New Coronado Solar Telescope - First Light

[Ad Astra]

Hi Folks,

Our spring weather has been nothing special (lots of high clouds and haze), but we got some good clear sun today and we were able to break out the new dedicated 40mm solar telescope from Coronado (now associated with Meade Instruments, I believe.) No, it isn't mine (worse luck!), this one belongs to the school astronomy program where I teach. Still, it's quite wonderful to get to play with new toys now and again! You might not think that a 40mm scope was much good - until you tried this one. I must admit I was very impressed!

The scope itself is very nice, heavy weight brass construction with a black anodized clam-shell mount that fits 1/4-20 standard threads that you find on most tripods. It needs a dovetail adapter so I can put it on a proper equatorial mount, but I'll have to see to that later. It comes in a wooden box finished with black leatherette vinyl - foam liner fits pretty well - scope could easily go on an airline and fit in the overhead bin. It comes with a 25mm lens that is done in brass tone to match the scope, but the view of the solar disk is very small and a bit unsatisfactory without a 2x Barlow lens. We opted for a 12.5 mm plossl that worked very well for us. I tried that with a Barlow, but it really needs an EQ mount to track successfully at that point, so I backed up to the 12.5 for student observation.

Setting up was a breeze. Pop it out of the box and attach a standard tripod shoe (we use a heavy-duty tripod from Orion USA). The scope snaps onto the tripod and is ready to go in seconds. Aiming is a snap thanks to the ingenious solar finder. It projects a bright ball of light on a frosted glass screen - lining up takes just seconds, and keeping it that way as 75 students cycled through over a couple of hours was never a problem.

The view through the EP was stunning, but very sensitive to individual focus. Students routinely started with "I don't see anything but a red ball!" But as they mastered the helical focus, these soon turned to cries of "Wow!" and "I see LOOPS! Amazing!" We were easily able to use the tunable filter to bring out details from the disk interior or the limb where flares reached out in spikes, loops and whorls. The interesting thing was that we were able to see significant changes in these prominences over a period of just minutes. It was really brilliant!

The lab activity had the students looking through the Coronado scope, then through one of the venerable 6" dobs with a traditional visible light solar filter. The 6" showed one major spot with a well developed umbra and penumbra region, and 3-4 other tiny ones. The Coronado, by contrast, showed surface detail (super granulation?) and the sunspot, but the view off the limb of the prominences capped everything. After sketching what we saw, we tried to do a bit of mathematical analysis by using ratio and proportion to compare the size of the solar disk to the size of the prominence on the sketch. We got values of between 30-120,000 km, reasonably within the ball park for these monsters. I was very pleased.

One thing, if you use one of these, you will certainly need some sort of eye shade such as a wide brim hat or a towel to shield your eyes from sun glare while you look through the EP. I think a sort of towel rack made of PVC pipe might be in the offing... time to put on the DIY hat in the garage this weekend!

These solar scopes are pretty expensive, the 40mm I have is selling for about $1600 USD, although I've seen that you can get a new 60mm for only about $1200 at telescopes.com (don't ask me why, I don't get it either.)

Either way, I enjoyed this lots more than I thought I would, and the kids sure were impressed with it. I'm going to try it out with the camera over the spring holiday break next week, maybe I'll post some photos of the gadget itself, too.

Dan

[hobbesy]

I had first light with my second hand Solarmax II 40mm last weekend.

It's rally very good indeed, isn't it? And the little finder on it is just brilliant.

[Merlin66]

Glad you enjoyed the first "taster" of solar Ha...

We need as many solar observers as we can get.

The solar surface (and proms) changes by the minute..always something new and exciting to see - certainly NEVER boring.