Preparations for Imaging in July

In the wake of the Skyview Acres trip I have solved some of the problems I had noted. First, I confirmed something that a friend at the star party told me... appearances can be deceiving on the filter colors. SBIG tells me that the filters will often reflect the complement of the filter color and that you can see the actual colors by using a flashlight on them. So... what I thought was Red was Green, What I thought was Blue was Red and what I thought looked yellowish and assumed was Green, was actually Blue. That still left the problem of having to specify Blue in CCDSoft to get no filter over the CCD window. It turns out that in the settings window, beside the specification of the filter, there is a button for filter settings that allows you to change the name associated with a filter position. All I had to do was change the default settings such that the one labeled Clear was actually Blue and the one labeled Blue was Clear and that solved the problem.

One more thing I will do before July is to clean the filters. I had noted that the filter I was calling green was showing some brighter stars as being bloated. This led to some green rings around those stars when I did an RGB combine. A fellow imager suggested to me that this filter may be dirty. With a cleaning I think I'm going to be ready to do some great imaging in July! Primary targets will be the "Omega Nebula" and Bode's galaxy, both of which will be more difficult to image later in the summer. I've imaged Bode's before, but want to "go deeper" with longer exposures and perhaps some color. I've never imaged the Omega Nebula. After those I will be going back to some of the Nebula I observed last year to try to get better images with some of the new techniques I've learned.

I went back to some data I collected last year at OSP on the globular cluster "M22" with the idea of applying my improved processing skills. In the first try last year, I ended up only using the 6" exposure because it was the only one in which I could avoid saturating the core of the cluster... but such a short exposure lost detail in the outer parts of the cluster. With two learnings: 1) importing the files to photoshop as 16-bit TIFF' and 2) using the Curves adjustment in photoshop, I was able to combine all of my three exposures (total of 56") and keep the core from saturating (turning into a big white blob). Both pictures are included below for comparison, as well as the 30" exposure from last year with a saturated core. The 56" exposure (6"+20"+30") is a huge improvement! The dark skies at OSP are great for getting better sharpness in the stars. I'm going to try to image another one this August and include color.



A 30" exposure without applying my new learning. Note the saturated core.



A 6" exposure from last year without latest learnings. Detail in core but lost detail in the outer parts.



Summed exposures (6"+20"+30") with latest learning applied. Best yet!

Skyview Acres Star Party

With my son, I attended the Skyview Acres star party June 11-12 near Goldendale, WA. This was the first time I've used the new RV for this purpose and it sure does make things better! Being able to go inside and warm up in front of a furnace vent is such a pleasure. In this case though, the cold wasn't so bad... it was the dew.

With temperatures in the mid-40's I was hopeful that I could start my imaging season as early as May, based upon the weather history. Last year I started late enough that I never encountered any dew. This year I've imaged twice and both times there was more moisture in the air than any time last year (when I started in August after finally getting all of the necessary equipment). In May, in my backyard, I took an image of M101 and saw some strange artifacts in the background. I suspected dew or frosting in my camera and replaced the desiccant bag in the CCD chamber just before this trip. It didn't work.

My primary suspect now is either condensation on my objective lens or inside the camera on the cover plate to the CCD chamber. There was no evidence of a cleanliness issue on that plate or the filters when I replaced the desiccant bag. Next time I image it needs to be in dry conditions to test this theory.

The Skyview Acres site was bad for dew because there was a lot of fairly tall grass and moisture in the ground. That moisture became worrisome early in the evening when it started condensing out on my table. I never really saw or felt any on my telescope, but I can't rule out that it was there in very small droplets. Conditions were certainly on the edge.

I went ahead with my imaging both nights but quit in the range of 1am to 2am, primarily because of the dew concerns. On the second night I had thought the dew situation would improve. It had been warmer during the day and a bit warmer at night, but the dew actually seemed worse.

The first night I imaged two objects (M63 and M100) in black and white only. Early on it became evident that my camera was not working right and I diagnosed that it wasn't taking dark images properly. Instead, they were similar to the light images and when they got subtracted off with slight motion of the scope (unguided) it left "shadows" beside all of the stars. I got around this the first night by taking a set of manual darks (covering the lens with the cap) and taking light images only. The next day I took apart my camera and found that I had not properly set the color filter wheel in place on its axle and it had come loose.

M63 and M100 were targets because I had never seen them before (weren't in the sky when I started last year) and they seemed to be interesting objects (not just fuzzy blobs). M100 is a pretty spiral galaxy and M63 is a galaxy with an odd dark arc around one side of its core, earning it the name "The Black Eye" galaxy. These were both smaller and fainter objects than I've typically imaged in the past. M64 is 10'x5' in size and magnitude 9.3. M100 is 7.6'x6.8' in size and 10.0 magnitude. I used no auto-guiding that night, so I was confined to getting multiple short (1 min) exposures that I would later stack together. The resulting pictures are shown below, where, for M100, I included a pre-processing image and a post-processing image, to give you an idea of just how much clean-up happens even after the darks are subtracted and the images were stacked. Total exposure time on M100 was 21 minutes and on M64 was 11 minutes. You can easily see the "black eye" feature, but little else on M64. M100 could have used more exposure time, but it's really nice spiral shape is very evident... it's just really small! Objects of this size could really benefit from using a longer focal length scope for imaging.

