Sunday, January 29, 2012

Clouds = Time to Plan

It's been cloudy, and that means time for making plans.  I now have my cables in order for doing upgrades to my mounts. It took a few tries, but I now have my CG5-ASGT updated. It can now do all-star polar alignments just like my CGEM. I really like this way of doing polar alignments. It's fast, reasonable accurate, and simple to do.

Next up is the CGEM. I'm going to look at its tracking. The last night it was producing "V"s, a back and forth motion in RA coupled with a motion in DEC (which may  be a drift caused by polar misalignment). I've got to make a "before" chart of mount periodic error, then run PHD and PECTOOL to see what they can do to correct this. It will probably take a couple of clear nights, so no imaging in the immediate future.

Tuesday, January 24, 2012

Messier Marathon plans

The Minnesota Astronomical Society's springtime Messier Marathon is scheduled for a night I'm teaching. How could it be any other way? (If that night is cloudy and the next night is clear it will be held then.)

I've tried my hand at the marathon. some years ago--2004, perhaps?--I gave this a try and got 93 by starhopping. That was a long, cold night, but very calm and clear. It was a "fun-once" sort of thing, and I doubt I'll try it again anytime soon.
Instead, my mission for that evening is not racking up Ms, but instead to image them. Imaging with a difference, however. The intent is to create images that replicate how the objects look in modest telescopes (6 or 8 inches in objective diameter). These will really require very few light frames, and since the eye can't really see color, they can be simple luminance exposures, and fairly short ones at that.. During the course of an evening I should be able to image quite a few!

These are intended for the next release of my astronomy software, RSI New Moon.

Wednesday, January 18, 2012

The 10-Year Rule

Simply put, it is: "If you haven't used something even once in the last ten years, you should get rid of it." These are not easy words to live up to, particularly for someone like myself who has pack rat in his blood. But at least today I took a stab at it.

Gone are some Maxxum lenses from my Father's old Minolta SLR That hadn't been used since 1999. Also gone is the body of my Ancient Olympus OM1N SLR. This was probably last used in the mid 90s. I also have some Olympus-compatible lenses that I was going to sell, But I didn't, since they eventually prove useful.

The folks out at National Camera Exchange in Golden Valley were helpful in taking these items off my hands. I know I might have gotten more by selling the items someplace like EBay, but it seemed like too much hassle to do that. A week or so before I had taken the lenses to the MAS swap meet, but they generated no interest

It turns out that Olympus-compatible lenses can be fitted with an adapter enabling them to be used as Canon EOS lenses. No autofocusing or aperture control, but those are not important for astrophotography. So now I've got a bunch of lenses for using with my ST-83000M: 50mm f/1.8 Olympus; 50mm f/1.8 Canon; 17-70mm Sigma for Canon zoom; 135mm f/2.5 Tamron for Olympus; 400mm TeleAstranar f/6.3 (of dubious quality); 2X Vivitar Teleconverter for Olympus.

Before any of those can be mated to the ST-8300M, I need to get this. Hence the coupon clipping mentioned in an earlier blog entry. (The fund now stands at a about $110.) I'm particularly eager to try out the 17-70mm zoom and 135mm fixed focal length lenses.

Tuesday, January 17, 2012

Cold Weather Performance

Tonight I'm shooting O-III frames of the NGC 2244 (the Rosette Nebula) to add to those already taken the other night. Tonight will probably be the coldest night we've had so far this winter, which is not really saying much.  The next couple of nights we will probably go below zero for the first time this winter.  It's hard to believe this is Minnesota! Oh, and there's just a trace of snow on the ground. Really strange.

How well does everything run at 9° F (-13° C, the current temperature on our screened porch)?

  • Gateway Laptop
  • ST-8300M (which I'm running at -30° C just to match existing dark frames
  • Extension cord from house (it's one of those low temperature cords, highly recommended. (Note added: at 5° F the cord began to stiffen a little, but it was still easy to coil for storage.)
  • AT72ED, focuser remains smooth (Note added: at 5° F the focuser became rather resistant to change, as if the lubricant were solidifying or parts were tightening because of differential contraction.)
Less than perfectly, but passable:
  • Me
  • Cables (all are very stiff)

Not very well:
  • SBIG filter wheel.  (reports an error when moving from filter to filter, but gets there okay. I've noticed that temperatures in the teens or lower cause this behavior. Maybe these are built for the weather in Santa Barbara?)
  • CGEM mount. It looks like the mount is moving in fits and starts, elongating the stars in right ascension. I can't yet tell if this is periodic motion that can eventually be eradicated. It might well be something else, perhaps caused by the stiffening of lubricant? I tried to change the balance in RA, but that didn't help. Most of my images from the evening have very elongated stars. Maybe I can compensate by using the Ha image as luminosity and red, the OIII as blue and the SII as green?  Time to experiment!
It's perfectly clear tonight, with just the lightest breeze; by the end of imaging at midnight, the temperature had fallen to 5° F (-15° C). The poor CGEM simply couldn't track correctly in RA with the temperature in the single digits F. I'll have to look into this, as winter evenings around here are typically near that range.

