Imaging Saturn

In planning to capture some images around the time of opposition, Alden and Ron met me at the Science Centre on Monday [April 9th]. Alden brought the C8, and Ron brought the keys!

Alden and Ron, happy in the dome! Great mentors!

As it turns out, the seeing has been pretty lousy lately, and the forecast for this weekend is pretty terrible; there is little chance the skies will clear on the eve of opposition, tomorrow: April 15th. [Well, today: it snowed today, and it’s totally overcast].

My plan for Monday was to set up the C8 on the rooftop and try to learn to collimate [align the lens elements of] this Schmidt-Cassegrain, and to test my D7000 and Solar System Imager IV on both it and the LX200 housed within the Kallium Observtory dome. Ron and I arrived first, though he suggested I go get warmer boots since the forecast was for cold. When I returned Ron and Alden had already hauled the C8 up those stairs, and I was well outfitted: Sorel’s, toque, snow pants [which I didn’t need in the end]; both cameras, two telescopes, mounting accessories, a bunch of lenses, and junk food.

We set up the C8, opened the dome, synched the LX200 to Venus and set it to track, and we spent some time trying to focus the C8 on something; anything. Shane had agreed to assist me with collimation [thank you for the coffee, Shane]. I understand the concept, but didn’t want to break the darned thing. We had 3 sets of allan keys and I was surprised by how tiny the screw size is. We worked out a system: I centered the chosen star, described the position of the shadow of the secondary mirror [up/down/left/right]. I removed my eye from the eyepiece, Shane used a flashlight to insert the allan key and made an adjustment, removed the key and got his hand out of the way; I re-centred the star and described the new position of the shadow, and so on and so forth. We came very close, at one point, to a near-perfect centering of the shadow, and probably should have left it at that. The allan key was attached to a set, which was too heavy to leave inside the screw after each adjustment: so, get single screws, or use Bob’s knobs.

After more than an hour, maybe, of fooling around, Chris and Mike showed up to say hullo. Shane and I had already noticed some evidence of moisture damage on the inside of the lens [reminding me of all those moldy lenses I saw during the time I worked at Henry’s camera store]. By then, there’d been plenty of time for the C8 to come to ambient temperature, yet we still couldn’t resolve a decent focus, even accounting for viewing conditions [I think]. I think at some point Chris wondered what the Craigslist for-sale subject header might be!

The Regina Centre Celestron 8″ set up in general relation to Polaris, on the rooftop of the Science Centre, just outside the dome.

By then, it was just Chris, Mike, and I, and I managed to disassemble and re-pack the C8 on my own [well, Mike had some fun with that monster tripod all on his own], and turned our attention to the LX200. It was close to 10:30pm, so Saturn was a bit higher in the sky [about 20˚ above the horizon]. Earlier, Ron, Alden and I had some trouble resolving an image even after the dome had been open for over an hour; closing the door to the main hallway fixed that, since it was sending warm breeze to swirl around the room. At this point, the main challenge was achieving focus given the drawbacks of the location of the telescope.

Firstly, it’s mounted to the floor/building in a way that does not reduce shake [according to Ron and Chris and everyone], and perhaps amplifies it. Secondly, Regina is windy, and the building shakes in the wind. Thirdly, every vehicle that drives by sends waves through the earth and the building. Fourthly, any human movement in the dome, including breathing and speaking, cause shake. So I connected the CCD and Shane, Mike and I looked at my macbookpro screen for a while. Eventually I hinted for solitude and they cheerfully took off.

Saturn blows my mind. Using the eyepiece and my eye with a couple of lenses [they HYP zoom and a 24mm I think – I need to take better notes], I was able to clearly focus on the planet and it was stunning. I could see a bunch of moons [SkySafari says: Titan, Hyperion, Rhea, Mimas, Dion, Tethys, Enceladus, Iapetus, not sure if I saw all of these, but this cluster seems to be as much as I recall]. I wished I had more stamina to just stand there and peer, or better gear to use my monitor to see with such clarity. Saturn is stunning.

I did a bunch of CCD tests experimenting with the gain controls, and with the frame rate when I finally figured out how to control it. Click HERE to go to the images below.

I then attached the D7000 to the star diagonal with Peter’s HYP24mm, and prime [having removed the star diagonal], and also did some hand-held projections. Click HERE to go to the images below.

So, by now, I’ve collected images on two night during 2012 and I’m uncertain if I’ll have time to capture more here in Regina before I need to head to Toronto for the summer to finish up the phd. Maybe the night before my departure, on Astronomy Day. I hope in September I’ll make it to Grasslands with Chris and Mike, and maybe in Toronto I’ll connect with Rob and Dan, with the local clubs, the fella from Efston at the Petrie observatory, and whatever else I can muster.

CCD Images

Well, I filled in this entire section, hit the publish button, and got timed out and lost everything. I should know by now to select and copy all before making such moves. Here I go again.

I shot 20 short video clips with the SSIIV, experimenting with gain and exposure, and then found the frame rate controls; I selected two clips for testing and including in this blog post.