The second night I imaged three objects: M101 (spiral galaxy, 21.9'x21.4, mag 8.4), M5 (globular cluster, 23'x23', mag 5.7) and M8 (The Lagoon Nebula, 17'x15', mag 5.0), in that order. You can see that the sizes of these were around 2x or more larger and they were all brighter than M64 and M100. Images, post processing are shown below. M101 needs more processing work but may be too limited by the artifacts for the color image to ever be all that good. Both color images are LRGB, combining Red-Green-Blue filtered images with an image taken without any filter (Clear). This is the first time I've created such images successfully, having utilized Photoshop and instructions from Ron Wodaski's first book. In order to get the color to come out right, I had to pretend that the Blue filter (Blue based upon appearance) was Red and vice-a-versa... something I still need to explain. When I had the camera apart, I tested the filter wheel and noted that what was specified by the software was not what the ST-402 camera delivered. Instead, "Blue" was clear, "Clear" was green, "Red" was blue, and "Green" was red. I thought I may have gotten the filter wheel on in the wrong position, so I changed it 180 degrees and the got the same result. If my error is judging the filter by its naked eye appearance, that still can't explain why specifying "Blue" results in no filter in front of the CCD. An email to SBIG is warranted.

All in all, this was a good trip. The M8 photo was pretty good and I again learned a lot about what can go wrong. Hopefully future sessions will be better because of it.



M101 - Luminance image, 37 min exposure (37x1). Processing needs more work!



M101 - LRGB image (37' Luminance + 12' RGB)



The Lagoon Nebula in Black and White (Luminance 100')



The Lagoon Nebula - LRGB image (100 sec Luminance + 3 min RGB)


M5 - Globular cluster. A single 10 sec. image w/curves adjustment and unsharp mask.



M100 - Pre-processing after dark subtraction and stacking



M100 - Post-Processing (Gradient removal, Curve adjustment, blurring)



M64 - The Black Eye

Getting started in 2010

Last night (May 8th) the clouds went away and the temperature was a bit chilly but tolerable. I decided to do some test images in my backyard to help prepare for the 2010 season (my second as an astro-imager). Though I had no serious hope of getting really good images (because of the light pollution of the city), I felt it was worthwhile to 1) test out my home-built light box for taking flat-field images, 2) try out using CCDSoft (instead of CCDOps) to control the camera, and 3) to make sure there was no frosting in my camera after one observing season and storage in the wet Northwest.

Setup of my hardware went well (it all came back to me after the many months of not imaging). When I got to polar alignment I encountered the effects of my first brain fart... the telescope was not slewing to the right locations for my alignment stars. Oh yeah... it's 2010 and it's May, not October... it helps to enter the right date into the system! Because of my limited horizon and expectations, I did only a one-star alignment on Mizar and did my focusing there too. CCDSoft connected to the camera just fine and I didn't have much trouble using it. I've heard of people not liking the focusing tools, but they seemed to work well for me (though I wasn't controlling an auto-focuser or trying to control the mount).

I initially tried to go to M81 (Bode's galaxy), but didn't find it in the field of view (FOV). The image I took was extremely noisy (light pollution). I decided to try another object, so moved to M51 (Whirlpool galaxy) and this time I met with success (higher in the sky with less light pollution and closer to my alignment star). I decided to just take short exposures without auto-guiding. I took one 30" exposure and then took 14 or 15 one minute exposures. All of the single images had pretty noisy backgrounds but they came out nice when added together.

I finished up and took flats with my DIY light box, using a range of exposures with 12 images per exposure. It was during this process (when I'd already turned off my mount) that I found that I had not seen the 'filter' window in CCDSoft and had taken all of my images to that point with the red filter (brain fart #2... but perhaps excusable because it was the first time I'd used the software). I took a few series of flats with the clear filter just for comparison and then wrapped up for the night.

When I did the summation of my images after tear-down, the background noise cleared up, but I did see artifacts that I'm pretty sure are the result of humidity based upon what I've read. This is what I had half-expected and feared might delay my imaging season a bit more. I have asked SBIG to send me a new desiccant pack and I'll have to open up the camera and do a replacement (and clean the CCD window). Whether I can get this done in time to take advantage of May's dark nights is questionable at this point.