Monday, January 16, 2012

Yet Another Accessory; Prelude to PEC

Like most go-to mounts, my CGEM can have its software upgraded. The CGEM also has the ability to compensate for periodic error in its tracking motion. Both of these require that the mount's hand control be connected to a computer. And there's the catch.

For some reason, Celestron refuses to create a cable that goes from hand control to a USB port on a computer. It continues to use a cable that requires the computer to have a serial port. Almost no laptops manufactured now have serial ports. Serial ports disappeared years ago, not long after parallel ports passed into oblivion. So why does Celestron continue to require them? Apparently so that they can overcharge for their branded serial to USB cable, which runs from $39 to $45, depending on the vendor. It's vaguely like what how many big-box stores charge for $60 HDMI cables that can easily be found elsewhere for $3.

In fairness, Celestron does include the hand control to serial port cable with the mount. So there's no need to purchase that half of the link.

Getting serial to USB is up to you. So far as I know any serial to USB cable will work; there's nothing magical about Celestron's model. So it's off to for a  cable that costs only about $11.

Saturday, January 14, 2012

Clip and Save

I'll admit to being a very frugal person. I have very few hobbies, and the only one on which I've spent an appreciable amount of money is Astronomy. Which you probably could already guess.

Back somewhere around 2003 I went to a local star party hosted by the MNAA. If you know the MNAA, "star party" is probably too formal a phrase for their get-togethers. I took along my Orion XT-10 Dob. One of the MNAA members let me try his Tele-Vue 31mm Type 5 Nagler with an OIII filter. At that point I had neither. If you know your eyepieces, you know that around then the 31 was one of the most expensive eyepieces around, and possibly one of  the heaviest. When I used it to look at the Veil Nebula, I was blown away. He and I decided that the 31 was made for the XT-10. Actually, given that back then they were both around $640, perhaps the XT-10 was made for the 31.

The hook had been set, and I realized the value of the 31.  There was no going back to my relatively inexpensive eyepieces, the best of which was a Panoptic 19. The 19 was a darn good eyepiece, but the 31 was something special. I had to have one.

But—how to pay for it? The Sunday advertisements gave the answer: By clipping grocery coupons. I held to a rule that I would only use coupons for things we normally used, not junk or extravagances. And several years later, I had saved up all the money I needed to buy the 31.  In fact, I kept clipping until I had enough for the OIII filter, too.

But wait, there's more to the story.  The person who hooked me on the 31 had sold his TV-102 a couple of years earlier to someone I knew from the annual star party at the Jeffers Petroglyphs. I had seen the 102 at that star party and greatly admired the views it provided. I became the 102's third owner in 2004. And yes, it works with the 31 as if the two were made for each other.

So why do I bring this up now? I've started clipping again, saving for a Canon EOS lens-to-ST-8300M adapter (about $300!).

Friday, January 13, 2012

One More Reason to Like the Internet

During the Summer of '10 I managed to break my CGEM mount when a Celestron power supply went wacko and fed it a voltage that was too high. While trying to pin down the problem I also hooked my CG5-GT to the bad supply. That mount also died. The little red LED didn't light, the hand control stayed dark.


The CGEM was new and still in warrantee, so Celestron fixed it. It has worked beautifully since returned, and I highly recommend the mount to anyone seeking something that can gracefully carry up to 30 pounds of gear. The CG5 languished, however, since it was not needed. Frankly, I admit I was not in a hurry to get it open and find that it was dead; which would mean that its resale value had probably fallen from $400 to $100. Not to mention that it was relatively useless.

I wanted this mount back in working order either to sell it or to use it at star parties as a platform for wide-field DSLR imaging of constellations.

Today I decided to open up the seemingly deceased patient, hoping that inside lurked a fuse or some component that could be replaced easily. No such luck; I found that the CG5's brains are on two small circuit boards devoid of fuses. Nothing seemed to be out of normal in appearance, so it looked like a case of blown electronics.

A google search ("repair CG5") turned up a 3rd party repair service that had gone out of business last December. There were also threads that reported dead mounts because of loss of contact in the center pin of the power socket. I dutifully widened the split center prong but nothing changed.

Another commonly reported problem was the failure of the on/off switch, which was said to go bad often in CG5s. Cleaning or bypassing the switch was said to sometimes restore function. I took out a jumper cable and easily bypassed the switch, hooked up the power supply, and the mount lived! The handset fired up, ready to do an alignment.

I popped the top off the switch and inspected it.  The contacts were a little dirty; there was the slightest hint of arcing damage by on the business end of the tiny, see-saw like strip of metal in the switch. I scraped it all clean, put it back together and the switch now works.

All thanks go to the Internet, and the people who shared their solution for a specific problem. They saved my mount!

Wednesday, January 11, 2012

Recent Imaging

I've been imaging over the past few days. The horsehead image from the last post did get its green and blue parts taken:

Flame and Horsehead nebulae
The Moon was Gibbous and nearby; some of its light snuck in and caused the blue-green flare at lower right. This has since been solved by extending the dew shield with some craft foam.

