Skies were clear again this evening, offering a magnificent view of the moonrise across the valley. Temperatures, accordingly, were dropping rapidly already into the low teens by 7:30pm. Plus or minus single digits were likely to result.

Anyway, here’s a waning gibbous moon silhouetted against a nearby home. Had I prepared for this shot (notice a recent trend?), I’d have gotten setup outside a bit early…. with a tripod… and thought about the required ISO setting. This shot at ISO100 was not quick enough to pull in any foreground details. The scene moved by so quickly, that I had little or no time to make adjustments. This shot was 1/500 second f/5.6 @ISO100. A better setup might have been set to ISO800-1600… and perhaps about a 1/125 second exposure. This would have allowed for all kinds of details in the foreground. Once this detail was acquired, I’d have had considerably more options available during image processing to seek some sort of balance.

Astro Photo Details:

* Designation: The Moon
* Magnitude: roughly mag -12
* Size: roughly 1/2*

Astro Photo Processing Details

* Canon Digital Rebel XTi
* 1/500s at ISO100
* Gimp Curves

I found myself without a tripod for this shot taken alongside the road (hence the reduced image size). There was a bit of motion in the exposure, but I still managed to capture the Moon Pillar. This was a really beautiful scene… and makes me want to never be without all kinds of equipment. Oh, well…

Moon pillars are most apparent just after moonrise or just before moonset as the moon is sitting just above the horizon. Moon pillars are caused by moon light reflecting off tiny particles of ice in the atmosphere.

Here’s a closeup of January’s Full Moon, aka The Full Wolf Moon. Skies were clear and cold last night. Fortunately, there was no wind and the atmosphere was bone dry. Temperatures were approaching the single digit range, but with all the layering I’d done, I was surprised at how comfortable I was. I even had my mittens off for an extended period of time.

Astro Photo Details:

* Designation: The Moon
* Magnitude: roughly mag -12
* Size: roughly 1/2*

Astro Photo Processing Details

* Canon Digital Rebel XTi
* 1/500s at ISO100
* Astro Physics Starfire Refractor 160mm f/7.5
* PhotoShop CS2 Curves & Levels (mac version)

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A beautiful full wolf moon rose above the hills to the east of my home this evening. After countless weeks of cloudy, snowy skies, it was a joy to see anything in the night sky. I actually noticed the moon a while earlier (while east of the hills seen in the foreground. With a much lower eastern horizon, I knew I was going to have a nice shot on my hands when I got back home. NOTE: clear skies typically usher in arctic temperatures in this area. Temperatures were already down into the mid-teens by the time I took this shot. Single digits or even negative numbers are not out of the question as the night progresses.

The Full Wolf Moon is the name given by Native Americans to the January full moon. With deep snow blanketing their hunting grounds, I’m sure that the wolves howled a bit more intensely as the January moon rose. This moon was also referred to as the Full Snow Moon. This is a term that is quite fitting for this area, as there is easily 30″ of snow on the ground… with accumulations to climb (perhaps significantly) before they begin to drop in earnest.

Astro Photo Details:

* Designation: The Moon
* Magnitude: roughly mag -12
* Size: roughly 1/2*

Astro Photo Processing Details

* Canon Digital Rebel XTi
* First 1/160s at ISO100 ~ 80mm
* PhotoShop CS2 Curves & Levels (mac version)

We’ve all seen amazing astro photos created by ‘amateur’ astronomers. Some are on par with the finest works of professional observatories just a few years ago. What’s their secret? Well, there are a number of secrets… more than can go into a single blog post. First, there have been amazing breakthroughs in CCD technology in the last several years. Combine this with dramatic price reductions and high end astrocams are within reach of many an aspiring astrophotographer. But, guess what? The finest CCD camera on the market all by itself isn’t enough to catapult you to the top tier of the astrophotography world.

