New Forest Observatory ®

I spent a couple of hours yesterday taking the imaging Sky 90s off the mini-WASP frame, collimating them with the Takahashi collimator, and then putting the whole thing back together again.  Well – as far as the collimator goes, both Sky 90s are pretty much spot on with the collimation, now just need to see whether an imaging camera agrees with the collimator.

The two imaging Sky 90s are the 9-grub screw collimation adjustment version, and collimating these scopes is relatively straightforward (I wouldn’t say easy).  I also have one of the original 3-grub screw versions of the Sky 90 and as far as I can see it is not possible to collimate these using the grub screws (the reason for this is obvious if you take the lens cell apart).  So what I might do with this Sky 90 is get the lens cell modified so that I can adjust the lateral position of both the front (Fluoride) lens and the rear (glass) lens of the doublet and get myself a third viable imaging Sky 90.  This is a LONG term project!

Nick Hudson (True Technology) visited the New Forest Observatory yesterday and brought with him an essential piece of kit for tuning up the mini-WASP array.  Yes – the thing that has been halting any further progress on mini-WASP commissioning has hopefully now been sorted with the arrival of a Takahashi collimator.  This collimator is very interesting, it is basically a Cheshire collimator with bells and whistles.  So on the end that you “look through” there is an adjustable eyepiece, this allows you to focus in on each of the “doughnut” reflections that you get off each glass surface in the lens cell.  I will now spend this weekend seeing if I can bring the Sky 90s into the tight collimation I know they are capable of.  With spot-on collimation the Sky 90 will cover an APS size chip and give good star shape (and size) right across the diagonal.  If collimation is even the tiniest bit out you will get coma in at least one corner of the chip.  Cheers Nick – you have rescued this (rather ambitious, meaning almost too much for me) project 🙂