The rearrangement of my astrophoto setup proceeds. If somewhat frantically in the face of the upcoming Transit of Venus. Another device has joined the toolkit, a bit of hand-wired electronica that gets the job done.
This particular device will allow remotely guiding of the telescope during the seven hour long event. The computer sitting beside the telescope will be controlling both a camera and the mount. Also set up on the computer is a VNC server, so I can remotely view the screen from inside. With this arrangement I can keep an eye on the whole setup, including nudging the telescope as needed to keep the Sun centered in the image. Since the mount will only be roughly polar aligned, set up during the day, I expect to get a fair amount of drift during the event.
I did not design the device this time. This would have been completely within my capability, but why do so when someone else has already done the job? This is typical within the astronomy hobby, where many designs are shared for the benefit of everyone. In this case it is the USB to ST4 adapter designed by Gene Nolan.
All I had to do was follow the schematic and download the code into the microcontroller, the device worked first time. Gene does sell kits, but I wanted to do this quickly and had everything I needed on hand except the microcontroller and opto-isolators.
The only real problem that cropped up during construction was the wrong part received for the opto-isolators. The DigiKey description read DIP-8, so I ordered it, expecting to get something that fit into the DIP socket I had already wired onto the board. When the parts arrived I found that they were indeed DIP… lead-formed DIP packages meant to be surface mounted, with chopped off leads. I ended up soldering the devices to another DIP socket, using it as a header, which then plugged into the socket on the board. It looks funny, but it works.
It did take a couple hours of downloading and installing the drivers and other useful software packages to get everything working. This includes the very useful ASCOM driver framework, and PHD Guide. Both of which I plan to use beyond the upcoming Transit of Venus to do more astrophotography.
My wife may have been a little perturbed by the testing setup strung across the kitchen table, a laptop and the heavy Losmandy head, a Canon 60D camera, all connected by a snake pit of cables. But it worked, first time, that is always nice.
Another new Moon weekend, another observing outing to Mauna Kea. With some shiny new astro equipment to play with I decided to load for photography instead of visual. Disassembling the photographic mount I realized it had not been taken apart in over two years, setup in the garage and used in the driveway. I did not expect to be alone, a few other local observers had indicated plans to get out this night.
Worry on the drive up, the cloud deck seemed quite high. I was concerned that the Mauna Kea VIS, at 9,200ft, may be in the clouds. With wipers and headlights on, through the heavy fog I drove, not encouraging when you expect to use a telescope. The worry persisted until the last switchback, ascending through the last wisps of cloud just a few hundred feet below the VIS to behold a cloudless blue sky overhead.
As expected the Mauna Kea Visitor Information Station was a zoo. A dozen summit tour buses added to a heavy Saturday night crowd. The parking lot was full with even more cars parked along the road. Not a real problem, the tour buses use reserved spaces right in front of the building. They pull out about an hour before sunset, headed for the summit with their customers. We swoop in on the vacated parking spaces and set up our gear.
The crowd is an interesting experience. Well over a hundred folks waiting for dark and the evening program. There are the usual issues of headlights and camera flashes. It may not be all that dark for a while, but we gain a nice paved place to setup, and there is electrical power available. The crowd will slowly wane as the night progresses, mostly gone by 9pm, driven off by the cold. At 10pm the VIS closes and the remaining lights are turned off.
In addition to the VIS telescopes, there were quite a few local amateurs taking advantage of a moonless Saturday night. Cliff and Tony brought Cliff’s 24″ Dob, a two person job to move that ‘scope. Wayne brought photography gear. Mike was likewise set up for photography, planets instead of deep sky, using a Flea 3 and an ancient 10″ Celestron. Olivier brought his 19″ Pricilla, providing plenty of glass for visual astronomy while the cameras exposed for hours.
It was Malalo o Ka Po Lani, cultural night at the VIS, with a special lecture. This meant a large crowd, most of whom stayed to enjoy the perfect skies the mountain provided this night. They wandered around the telescopes asking lots of questions. While the photographic ‘scopes did not offer views through the eyepiece, there was still a lot of interest in the process. I chatted with many folks as I worked, fiddling with the complex equipment necessary to take photos of the sky.
It was quite the gathering of Losmandy G-11’s! Wayne brought two, Mike brought one to carry the old 10″ Celestron, I had mine setup for photography with the AT6RC. Add the three that the Mauna Kea VIS uses! A testament to these well-built mounts, some of which are two decades old.
The astrophoto gear was working nicely. There were a few issues to deal with at the beginning of the night, the usual new gear stuff. A few things I need to fix before next time… need to remount the guider so I can co-align it with the imaging ‘scope. I need to mount a real finder, and make it easier to hunt down the targets. But overall I was pleased, the new setup worked as I hoped it would.
I will write more about the SBIG ST-i later. The short version… Much easier to use than the ST-4, accurate, painless acquisition of guide stars, it just locked on and stayed there. The only real drawback is the inability to dispense with a computer. I recently re-built one of my older laptops for use as the astrophoto machine. But since the computer is going to be there, I may as well use it, time to integrate the DSLR with the computer and shoot tethered. I have the software, just that I had tried to keep it simple in the field.
Another pleasant surprise was the ease of focusing with the AT6RC with a Bahtinov mask. I have been wondering about the stock focuser on the new ‘scope, how well does it handle the heavy DSLR camera. One lesson is that it locks the focus quite well, I noticed no drift each time I checked focus. Indeed, at one point I pulled out the 60D, swapped the focal reducer and adapter onto the 20Da and checked focus again, it was still perfect.
While my camera took exposure after exposure, I took in the views that big glass can produce. Bouncing back and forth between Cliff 24″ and Olivier’s 19″. No surprise for a spring session, galaxies were in rich supply. We viewed a lot of the showpiece objects, from Ursa Major to Virgo and Corvus.
This night was the type of night we hope for when planning an observing outing… Not too cold, no strong wind, and no clouds. Just a dark sky to delight the imagination all night long.