New Scope Arrives

The new scope has arrived. The seller did a nice job packing it, and it's in beautiful condition. The only way to tell that it's used is a few clamp marks on the dovetail.

First impressions of the focuser suggest it's a great improvement over the GSO I've been using on my ST80. Tonight or tomorrow I'm going to reconfigure my imaging set up to have the AT72ED and ST80 side-by-side to see how it all balances out.

Of course, the forecast for the week ahead is clouds, clouds, and even more clouds. So don't expect a star test report, much less an image made using it anytime soon.

The Waiting Game: Dollar Days

No, I don't mean "Dollar Days" as in when a store offers a sale where most items are priced in whole numbers of dollars. It's a measure of anticipation and patience required when you've purchased something that must be delivered at a later date. I thought of this in 1978 when I ordered my first real telescope, an 8" f/6 Meade Newtonian on a GEM. It worked like this: The total cost was about $600, and the wait between placing the order and receiving it was two months (60 days). Multiply the two together, 60x600, and you get 36,000 $days. The larger the amount of dollar days, the greater the "anguish" of waiting you must endure.

I recalled this as I was checking the UPS tracking number on my incoming AT72ED. It has a price tag of $316 (including shipping, insurance, and a nudge for PayPal) and the wait is 5 days. That's a paltry 1,580 $days. Hardly even a mild test compared that old Meade.

Oh, and the telescope is black. I would have settled for any color. At night all telescopes are the same color, and all home-made telescopes look like they were made by a master craftsman.

Although I might have haggled a bit over the price if it had been the pink model from Astro-Tech. Pink would be a conversation started at star parties, which is fine. But I have a feeling that the pink models don't sell quite as well. I base this on the fact that some retailers call them purple.



A pink AT72ED

This doesn't look very purple to me, but pictures can be deceptive.  Have you see one of these in real life, and how does it look to you?

The decline(?) of Sky and Telescope printed magazine

I was trying to round up my S&Ts from the many places in my home into which they diffuse, and I was struck by how much their thickness varied over the years. With so many magazines failing or on the ropes, it set me thinking. The only thing to do was to enter the number of pages in each issue into a spreadsheet, right? And once having that done, It was logical to graph the time series. Cue Rod Serling--"Submitted for your consideration:"



Sky and Telescope Pages per issue, Feb 1997-  Jan 2011

This shows pages on the vertical axis and time on the horizontal. The dots and black line are for S&T, the green line is the Standard and Poor's 500 index scaled for comparison.

Some observations:

• The general annual pattern is lots of pages in the December and January issues for obvious reason; a minimum in the spring and an uptick for July/August (graduations, Father's Day, it's warm out), another drop in September/October/November
• S&T tracks along with the S&P very well through 2004.
• After 2004 S&T declines rapidly in comparison to the S&P.
• S&T does not recover along with the S&P in 2005-07 nor 2009-11
• S&T dips to 82 pages for one issue in the spring of 2009, then holds constant at 86 pages through January 2012
• The Dec/Jan surge is missing for the holiday seasons of 2009-10,2010-11, 2011-2012

It of looks like S&T is hovering at a size of 86 pages despite a multi-year trend that suggests it should be much smaller at this time. That there were no Holiday surges in the last three years suggests that astro vendors have shifted their advertising bucks elsewhere.

Is the printed version of S&T a lingering relic? Will becoming an e-zine save it? I usually resubscribe in three-year increments, but I think from now on it will be only a year at a time.

Update (January, 2013): The 86-page flatline begun in April 2009 continued another year through the February 2013 issue except for the June issue, in which the page count was only 82. This was matched the record low of May 2009. As you can see from the chart, the spring into summer season has generally had slimmer issues.

The S&P index now stands about 15% above its value during January 2011, so S&T continues to lag in comparison. 

Yet Another Telescope

Telescope #5 joins the fleet.

For a while I've been looking for a better way to do wide-field astrophotography. I started by trying to use my ST-80 in this role. Its focuser (a replacement GSO model) just wasn't up to carrying the weight of my SBIG ST-8300M, and its optical quality was not very good. As I've mentioned in past posts, I looked at getting an adapter that would let me mount Canon lenses on the SBIG. That seemed a little too single-purpose, given the cost ($280).

Last night (Christmas Eve) someone put an AT72ED up for sale on Cloudy Nights, and I jumped on it. At $285 + shipping I hope it will be the most flexible solution.  It's a bit faster than my TV102 (f/6 vs. f/7)and much shorter in FL (432 vs. 700 mm). Its field of view is a spacious by 2.4 by 1.8 degrees. Questions remain: How robust is the focuser? How well will the Orion field flattener work with it? Commenters have noted that its focuser is much better than the standard 2" focuser by GSO. I've never read about someone pairing the Orion FF with this scope (most people use the AT or WO FF) so I'll have to find out for myself.

