2014 imaging plans

Entering a new season of better weather in the Pacific NW, I'm now prepared to try to out-perform last years efforts at imaging deep space objects. For my Celestron C8 SCT (1992 version), I've purchased a new Off-axis guider (OAG) and a new, smaller, more sensitive guide camera with the hope of eliminating many of the guiding issues I've had with a separate 50mm guide scope. The OAG unit is the lastest Celestron version and it appears to be very good quality... much more solidly built than the Orion Deluxe OAG I had previously (and broke!). The new guide camera is a Starlight express "Lodestar" (monochrome), which comes highly recommended by my peers at RCA, with small size and good sensitivity. When I tried to use my SBIG ST-402 camera for OAG, I found that there was too little room left over between the camera and the back of the scope.

I use a reduce/corrector on my C8 to shorten the focal length and flatten the field. This requires that I get about 105mm spacing between the reducer/corrector and the imaging CCD. Fitting the pieces together, I find that, with no additional spacers, the distance comes out nearly perfect (104.5mm). I'm going to need at least one practice session where I determine the right distance to achieve focus with the Lodestar and to determine the optimum adjustment of the pick-off mirror into to the incoming light (keeping it from going to far into the CCD's field). Finding undistorted guide stars is the big concern, but the new camera and the adjustability of the OAG should help.

Due to the fragility of the ST-4 cable used to connect from the camera directly to the mount, I've been advised to instead guide through ASCOM directly from my computer. Though I've played with this a little before, it's going to be a new learning curve. I'll also experiment with guiding via Maxim DL.

If I can't get clean enough guide stars, I may need to consider upgrading my SCT to a new "Celestron EdgeHD 8", to get a flatter field. In the end, will this be the secret to better guiding or will I find that the variables I've eliminated (mirror flop and differential flexure) were never a big part of my problem? If the latter, I may have to consider getting a new mount.

Late May will likely be my first good window of opportunity to use the new setup under good conditions (clear skies, no dew and decent temperatures).

April 14-15 Lunar Eclipse

The first of four dreaded "Blood moons" has passed and my experience was that it wasn't very bloody, except when I imaged it. While I entertained the idea of going to a more remote location to view this eclipse, the weather reports influenced me to stay local. Though those reports weren't great, they weren't that much worse than other places. I ended up watching from my backyard and, while I did see the eclipse begin and enter totality, heavier clouds came in and kept me from seeing the end of it. Though there was visibility, it was poor because here was a thin veil of clouds throughout.

I started out trying to image it using my Nikon D40 with just my 200mm telephoto lens. I ended up switching to using my Nikon D40 mounted to my Orion 80mm refractor. I ended up wishing that I had used only the telescope from the beginning.  Because of the conditions, I wasn't able to set the telescope up such that I could track the moon (no polar alignment), so I had to keep it in the field of view manually. None of the images are anything to brag about. My key learning was: Don't even try to image a total eclipse if you don't have clear conditions, and if you do have clear conditions, use a telescope with tracking so that you can use long enough exposure times to get the best quality image.

Visually, I didn't see any red through a lens on the telescope. Only the CCD imaging brought that out. I would be interested to hear what color people saw with the naked eye under clear skies.

Here are some of the images:

Before eclipse - 1/1000th sec. telephoto T0

Early in eclipse - 1/1000th sec. telephoto T0+38 min.

Nearing totality - 1/10th sec. telephoto T0+1Hr 21min

Almost there - 1 sec. telephoto T0+ 1Hr 30 min.

Totality - 1 sec. telephoto T0+1Hr 32min

Totality - 2 sec. 80mm Refractor T0+1Hr 56 min.

