Messier Marathon Night Results

"Mission Accomplished!" to use a cliched phrase. "Goal Reached" might be a little better, or maybe "Dumbness Overcome."

This was one of my first attempts to use my DSLR in quite a while, and I managed to make a lot of mistakes early on:

• Forgetting to return to ISO 1600 from the composing setting of 6400
• Forgetting to set the shutter control to bulb
• Forgetting to increase the number of frames on the DSLR controller from the dark frame to light frame counts

And so on. The evening began with starts and restarts, but once it got going it went well. The time I lost meant I wouldn't go after the dimmer planetary nebula I had included on my object list in the last post, but that was okay.

All the hardware worked perfectly, although some went untested. The dry air and the gusty to breezy conditions meant the dew preventers weren't needed. It was only around 2 A.M. that frost began to appear, and my scopes stayed clean until the end a little before 3 A.M. The DSLR power supply worked perfectly and the 35Ah battery was barely tested running that and the mount. I used my laptop for PHD with its power supplied by it's own battery augmented with a Duracell 600 battery pack. The Duracell ran down pretty far in the five or so hours, so this might not be a good option for multi-night imaging. For more power conservation I need to find a way to turn off the laptop's display, not simply dim it.

The evening tally was six Arp galaxies and one planetary. In terms of Messier objects it was 9 1/2. Let's see some marathon images:

Leo Triplet (clockwise from NGC 3526 at top, M65, and M66) Together these are Arp 317. M66 is Arp 16.

M49 (right of center, Arp 134)

M60 (left of center, Arp 116) and M59 (right of center)

M87 (Arp 152)

M90 (Arp 76) and M89 at bottom edge

M97 (Owl Nebula) and M108 at bottom edge

All the images are based on 10 three minute exposures with a Canon T2i (at ISO 1600) riding on a TV 102 operating at f/7--except the image of M90, which was 5 three minute exposures at ISO 6400 (see list of mistakes above). These were calibrated with 20 dark frames collected throughout the night as the temperature fell from around 30°to 20°F. They obviously haven't been flatted. I reprocessed them to include synthetic flattening, and now they look a lot nicer!



An inspection of single light frames shows that they surpass visual observations, so why not bring back the idea of an Imaging Messier Marathon? Three minutes at ISO 1600 is about the same as 45 seconds at ISO 6400. 3/4 minute times 110 objects is only 82 minutes; out of a six hour marathon night that leaves four and a half hours for acquisition and composing images. Definitely doable.

That aside, the evening bumped my Arp list count to 26 and my planetary list count to 23. Both lists are about 1/4 done!

Onward to warmer weather!

November 2015, A Great Month for Imaging

Pleasant fall weather and clear nights are the dream for every autumn, and occasionally that's exactly what happens. This year's September, October and November allowed me to image on 15 nights (or more, I may have missed a counting a few). And that's not counting a few clear nights during full moons when lunar observers were probably having fun. I did some work on the Arp and planetary nebula observing programs, and made time for a pretty objects as well. Here are a few of this autumn's images:

Messier 33, Canon T2i and AT65EDQ

Messier 45, SBIG ST-8300M LRGB and AT65EDQ

NGC 246, SBIG ST-8300M RGB and C 9.25

I really like the way the Canon and AT65 work together to make for light-weight, large field imaging. The previous (and only) deep image I'd done with the T2i made me wonder about how noisy the camera was, but the M33 image background came out nice and smooth, probably aided by the temperature being in the 40s F.

Winter's here now it appears. Temperatures are in the teens at night and there's an inch or two of snow on the ground with several more inches in the forecast.

My winter goals this year are modest compared to last year when I was in a mad rush to complete the bright nebula program. A nice narrowband image of Barnard's loop would be nice, and perhaps if the conditions cooperate one or two of the big winter nebulae with the Canon/AT65.

Two little wiring projects are planned, too. I want to replace the cord on my CGEM's handset with a longer flat cable and make a 12V to 7.4V power supply for the Canon.

Plans are afoot for club members to gather for an imaging SIG meeting and mirror making seminar in January or February. I hope to attend both.

First Light Image for Gary Honis Modded Canon T2i

Two weeks after getting my camera back from Gary Honis the clouds parted, the moon was out of the sky, and my schedule permitted me to try it out. Finally!

As a target I chose The North American nebula, something I'd imaged before with my ST-8300 in LRGB. The imaging site had light green sky brightness, not nearly as dark as for the CCD image. The telescopes were nearly the same, an AT72 at f/6 vs. my current AT65EDQ at f/6.5. Total exposures were 81 vs 100 m so it's almost a dead heat in terms of expected brightness. Because of the high humidity and the lack of a window heater the CCD was cooled only to about 0C.

Here's the T2i image:

NGC 7000 with Canon T2i and AT65EDQ at Cherry Grove 2015

and here's the ST-8300M image:

NGC 7000 with SBIG ST-8300M and AT72 at Iowa Star Party 2013

The difference is mainly one of brightness and contrast, which is almost certainly a result of my processing. I think the CCD image is a little washed out. I like most aspects of the DSLR image except for the vertical bands that are most apparent on the right portion of the image. These appear to come from the dark frames (I shot only six) and my inexperience processing DSLR images.

Related to those bands, one big change I'm going to make this year is learning how to dither. Based on what I've read it's helpful to let the camera cool after the image is read, and that "lost time" is perfect for dithering.

For this image I powered the camera using the Neewer AC power adapter and controlled the acquisition with the Neewer controller. Both worked perfectly.

