Happy New Year!

It's been a long time since the last post, mostly because I haven't had much to write about: Let's get right to the excuses:

• It was a terrible year for weather; it seemed as if every imaging opportunity was clouded out
• My transition to computerized imaging that started the winter of 2017-2018 kind of slowed me down
• There was the mini-fiasco of the very late arriving Planewave 12.5" scope for the imaging platform. It didn't arrive until after the Nebraska Star Party and didn't get onto the mount until late August. Basically the delay pushed the timeline back about 6 months
• Unlike a lot of years, this year winter arrived early (November 1) and stayed. There was no pleasant, gradually cooling autumn to image through

So, now that that's out of the way, we can get on to catching up. After such a dismal year what could a person do other than double down on what seems at times to be a frustrating hobby? That's right: I am upgrading things.

A) MOUNT

The old CGEM mount is out, replaced by a Losmandy G11G. In the pantheon of mounts, the CGEM is somewhere around "tier three." The best "lightweight" mounts are made by Astro-Physics (Mach 1GTO) and Software Bisque (MyT).  Both of these price in around six to eight thousand dollars when you add the usual bells and whistles. The G11G doesn't quite deliver the superb performance of these two "tier one" mounts, so I'll call it "tier 2," and it's about $4500 fully loaded. I went for the Gemini II version (that's the second 'G' in G-11G) even though it's not necessary for imaging--it's just nice to have in case I decide to return to visual astronomy.

The G-11G is a major upgrade from the CGEM. Let us count some of the ways:

1. It's solid. Push on the GGEM head and it wiggles a little, whereas the G11G doesn't budge. There is simply no play in it
2. I expect it will track far better than the CGEM. My CGEM had substantial periodic error that I could never really get rid of. The G11G will probably be an order of magnitude better
3. It can connect to my laptop by way of an Ethernet cable, not a funky USB-to-RS 232-to-hand control cable.
4. It's lighter than the CGEM. The head weighs over 10 pounds less and disassembles into two pieces to become even more portable. On the minus side, the field tripod is large and heavy compared to the CGEM's tripod.
5. Its carrying capacity is far greater than the CGEM's. There's no telescope I own or am ever likely to own that will push the G11G to anywhere near its capacity
6. There are more differences, but until I can actually begin using it (2018 crumby weather, see above) I'll not comment on them

B) FILTERS

I'm not going to say that my Baader filters are inadequate, but it's become clear that they do have internal reflection issues. And in the case of the narrowband filters their 7nm bandwidth is not as good at rejecting sky brightness as narrower filters.  So out they go to be replaced by Astrodons. I plan to purchase new LRGB filters. The H-alpha filter is a needed upgrade; but over the years I've hardly used my S-II narrowband filter, so that won't be replaced. I may not even replace the O-III filter. The size filters to get will depend on part (C)...

C) CAMERA

As I write this, my thought is to continue using my SBIG ST-8300. It will be interesting to see if it still functions after a few years of rest! If I stay with it the above filters would all be the 36mm round unmounted type.

This is kind of wide open-I have the option of upgrading my ST-8300 to an STF-8300 or maybe jumping to CMOS. Cooled CMOS monochrome is an intriguing technology, but I kind of feel it isn't quite mature enough yet. If I go that way or get a different CCD it's possible I'll be able to use 31mm filters and save a little money. I have some research to do!

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I made a rare appearance at last night's monthly club meeting. I was there for two reasons-to take part in the pre-meeting meeting of the Cherry Grove Observatory committee, and to pick up some swag.  I did most of the graphics designs for the ALCON 2018 national meeting and had asked for payment in the form of some items my designs appeared on. One of the club officers was kind enough to bring some to the meeting for me.

I mention this because the planned guest speaker was unable to appear at the meeting and was replaced by a video presentation about climate and climate change. I admit at first I was skeptical of what the presenter's agenda was, but it turned out to be excellent.

The speaker, Dan Britt, is a physical geologist who has studied climate change on geological time scales. While he's rather circumspect about stating his conclusions, he clearly lays out the geological evidence that illustrates how anthropogenic carbon dioxide forcing is the driving force (by far) in contemporary climate change; surface temperature is increasing and the seas are rising in his view.