Secondly, the degree of control available to astrophotographers through the latest image processing software programs is unrivaled. With an off the shelf computer and off the shelf image processing software, aspiring astrophotographers can coax an almost unimaginable amount of detail from raw images. Additionally, many kinds of ‘mistakes’ can be cleaned up with these programs. Still, with just the latest copy of Photoshop, you won’t find yourself among the top tier of astrophotographers.

I’ve saved arguably the best and most important component of high-end astrophotography for last. Polar alignment. Without a precise polar alignment, your hopes of taking the spectacular images that’ll end up in Sky and Telescope or on the APOD simply aren’t going to happen. Sure, you can get lucky and shoot some phenomenal passing event. I know, I’ve been lucky a few times I’ll certainly take luck over skill any day. But, that said… if you want to take seriously amazing deep sky images, you must have an absolutely spot on polar alignment. Skip this step and you’re doomed to ‘nice’ shots… but not truly amazing.

Polar alignment involves adjusting your telescope’s mount such that the polar axis of the mount is pointing at the north celestial pole. Huh? Ok, its not as complicated a concept as it might sound. Let’s think this through. We all know that objects in the sky (sun, moon, stars) seem to rise in the east and set in the west. This phenomenon is caused by the Earth’s rotation. Earth is spinning on its axis and astronomical objects (not bound to the Earth) are seen to move because of this. The polar axis of your mount (when aimed properly) corresponds to the axis upon which the Earth turns as it rotates. Simple, right? When properly polar aligned, your mount only needs to make use of one of its two motors to keep the image centered. The RA (Right Ascension) gears compensate for the Earth’s rotation and keep your image centered in the eyepiece or in the camera’s field of view. If your alignment is off, the mount needs to make corrections on two axis. This is almost impossible to do with incredible precision. For visual use, this really isn’t even a critical issue. Simply eyeballing the telescope’s direction as north is ok. For lunar or planetary images you might even stop at this point. However, for deep sky images, you’ll need to go the extra mile to get your scope precisely polar aligned.

Ok, so how do we actually go about precisely polar aligning your mount? First, get the scope roughly polar aligned. Simply pointing the mount’s polar axis to the north star (Polaris) is a good first step. Next, you’ll want to make use of the ‘drift method’ of alignment. The drift method is a technique whereby you point at a couple of specific stars and watch the star drift out of the center of your eyepiece over time. Hence, the name. Adjustments are then made to the mount itself to bring you closer to alignment. This processes is repeated until there is no more drift. Note, that as you fix one axis, you can be slightly messing up the other, hence the iterative nature of this adjustment.

Azimuth Adjustment

To proceed, choose a star near the intersection of the meridian and the celestial equator. The closer the better. I’ve seen references say you should be within 1/2 hour of Right Ascension and 5* of declination. I’m not sure how these tolerances were picked, but I’ve tried my best to follow them. You’ll find that at times, this is easier said than done. Sometimes, there simply aren’t any bright stars in those areas. A goto scope and some good astronomical software will be helpful to find these points (you’ll need a pretty accurate pointing model to find these). To get the stars perfectly centered, you’ll need an illumated reticle eyepiece. I have a non-illuminated one at the moment and usually have to use a red light to help me see the lines that crisscross the eyepiece. Accuracy here is pretty important. Additionally, the higher the power your setup the better. So, either get a very small focal length eyepiece… use a barlow… or both. The higher the power, the faster you’ll notice the drift and the more closely you can watch for improvements.

For this star, you’ll only be making adjustments in azimuth. If the star drifts to the south, adjust your polar axis to the west. If the star drifts to the north, adjust the polar axis to the east.

I like to try to use a consistent time period for the drift, say 2 minutes. This way, you’ll start to get a feel for how quickly your improving things. If you drift out of the eyepiece in 2 minutes the first time, and then only 1/2 way out of the eyepiece the second time, you know that you’re making good adjustments and should have things nailed shortly.  If you use widely divergent intervals, its much harder to gauge how you’re progressing. You can still do it, but it starts to feel much more hit or miss. I usually like to get 3 or 4 iterations on this star before doing an about face.

Additional Resources:

Celestron

Jerry Lodriguss