Friday, November 17, 2017

DSOs with an inexpensive IMX224-based imager the Mallincam SR AG1.2C

How low can you go? With the advent of easy to mass-produce, high-quality, CMOS-based, highly sensitive, low-noise imagers, prices are dropping daily on very capable imagers. I've been very impressed with what I've read recently about IMX224-based imagers--especially the low read noise of the camera and its ability to handle high gain settings--so I recently acquired a Mallincam SR AG1.2C, an imager that costs less than $300. This tiny imager could probably be carried around on your key ring! But, as a serious imaging too, does it cut the mustard?

As expected, the clouds rolled in the day the imager arrived, so I spent some time building a darks library at different gain and integration settings. These darks tell an interesting story. The AG1.2C is really low noise! Here are a couple of those images:

This is a moderate gain image (gain 20) and a 40-second integration. The image shows very little noise and amp glow--remarkable performance for an uncooled imager!

Performance on darks is one thing, performance in an imaging setting is something else. The night before last offered an opportunity to try the SR AG1.2C, using a 6 inch RC scope and a .5x focal reducer. This combination produced a nice image scale, as you can see from the image of M33 above (it was cropped very slightly at the edges to chop off some stacking artifacts). 

This image is a stack of 10 x 30s integrations at gain 20. Capture was in MallincamSky, with stacking in nebulosity. It is by no means perfect, but I'm quite pleased with the result from such a small and inexpensive imager (image is a jpeg processed to meet size limitations of attachments).
As a reference image-scale, here's a pic of the Bubble Nebula taken with the same setup. This is a stack of 50-second exposures at gain 20 (20 images stacked).

Sunday, October 29, 2017

A Ghost for Halloween

The Ghost of Cassiopeia (IC59 and IC63) is an emission and reflection nebula illuminated by the bright star in this image, Gamma Cassiopeia (also know as Navi). This is a stack of about 100 x 30-second integrations in H-alpha. Scope: ST-80 @ F/4; imager, Mallincam DSm. It was a cold night tonight and this little ghost seemed to be perfectly in the spirit of the upcoming holiday.

Friday, October 20, 2017

Thursday, October 19, 2017

A Celestial Pelican

The Pelican Nebula is part of the much larger North America Nebula. It is an interesting place--a bright, HII emission nebula peppered with evolving stars and gas clouds. Young stars are slowly heating the cold gas of the Pelican, causing a vast ionization front to move outwards in the cloud, with dense filaments of cold gas punctuating the cloud.

Below is an annotated version of the image:

Some of the dark pillars (especially the pillar at the 2 o'clock position), contain Herbig-Haro objects, which are clouds of nebulosity caused by narrow gas jets shooting from new-born stars  Herbig-Haro objects are short-term phenomena, lasting at most a few thousand years as the gas jets move away from the star into the surrounding nebula or interstellar space.

This image was captured in hydrogen alpha light. It is a stack or approximately 20 x 30 second integrations. Imager: Mallincam DSm; telescope Orion ST-80; mount iOptron ZEQ25.

Tuesday, October 17, 2017

Astroimaging is a bit like fishing...

Astroimaging is a bit like fishing--conditions can be great, but sometimes, the fish just don't bite. Last night was just like an unsuccessful fishing trip. The skies were clear and I fired up the big scope. Unfortunately, a lot of the things I wanted to image were in areas of the sky either obscured by trees or the edge of the observatory dome (that's a problem I need to fix). I did manage a couple of shots of the Triangulum Galaxy and the Helix Nebula, but the camera I was using had problems. The images were really noisy and there was lots of false color and amp glow (the purple tinge around the Helix image), to say nothing of the dust bunnies. The Helix is a difficult object to image at the best of times, however). I'm not sure why this happened (bad cable, software issues?) but the pix are pretty crummy. Oh, well--maybe I'll have better luck next time.

Saturday, October 7, 2017

My Observatories--a Brief History

Like most amateur astronomers, I dreamed for years about having my own observatory.  And it remained just that, a dream, until I acquired a Meade 14 inch ACF scope. I’d always wanted a large aperture scope, and I toyed with the idea of a big dob—18” to 20” aperture. But I also loved GOTO scopes and adding those capabilities to a dob added a lot to the price. The (at that time) newly-reengineered OTA and mount for the Meade 14 inch ACF offered large aperture and GOTO performance at a very reasonable price.