This is a presentation for a non-technical audience, so don't expect to be challenged by esoteric details of the science involved. But what he says is in perfect accord with my understanding of the science.

Highly recommended: https://www.youtube.com/watch?v=xgNxF2HlN3w

An Imaging Platform is Born

In the spring of 2017 an anonymous donor (hereafter called 'AD') came forward with an offer to fund what was needed to make the Minnesota Astronomical Society's dark sky site at Cherry Grove a high-end imaging site. Basically the AD was volunteering to fund the purchasing of a new imaging platform. The money would come with a few strings:

• The platform would make use of an existing underutilized mount in the observatory. This mount was a Mathis MI-500, a huge mount capable of carrying 180 pounds of imaging gear. The mount is already outfitted with an Astro-Physics GTOCP4 control box and handset.
• The platform must be easy for beginning imagers to use.
• Purchased telescopes must to be able to fit under the roof. The purchase of large refractors like those installed at the club's other two sites was discouraged along with truss-tube scopes.
• A person or people need to be found who will maintain the platform
• Adequate training must be provided for those wishing to use the platform

Existing Facility

Cherry Grove Observatory (CGO) is a large roll-off roof building located in Goodhue county, Minnesota, about 23 miles northwest of Rochester and 20 miles south of Cannon Falls. While it's not a truly dark site (light green zone), it's far darker than the other club observatories. Horizon glow from the metro area of Minneapolis/St. Paul 60 miles to the north can be seen, as is a growing glow of light in the southeast from Rochester.

Cherry Grove. Warming house at left, observatory on right

The Process

The task of choosing gear for the Imaging Platform was passed to the small committee that oversees CGO. None of the committee members are imagers, and they thought it best to form a task force of imagers to make recommendations for what to purchase. That's when I entered the story.

Recruiting task force members went reasonably well for something like this. Some people agreed to help, others said they weren't really qualified or had other obligations. Five volunteers were quickly selected and I was designated the chairperson, probably because I had advanced some ideas for what might be done in an earlier request for help from the CGO committee.

The early going was hindered by a lack of any idea for what the AD was willing to spend. We quickly settled on a two-tier recommendation for what might be possible at around $10K and $20K.

Guiding Thoughts

Beginners will be using it, many with DSLRs but a few with CCDs or newer cooled CMOS cameras. Astrographs for which no flatteners are needed are simple and convenient. Beginners wouldn't have to be concerned about having the correct spacing rings.

What will people want to image? Probably the objects that image well from dark sites: Diffuse and dark nebulae, but not solar system objects. That suggests a telescope with short focal length and fast optics.


Many objects are small. After diffuse nebulae likely targets will be planetary nebulae, globular clusters, and external galaxies. The way to image them is with a longer focal length scope. Since these tend to have higher surface brightness than many diffuse nebulae optical speed is less of an issue.

Beginners will bring a wide variety of learning skills. Some will be happy to learn how to use software to control the mount and camera while others may be reluctant to use more than the mount's hand control. We should try to accommodate as many people as is reasonable.

Given all of these factors we decided to go with a platform that would provide two imaging astrographs in tandem-one short focal length, the other much longer for those tiny planetaries and galaxies.

As we looked over the available scopes it became clear we the low cost option of about $10K was unrealistic. In fact given the cost of all the accessories, shipping and taxes the higher tier of $20K would be inadequate, too! After a talk with the AD it was decided to go with a budget of between $30K and $35K.

At that point we were ready with our recommendation: A Takahashi FSQ-130ED as the short, fast scope and a Planewave 12.5" CDK. Along with the Tak we decided to get the 0.6X focal reducer and 1.6X tele-extender to provide three focal lengths: 390mm, 650mm, and 1040mm.

Current Status

The club's Board signed off on the purchase and we placed our order with Oceanside Telescopes.

The Tak has arrived and is on the mount for testing. So far it's living up to the Tak reputation: Exceptional optics and build quality. It's a great scope!

Takahashi FSQ-130ED on the Mathis mount (to be remounted when the Planewave arrives)

The Planewave is scheduled to arrive in July.

We hope to have the platform fully functional by autumn -- if this year's run of cloudy nights will ever relent!  I'll post images taken using the platform as they are created.