Dual Laser Milky Way Photo Op

The island is home to a vibrant community of photographers, a mix of professionals and serious amateurs. There is one set of photos everyone, and I do mean everyone wants… Dual lasers on the Milky Way.

Dual Lasers on the Galactic Center
Both Keck lasers aimed at the center of the Milky Way galaxy
Just occasionally both of the keck telescopes, and both lasers, are focused on the center of the galaxy, both stabbing right at the heart of the Milky Way.

Opportunities to see and photograph this are few, and occur strictly during the summer months of June to August, when the Milky Way is high overhead. furthermore, these opportunities occur only when Andre Ghez and her UCLA Galactic Center Group have both telescopes scheduled.

July 25th was such a night, a good opportunity to get both lasers. Andrea’s group has the first half of the night, turning over the ‘scopes to other astronomers just after midnight. Actually there were a few nights this particular week, we just chose the 25th. After this galactic center season is over, at least until next year.

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Milky Way Gallery


Yeah, that didn’t work…

Eighty four images representing four and a half hours of exposure on the target. In this case NGC2244, the Rosette Nebula. It takes a few minutes to setup the software to align all of the images, then it takes about half an hour for the software to digest everything and produce a result. At the end of this you get to see if the effort worked. Sometimes it does not.

Complicating the issue is that a number of the sub-frames are taken at different exposures. Finding the correct stars in the these different exposures gives the software fits.

Misaligned Rosette
The result when the alignment routines fail to align all 84 images of the Rosette Nebula.

The Gear

The current astrophoto setup in the driveway… The TeleVue 76mm atop the iOptron ZEQ-25 mount. The camera is currently the Canon 6D, providing a 5.35° x 3.57° field of view with a 3.52 arcsecond per pixel image scale.

Atop the main scope an SBIG STi provides auto-guiding. With a 100mm lens it has a 15 arc-second per pixel image scale. It is mounted with a custom mount machined for this setup.

The setup is intended to provide a high performance astrophoto setup with a minimum of fuss. This is about as far as I can reduce things without giving up performance. It is pretty portable, airline luggable at least. The whole setup fit in two suitcases for the trip to Oregon Star Party last summer.

The only real issue with this setup is the laptop. The big old 17″ HP Pavalion chews a lot of power, requiring an AC outlet to supply. I have my little Asus netbook configured to run the setup, a far more power efficient machine. With the netbook I can setup anywhere and shoot.

Cable management is a bit of a chore. A lot of separate cables must be routed to connect everything together. Much of the time I keep the setup assembled in the garage for deployment in the driveway. The cable tangle can be tamed with a handful of zip ties and velcro strips this way. A wheeled dolly allows the entire setup to be rolled out of the garage.

With this setup I have a capable astrophoto rig, capable of producing very nice material for processing. I just need a chance to get out and use it more often.

Astrophoto Setup
The astrophoto setup in the driveway.

Oregon Star Party 2013

The plan is simple, a vacation combining a visit to my family and a run to Oregon Star Party. I miss doing the larger regional star parties, six telescopes is a big star party on the island. OSP would feature hundreds of telescopes, speakers, and hopefully dark skies. I also volunteered as a speaker, may as well bring and share little Keck experience.

Andrew and the Galaxy
The author taking astrophotos under the Milky Way Galaxy
Heading to a major star party takes some planning. Worse, I would be doing this with what could be packed for airline travel. The answer would be to implement my usual star party plan… Set up for astrophotography, this would allow vising other telescopes while my camera ran under computer control. Good astrophotography can also be done with relatively small equipment.

The site is quite remote, no nearby hardware store to replace a missing bolt, no internet connection to allow download of a missing driver. The setup would have to work with what was packed to start with. Several iterations of packing showed that two cases would be required to carry the setup. An ancient hard suitcase I have had since my Air Force days, and a hard equipment case purchased years ago for a portable telescope I have yet to build. At least both had wheels and could be hauled by one person through an airport terminal.

After a few very nice days visiting with my parents I steal away in the camper for the drive to OSP. Four hours sees me over the Cascades, into the Ochoco Mountains east of Prineville. It is a very pleasant drive, a beautiful day, open roads, Mt. Hood soaring over the trees that line the highway. The sort of driving you just can not do on the island, the sort of vacation I grew up with.

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The iOptron ZEQ25

I had been looking to acquire another astrophoto toy. The desire is for a small, portable astrophoto setup. Yes, I am aware that the words “portable” and “astrophoto” do not really belong in the same sentence, all things are relative.

Thus I have decided on the new iOptron ZEQ25. It is a new design, with some radical differences from the more traditional German equatorial mounts.

The mount is pretty small, a mere 10 pounds of steel and aluminum. Compact enough to be packed into a suitcase for air travel. Performance sufficient to do wide field astrophotography with focal lengths up to 1000mm and a DLSR camera. Perfect for use with either my TV-76 or AT6RC. Unlike my old Losmady G-11 it features a modern GOTO system and can be run from the computer.

AT6RC atop an iOptron ZEQ25 mount, note the additional counterweight necessary
The chatter over at Cloudy Nights was promising. A few early production mounts were in the hands of some stateside amateurs, and they have been posting their impressions and images. I was particularly impressed by the measurements of periodic error with results around two arc seconds. This was a small mount that could very easily be a good astrophoto option.

I ordered the mount from the good folks at OPT. It was not yet listed in the website catalog, but a phone call confirmed they were expecting delivery of three mounts shortly. I put down my deposit. A week later I had confirmation that the mount had been received and was ready for shipment to Hawaiʻi as promised.

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It looks like it may clear. There should be a few dark hours before moonrise. Maybe I can get the new astrophoto rig out and get everything working properly.

<Commence tropical downpour>

Nothing like two tenths of an inch of rain in half an hour to put a damper on astronomical plans.

Maybe it will clear later.

Scope and Rain
A tropical downpour ends plans to use the ‘scope.

Shift a Little Weight

The trade-winds have returned for the evening. And while they are welcome for the comfortable temperatures they bring, the winds are unwelcome for the problems they create at the telescope. I am trying to get in one last exposure sequence for the evening, but the guider graph shows trouble. There are constant errors, not small errors either. The Right Ascension axis seems to be the issue, with errors of +/-3 pixels on the guider. This is just not going to work.

I watch the graph for a while, trying to figure out what I can do. I have had an issue where the guide star was the source of the problem, two stars to close together, a double star I did not notice when selecting my guide star. I stop the guider and select another star… The problem continues.

As I feared, my problem is most likely the wind this evening, a continual issue on this rock I live on. A speck in the middle of a very large ocean, the winds are a fact of life here. I only shoot with small telescopes, less sail area to catch the wind with a short tube. A TeleVue 76mm, an AT6RC, or simply a wide angle camera lens. The smaller scopes provide less loading for the old Losmandy G11 I mount them on.

I decide to try something else, shifting the balance to load the RA gear down. I gently slide the counterweight down the shaft about an inch. There is barely a blip on the guider as I make the adjustment. Better yet the guide error graph settles down! Looks like I will be able to get in a few more exposures before putting the ‘scope away.

Guider Error Graph
The guide error graph showing the effect of shifting a counterweight.