Wednesday, March 5, 2008

The GSW Super Planisphere - a great product!

Sunday evening, March 2, I almost drove to Bedford, Ma to observe with Greg Stone, but at the last minute he was clouded out so I stayed home and set up in the State Park across the street. It was very cold and windy, but the chemical warmers in boots and gloves worked wonders.

The XT8i COL has been giving great warp factors of +0.1 every time since I carefully leveled the base and adjusted the vertical stop to insure that the OTA was at a perfect 90 degrees to the base. Once you do this, you can set up even on sloping ground and still get perfect COL alignment. In fact, one trick I recently read about to make observing near the zenith more convenient with a Dob is to purposely shim the base on one side by several inches before doing the alignment. If I try this, I'll use a couple of 2x4's to start.

I spent about an hour just poking around the clusters in Auriga, and taking a few peeks at M42 before it got too low in the west, and of course looking at Saturn. I made an attempt to do some AP with the new Orion SteadyPix camera mount and a Canon S410 Powershot, but no luck at all. I'll post on that separately if I make any progress.

I purchased the GSW Super Planisphere2 about a month ago, but Sunday night was the first time I was able to convince myself to put down the eyepieces and and COL for a while and just spend some time learning the sky a bit better. (Part of the problem is that clear skies have been so rare the last few months that when it does clear up I want to use that scope all I can!) I am completely satisfied and actually overjoyed with how much the product helped me.

I've had a scope for only a year so I am a real beginner. I would say I knew the easy constellations (Ursa Major, Cass., Orion) but Perseus was "over there somewhere" and any two similarly bright stars could have been Castor and Pollux, and many times were.

I have tried planispheres from several manufacturers with the normal amount of success, but for me they show too many things crowded into too small of a space. The P2 (as I'll call it) does come with a traditional whole-sky planisphere with date and time circles, but it is used more as an index to the ten double-sided disks which show individual constellations at higher magnification. I have a lot more to learn about how this index planisphere works, as it has a compass built in, and tells you which way to look and how high in the sky the constellation will be found on your time and date, etc. All very useful, but I haven't really worked on it so I'll defer that for now.

The individual disks were the key for me. They are about 8" in diameter, and each covers between 1 and 3 major constellations. The background is a deep blue and the stars are white with larger dots for brighter stars, and the main outlines drawn in. They are printed on both sides, so there are actually 20 disks on 10 cards. The brighter Messier objects are indicated but the key is that the disks are simple and they match the sky as observed in my typical suburban skies very well. This is good, but also a sad commmentary on how much light pollution is up there.

Around the outer edge of each disk are the names of the neighboring constellations, and the disk number on which they can be found. This is so useful! If there is an arrow next to the name, it indicates that the neighbor is some distance away in that direction, but if there is no arrow it indicates that the named constellation is "right next door." These small things make a huge difference when you are just learning your way around the sky, like a child exploring his neighborhood for the first time.

Just inside the ring of names of neighboring constellations is the name of the disk you are holding, printed over and over around the edge so it's easy to find any disk by number if you can see a bit of its outside edge.

I found the best way to use the disks for me was to hold one up in the light of my red headlamp, tilting the bottom of the disk away from me slightly to avoid glare from the smooth surface of the disk. (Here's where my bifocals came in really handy.) By rotating the disk until it matched that part of the sky, all the relationships to neighboring constellations were immediately apparent without the distortion imposed by a single disk trying to cover the entire sky. This is a big help! Leo was easy to spot, neighbor Cancer much dimmer but still apparent, Bootes and Virgo were both exact matches for what I could see on the disk even though they were just rising in the east. The bright stars in each constellation (Regulus in Leo, Arcturus in Bootes, Spica in Virgo, etc.) have now become easier to remember. I could not have told you any of these stars by memory yesterday - hope I got them right! :-) Perseus has a home now between Gemini and Cass., and I can find the double cluster easily now. Ursa Minor was hard to see early in the night, but later as it rotated up out of the skyglow to my north I could finally see most of its stars, and using the disk as a guide really helped.In summary, I could not be happier with this purchase. I think I learned more in an hour than with all the planispheres I've used in the last year.

The product also comes with a card to place on the ground with letters on it so that up to ten people can stand in a circle facing out by the correct letter, and each use one of the disks to identify things in their part of the sky.I guess the people then rotate around the card, passing their disk back to the person taking their place. This would be a very good educational program for beginners, but again I have not explored this feature enough to comment on it.

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