Not Quite The Right Length

So the thumbscrews from KustomPCs came in just under 24hrs from Scotland!

Great service, however they are not long enough......

At 4mm in length they match the original thumbscrews, however can only be screwed in upto the head and no deeper this makes them useless, still, I have a nice set of PC case screws....

I have decided to order some 'eyepiece' thumbscrews from 365 Astronomy. They are M3 with a 10mm thread length, which should ensure they are long enough. 

Back in the Saddle….so to speak!

December 30 2013

Wow, its been 11 months since I last did any real astronomy or astrophotography. The past 11 months have been difficult due to weather, motivation and life in general.

Anyway, I have decided that 2014 is going to start off on the right note and to get myself going I am starting with the age old job - collimation. 

But, not collimation of a conventional scope, rather my AstroTrac (AT) Polarscope. To help others I have decided to document the process in one place.

So how do you collimate the polar scope of an AT and what do you need to do?

Collimation is two fold. Firstly, we need to make sure that the polarscope reticule is centred, secondly we need to make sure the polar scope arm rotates, centrally, about the AT.

Step One - Polarscope Reticule Centring

The initial step is to ensure that the polar scope is centred about its own axis.

To do this you need to first set up your AT and aim the polarscope on a distant object such as a pylon, telegraph pole or any other distant, stationary object

Once you have chosen your object align your polar scope so that the centre (the intersection of all markings) is aligned to the top, or other definable point, of your object. Once aligned you can rotate your polarscope through 360 degrees. A correctly collimated or centred polar scope will keep its place when rotated. If your polar scope is badly collimated you will see the centre move around and off your definable point as you rotate.

I chose a distant radio mast with a conveniently placed light ontop. The following set of photos show how the light is covered, but then emerges as I rotate the polar scope around through 360 degrees:

This clearly shows that the polar scope is in need of collimation.

Here is where the fun begins!

To collimate the scope you need to adjust the 3no grub screws that are located around the barrel near where the illuminator sits:

To help with the adjustment I have ordered some 3mm thumbscrews to replace the grub screws used.

I currently have them on order from here:

http://www.kustompcs.co.uk/acatalog/info_24014.html

Now I just have to wait to see if they are long enough......

Astrotrac Second Light

February 28 2013

Hold on, two clear nights in a row, this has to be some kind of record! After yesterdays failure tonight was a lot easier. Set up was quicker and I managed to set the Astrotrac to track this time.

My target was Orion with my Nikon D7000 and 105 macro lens. I have only captured an hours worth of data as my batteries werent fully charged by the results can be seen below:

It was so refreshing to be out imaging again with a quick set up and tear down time and I cant wait to take it away to some real dark skies. What it has told me, however is I need to work on my editing skills!

Astrotrac First Light

February 27 2013

Clear skies! Who would have thought, the day after a new purchase of astro kit and the skies are clear! Upon closer inspection there appears to be high level cloud and the seeing is particularly crap but that wont stop me setting up and practicing with my Astrotrac. Im still waiting for a new replacement illumination module but for now I can use the faulty unit.

Set up was easy. A Manfrotto geared head sits on my tripod and the Astrotrac atop this. This allows adjustment in the three major axis to help balance and polar alignment. On top of the Astrotrac a Manfrotto ball head and my camera, allowing the camera to shoot any part of the sky.

Aligning is quite simple, the polarscope is mounted to the unit and rotated so the constellation orientation matches whats overhead. The geared head is then tweaked to bring the pole star into the gap as marked. This can be further refined if you have good skies using the second and third star epoch markings in the polar scope.

Once aligned the unit can be powered with its supplied cigar lighter and powerpack or via AA batteries. After pressing the start button the screw unwinds about 25mm to balance and get itself ready, a further press of the button will see a green pulsing light and your away tracking.

Now, In my haste to get imaging I forget to actually set the Astrotrac tracking so ended up with an hours worth of subs all with star trails. Still, the as I said above the seeing was terrible with high level cloud that the data collected wasnt usable.

New Toy

February 26 2013

Today my new toy arrived. An Astrotrac! Speedy delivery from FLO saw it land on my desk at 9:00 this morning the day after it was dispatched.

I have been a little frustrated with how long it takes to set up my EQ mount and get going and it will be a while before I am in position to think about a pier and obsy. That, combined with some local holidays around the UK coming up (to places which promise dark skies) I decided to get something that was more portable, and also easier to set up to get me back out imaging.

I had looked at various items such as a Polarie and GPDX after advice from various people but settled on the Astrotrac as it satisfied my thirst for well constructed kit but also had increased capacity over its closest rivals.

So what can I say? The Astrotrac is indeed a very slick piece of engineering. Two aluminium arms are connected by a precision screw which gives up to two hours of sidereal tracking. An illuminated polar scope allows accurate polar alignment, now all I need is some clear skies.

A slight hiccup with a dodgy illuminating module and no instructions but this was quickly resolved by FLO with no quibbles.

A General Update

February 24 2013

So its been over 3 months since my last post and I have a bit of free time so thought I would let you all know whats been happening.

My weather station has, unfortunately been returned. After the second anemometer failed I thought it best to return the complete station for a refund. I think further research into this will be needed and may a bit more money spent on a units if I decide to venture into weather records.

The wife and I have booked a couple of week breaks this year, one in Skye and one in west Wales. Both breaks are to the places with good dark skies and good opportunities for mountain biking - perfect. In order to limit the amount of kit Im taking I have decided to buy myself an Astrotrac. Hopefully this will also get me imaging more as it will be easier to set up and use than my NEQ6 and 250p DS. Ultimately I plan to have this mounted in an obsy, but thats a while off yet.

So, feel free to come back and check out my blog as Ill be updating it when my new toy arrives.

Weather Station Update

November 4 2012

So its been slightly over a month since Ive got my weather station I thought I would post the highs and lows recorder for October 2012.

There is a slight bug at the moment in that the anemometer works intermittantly. The other day it was spinning but hasnt spun for several days since. Therefore the wind readings will be skewed in terms of speeds.

Anyway here goes:

Summary for October 2012

Temperature (°C)

Mean Minimum: 7.5

Mean Maximum: 12.5

Minimum: 0.0 day 27

Maximum: 15.3 day 02

Rainfall (mm)

Total for month: 75.0

Wettest day: 12.9 day 05

High rain rate: 18.0 day 15

Rain days: 24

Wind (mph)

Highest Gust: 36.5 day 17

Average Speed: 5.6

Wind Run: 4104.4 miles

Gale days: 0

Pressure (mb)

Maximum: 1026.4 day 23

Minimum: 976.7 day 31