Showing posts from October, 2013

An Active Sun!

Maybe this SolarMax will not be so disappointing after all!  The sun is crackling with activity at the moment. Below are two images taken today with the ASI120MM. As for the Newton's Rings, I seem to be stuck with them. I have tried flats and software moire removal, but neither worked. I will continue to use the ASI for solar imaging because, apart from the rings, it produces superb images!

ASI120MM Test Image: M15 (Stacked and Single Image)

Here's an image of M15 taken last night with my ETX 125 and the ASI120MM. The exposures were 7 seconds with the gain at 60. As you can see, this camera did a very good job. The first image here is a stacked image of 15, 7-second exposures. I stacked in Registax and did a little processing in Photoshop. I kept the exposures short to see just how well this camera would perform. I also kept them short because, although the ETX keeps objects in the FOV for hours with no problems, it does tend to "dither" quite a bit while tracking, which means the object moves around in the imaged field, leading to streaking. I had to select the best 15 frames from the stack of 80 I accumulated for final stacking. What appears to be a satellite trail (visible on only one frame) is visible below M15 itself.

The next image shows the results after simply stacking in Registax:

The final image is a single frame capture, unprocessed in any way.

I think these images give a good idea of the perform…

Active Areas on October 23, 2013

Here are a couple of images I took today--with the inevitable Newton's Rings. I tried a couple of things to reduce them. As I track the scope manually, I can't take well-registered flats. My solution was to take an original image and add Gaussian blur to eliminate the rings. However, the final, processed product was unusable (all detail disappeared apart from the rings!). I then tried tilting the DS filter using the gold wheel, but that changed only the brightness of the image and the rings remained unchanged. Lastly, I pulled the imager almost clear of the barlow and refocussed the scope. I then tilted it by 4-5 degrees. Depressingly, the rigs remained unchanged. They are also there if I don't use the DS filter, and/or remove the barlow. I will try building on of the "tilting" devices described on several websites to see if I can fix this problem.

Another Washout for the Orionids

The Orionids is a meteor shower made up of debris scattered by Halley's Comet. I was hoping that tonight I might be able to capture a few meteors using the ASI120MM in all-sky mode. But, like last night, after a clear start to the evening, the clouds rolled in by 8:15 or so. This has been the pattern for many nights: clear or very nearly clear days and clear evenings followed by cloud by 9 pm. It has been a frustrating year for astronomy here in Indiana. The video is too large to upload, even in compressed form. Below is a still frame. Click for a larger image.

Update--it did clear around 9 pm and I captured more video. No meteors, but you can see Cassiopeia emerging from the trees at the bottom of the image.

Solar Active Areas 10/20/2013

Here are some images taken with the ASI120MM yesterday. They are probably the best solar images I have ever taken, but they are marred by Newton's Rings--the dark banding on the images, which can be a problem when using monochrome imagers with narrowband filters (in this case, a PST-DS). Some internet posts on the subject suggest the problem is due to the use of a barlow lens, but I have found that the bands are there even without the barlow. Ironically, these bands are more of a problem for high-quality imagers than for lower-tolerance devices. There are a number of potential ways to remove them and I am exploring these options.

Time Lapse with ASI 120MM all-Sky Lens

This video is a 2 hour time lapse taken with the ASI 120MM and the supplied all-sky lens. The image is a series of 7-second exposures covering 2 hours (the inevitable clouds roll in a quarter of the way through). The sensitivity is excellent and the noise very low. In the early section, you can see significant faint detail around several of the stars (you have to look carefully in this compressed version). This is the nebulosity of the Milky Way itself. It's quite an achievement to see that with an almost-full moon above the horizon and high-level haze.  This appears to be an excellent camera, and superior to the MC in both noise and sensitivity. (Note--the video is compressed. the artifacts seen here are not in the original video, which is pristine).

ASI120MC vs 120MM Long-Exposure Noise

I decided to order a 120MM to compare the monochrome version of the ASI camera with the color version. The color version generates significant noise with longer exposures. This noise, can be reduced by adding an external peltier (as demonstrated in a an earlier post). Below are two images comparing the noise of the 2 imagers with an approx 17-second exposure.