I also had a couple of clear nights during which to image the Rosette nebula. I collectd H-alpha the first night, but it was partly cloudy the second night and I didn't get very many OIII frames.  Consider this a preliminary composite image:

Rosette Nebular (NGC 2244)

The Moon was even brighter and closer to the target than for the previous image, but the dew shield extender worked fine. Next chance I get I will collect more OIII data, and for the first time try to get some SII as well.  I'll get a Hubble Palette image yet!

Wednesday, January 4, 2012

AT72ED First Light!

Tonight is the first imaging night for the AT72ED (at least for me with this telescope). My target is the area around the horsehead and flame nebula in Orion. A preliminary look at the images is encouraging. I think I may need to adjust the distance between the flattener and the CCD a little. It was H-alpha tonight of course.

The evening has had waves of altocumulus and altostratus move through, so it was fortunate I didn't set up the autoguider. It would have lost its lock several times. Speaking of lost, I wonder how many light frames will have to be rejected because of the clouds.

If tomorrow or Thursday night is clear I'll try a broadband blue filter (perhaps in combination with an Orion astrophotography filter) to pick up the reflection nebulae in the field of view.

Crazy weather for this time of year; the temperature was in the mid 20s with a very light breeze.

Added note: a couple of images taken using the AT72ED are included in the next blog entry.

Monday, January 2, 2012

Buying a first telescope

I have started or resumed this hobby four times, so in a way I have had four "starter" telescopes.

The first one was when I was a child, about ten years old. It was a Gilbert 2.5" Newtonian--which explains the sig line I use in my astro club's forum. Shoddy mount, shoddy tripod, shoddy finder, shoddy eyepiece, shoddy focuser, etc. In all ways it was inferior, but I loved it; I was a patient little kid, and was willing to fight that telescope for every view I could wrestle from it. For the astronomy-interested child with the right temperment, any telescope is like a piece of heaven on earth. Even the much-maligned department store scopes will serve. But I would advise buying something better.

Teenager: 6" f/8 Edmund Newtonian on a GEM. Darned good scope.

Graduate Student: 8" f/6 Meade Newtonian on a GEM. Also a darned good scope.

Adult (at least chronologically): ST80 Refractor on a GEM. Then a 6" f/12 Mak-Cass followed by a 10" Dob, then a 4" apo, and last a 72mm ED.

Lesson: Don't sweat the decision on the first telescope too much, as you will soon decide it is not completely adequate for your needs. It's good to start with a general purpose scope. Using it you will learn about telescopes, and about yourself: What you like to see, What you're willing to put up with, What you want in terms of bells and whistles. Then when it's time you'll better know what you want in The Next Scope.

My 6 and 8" Newts were close to being perfect general purpose scopes. Both had 48" focal lengths, which made them useful for planetary observing without having to resort to really short focal length eyepieces. They were at what seems like a nice balance point between fast and slow, so faint fuzzies were OK in them. Which one to get depends on the subjective factor of portability. The 6" was much lighter than the 8".

All that said, I agree with the advice of a 6" or 8" Dob. If you're thinking you really like looking at solar system objects go with a GEM that has a drive for right ascension. If instead your heart beats faster thinking of the faint fuzzies, get yourself an erect-image finder. That really helps with star hopping.

Speaking of star hopping, I'm old school. I think that Go-To drives are are appropriate in many situations, but not on a first telescope.

Telescopes are tools you can use to extend your senses to a cosmic scale. When you learn how to use your telescope and get to know how it reacts--what it can do and how you can get the most out of it and yourself--you become a craftsperson versed in its use. That's when the connection between you and the cosmos becomes direct in a special way. This will sound a little metaphysical, but I think that's when the telescope becomes a part of you and no longer is an artificial interface between you and the sky. The joy of that sensation is one of the reasons I love astronomy.

Sunday, January 1, 2012

Planning for the new year

It's a new year, and that puts me in the mind to start thinking about star parties to attend. There aren't many firm dates for these yet, so right now I have to guess a little on when they'll be. Let's look at the dates we know and use the new moons for guidance:




July 15-20: Nebraska Star Party.

July 19-22: Wisconsin Observer's Weekend (WOW). This looks promising, and is much close than the Nebraska Star Party

The August new moon is around the date of the weekend that items are submitted to the Minnesota State Fair.

South Dakota Star Party/Northwoods Starfest. Dates unknown.

North Dakota Badlands Star Party, in Teddy Roosevelt National Park North Unit. Dates unknown.


Iowa Star Party. This is usually around labor day, but this year the Moon is full on August 31. Probably they will have to push it to September 6 through 9. Augsburg College (where I teach) doesn't have the schedule out for Fall of 2012 yet, so it's about a 50% chance I can make it.

Jeffers Petroglyphs star party (once promoted as the Prairie Grass Stargaze). This is probably going to be in around the time of new moon in September, the 13th to 16th. I will be able to attend only Friday and Saturday nights at most, possibly only Saturday night. Bummer.


October 10-14: Heart of America Star Party, October 10-14. Day Classes make it impossible to attend.

So the year does not look very good at all. I'll probably go to the WOW, and make trips to Onan and Cherry Grove.