Back to the Ochocco Mountains

I spent four nights doing astro-imaging at Indian Trail Springs in the Ochocco Mountains from Tuesday July 9th to Saturday July 13th. The first two nights were spent using my C8 Schmidt-Cassegrain and the last two nights I used my 80mm Orion EON refractor. I wasn't pleased with my auto-guiding the first two nights and it was that which prompted me to switch to my refractor the third night. Part of this was due to an out-of-focus guide scope (50mm Orion)... something I eventually corrected... but I don't think that was the whole story. While my guiding with the refractor was better, it still showed the variation observed on the C8, just with smaller amplitude. My best guiding was on the last night with the refractor and in particular when I was tracking west of the meridian. The one picture I feel is worthy of posting here is an image of the Easter Veil Nebula, NGC 6992, which was based on the median of 21 five-minute exposures with the refractor (see below).

Moving forward, I want to improve my guiding with the C8 and I'd like to again try using off-axis guiding. The last time I tried it I almost located a guide-star, but lost it and gave up in frustration. My plan this time is to try using a more sensitive guide camera (my ST-402) rather than the usual Orion Starshoot Autoguider. I'm going to try this out some time before the next new moon and hopefully be ready to do some improved imaging with my C8 in August. Whether I go to the Oregon Star Party or not is still up in the air, dependent upon forest fires, weather, and whether I want to deal with such a large crowd of people.

One night in June

Clear, dark skies have been practically non-existent in the Portland area so far this spring. What few there have been have mostly come unexpected (after a forecast of clouds), keeping me from taking advantage of them. With spring drawing to a close, I was determined to take advantage of Wednesday, June 20th. Initially, southern Oregon was forecast to be clear for three nights, the 20th through the 22nd, but this changed as the days drew near and spoiled what was to be a three-night RV expedition to Burns and perhaps Lakeview.

The night before I was to get the RV out of storage with the help of my son, I realized that the RV keys were in the glove compartment of our CRV, which was being used that week by my wife on her outing to Camp Namanu for volunteer work. My son graciously volunteered to drive out to the camp to get them. Had he not done that, I would have taken our Honda Civic on the astro-imaging expedition.... I was that desperate for my first night out in 2012.

So, yesterday I drove the RV over Mt. Hood and down Hwy 97 to Sunriver, OR, where just across the highway is a place that I used on one of my first imaging trips back in the 1990's. I arrived at this place, a rock quarry surrounded by forest, and was disappointed to find that the horizon, particularly in the south where I wanted to image, was not good. On to plan B... I went a few miles farther down 97 to Cascade Meadows RV Park, where I claimed a spot on the south edge of the park, overlooking a large meadow. I had visited this RV Park for imaging a couple years ago and found it to be relatively good.

Though a few clouds teased me on the western horizon, spilling over the crest of the Cascade range, and a few mosquitoes had me wondering if I was going to be swarmed, everything turned out pretty good. I came with a plan to image M104 (the Sombrero Galaxy) for the first time, to get a better image of M8 (the Lagoon nebula) than past attempts,  and to utilize eye-piece projection to image Saturn. In the end, I decided to use my Celestron C8 SCT with a new 0.63x focal-reducer/flattener. I've been wanting to reduce the weight on my C8 setup and was debating whether to resort to using the old 80mm refractor as a guide-scope or to use my new, light-weight Orion 50mm guide-scope. Some people have said that the 50mm might have problems guiding the C8 with its long focal length, however I had read where someone had done it with a 0.63 focal reducer and had no problems... so I gave it a try. That part of it worked out well; I had no guiding problems all night. I had considered also trying my new off-axis guider, but decided against it because I felt I would be over-doing the experimentation (and I really wanted to image my high priority targets).

I started off imaging M104 using prime-focus. The final product is shown below, the result of averaging two five-minute exposures (yes, I should have done more, but I was running out of time after struggles with the setup... more on that later). I've always liked this galaxy and it was great to finally image it. No darks or flats were used on this image.