The flats came out with all sorts of features. I did a median average of all images and applied them to my summed-up light frames and what I saw was that it didn't seem to introduce any artifacts but it did bring back the background noise. What I had missed was that I should have taken dark-frames for the flats and adjusted them before trying to apply them to my image of M51.

The clear-filter flats I took had a feature that was quite different from the red-filter flats... what appeared to be fringing effects on the right side of the image. I'm hoping this isn't the product of a flaw in my light box, but I'll need to do a bit more imaging and diagnostics to figure it out.

Given that I didn't expect to get any good images last night, it was a very good night of imaging because it brushed the cobwebs out of my mind and resulted in some great learning that will help me do better next time. I'm very happy I'm not discovering these things after having ventured a hundred miles away to take advantage of dark skies, as it would have been a big waste of time and money.


Fourteen minutes (14x1')of M51 without flat adjustments. Frost artifacts?


My first flat-frame image with the DIY lightbox. A lot of defects!

Emerging from the winter

Winter is drawing to a close and I'm almost ready to begin astro-imaging again. This season will be far different from last season in that it will be a FULL season. Last year I didn't get my equipment setup finalized until August. This winter I've been preparing by reading "The New CCD Astronomy", by Ron Wodaski. My hope is that I can take my imaging to another level this season by beginning to use flat frames, achieving better polar alignment, and utilizing Photoshop (which I now own) for more sophisticated image processing. I'm in the process of gathering raw materials to build my own light box based upon plans I've found on-line. I would also like to spend some time studying the errors in my mount and auto-guidng and quantitatively monitoring the "seeing" so that I can understand what the key variables are in the quality of my images. I will try to transition from using CCDOps for camera control to using CCDSoft v.5, which seems to have much better features.

There is good weather coming this weekend with clear skies and low temperatures in the low 40's. I may try to do some imaging but may end up waiting until the next new moon.

Backyard observing with my C8

Last Friday night I imaged for the first time from my backyard with the SBIG camera and did so on my 8" Celestron SCT, another first. Fall weather is definitely setting in. I could feel the moisture in the air and the temperature was much lower earlier in the evening than on other nights I've observed. I put together my setup with the idea that I would finish by around midnight to avoid any risk of dew affecting my optics or my camera.

Doing the setup for the first time with new equipment took awhile longer than usual of course and there was some learning involved. I had to use all three of my eleven pound counter-weights to balance the telescopes and accessories (C8 with the Orion 80mm guide scope attached, ST-402ME, flip-mirror, 30mm eyepiece) properly. I did the polar alignment with just two stars and it seemed to be adequate. What made it difficult was that I hadn't taken time to align my guide scope and C8, which made centering the alignment stars difficult. Using the APO I typically use a reflex sight, but do not yet I have it mounted on the C8 (something I need to do but it isn't trivial). As expected, with the C8's longer focal length I don't have the wider field of view that I have with the 80mm refractor, making finding the stars more difficult. It took longer than it should have, but I got it done.

My targets were to be Jupiter and the Dumbell nebula (which I've imaged with the 80mm refractor). Unfortunately, Jupiter passed behind the trees before I could get my scope set up, leaving me only a narrow window later in the night to capture it as it passed through a narrow gap between two other trees. I moved on to the Dumbell nebula and my alignment was good enough to put it in the scope on the first try, though some centering was necessary. I took a quick 30" monochrome image of it and was struck immediately by the higher level of background noise which I believe is associated with the light pollution in the city. I set up the auto-guiding and took a 120" image and found it to be decent enough to go ahead with an RGB image. Again I limited it to 120" and a version of it is shown above. Focus was good based upon the use of the Bahtinov mask, but this image has the appearance of being a bit out of focus; I believe (hope) that this is just a function of the poor seeing conditions. I am pleased with the fact that I fairly easily found and imaged this object with the 2000mm focal length C8 after being told by more experienced people of how difficult it is. It definitely makes me want to use the C8 more often in the future on the smaller objects. You can go to my earlier posting with the Dumbell through the 80mm refractor to appreciate the difference in the size of the object in the picture.

I did capture Jupiter in the narrow window available to me later that evening. However, as I half expected, it was way too bright for my camera even at the shortest exposure time. When I processed the image later and reduced the brightness I could barely make out the bands in the atmosphere. To try to address this in the future I've ordered a polarizing filter that should allow me to reduce the brightness up to 40%. I can also try to stop-down my aperture. Unfortunately, I apparently have no ability to adjust the gain on the ST-402. I'd like to hear other recommendations if anyone cares to comment.

Unfortunately clouds and rain are moving in and I will not be able to image again for the foreseeable future. I'm still hoping for an opportunity in October on the east side of the mountains.