The seller is someone who just upgraded to an AT111 and apparently decided he could do without the 72. As for me, this will probably take the place of my ST80 as my travel scope. The ST80 now can retire to its role as Autoguider, for which it is well suited.

Serendipity and a cranky cable

Tonight I thought I'd go back to the Horsehead and redo the H alpha exposures. But when I asked the GoTo to take me there, it instead put me right on the Flame Nebula. I decided to go with the what the mount apparently preferred.

I'm current imaging with my MK-67, an f/12 Mak-Cass. Its focal length is 1800 mm. The ST-8300M's pixel size of 5.4 microns  is about 1/3 the size it should be (about 16 microns for the average poor seeing I get here). I'm therefore binning 3x3 on the camera, which give me about 1.65 arcseconds per pixel. Looking at some of the subs, this seems to work very well.

As I write this I've got 22 subs in for the Flame. Tomorrow night I'll go back (unless the mount has other plans) and shoot some other bands if it holds clear.The odd lines I mentioned last time are gone. I asked on the MAS forum about the noise I was getting the other night. It looks like the best suggestions were about bad or loose cables. Something was acting up tonight when PHD went crazy. The oddest thing was that each exposure caused the PHD window to jump back and forth by about the window frame's width (8 pixels or so). It also couldn't calibrate correctly. Multiple restarts didn't fix this, nor did unplugging the USB cable at the laptop.  However unplugging and reseating the cable at the autoguider did the trick. I begin to suspect that the autoguider's socket is the problem.

The Horsehead image came out okay, but needed more exposures. I think the flame will look much better. I aim to get 30x5min exposures for it.I'll post the Ha images in the next couple of days.

A blurry cross and noise

Last night I tried to image an Einstein Cross and the Horsehead nebula. The lensing galaxy was imaged, but 20 or so 2-minute exposures were not adequate.  I'm also fairly certain that a 6" telescope is not adequate for resolving this feature.

The horsehead was interesting. It took a lot of time to compose the image. The focuser and extension tube didn't have a good grip on the CCD, so focus drifted a little. Polar alignment was good, as 5" exposures had round stars. There was what I think is some sort of electrical interference coming from (pick one or more) the mount, laptop, or power strip. This resulted in some random noise and narrow horizontal bands. I'll see if I can pin down the source when I shoot dark frames tonight. Tomorrow night is supposed to be clear again, so I'll retry at least the horsehead. I need a target for earlier in the evening, as the HH doesn't clear the trees until several hours after darkness begins.

Next Telescope?

I enjoy wide field imaging, and it's easier for someone like me who is learning astrophotography. Tracking errors are less evident, and the hardware to image is smaller and less heavy.  The mount has an easier time carrying the load, and the smaller profile means wind presents less of a problem.

What should it be? I had my sights set on an AT65EDQ, a triplet with built-in field flattener:

Astro-Tech AT65EDQ

Typical Moonlight Focuser

But it seems to be no longer for sale, and if it comes back it will probably have a long period on back order.  The AT65's focuser is probably not capable of carrying my ST-8300M and filter wheel. So it almost demands a focuser upgrade, and that is expensive: Something like $400: Above is a high-quality Moonlight focuser that would be perfect.

When all is said and done, it's nearly $1,000.

Another option is to use the two Canon lenses I use with my XTi. This requires an SBIG adapter that costs $280:

SBIG EOS adapter for ST-8300 w/filter wheel

This covers the focal length range from 17 to 70 mm, which is shorter than I want. If one of these were to pop up for sale used, I'd probably go for it for full constellation imaging. Moog adapters used to be available for this purpose, but their business has been scaled back and because of the filter wheel, this would require custom work on their part.

I already have a field flattener for my ST-80, so any short-focus telescope is basically ready for imaging. What I want is something with a better than average 2" dual-speed focuser and focal length less than 430 mm. The model I've read about that seems to have the best focuser is the AT72ED; new this is $380 and used usually round $250-$300. Another scope is the Stellarvue SV70ED, which also gets very good reviews.

Astro-Tech AT72ED

Stellarvue SV70ED

I've put in a "wanted" post on my club's web site, and I'm watching Cloudy Nights and Astromart for used scopes and SBIG-Canon lens adapters.  I wonder how long it will take for something to show up.