Sunday, August 21, 2016

16.3 V Power Supply for Losmandy Gemini

My G-11 performs quite well and I am very happy with it, but I do note that despite careful balancing I occasionally get Dec or RA Heavy Tr warning messages.  I've read numerous times in the Gemini forum that these mounts are a bit under powered at 12-13 volts from a battery.  The Gemini system can take up to 18 volts, but most users seem to recommend 16 volts.  The Losmandy power supply provides ~ 15 volts from 110 V AC, but I prefer to operate my astro gear from battery power even in the observatory.

After scouring the internet I came across a regulated DC converter that increases ~ 12 volts to 16.3 volts and can handle up to 6 amps.  The device is sealed and is available on Amazon at a reasonable price.     Here is the back of the device.

Here is the front of the device.  I've used wire nuts to connect a 12 v accessory power plug (cigarette lighter plug) to the input wires.  To the converter outputs I've used wire nuts to connect the Gemini power plug with the 2.1 mm right angle plug.

When plugged into my battery, the output to the Gemini unit reads spot on the advertised 16.3 volts.

Here is the finished unit attached to the side of the pier with heavy duty Velcro.

I'll be curious to see if my G-11 performs any differently and if I get the RA or Dec Heavy Tr warning messages.

Saturday, August 20, 2016

August 20 Update

While we had over 9" of rain over August 11 & 12, and the yard and street flooded, we were spared any damage to the house or observatory.  The worst of the rain was North of Lake Pontchartrain and West of I-55.  Many thousands  of people have been impacted, many without flood insurance.  If you are able to help, please contribute to one of the many charities and volunteer organizations that are providing aide.

Unfortunately the weather of late has not allowed any viewing but I hope to get back out under the stars in the very near future.  I have been able to complete a few small jobs in the observatory; installing foam insulation strips around the doors and building shelves in the office.

I recently learned from veteran video astronomer Ken James about a site that shows sky darkness around the globe based on satellite video infrared imaging.  The site is and I really like the maps.  The color coding for levels of light pollution, at least in my area, appear reasonably accurate.   There is also the option to display light pollution based on user submitted Sky Quality Meter readings, although this option didn't offer any data in my area.

Sunday, August 7, 2016

August 5 report

Earlier this week I updated one of my favorite astronomy software programs Deep-Sky Planner to version 7.  I've used this program for several years to plan my observing sessions and to record my observations.   I find the program exceptionally easy to use, full featured, reliable, regularly updated, and very well supported.   I've considered writing a review, but I've found that Rod Molise has penned very good reviews on his blog and in Sky & Telescope  magazine July 2015. If you don't use planning software or if you use a different program, give Deep-Sky Planner a look.

Aug 5 - A very warm & humid night but after an afternoon thunderstorm the skies are remarkably clear. Only a few spotty clouds. The rain cooled off the temp (it is 78 now at 2100 hrs). Mosquitoes are thick and I have the Thermocells going but I've already been bitten once.

My plan was to work on a drift alignment of the mount.  Since mounting my G-11 on the pier in the observatory I've used the polar scope to align, but I do observe image shift between 90 second exposures.  For this setup I'll used my Mallincam with no focal reducer or Barlow.
I followed the instructions written by Ray Shore and posted on AstroPhotography Tonight.  This was my first attempt at drift alignment and I approached it tentatively, making small adjustments, measure the drift, tweak some more, remeasure the drift, etc, etc, etc...  I did find settings that resulted in no perceptible drift for over 5 minutes, but after aligning the altitude and returning to check the azimuth, the drift had returned.  This back & forth went on for hours and frankly I'm not so sure that my final alignment is any better than when I started.   I'll revisit this process at my next observing session and hope to home in on a more stable alignment for my mount.