Mobile imaging with a 10 Micron GM1000HPS

[Tonk]

I've recently written a review on using the smallest of the 10 Micron mounts for Ian King, so I thought it might be useful to share some images of the rig that I used in the write up.

I've been developing an efficient mobile rig over the last 12 years for comet chasing given that the chances of capturing a good comet next to some exciting DSO is low from a fixed location in the UK. I have a series of preferred dark sky locations ranging across  the north of England from the Forest of Bowland via the Yorkshire Dales then across the Vale of York to the North Yorkshire Moors (I even shot one low-in-the-sky comet from my western most site in the evening and then travelled across the Dales to my eastern most site to catch it rising - to avoid the Pennine hills in between from limiting the horizon).

The criteria for the rig is it must be quick to setup, quick to polar align, be used unguided and not need a laptop to control it and can be powered and transported from the back of a car. My use of a laptop is limited to focusing and framing at the start of the session. The main imaging runs are controlled with an intervalometer to keep power usage to a minimum. I power my DSLR camera from the car battery using an Astronomiser power cord. 

The rig was originally developed around a Losmandy GM8/Gemini controller but was converted about 18 months ago to use a 10 Micron GM1000 and its controller. This increased the unguided performance from ~4 minutes to well over 10 minutes when using a Televue 85 (FL ~500 mm). This upgrade required a custom adapter ring made by AstroParts Ltd  to attach a 10 Micron base plate to the Losmandy tripod. The 10 Micron is significantly heavier than the GM8 and has the added disadvantage in that the clutches must be released when transporting or lifting which means that care must be taken to hold it right or heavy bits spin around! I bought the mount travel bag to ensure the mount doesn't get scratched when in the back of the car.

Polar aligning the 10 Micron mount is quick (~20 minutes) and very accurate (~15 +/- 2 arc seconds error now that I'm practiced) so its turned out to be an excellent mount for high mobility telescope astrophotography. 

[StuartJPP]

That looks like a very nice portable setup Tony...being able to get long unguided exposures is the holy grail for portable equipment. I have seen your comet photos before, they are what got me interested in them in the the first place...

My portable setup has changed recently but hasn't had much use yet due to weather...I am hoping that I can still be airline friendly, should be...

[perfrej]

I'll have to try portable with GM1000HPS in late August when it gets dark again. It is an interesting setup that I have only tried a few times as tests. I have recently made some imaging tests with my 2000 and very few points in the model. Surprisingly enough, the 18-point model I have in it right now has yeielded good round stars at 30 minutes unguided subs. I usually fill the model with the full 100 points...

/per

[Tonk]

One thing I forgot to mention was I definitely needed the GPS unit for both controllers (Losmandy Gemini and the 10Micron) - unless you know in advance exactly were you are going and plan accordingly or have other means to read your geographical coordinates, altitude and also have access to accurate time. If you want to be really accurate with low alt objects you will also need a barometer to enter air pressure for refraction compensation when sidereal tracking. For the 10 Micron - dual axis tracking is a must.

Per - I find that 15 to 20 stars is good enough for the FL/exposure times  I use (for all DECs) - especially if you do the PA mount adjustments off a star close to meridian/equator and at least two iterations of the model building/PA adjustments. Limiting to 20 stars max keeps the time to set up reasonable. I use a Barlow and an astrometric 12mm eyepiece for star centring.

The 10Micron rig is very likely *not* airline friendly (I haven't tried to find out yet)  but the Losmandy GM8 rig was (its been to Teneriffe, Cyprus and a few other places). The Losmandy mount and tripod can be heavily dismantled right down to the individual parts and I had a Pelicase to transport it all having got a packing scheme worked out to layer in all the bits including the separated tripod legs (might be worth digging an image of that packing! - the counterweight system was an empty bag to be filled with stones at the destination). The issue with the 10Micron is its significantly heavier and *cannot* be dismantled - it would void the warrantee and supposedly upset the absolute encoder calibration*. The mount head is covered with "warrantee void" detection stickers (you can see one in the picture - the yellow rectangular label)

(*the encoder calibration correction data is factory set in the controller so you can't even swap controllers  according to the bumf)

[perfrej]

OK, 20 points.. I'll do some testing when it gets dark again...

The control box can be exchanged, but you need to have the factory load your encoder calibration into it. In other words, if you need a replacement (or duplicate) control box - no problem. If you want to use one box with two mounts - no go.

/per