I remember the day the scope arrived in very large boxes from a freight delivery truck. I opened the OTA box and was, frankly, terrified by the size and massiveness of the scope. I stored the OTA in my home, with the tripod in the garage. Using it involved having my son help me haul the huge storage box into the driveway and then lifting the massive forks onto the tripod. Fortunately, the scope set up from that point on was fully automated, so once mounted, I was up and running quickly.
But then I decided to start imaging. Adding the ultrawedge to my setup complicated things a lot! I lost the scope’s auto setup capabilities and the extra few inches height the wedge added made it much harder to put the scope on the mount. It was obvious the I had to do something or the scope was likely to spend most clear nights in its storage box.

Enter JMI Wheelie Bars—a real life saver!  With the scope on the Wheelie Bars, I could just roll it out of the garage and within 5 minutes, be aligned and imaging. The only issue was that my home is surrounded by trees—much of the sky and many of the interesting objects are frequently below the tree line. If I was to get the most out the scope, I needed an observatory in a place where I could see more sky.

I toyed with the idea of buying some land out in the county. I was talking to a friend who ran a tree plantation out in the county and he made a very generous offer—could build an observatory on his land! I drove out the plantation and found an ideal site with a huge horizon. Add to this the fact that it was a dark sky site, and it seemed I had found the perfect place!

The only issue—I had a very limited budget to build an observatory.

Then I found an article online on how someone had converted an inexpensive 10’ x 12’ steel shed into a runoff observatory. This offered a perfect solution. I didn’t have much in the way of DIY skills, but I decided to give it a go! I had to build a roof frame for the rolloff, reinforce the walls and add some insulation, but the job wasn't too had, even for my limited skills.

The result was Walnut Ridge Observatory:
Roof frame under construction

Runoff frame installed on castors and anchored

Interior frame complete

Insulation in place

Hardboard walls installed

The Observatory is almost complete

Runoff frame built from treated lumber

The runoff works!

Holes cut in floor for tripod

Desk, scope, and Plaque Installed

The observatory was a great facility. I ran power from a nearby barn and I could be up and running is less than 5 minutes. Add to that a huge horizon and dark skies, and I was in heaven!

For a while…

There were a couple on nagging problems. One was that the observatory was on a plantation. That meant I had to unlock, open and close, and relock large farm gates to get to the site. In addition, it was a 9 mile drive to the plantation, a drive which seemed to get longer every time I made it. The drive back after a long session was not something I looked forward to. I began to dread clear evenings which I hated to waste, but the almost 20-mile round trip was getting to be a challenge. I had a great site, the ability to start observing quickly, but it was complicated by a long drive and farm gates.

It is a truism that the best scope for you is the one you use most and the 14 was at risk of being used only very occasionally.

With that in mind, I started looking for options nearer home.

The runoff shed had worked well—it had withstood near-tornadic and gale-force winds, but I was never able to completely waterproof it—there were small leaks in several places, so the scope had to be covered at all times. Add to this Indiana humidity and there were times the scope was dripping under its cover. I decided another steel shed would not work.

It was then that I discovered a product made by a Canadian company founded and run by a passionate observer who also happened to be a rock musician—Wayne Parker's Skyshed. Although they offered several different designs, including runoffs, I was more interested in the Skyshed POD. Small, expandable, waterproof, and (above all) with a dome (don’t all amateurs, deep in their hearts, really want a dome?), it offered perfection…if the scope would fit.

After a few very helpful conversations with Wayne Parker, the owner of Skyshed, I took delivery of a 5-bay, insulated pod with black bay interiors.
Lots of boxes!
Like the scope, the delivery was mildly terrifying—a collection of huge boxes that completely filled my garage!  The POD is made of thick, playground-style plastic—no need to paint and no problems with termites, rust, etc. Even in the boxes, it looked formidably robust!

And they are BIG boxes!

The first thing I did was to do a rough assembly of the walls in the driveway so see just how well the scope would fit—and it was perfect, even for such a big scope. Not too tight and with a good amount of room for equipment, chairs, etc.

Checking the fit

Then I got my break on a site. My wife worked as a teacher at a local Montessori School and they were highly interested in science and astronomy. I asked them if I could site the observatory there and, in exchange, offer observing nights and outreach programs. They agreed, and the Indiana POD observatory was built in their grounds.  While the horizon and sky conditions were not as good as those at the plantation, they were much better than at my home. I had a decent view of the eastern, southern, and northern sky, but I was blocked to the west by a building. It seemed a good compromise, as other potential locations on the grounds had interfering trees. I also could not get electrical power, but a combination of a Celestron Power Tank and a portable generator solved those problems.

