A Mobile Imaging Setup

This is the first summer of my retirement and I'm using it to go to a number of star parties. For the first time I've traveled to the Nebraska Star Party (just south of Valentine, NE), and coming up are the Iowa Star Party (near Coon Rapids, Iowa) and the Northern Nights Star Fest (northwest of Aitkin, MN). All three of these are intended to be imaging trips, and toward that end I've designed my imaging setup to be self-contained, compact, and reliable. I travel in a mid-sized sedan, so there's a natural limit to what I can carry.

The first thing to do is to leave the bells and whistles at home. Keep your gear simple and you'll be rewarded with less hassle when you set up or break down. Remember, if you forget something and no one can lend you a replacement you may be out of luck for the entire party.

What's the least you need? The essentials for imaging: an imaging telescope (including finder), an autoguiding scope (if you autoguide), a mount and tripod, a camera, an autoguider, cables for all these as needed, and batteries to power everything. If you anticipate a chance of dew, a dew prevention system is good to have on hand. Probably you'll need a laptop if you're using a CCD camera.

Oh, and let's not forget a table to put that laptop on. Like a good observing chair, a table is an important part of imaging. I use one much like this. Mine was purchased about 12 years ago from Target for a scant $20, and is one of the best astronomy accessories I've ever found. The roll-up aluminum table top is particularly nice as it's impervious to dew and frost and when you cook food, it doesn't care if you set a hot pan on it. Sadly, my table is reaching the end of its life and some plastic parts are starting to crack. I'm repairing it with J-B Weld as needed, but sooner or later it will need to be replaced.

Batteries will be the heaviest things you'll have to lug around. While it's certainly possible to use your vehicle battery as the sole power source, that's probably not practical for multi-night imaging. Remember that most car batteries are designed for starting your car, not supplying a several amps for many hours. Deep cycle batteries are better for this. You can pay a lot for these or get them at farm and ranch retail stores for far less, as I did.

I use three batteries, which is almost certainly overkill. Two are lead-acid deep cycle marine batteries with a combined capacity of about 140 Amp hours. These power the mount, laptop and camera. The third is a sealed lead battery with about 20 Amp hours that powers my dew strips and can power things like fans. (This battery has the advantage of being easy to recharge.) These batteries can power everything for at least 15 hours, which is a solid three night's worth of imaging on most trips. It's possible they can go longer, but I've never had that much good luck with consecutive clear nights!

[My CGEM mount draws about 1.5 A when tracking, the ST-8300m CCD about 2 A (that's a guess based on its 3 Amp requirement at peak cooling load), and the laptop about 1.8 A (also a guess based on the AC adapter and having a battery that's pretty much gone dead after all these years. That's a total of 4.3A. My two deep cycle batteries should be able to supply that for about 32 hours, or 16 hours if we only take the batteries down to 50%. So my 15 hour estimate above seems reasonable.]

Imaging Setup at the 2014 Nebraska Star Party

The above picture shows how this all looks, minus the "Y" stalked dual finder mount, CCD, and laptop which are all sitting in the shade at this point. The three batteries are sitting on the ground below the mount.

For this trip I took my little refractor, the AT65EDQ. That's the scope I'll take to ISP, but for NNSF the bulkier C9.25 is making the trip.

Regardless of the scope, all of this gear fits quite nicely in my car with room left over for everything I need to set up camp. Best of all, it seems to work quite well!

Two dark-sky images

Just back from the Nebraska Star Party and the smaller party in SW Minnesota.

First, from Minnesota, the Rho Ophiuchi nebula (IC 4604, the blue reflection nebula at top):

At bottom is the emission nebula IC 4603. This is about 1.5 hours of LRGB data. This will need to be reprocessed to get rid of a distracting satellite track. The image above has been reprocessed to get rid of the satellite tracks and improve the color balance.

The first image from NSP is the Iris (NGC 7023, vdB 139) at right in the image,

The small bright nebula at image left is Sh 2-136. About 3.7 hours of data went into this image. I'll probably reprocess this and adjust the color balance a little. It looks a tad too yellow-green to me.

Still awaiting processing are the Cat's Paw nebula, Sh 2-183, and NGC 1333 (vdB 17). For those I binned the color channels 2x2, and I need to shoot some dark frames to match.

More about NSP 2014 in a subsequent post.

Sh 2-137

The list rolls on with another faint nebula: Sh 2-137 in Cepheus. This object its also known as LBN 498 and has a brightness value of 5

This images represents 3.5 hours of integration on a night with a bright waning gibbous moon.

Sh 2-137

The bright star at left is GSC 04271-2621 with magnitude 4.57.

No Luck With the State Fair; Weather Update

Just a quick update--my entry into the Fine Arts competition was not accepted. That means I get to keep my nicely framed picture, although I'll probably make it a gift to someone.

Unfortunately the judges don't give explanations for their decisions. I'm going to speculate that it was seen as lacking a sufficient element of artistic merit. If that's their reasoning, I can certainly understand it.