---

Only a little over three weeks remain before the Nebraska Star Party. I've prepped three images for the astrophotography contest, one from Jeffers on the way to the 2014 NSP, one from my first night at NSP, and one from last fall. I need to give my binocular mount a couple more coats of varnish and it will be ready to go.

Another Star Party Cloud-Out; Camera update

Today is the Saturday of the Two Rivers Spring Star Party and I'm posting this blog when I should be enjoying dark skies. The sad fact is that the entire run of the party has been filled with of clouds and rain and I've bailed out rather than sit in a tent for the remainder of the party.

AMENDED: The IR Satellite loop suggests that Saturday night is starting out clear. It won't stay that way, though; by midnight or 1 A.M. clouds will cover from the west. It still wouldn't have been a suitable night for my imaging.

A tale of woe: My last several parties are the Iowa Star Party (two out of two nights unsuitable), The Northern Nights Star Fest (three out of four cloudy/rainy nights) and now the TRSSP (three out of three cloudy/rainy nights). That gives me a whopping one night out of nine that I could see the stars.

The next star party is the Nebraska Star Party in July. Maybe I should ask them to pay me to stay away.

---

The T2i arrived sooner than expected! It's amazingly clean--it looks almost brand new, and more importantly looks to be 100% functional. I've communicated with Gary Honis about the modification, and he's got a slot open at the end of May. Maybe I'll have the modded camera back in time for the NSP? It could ride my CG-5 mount and do wide-field imaging while I'm using the CCD for other objects.

A New Camera

Last time I mentioned that I was considering purchasing a DSLR for imaging and had narrowed the field of candidate models to a short list.

The winner is the Canon T2i. I was able to pick one up on eBay for $183. (Here's hoping that it arrives in good shape and performs as well as the seller says it will.)

Here's how the T2i compares with the other candidates:

The 40D (introduced in 2007) has a sturdier build valued by professionals but lacks the video capability of the T2i that can be used for solar system imaging. The 40D is considerably larger and is 10.3 oz. heavier than the T2i; after imaging with the ST-8300M+FW8 tandem I'll appreciate the difference in weight and bulk. The T2i's pixel size is much smaller (4.3 vs. 5.7 m) making it a better match for my AT65 and TV-102. It's reported that the T2i's sensitivity is 2 f-stops better than the 40D.

The XSi (2008) is one model more recent than my XTi and has a large number of owners doing astrophotograpy. I suspect this is because it was the first consumer-class Canon camera with LiveView and USB one-cable operation. The XSi lacks video, and the T2i is said to be 3 f-stops more sensitive.

The T3i (2011) has slighter less noise than the T2i (2010), but it lost the crop mode video capability that helps with solar system imaging. The T3i adds the tilt-out display that's useful when the camera is used without a laptop but this feature is of little value to me. It also costs more to purchase being a year newer.

The T2i has a better display screen for focusing than either of the earlier models.

Assuming that the purchased camera checks out okay I'll be sending it off to Gary Honis for his Baader modification.

---

Two Rivers Spring Star Party Update--- It begins in three days and the weather forecast for the party is terrible: Every night mostly cloudy with a 40-50% chance of rain. Ugh.

A More Diverse Imaging Capability

It's been cloudy, or clear with a waxing moon. So I've been working on small projects and considering a purchase.

The parallelogram binocular holder

 is coming along. This week completed all the work needed to completely assemble it. Amazingly it actually worked, providing the 11x80 binoculars with smooth freedom of motion. This morning I stained the pieces and tonight (or whenever the rain ends) I'll give it a nice coat or two of spar polyurethane.  No one is going to mistake it for the handiwork of a skilled wood worker, but it will work. And in the dark of night when it's used no one will notice the rough corners.

Remounting the Finder and Autoguider on my C925

The finder shoe on Celestron's C925 sits a little off-axis, making it more convenient to use. The small stock finder is so lightweight that the torque it produces is negligible. But the torque can become substantial when I configure the scope for imaging. For imaging I use a "Y" shaped mount that carries both a 9x50 finder and Orion MiniGuider. These throw the scope quite a bit off balance around the declination axis.

One solution would be to add a counterweight on the scope's opposite side, but it could be messy trying to figure out how much weight should go where.

A better solution was made possible by a dovetail bar installed on the scope by its previous owner. The bar extends from front to back and is made of stout ADM manufacture; it works great as a sort of handle for lifting the scope.

It was short work to drill a couple of holes in the bar, tap threads into them, and fasten a spare Vixen-style finder shoe I happened to have. This shoe has a flat base and fits perfectly onto the bar. Now the finder/guider tandem sits exactly opposite the scope's base and the torque should be gone.

Now the purchase: Adding Imaging Flexibility

I'm seriously considering adding a DSLR for imaging. This isn't intended as a replacement for my ST-8300M, which gives me the ability to do narrowband imaging from my back yard.

Perhaps this is a case of gear envy brought on by lousy weather. Maybe it's just me getting a little tired of having to shoot flat frames for every channel when I do LRGB. Maybe it's just an itch caused by some unexpected funds coming from the closing of my software business. In any event, I've been investigating used DSLRs.

Let's start with a price point of $600 maximum for a modded camera body. Preferred would something under $400. Under $300 would be great! And because I'm somewhat invested in Canon lenses, I'll consider only a Canon body.

Models being considered are the 40D, XSi, 50D, T1i, T2i and T3i. I've seen and handled the 40D; it's a nice camera, better built to resist the elements than the XSi is. The 50D is said to be a step up from the 40D; of the three Tn cameras the T2 stands out because of its crop mode video capability which makes it suitable for solar system imaging.