The POD installed!

The build was easy as Skyshed had an excellent video to help assembly. Wayne was also available in real-time whenever I ran into a problem—superb customer support! The POD is watertight, but I added the extra insurance of the POD cover, just in case. The result—even in storm-force winds and driving rain, the observatory stays perfectly dry!

Checking the autoguider computer

An imaging run from the POD

Still looking good after 3 years!

There's lots of room for me, equipment, and the 14 inch, as this pic shows

More importantly, the POD has more usable space than the significantly larger runoff shed.  With the 14 inch in there on its tripod, as you can see, it's very spacious!

Monday, October 2, 2017

H-alpha Cocoon Nebula

I tried some Ha imaging with the 8 inch f/4 scope the other night, but the results were mixed. In Ha light, the Cocoon usually resolves into a number of delicate shells, but tonight's result does not show this structure. There was a slight haze, but I do not think the sky conditions created any problems. I stacked and processed about 24 frames, but the image is a nebulous blob. I will try again on the next clear night.

Thursday, September 28, 2017

The Sun 9.28.17

The sun continues quiet. ARs 2682 and 2683 dominate today's picture, with AR2681 barely visible toward the solar rim. Clouds and trees interrupted today's imaging session, but the final image is not too bad.

Tuesday, September 26, 2017

A Cosmic Wizard

The Wizard Nebula is fiendishly difficult to image, and I have never been able to get more than a fuzzy blob in any image I have attempted. But last night, my luck was in and I was able to take this image with my Mallincam DSm, VRC 6 scope, MFR5-II FR and H-alpha (7nm) filter. This image is a stack of 30 x 35s integrations with very aggressive histogram stretch.  It's not perfect (there are stacking artifacts from slight mount drift), but I'm very pleased with the result. I may try an OIII image of it later.

Monday, September 25, 2017

Dark Sky Bonanza with Mallincam!

I had the opportunity to capture some images from a wonderful dark sky site in southern Indiana--the shores of Lake Patoka.  The skies were amazing, with the Milky Way clearly visible. We were blessed with Mag 6 skies and good seeing. I took the VRC6, ZEQ25, DS16c, and a somewhat indifferent 2 inch focal reducer. As I had lots of people with me, I had to set up quickly and I didn't have time to fully adjust polar alignment or to ensure the best orthogonality of the imaging train--the idea was to just get some quick captures to keep everyone happy. I've posted some of the images to my album (briansxx), and they show just how well this setup works for fast imaging for public outreach. Integrations were between 20 and 30 seconds with x2 binning and gain close to max, with just 2 or 3 frames stacked in the MC software. I took one 30-second dark, which I used for all integrations (the only exception is the image of the Lagoon, which was a single capture with nio darks). I filtered out some of the noise, but the results are quite decent. With binning and a relatively fast scope (VRC6 at about f/4.5), the DS16c really delivers, with very little tweaking needed.

Thursday, September 21, 2017

The Eastern Veil Nebula

Last night, conditions were very good for narrowband imaging (specifically, 7nm hydrogen-alpha). One of the most spectacular objects for this kind of  imaging is the Veil Nebula. The Veil is an ancient supernova remnant in Cygnus, and is high in the sky at this time of year. This image was captured with a Mallincam DSm, VRC 6 Ritchey-Chretien scope, Ha filter, and Mallincam MFR 5 II-x focal reducer. The final image is a processed stack of 20 captures.

Sunday, September 10, 2017

Ha Imaging of the Crescent and Wizard Nebulas

I gave Ha a try again last night--ST-80, MFR 5 II-x, Mallincam DSm, and 7nm Ha filter.  I'm not even close to duplicating some of the Ha images I have seen by others with exactly the same setup!  I can't come close to the contrast and subtle details, and I can't match the pinpoint stars--mine look distinctly more bloated, even with post-processing (I think the focal reducer contributed to the weird halos--and maybe orthogonality issues). 

But I accept the challenge--I'm going to try again tonight and see how things go.

The attached images are my captures--stacks of 10 (Crescent Nebula) and 20 (Wizard Nebula)--45-second integrations. 

What a Difference a Day Makes!--The Sun 09/09/2017

After all the excitement of X-Class flares and auroras as far south as Kentucky (but we did not see them here in Indiana, unfortunately), the sun today looked more like a sedate star in a solar minimum:

Today's image is dominated by AR2678, toward the center of the disk. ARs2673 and 2674 are close to the edge of the disk and will disappear in the next day or two.