As you can see, there is a marked difference in noise levels. I have read that the MM version if also 4 times more sensitive than the MC, with a significant improvement in QE. I will be returning the MC and will order a filter wheel shortly. I'm looking forward to doing some deep sky imaging with the MM!

AR1861 on 10-14-2013

Here's another pic of AR1861, looking a little quieter today, although still capable of X-Class flares. The PST-DS also captured some dark filaments around the spot complex.

Test Shots of the Moon tonight (10-13-13)

Here are a couple of test shots of the moon taken tonight with the ETX 125 (no Barlow). These images were a test of the ASI camera and it looks pretty good. The shots were actually taken through the intervening leaves of my neighbor's tree! Click on each image for a larger pic.

The Sun on October 12, 2013

Here are some pix of the sun taken today. I've focused primarily on the AR 1861-1865 complex as it has the potential to release X-Class flares. Seeing was poor/fair, with lots of water vapor in the air. The images also show some comparisons between the old Lifecam and the new ASI imager.

The LifeCam image at 1280x720, 30 FPS gives a good chunk of the whole disk. For the ASI, I had to use a Barlow to get good focus. In addition, I had a hard time getting a good framerate, so I captured at 640x40 @47 FPS. The first image, after processing, is a zoomed in view of the active area.

Finally, here's one more shot (not as cropped, but with some additional de-noising and sharpening:

There was also a rather nice prominence visible, too:

I have noticed some artifacts on the ASI images after output from Registax--a pattern of dots. I'm not sure what they are (artifacts of the Bayer Matrix?), but de-noising seems to remove them:

ASI 120MC and Peltier--An Experiment

The ASI 120MC is a truly flexible camera. It can do planetary imaging as well as deep sky. However, like all uncooled cameras, it produces significant amounts of noise. While dark frame subtraction can take care of much of this noise, cooling the chip can greatly reduce noise and minimize processing. It also makes it easier to see deep sky objects as you monitor the exposure.

The camera's metallic case is a good conductor, so I decided to experiment to see how much cooling I could get by surface mounting a peltier cooler. I bought a very inexpensive (less than $5) 93-watt peltier and a $15 PC heatsink and fan.

I then mounted the peltier to the heatsink (the heatsink has a conveneint adhesive thermal pad).

All that remained was to add a 12v power supply, place it on the imager, and turn the contraption on!

The results are very interesting. The following images are captures showing chip temperature and the resultant image noise for a 17-second dark field exposure (click for a full-s…

Niches Land Trust at Walnut Ridge

This is a late write up, but on September 21st, the local chapter of Niches Land Trust held an event at Arbor America, West Point, IN. Walnut Ridge Observatory is located at Arbor America and 20-30 people came to the stargazing event.  We were fortunate to have what was the best night of the year so far for seeing and transparency and the views of objects, from the Moon and Neptune to the Dumbell, M31, M13, the Ring Nebula, Alberio and other deep sky objects, was superb.

In the video below, I took a quick pan from the west to the east at sunset. The sky is showing a fine example of the Girdle of Venus, surrounding us in a pinkish glow (called an anti-twilight arch). The dark layer visible especially in the east, separating the pink glow from the horizon, is the shadow of the earth itself.

New Camera!

Here's an image of the cloudy skies over my home taken yesterday night with my new ZWO Optical ASI 120MC. The image is a 30-second exposure. The Summer Triangle stars Vega (top right), Deneb (top left) and Altair (bottom) are clearly visible. You can also see from the treeline why I had to build Walnut Ridge Observatory--there's not a lot of sky visible through the foliage!

The camera comes packed in a pleasing box and has a really useful accessory--a removable 180 degree all-sky lens (which I used to take the picture above).

The camera has a very respectable QE of 55, is capable of high framerates at reduced resolutions (up to 65FPS) and can handle single exposures of up to 1024 seconds. The I120 is not cooled, which means long exposures can be noisy. However, I plan on adding a removable peltier cooler to the back of the case. For less than $25 extra, I'll get very superior performance. The camera also comes in a monochrome version. While the monochrome camera has some …