Orion Captured in Color

I spent last night at the White River Sno-park about 6 miles east of Government camp on Hwy 35. It's just a big parking lot which is almost completely unvisited this time of the year. Of course my goal was to complete the quest that began on Sunday to image M42 in Orion. This time I powered down the computer with about 72% computer battery life remaining (around midnight) and waited for Orion to come up over the eastern hills. I spent my battery's first 28% on the Veil (West) Nebula after having captured the "East" version last Sunday. That image is as yet unprocessed because I spent all of my time so far on M42.

I'm learning something new each time I go out. I learned this time how to use the "auto-grab" feature to capture color images... manually selecting the filter before the "grab". I took exposures at 5", 15", 30", 60", 90" and 120" and found that blooming (over-exposure) of stars was very bad on the blue filter at 120" and bad at 90". When I got back I found that they were also present at 60". After seeing the blooming I spent the rest of the night gathering 30" exposures with RGB and Clear filters, getting about twenty four exposures in all (12 minutes). The challenge now is finding the best way to calibrate, register, stack, and RGB-combine all of them. With the software I have (CCDOps and DeepSkyStacker) it looks like a very difficult task.

I did just find out that I can easily fix the blooming artifacts using a utility in CCDOps and this has enabled me to produce the image above from the single 120" exposure. Sorry... no RG colorblind version yet. Had I know they would have been this easy to fix I would have taken more of them. Given that I have six times more data than what is contained in the image above, I believe I should be able to improve the image significantly with more work... but it won't be any time soon. I think this is why most imagers talk about image processing being their "winter project".

Wind and the moon are returning, so last night was my last night imaging with the 80mm refractor for at least another month. If the weather ends up being good, I'll go to SkyView Acres in October. I may try to set up my 8" SCT in the back yard (moon or no moon) if the weather permits, just to start debugging that setup and appreciating the difficulties associated with a longer focal length scope.

Orion the Hunted

I just returned today from a new observation site (for me) called Skyview Acres near Goldendale, WA. It is a piece of land owned by a Washington astronomy buff who bought it with the intent of using it to host star parties. I just went for one night (Sunday), however people were there from Thursday through Sunday nights. Sunday, as I had suspected, turned out to be the best night for observing/imaging with almost no wind, no significant dew and very clear, dark skies.

My main objective was to use my new color capability to image M42 in the constellation Orion (The Hunter). Unfortunately, with Orion coming up only after 1am and not getting reasonably high in the sky until about 2:30am, I ended up draining most of my battery life before 2:30am. I felt I was getting some very good images and was on a roll that was hard to stop. I powered down with about 18% battery life remaining, which I thought was enough, however shortly after I started imaging the computer automatically powered down and interrupted the imaging after the exposure with the green filter (leaving the blue not done). It was only a 30 second exposure, but I got a tantalizing taste of what Orion can be like on my camera. Despite my not taking the time to carefully center it, I got lucky and it was very well centered (amazing because it nearly fills the field of view). The red filter exposure is shown here with the contrast range increased to show detail in the outer boundaries (saturating detail in the core). Amazing! I've got to get back to this and this time save my battery power!

Okay, now for those good images I was speaking of... at the top, after M42, is the Pelican nebula followed by a blue version for the red-green color-blind people of the world (like my two brothers). Following this are (likewise paired with blue versions) by the Veil Nebula (East), and then the Bubble Nebula. I used the new Bahtinov focus mask to establish my focus up-front, and I thought it was doing pretty well until I got home and saw the Bubble Nebula image... which seems to be a bit out of focus. I had rechecked the focus later in the night with the Bahtinov (before M42) and it looked good, so I don't really know what went wrong. Pelican and Veil are both pretty good.

I also imaged Pleaides, M78 (also in Orion), and M1 (the Crab Nebula), but those did not seem worth publishing here. Crab doesn't have a lot of color, but has a lot of detail that is worth going back and imaging with longer exposures. Pleaides is just tough because it is so bright. M78 also requires more time than I gave it.

The Skyview Acres site worked out very well and I'm looking forward to possibly going back in October. It is NOT a quiet site. There were two donkeys that brayed intermittently through the night. I can't describe the sound well here but I can say that it would have been a bit spooky if I hadn't known that they were donkeys and if it wasn't at the same time so funny! There were also dogs barking, coyotes yapping and howling, bird sounds, guns being fired in the distance, car noises in the distance, and in the morning a lot of noise with neighbors getting up and tending to chores. There was one bright yard light in the distance but it was very tolerable for people imaging (all three of us there were imaging). There was a lot of wildlife... I mentioned the coyotes, but there were a lot of deer walking through the meadows in both the evening and the morning after. I also saw a flock of six wild turkeys and a bunch of bluebirds (seldom seen here in the west side of the mountains).

Both of the other guys there had pickups towing trailers. I had the back of the Honda Civic to sleep in and no, I didn't get any sleep, despite trying after the computer battery died. I got home on a caffeine tablet and haven't yet gone to bed. I already thinking about how I might be able to get out and take another shot at Orion tomorrow night!