The Sombrero Galaxy (2 x 5 min with C8 w/0.63x focal reducer/flattener)

When I finally moved on from M104 (which was getting too low on the horizon), I had already eaten into my allotted time to image Saturn. I left the focal reducer on and used my new Orion adapter that would fit over an eyepiece. I centered Saturn first using prime-focus and then quickly switched to the eyepiece (17mm). I had a hard time finding focus because the image seemed over-exposed (even at the very shortest exposure times) the distance between screen and focus knob was large (I really need to install that electronic focusser!). I tried an 8mm eyepiece with my light green filter,  hoping that would improve the exposure enough, but I had no luck. I never did get a good image of Saturn, despite the fact that it looked good to my eye directly through the eyepiece. I'm going to have to try this again sometime, maybe without the focal reducer to cut down the image intensity a bit. It would also help to be imaging a planet that was a bit higher off the horizon (the seeing seemed very bad).

After "visiting" Saturn, I slewed the scope to the Lagoon Nebula, which I don't think ever gets above 30 degrees at our latitude. The seeing is always marginal, but it is a bright object and nevertheless has the potential for good images. I took six two-minute exposures and five five-minute exposures; the latter is shown below. I will probably try to brighten the color in this a bit, but I'm pretty happy with the detail that is in it.

The Lagoon Nebula (5 x 5min with C8 w/0.63x focal reducer/flattener)

At this point I had a repeat of a problem that occurred in my initial setup: while slewing, the power cable for the mount jiggled and re-set the software forcing me to re-do the polar alignment. I couldn't do it. Both my Orion "EZ Finder Deluxe" and the 50mm guide scope were not be aligned well enough to the center of the FOV of the C8 that I could find the alignment stars. In hindsight, I could have played around with the EZ Finder more (I just found the adjustment screws for it), but the guide scope was at its limit and still not close. I guess I just got lucky in my initial alignment... it happened to be close and adjusting it put me close to the other alignment stars. No such luck on two attempts mid-way through the night so I decided to switch back to using my 80mm refractor where I never have had such  problem.

With what little time I had left, I decided to just image M51, the Whirlpool galaxy, which I never seem to get tired of imaging. At this point I noted that dew was starting to become a problem on the 50mm guide-scope. I considered just quitting for the night, but fought the urge off and pulled out my home-made dew heaters, which I made last season but never used. The worked great! I finished up the night with three eight minute exposures of M51 and it came out pretty nice (see below).

The Whirlpool Galaxy (3 x 8min with 80mm refractor)

After finishing M51 I looked to the south and became aware of clouds moving in. I looked to the northeast and saw the sky already beginning to brighten a bit at 3:30am (the draw-back of summer solstice). It was time to quit after another night of learning a few things the hard way while making a little bit of progress. I know that I need to come up with a robust fix to that power-cable issue and well as the finder-scope issue for the C8. I need to figure out how I'll make my next attempt at imaging a planet (probably Jupiter in August given that the weather is looking like crap for at least the next week and Saturn leaves us in July). I improved my focusing technique a bit tonight by making use of the mouse selected sub-frame capability in MaximDL and  using longer exposures to focus on the fainter stars near my imaging target (necessary to re-focus more often using the C8 due to "mirror-flop", so this is useful). All together, it was a good trip. After about three hours of sleep and a breakfast at the RV Park, I drank my "5Hr Energy" and took off for home... satisfied.

The Venus Transit of the Sun

Instead of there being a weather front coming in, as in the case of the annular eclipse, the Venus transit was plagued with a front moving out. If I had trusted the local weather forecasts, I might have stayed in my local area and imaged the transit. The satellite photos that morning (6/5/12) were promising. I took off at 6:10am and drove to Red Bluff, CA, where I had imaged the eclipse. The weather forecasts there were showing about 34% cloud-cover in the afternoon and evening and were a lot better than other areas within reasonable driving times.

