Sunday, March 31, 2013

tasted my own medicine

The last couple of nights, when I've been playing with the alignment controls of the GoToStar IDEA system, I felt a little uncomfortable when it suggested stars. I know where Aldebaran is. I am pretty sure about Alphard. I know a bunch of stars. But the funny thing is... OK, you know, well... I know Dubhe, I do! I do know Dubhe. For certain I know its parent constellation. Really! But... well... I'd have to look it up, to be sure. The Markabs and Mirfaks always confuse me. OK. OK? Happy?!

I had started thinking about this when first learning the system. But last night, after checking the ideaxuwen Yahoo!Group, I began making a list. While waiting for it to get dark, I transcribed the named stars shown in the hand controller. I also noted the assigned number. Ended up with 189 "potential" entries. The HC was automatically skipping some, ones not visible to me, given my location, and the time. I actually saw it, on the fly, dynamically added and excluding stars. Then I started to walk through the alignment process to see what stars it encouraged me to select. I noted these. It was a very short list, a subset, with 13 entries.

Later I moved and merged the two lists to a spreadsheet. Added the Bayer name and the constellation and a "location" column, for the general impression (for me, in North America) where the star lay. The alignment star and hemisphere fields I'd use for filtering.

This morning, I fired up the hand controller. Already, I captured some different stars, with the 12 hour time difference. Like Zubenelgenubi! So, now, 191. From the version 090630 firmware. But then I changed the location to Melbourne, Australia; adjusted the time zone offset. Restarted the mount. And plucked out a few more entries. Finally I tried an alignment (or simulated it). Oh ho. It suggested Suhail, in Vela. Curiously, this was not in the named star list. There's no space for it either. Weird. I wondered if there might be stars beyond 191...

At first, I didn't think I'd get them all. There remains but one star, # 44, between Ancha and Antares, I don't have details of. Angetenar, perhaps? Or Ankaa?!

With the list compiled, I applied some cell and page formatting, kicked in the two filters, and printed the "short list." 22 entries. And, happily, I know most!


name Bayer    constellation general location
Aldebaran alpha Taurus obvious bright star in V, within Hyades
Alphard alpha Hydra bright star, below Cancer and Leo
Alphecca alpha Corona Borealis   between Hercules and Bootes
Alpheratz alpha Andromeda apex of narrow V, top-left of square
Antares alpha Scorpius obvious bright star, neck of scorpion
Arcturus alpha Bootes obvious bright star, above Virgo
Betelgeuse   alpha Orion top-left of Orion rectangle
Capella alpha Auriga obvious bright star, opposite Taurus
Deneb alpha Cygnus tail of swan, toward Cepheus
Denebola beta Leo tail of the lion, toward Virgo
Dubhe alpha Ursa Major outer edge of pot, toward Polaris
Hamal alpha Aries bright star, in middle of arc
Markab alpha Pegasus bottom-right of square, near Circlet
Mirfak alpha Perseus bright, centre of constellation
Mizar zeta Ursa Major second star in from end of handle
Pollux beta Gemini bright star, near Procyon
Procyon alpha Canis Minor obvious bright star, above Sirius
Regulus alpha Leo obvious bright star, bottom of Sickle
Rigel beta Orion bottom-right of Orion rectangle
Schedar alpha Cassiopeia brightest star, bottom-right of W
Sirius alpha Canis Major obvious bright star, neck of dog
Spica alpha Virgo obvious bright star, near Corvus


This handy small paper document, er... card, I'll keep with the mount. Now if I just had a laminator!

As usual, I'm probably over-analysing this. The alignment stars that will be suggested will be bright. The lucida of constellations. So if one knows which constellation the stars belong to, then that makes it easy. Still, I need to improve my comfort (and speed) when aligning. Focusing on this short list will help.

Now, this is a work in progress. I fully expect others to pop up, at different times in the year... For example, I'm surprised Castor or Albireo is not suggested. We'll see.

§

There were some "issues" in all this too. It is not clear, yet, what the Nanjing people meant by Marfik. There's Marfak, Al Mirfak, Mirfak, Marsik, Marfic, Marsic. Which could refer to theta or mu Cassiopeiae, kappa Herculis, or lambda Ophiuchi.

I already learned that the Mirfak entry meant alpha Persei, not the star in Hercules (by checking the RA and Dec values). Phecda and Pherkad threw me for a bit. I probably wrote it down wrong. The former refers to gamma Ursa Majoris (aka Phad) while the latter is gamma Ursa Minoris (near Kochab).

From my notes, Muscida is the nose of Ursa Major, no issue there, but I'm still unclear if the Bayer is omicron or pi. Stellarium shows omicron. I don't think this is a GoToStar issue. In the same vein, I think Propus, in Gemini, is correct in the hand controller but some refer to it as eta, others iota.

I noted that the 8 named stars in the Pleiades are not used, so far as I can tell, for alignment purposes. That's a good thing. Whereas other manufacturers do so! Without a detailed knowledge of the famous open cluster, it'd be easy to choose the wrong star. And that'd be silly.

No comments: