IN CENTAURUS - I put a magnitude limit on this tour and went through five galaxies. Saw 1.5 of them

I finished off by playing with MODE IDENTIFY - target an object, and ask the Argo what am I looking at. I put an unknown star low in the west in the FOV and queried.... it told me it was Zaurak in Eridanus. Okay, I'll have to accept it's telling me the truth. Bright pink thing to the north west - it's Mars - bingo. Flip it over to the bright star rising in the east - Spica. Back to the mystery star in the west - Zaurak again. Feeling playful, I find a faint mag. 5 star somewhere east of Centaurus A - and it identified it (can't remember the name)!!!

Great fun to play with it, and it will be a fantastic tool for serious observing.
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