I arrived in Red Bluff about 1:30pm and, after stopping to hydrate myself and stock up on “5-hour energy” for the drive back (later that day), went straight to the same old quiet place on the country road east of Red Bluff. The transit started around 3:10pm, appearing first as a  “mouse-bite”, and I imaged it until it was fully within the area of the Sun. At that point, I changed to eye-piece projection, using a new adapter that makes it easy to perfectly position the camera behind the lens. Some experimenting at home had taught me that a 17mm eyepiece would work, giving me good magnification (~ 29x) while keeping the exposure time short enough for unguided imaging. Unlike during the eclipse, this time I utilized the hand-controller of the clock drive to keep the image centered (after first getting it centered with a lower power lens).

Focus was again the toughest part of this. I continued to simply “eyeball it” and to make many re-adjustments hoping that I’d get a few that were well focused. When the total eclipse rolls around in August 2017, I’ll want to be set up the night before, be polar-aligned and not have to be making any centering adjustments. Longer exposures will likely be required for totality. I’ll also want to have the focus well-adjusted and locked going into totality. With my SXVR-M25C camera I should be able to do computer downloads quickly enough that I can better zero-in on best focus… but I’ll need to experiment with it to confirm.

Here are a couple of my images from the Venus transit. More can be found on my Picasa site.  For now, I think I’m done with the Sun in 2012 and ready to move back to deep space and some experimentation with imaging the planets using eye-piece projection and my new capability. 

 The "Mouse-bite"

 Full enclosure

One of the few clouds I encountered

 Eye-piece projection results

2012 Annular Eclipse

First on my list of anticipated astronomical displays this season has been the May 20th annular eclipse of the sun. This a bit short of a total eclipse because the moon is smaller than normal and leaves a ring of sunlight at the peak moment... if you are in the right place to see it. The band of visibility for this "ring of fire" (annularity) passed through Crescent City, CA to the southeast, through the area of Reno, NV and on towards New Mexico. This band was wide enough that the ring could be seen as far north as Ashland, OR and as far south as Chico, CA. For me, this meant a road-trip, but how far I would have to go would depend upon the weather.

I followed the weather for the ten days before the event and saw it go from clear to partly cloudy to overcast and then back again to clear. As May 20th drew closer, the weather reports stabilized to partly cloudy in the farthest southern extreme of the band of visibility, with the weather farther north being progressively worse. A weather front was moving in and even in the far south, the evening of the 20th was expected to get worse sometime between 6pm and 8pm. The peak moment of the eclipse was to occur between 6:28pm and 6:29pm.

Had the weather been completely clear, my friend Ed was willing to fly me south to see it in his small plane. The weather made that too risky (risk of being grounded in CA for a few days, or more). So, it became a car-trip and I planned initially to go to near the center of the band at Shasta Lake, CA. The day of the trip, I ran a simulation and decided that it would be best to go farther south to have a better chance for clear weather. Ed was going to go with me, but decided that was a bit too far and decided to stay home. I ended up taking off Saturday afternoon (5/19) after reserving a motel in Ashland, OR. My plan at that time was to drive to Chico, CA the next day.

I took off from Ashland about 8am and made it to Red Bluff, CA (about 40 miles north of Chico) before lunchtime. At that point, the weather looked pretty clear, with some clouds to the northwest, where the front was approaching. I decided to get a motel there in Red Bluff and to check out the weather again on internet in addition to confirming my simulations of the eclipse. It was too early to move into the room so I took a drive out east of town looking for locations from which I could observe and image the eclipse. I ended up finding a real nice spot off a country road that would ensure me good privacy and a great view of the western horizon. I decided that, assuming the weather continued to look good, I would stay in Red Bluff for the eclipse. What I found was that Red Bluff was still looking good through 6pm and the satellite showed the clouds moving from the SW to the NW and not heading directly towards Red Bluff. The simulation suggested that I might not see a full ring at the Chico location. At 4pm, about an hour before the eclipse was to start (5:13pm), I headed out and began my setup, which utilized my Orion EON 80mm refractor and my Nikon D40 arranged for prime-focus imaging. I could not do a decent polar alignment, so just did what I could using a compass and planned to manually keep the sun centered instead of using the clock drive.

