Tuesday, October 28, 2008

A new pier

I spent yesterday making sawdust and a new portable pier for the ETX. It's a bit wobbly but it works fine and I was able to try it out tonight. I saw Eps Lyr easily and Albireo was a pretty gold and blue pair, the blue partner noticeably dimmer. My new alignment scheme is working good. I set the Alt to 63.5 and scan for Polaris, then set Alt to 37.5 and do an easy alignment. I could probably just sync on Polaris and be pretty close. I've been using Vega but it's about to disappear over the top of the house. My view of the sky is pretty limited in my little dark 'observatory' behind the house. The andromeda galaxy was nice tonight. I was able to see about 12 other stars in the field with Eps Lyra centered. That means I was seeing down to about 7.5 mag at 7:38. By 9:30 it was much better. I was able to find the double cluster (NGC869 and 884) both manually and from a list of clusters in the autostar. It's not bad and I was able to make a rough sketch of the field stars that matched CdC with the horz axis swapped. The BIG DEAL tonight though was my experience with the dreaded 'cord wrap'. I was flipping back and forth between Cygnus and Cassiopeia and wondering why the ETX was getting lost. I'd center Deneb and goto Shedir and no bright star was in the field. I finally noticed that the cord was almost wrapped around the base of the ETX when pointing to Cas and the motors would pretty well shut down at that point. Clearing the cord put everything back in order again.

Thursday, October 23, 2008

Ekland's J and a new alignment technique

I headed out about 8:00 tonight to try the ETX in my backyard observatory. There seems to be a new ultra bright streetlight on that side that I didn't notice last spring so it's kind of bright back there now but I was still able to see all 5 stars of the Cassiopeia "W" with averted vision and was able to make out Polaris so that's not all bad. I decided to try finding Polaris with the ETX in an attempt to get a better north orientation. I set the OTA to my latitude angle (26 degrees) and then just slewed the scope in azimuth until I saw a relatively bright star. Then I leveled the tube with my level and started a two star alignment. It headed to Vega as before and like last night I had to go hunting for it. I used the spiral search this time and found Vega but it took awhile. Turns out my 'north star' wasn't really polaris at all. It then took off to Altair and even that wasn't in the FOV. I found Altair and synced Autostar and then told it to find Polaris. Bingo, right on the money but it was quite a bit east of where I thought it was. I had the altitude right and noted that it was 63.5 degrees on my declination scale. That makes sense because after all, it IS a dec scale! My 26 plus 63.5 makes 89.5 and that's awfully close to 90.
Next I went after M29 and Ekland's J mentioned in the Nov issue of S&T. Ekland's J looks like a J alright. I counted 11 'stars' but it turns out one was CR419 and another was NGC6910.
Next I tried M52 and NGC7289 in Cassiopeia. There was a faint fuzzy but nothing in particular. I found Eta Cas but wasn't quite able to split it. Perhaps with a higher power EP.
M15 and M2 were both visible but faint globulars. M2 was just like CdC shows it and from the star field I saw, it looks like my 26mm plossl ep gives about a 4 degree FOV. M15 looked about the same.
All in all it was a pretty good night until the smoke from someone's (Reynosa?) burning garbage made it too smokey outside. The shopmate still makes a pretty good stand although some angles work better than others. The $1.50 Walmart desklamp with a 4w reddish bulb makes a pretty good red light but needs to be redder. It makes a good reading light and beats a flashlight hands down.

Wednesday, October 22, 2008

Dumbell and a coathanger

It was a perfectly clear night in south Texas and I finally decided to put the ETX-70 through its paces. I spent yesterday wandering through the Autostar's menu tree and 'training the drives'. Tonight I set up the ETX on my trusty shopmate, aimed it at the fourth palm tree up the street (north), leveled it with my little 10" level, and did a two star alignment. First off was Vega, high in the sky. It skewed to the right spot but no Vega so I hunted around for a bright star and found it. Then I hit enter and off to number 2: Altair in Aquilla. Bingo, not dead center but at least in the FOV. I synced on Altair and then went hunting. First off was Jupiter since Venus had since slipped out of sight behind a palm tree. It was also out of the FOV but wasn't far off. For some reason or other, I could barely make out one of the moons tonight. I decided later that the farther the ETX has to slew, the greater likelyhood that the object will be out of the field. A compass and better leveling is probably in order but this first setup was certainly easy enough and quite acceptable. It was FAR easier to find things in my light poluted sky than with my 8" dob. At least the ETX gets me into the general vicinity. I forgot the magic button to push to activate the spiral search so will save that for another day. After slewing to several visible stars, I decided to push things and go for Messier objects. M56 and M71 proved to be too dim to find but M27, the dumbell, was quite visible as a fuzzy patch. I sketched a field of stars including some mag 8 ones that matched CdC nicely. Next I noticed that the coathanger was about halfway between Alpha Vul and Alpha Sagita so I slewed to Alpha Vul first, then watched as the ETX slewed to Alpha Sag and watched the coathanger slide by. Then I just manually navigated over to take a closer look. The sidereal tracking isn't perfect but I was able to observe long enough to sketch without having to constantly nudge the scope back into position. It even held position long enough to come inside to check CdC periodically. Very nice.
I'm not sure how people do astrophotography with this thing though. When viewing near zenith, the camera port is so close to the mount that one would need to use a very tiny camera. It should be ok for taking pictures along the ecliptic though.
Bottom line is that it'll take a few more sessions to get more familiar with this new toy but it'll be fun to tinker with. The ETX-70 certainly has its limitations but the portability and ease of use make up for most of them.

Monday, October 20, 2008

Oh happy days!

At long last, after a month of recovering from a damp disaster in Texas, we're back in our house, the furniture has arrived, new TV is setup, and my new to me ETX-70 arrived! First light was Jupiter and at least four of his moons. We were a bit late getting back from the store to get a new LCD HDTV (woo woo) and Venus had already slipped behind the neighbor's house into the haze. Jupiter was nice though, and the view through the Meade Super Plossel eyepiece that came with the ETX was clear and sharp with good contrast although it seemed a bit fuzzy at the far edges. There were a number of pinpoint stars in the field with Jupiter so that was a good sign. I haven't had it long enough to become familiar with the goto feature so I just unlocked the OTA and manually lined it up with Jupiter. It wasn't all that difficult to find even without the aid of a finder. The addition of a red dot finder will be a high priority I'm sure. Overall, the experience was similar to an earlier one I had a few years ago with an ETX-90 at a local star party here in the RGV. A teacher had brought one from her school but wasn't sure how to use it so we just unlocked it, found the moon, and admired the craters. This little guy should be lots of fun even with our local light polution. But in the meantime I'm going to watch a little tube on my other new toy.