New imaging setup

[alan4908]

I've recently completed a major upgrade of my automated imaging setup so, I thought I'd post a few pictures.

I've had my NEQ6 and SW ED80 since I started astrophography but I decided at the start of the year that I'd like to attempt unguided imaging. This was primarily motivated by the fact that when I looked through my ACP logs, I discovered that my major cause of sub error or imaging inefficiency was through some form of guiding related issue.

Mount

So, with limited imaging time in the UK, I decided to go down the path of unguided imaging and selected the 10micron GM1000 HPS. The main reason for selecting this particular mount was that 10micron have built up a solid reputation in unguided imaging and the GM1000HPS was sufficient to carry my proposed scope upgrade, a SW Esprit 150.

Although I have surge protection on all  my obsey mains outlets, we experience short power cuts quite often (eg power cuts lasting a few seconds) so I also decided to install a UPS in my obsey for the 10micron mount Linux computer.

Since my scope can hit the obsey roof, I also decided to transplant two roof closure safety switches that I had installed on the NEQ6 to the GM1000HPS. These are attached to the RA and DEC axis and ensure that the roof can only open or close when the telescope is in a predefined (safe) position.

Since time synchronization is very important for unguided imaging, I decided on a strategy of having the PC as the master clock with the mount as the slave. To keep my PC synched to an accurate time base I decided to simply reuse the (free) Meinberg NTP time server which I'd previously used with my NEQ6. Since having an accurate time synch is critical for unguided imaging, I also decided to explore how I could monitor what my PC clock was actually doing.  I discovered that Meinberg also produce a free monitor program that can be used to plot various statistics, these show that my PC clock is accurate to a few ms and is synched every 10s.

I also decided to purchase Mbox, an ASCOM compatible weather station that measures temperature and pressure, it can also be used with Per's 10micron ASCOM driver which I've configured to push time, temperature and pressure updates to the mount whenever the mount is slewing. Between exposures I dither which in ACP creates a slew to the mount.  

For my first experiments with unguided imaging, I decided to use my existing SW ED80 mainly because I thought it should be easier to learn on a relatively short focal length and lightweight scope.  Here, I had quite a lot of initial success but occasionally I had elongated stars which I believe were caused by a combination of cable snagging, poor sky modeling and scope flexture.

So, on the cable front, I decided to copy the method Per had used to route cables on his mount. On the flexture front, I removed the felt lined tube rings and replaced them with thin styrene, which I superglued onto the rings.  On the sky model construction, I discovered that making a sky model with a the maximum number of points (100) that are evenly spread across the sky gave more consistent results.

Scope

Whilst I really liked my ED 80,  I decided that I needed something that would get a bit closer to the various DSO's that I like to image. I also decided that I'd like something with a lower chromatic distortion but was  almost maintenance free.  So, after looking at various options, I selected the Esprit 150 mainly due to the very positive reviews. Since I wanted to get very accurate focusing, I decided to go for an upgrade on the focuser to a 3" Feathertouch.   To enable autofocus operation, I selected a Feathertouch stepper motor, mainly because of the simplicity of installation.

The first thing that struck me about the Esprit 150 is the weight distribution, which, as you would expect, is mainly towards the objective. Since my obsey is quite small, the only way of achieving balance was to attach a second Losmandy bar to the top of the scope rings and then attach some ADM counterweights can that slide along the rail prior to locking.

I decided to follow the same approach on the scope rings as my ED 80 - remove felt and replace with superglued stryene.  I was much happier having an all screw imaging connectors since I wanted to minimise flexture, I also liked the feathertouch "captains wheel" that allows you to rotate the camera - I always set this so that the RA and DEC axis are aligned to the camera axes. 

I'm currently using this with my existing camera, a Trius 814 which gives me a plate scale of 0.7 arc seconds per pixel. I was a little concerned that this might be too low but it turns out that I often experience seeing of 2.5 arc seconds, so after experiencing the initial results of this set up, I'm quite impressed. 

I also took the opportunity to do some observatory enhancements whilst waiting for the Esprit - I've now labeled all the mains outlets, since I was loosing track of what was plugged into what and installed some drainage channels around the base.   I'm not sure which looks more impressive, my drainage channels or my new set up !

Alan

New imaging setup

 

Focuser and stepper motor

 

 

 

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Observatory drainage channels

[andrew s]

Nice work Alan. It all looks very professionally done. I still have to automate my ROR so I would be interested to know how you did it.

I assume you use the internet to provide the master clock for NTP in which case there will be some jitter and offsets but over and above what the monitor records but I am also sure it will be more than adequate.

Well done regards Andrew

[Alien_Photons]

Looks fantastic !  You must be pretty excited.

[darknight]

wow, lovely scope and a nice write up, I can only hope my obsy will look that tidy.......oh very nice drainage channels

[steppenwolf]

Looking very smart and professional, Alan -  hope you get some good skies soon to put it all into action.

[alan4908]

1 hour ago, andrew s said:

Nice work Alan. It all looks very professionally done. I still have to automate my ROR so I would be interested to know how you did it.

I assume you use the internet to provide the master clock for NTP in which case there will be some jitter and offsets but over and above what the monitor records but I am also sure it will be more than adequate.

Well done regards Andrew

Thanks for the comments Andrew - I don't know how the Meinberg software calculates the internet jitter and latency from the various NTP servers, so I'm unable to comment on the accuracy of these parameters.  

I purchased my ROR from Ian King which came with my selected options of an electric roof and weather sensor. All these these components are supplied by Hitecastro. The electric roof has obstruction detectors, the Hitech weather sensor is both ASCOM and ACP compatible and incorporates temperature, moisture and a sky clarity detector. It estimates the clarity of the sky by taking the temperature difference between the ambient temperature and the sky temperature which it measures via an IR sensor.

On the automation software side, I decided to go down the ACP Expert route mainly because I wanted maximum flexibility in automation control and also because I had previously purchased Maxim DL. On the autofocus front, I started using Maxim's own system before progressing on to use FocusMax.  More recently, I acquired CCDNavigator. This has recently been integrated with ACP which allows you to image DSO's with a few mouse clicks, basically it automates the construction of observing plans.  I don't currently switch anything on/off remotely, mainly because I like to inspect my obsey after a night's imaging and so don't find it too inconvenient to switch a few things on/off. 

I've found all of these products highly reliable, so I would have no hesitation in recommending them.

Alan

 

[alan4908]

1 hour ago, Alien_Photons said:

Looks fantastic !  You must be pretty excited.

Thanks - yes - all I need is some clear nights !

1 hour ago, darknight said:

wow, lovely scope and a nice write up, I can only hope my obsy will look that tidy.......oh very nice drainage channels

Thanks ! - glad you like the channels.

25 minutes ago, steppenwolf said:

Looking very smart and professional, Alan -  hope you get some good skies soon to put it all into action.

Thanks Steve.