After taking a few photos to refine my focus, I took my first eclipse photo at 5:13, just as the moon became visible at the edge of the sun. I continued to photograph throughout the eclipse, taking well over 200 images until the sun descended into clouds with about 6 minutes left in the eclipse. I continued imaging through the clouds for awhile and caught some brief clearing before the sun disappeared into thicker clouds. I took the most photographs as the moon neared large sun-spots, as the trailing edge of the moon became flush with the edge of the sun, during the visibility of the ring, and as the leading edge of the moon became flush with the edge of the sun. A sampling of the images is available in this link to a Picasa web album. I've also included a couple of images below. Very few people drove by on the road while I imaged and only one, a nearby farmer and his wife, stopped to talk a bit. Their son came down on an ATV and got there just about during the peak of the eclipse. I let him look through the camera viewfinder a few times.

This turned out to be a great trip, with the weather and the images coming out about as well as I could have expected. The next time I image a solar eclipse will likely be in August 2017 when totality will pass directly over Portland, OR. By that time, I hope to have evolved my technique to the point where I do not have to play with focus as much (find optimum focus and just stick with it throughout). I also am unsure about what kind of exposure times will be required during totality. In this case, I used my Nikon D40 instead of my Starlight Express, because it gives me capability to go to shorter exposure times. What I would like to do on the total eclipse is to be at the location the night before to get polar alignment, so that I can utilize tracking during the eclipse. I would then be able to do all of my imaging through the computer, making it easier to fine tune the focus (using sub-frames and seeing the results near 'real-time' as I do the focusing). I would like to use the Starlight Xpress camera then because the computer control seems more robust and the down-load times are MUCH better than the D40.

The next big event of this season occurs June 5th as Venus moves across the sun, an event that will next occur in the year 2117 (so I better catch this one!). In preparation for this event, I've ordered a solar filter for my 8" Celestron SCT and plan to try using eyepiece projection to get higher magnification views. I have also ordered an adapter that will allow me to try this through the 80mm refractor. The transit will begin just after 2pm and continue through sunset (have to be farther west to see the whole thing). I'm back to tracking the weather reports and expect that I'll be heading east of the Cascades to image this. Before that day I hope to try out eye-piece projection in the backyard and finalize my methodology. Stay tuned!

 The "Ring of Fire"

Last view of full sun before the clouds won.

Shooting the Sun

I celebrated what is so far the best weather of 2012 by getting my telescope out after lunch and experimenting with imaging the sun. I had purchased an Orion solar filter for my 80mm Orion EON refractor earlier in the year but this is the first time I've been sufficiently motivated to try to use it.

I first very roughly aligned my telescope with the earth's polar axis (I knew about where Polaris is) and then moved the scope so that its shadow was minimized in order to get it pointed at the sun. I then mounted my filter over the dew shade. I had a feeling that the sun would still be bright enough through the filter that my astronomical CCD camera would be overly sensitive and unable to achieve a short enough exposure, so I started out using my Nikon D40. I mounted it using the T-adapter to a 2" barrel with SCT threads. I centered and roughly found focus using my D40 view-finder, but the focusing was a challenge because I needed to utilize the sun-spots to refine the focus and they were very small (low mag prime-focus photography). I resorted to eye-balling it and taking numerous exposures with small variations in the focus. Before this, I did some exposure experiments and found that about 1/800th of a second was somewhere close to optimum. What I found later was that I still had to decrease the brightness somewhat, so next time I'll probably go with a bit shorter exposure somewhere between 1/800th and 1/1250th. My best result in shown below. You can see that there were quite a few large sunspots visible. At this point I'm not sure how much better the result could have been. Tube currents due to solar heating of the scope are a limiter, but I think there was probably room for better focus.

This activity at least gets me somewhat prepared for the annular eclipse next month in Northern California and the Venus transit of the sun on June 5th.