1. Gain 50, Exposure 70, 12.5 frames per second:

50/70, 12.5fps – screen grab of video file [Quicktime

deconvulution radius 2.00, threshhold 0.61.
Black 20, white 90, gamma 1.18
unsharp mask radius 2.0, gain 0

Double Size; deconvulution radius 3.00, threshhold 0.82.
Black 20, white 90, gamma 1.18
unsharp mask radius 2.5, gain 0

Double Size; deconvulution radius 3.30, threshhold 0.88.
Black 20, white 92.8, gamma 1.18
unsharp mask radius 2.5, gain 0

2. Gain 50, Exposure 24, 60fps:

Quicktime screen grab, 50/70, 60fps

gamma .68. Black 4.9, white 80. Deconvolution 2.50 / .50

This image seemed to reveal some atmospheric detail/banding so I pushed the settings further:

gamma .36

Cool, huh? Though a bit too stylized, I think.

D7000 Images

I tend to shoot at the highest resolution possible while trying to keep the ISO as low as I can. I also shoot raw NEF files along with low res jpeg files. Looking at the jpegs files, the images collected below looked like complete failures for the rejection pile. But, opening the raw files and doing some manipulations pulled out some detail. Top left ISO 400, top middle and right ISO 250; the rest were ISO 1600. I did some general uncontrolled testing of manipulation through the photoshop raw editor: changing exposure through +1 to +4; reducing blacks to 1 or 2; adjusting brightness/contrast, clarity/vibrance; playing with sharpening and noise reduction [luminance can soften the edges]. These are selections from images that have 4928×3264 pixels. The largest area is actually the bottom right, from a hand-held shot: 261×331 pixels. The smallest is from the middle, 104×138 pixels, I think this one is also from hand-held. I have a lot to learn about how to control these settings for various results, and a great range of manipulation is possible. This gives me a preliminary idea that what might otherwise not appear salvageable has potential.

collection of near-rejects from D7000, combination of prime, with hyperion 24mm projection, and hand-held projection.

The two shots below are from what I’m calling the ‘best’ D7000 shots, but I’m not convinced I know what’s best just yet:

prime focus, selection 320×196 pixels with no interpolation

prime focus, same as above, cropped/interpolated to 600 pixels

The three images below are from a single file:

800×530 pixels, full frame of exposure, hand-held projection

320×196 pixels: selection from full frame, no interpolation

800×507 pixels, interpolated selection

Well, it finally cleared up enough last night for Alden and I to get together. Alden is a club member and manages the equipment, and offered to provide orientation for the  Celestron 8 telescope which I can also borrow this month.

I arrived and he had it set up in a spare bedroom. The tripod is a beast without telescoping legs, but workable. He managed to find a wedge, which turns the alt-azimuth mount into an equatorial mount. Basically, this means that once aligned to Polaris, the clock drive on the wedge will track with okay proficiency. I had read about polar alignment with an alt-azimuth mount, but with a wedge one just centers Polaris and starts the clock drive.

Alden also used a larger star diagonal and ocular mount, I don’t remember why…

After coffee we removed the scope and wedge and collapsed the tripod and moved to the driveway with Alden’s portable power generator [for the clock drive]. We began with a look at Venus, and it was apparent that a variety of factors made for poor resolution. The scope was not ambient temperature, and as time passed it developed visible condensation inside the primary lens. The atmosphere made for poor seeing, and there was a wind. The slightest touch of the scope assembly creates big bouncing. So Venus was fuzzy, but not so fuzzy that the phase was invisible: close to half, I think!

Jupiter was fuzzy also, but it was possible to see two nearby moons in opposition around the planet [I think this is the correct term for it], and another aligned quite a bit further away and below to the right. Oh yes: the star diagonal corrects optical mirror reversal, but not up/down reversal.

The moon looked good and Alden pointed out that ‘X marks the spot‘: so we attached the dSLR using, at first, Alden’s adapter with eyepiece. That didn’t work well, so we eliminated the eyepiece for a modified projection setup. The lunar X is visible for just a short time each month  [‘lunation’] during a precise phase of the moon:

We went back and forth between the moon, Saturn, and also Mars, which was a bright fuzzy reddish blob. Unable to resolve focus or clarity at all, we ended up testing all the gear anyway. The dSLR as described above, and directly on the star diagonal. Here’s the best shot of Saturn from last night, with a closer crop [also rotated and inverted to match ccd shot – i need to figure out which is accurate and which is optically inverted] below:

And then we attached the Solar System Planetary Imager IV. I was tickled pink when we were able to visualize Saturn on my computer screen, bouncing around and fuzzy as it was. I captured 5 short movie files in a couple of pixel dimensions, fooling around a bit with the gain. Here is a link to ONE. I might turn off the audio recording next time.

After proving that the CCD camera works, and confirming that it will work much better with better seeing and perhaps a better scope [lenses], we re-attached the dSLR using Peter’s borrowed Hyperion 24mm, but by then we were tired of fumbling with the star diagonal which was giving trouble.

Finally, this morning I took one of the videos and using Linkeos did my first stacking. 122 images aligned, then 41 images analyzed and stacked:

All in all it was an excellent night, and I’m very grateful for Alden’s mentorship and camaraderie. Next week he’ll help deliver the scope and accessories to my apartment and I’ll set up on the balcony. Hopefully John will be able to help me lug that thing to the dome roof on opposition weekend, since it’s likely I can’t set the thing up myself. We’ll see.