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The long-term forecast for conditions during the Jeffers star party suggests that the very cool weather we've been experiencing will come to an end just before the party begins. Temperatures will climb into the low 90s with dew points in the low 70s. Typical steamy Jeffers weather, and if it persists into the following week and the Nebraska Star Party, there may be some big bad thunderstorms to deal with.

Imaging Targets for This Summer's Star Parties

I'm probably going to four star parties this summer: The Jeffers Starry Nights (JSN), the Nebraska Star Party (NSP), the South Dakota Star Party (SDSP) and Iowa Star Party (ISP). I'm hoping to do quite a bit of imaging at these, taking advantage of the dark skies and slightly more southern locations. It's not much, but every degree of elevation helps!

I'd like to bump along my Bright Nebula list work, and take a couple of pretty pictures, too.  The dark locations let me image reflection nebulae that I can't get from my light-polluted back yard. Another constraint is that whatever scope I bring to Jeffers will also be the one I use at NSP. So what should I image?

(1) I'd like to go really deep on the Iris (NGC 7023). It's a reflection nebula on the list, and it's pretty. Near by are some barely luminous clouds. A wide field shot with my AT65 will take them all in. The Iris a better target during the JSN/NSP time period than in late August. This would be a multi-hour object, to say the least.

(2) I've always wanted a good image of the Helix nebula (NGC7293). This is better imaged around labor day, so it should be during either the SDSP or ISP. ISP has darker southern sky, so that's where it will be imaged. The C925 produces a nice image scale for it.

The Helix from 2009 JSN.

The above is my only Helix image, taken using my TV102, an unmodded Canon DSLR, 16 x 180s @ ISO 1600. Not at all adequate. A few hours (or longer) of LRGB could be much better.

(2a) Other objects I would like to go really deep on are the Ring--see a previous post about the outer shell-- and the Dumbbell. Those would be best in the C925.

(3) I have only one so-so image of the eagle nebula (M16) from a couple of years ago. Unfortunately it doesn't include the portion of the nebula that's considered LBN 68, a list item. So that should be reimaged from a dark site. This would probably look better in the C925 but the wide field of the AT65 would be adequate. Best during JSN/NSP.

(4) There are a good number of large list items in Scorpius and Sagittarius that would image well in the AT 72. These should be imaged at JSN/NSP. These include Sh 2-13, 2-16, NGC 6334, IC 4628, IC 4701 and LBN 52. An hour each should produce images that could satisfy list requirements.

So there you are:

• JSN and NSP get the Iris and the large list items. This means that I can travel to them with the smaller, lighter AT65. One pretty picture (Iris) and a flock of list items.

• SDSP and ISP get the Helix, Ring, Dumbbell, and whatever else comes along. For those it's the C925. Pretty pictures all, and perhaps list items left over from July.

Now it's all up to the weather!

Another Obscure "Bright" Nebula: LBN 185, and IC 1470

The AL Bright Nebula list has quite a few not-very-bright nebulae on it. Here's one that's bright enough to image from a red zone + a nearly full moon: LBN 185 in Cygnus, a 5 on the LBN brightness scale.

LBN 185

I believe LBN 185 is the bright area near the center of the image. There's another bright area at the left edge of the image, but so far as I know that has no designation. This took 3.8 hours of H alpha imaging, and even at that the background is still rather rough. A couple of nights before I also got this image of IC 1470:

IC 1470

On the other hand, IC 1470 is bright, and small. This was taken with a C925 at a focal length of 1480mm, while the LBN 185 image is wide field with a 422mm AT65EDQ.

Going a Little Deeper with M 57

When the first really deep images of M 57 started showing up, I was amazed at the wealth of structure that surrounded the familiar oval that gave the Ring it's name. As it turns out, many planetary nebulae show this kind of layered structure. The explosive events that drive the star's outer atmosphere into space aren't just a one-time event; instead, they can happen repeatedly, producing a set of expanding nested shells. The outer shells are older, farther from the central star, subjected to less intense radiation, more diffuse, and have had more time to cool, all of which means they are less luminous at visible wavelengths.

M 57 is quite bright and easy to image. Even the central star, elusive visually thanks to the diminished contrast in the Ring's interior, is easily imaged. But what about those outer shells? Can they be imaged by folks with modest gear?

Last night I made my first try at finding out. While waiting for another object to climb out of the trees, I had some time to spend on M 57. I used a C 925 SCT with a 0.63X focal reducer, an SBIG ST-8300M CCD camera shooting through a Baader Ha narrowband filter, and accumulated 39 minutes of 3-minute light frames. That's not very much, compared to some projects where one have a total exposure time of over five hours. But it was all I had time for last night.

The result was surprising, at least to me:

My image is on the left; at right is a deep image from the U of Oregon for comparison.

In both images the Ring is wildly overexposed, but you can see the second ring clearly in my 39-minute shot. Also visible are a couple of the brighter knots in the next outward ring.

The image scale here isn't the greatest, and only 39 minutes through an Ha filter leaves a lot of noise, but I think it's going to be worth going back to this and shooting for hours. 

If you haven't tried going deep on M 57, you might give it a try. The result may surprise you, too.