MercianDabbler

I'm curious... why the new diagonal?

I've been meaning to get around to figuring this out. Having re-read the manual several times I don't think I fully understood how to do it in 1988 when I bought the scope and now there is the additional complication of Polaris having moved beyond the positions shown in the manual. On the plus side I have an Android tablet and access to modern polar alignment apps but I can't say that I really understand how to use the two together. I've been struggling to ask this question in a simple way and have failed, so apologies for that. Hopefully someone will stick with me... The manual is somewhat terse in its descriptions... Whaaaat?? So line the RA hours and minutes for now (in local, DST or UTC??) up with the current day and month... I think?? Here are the dials... Skipping the straightforward stuff about levelling and uncovering the polar scope... finally the manual explains what to do with the reticle... My longitude is 1.5 degrees west. Let's say it is tonight (23 Oct 2020) at 21:00 BST. I have the option of using a tablet app. Most of these show a view that looks like the reticle, but my reticle was designed for the position of Polaris in 1986. It seems to me that this is solveable but I'm unsure which bits of the SP instructions are redundant if I use the tablet app. The tablet app on its own doesn't seem enough because I still need an accurate way to transfer the setting from the picture on the tablet to my alignment scope. One app (PolarFinder) provides a 'HA' number (I guess this is the Hour Angle for Polaris) and a 'P.Scope' number (no idea!) but the help suggests transferring the alignment by eye and does not explain what to do with these numbers. Can I rely on 'up' on the tablet being the same as 'up' in the scope? The big circle in the SP reticle is (if I understand the diagram correctly) 48 minutes of arc in radius, which isn't right for 2020. I'm guessing that the tablet app shows a circle that is correct for 2020. I think this should be 39 minutes radius given that the decl of Polaris now is +89° 20' 56.9" The change in Polaris position shown in the manual seems rather more than other sources suggest - I've read 1 minute in 5 years. Is the manual wrong? Another option (I hope!!) may be to just use the hour angle for Polaris from Stellarium but I'm unclear how to make this work using the scope dials. I'm hoping that I can figure out how to position the reticle so that Polaris should be exactly on the line towards the smaller circle but it seems to me that if I follow the instructions to the letter then that would have happened in 1986 but it won't work in 2020. Some bits of the instructions need to be ignored, but which bits? Then if I get Polaris onto the line I just need to judge where 39 minutes radius would be. Thanks in advance.

Definitely a Saturday. That was before the Interweb so you had to actually go and fetch things. Probably 2 hours journey each way... plus I wouldn't fancy driving into London on a weekday then or now. It was well worth a trip to BC&F anyway - I can't imagine having the discussion and swapping the eyepiece fitting on a scope as part of an eCommerce transaction. I'll check out that app, thanks. The Telrad does look like a good bit of kit but I'm probably already overloading the SP mount so I'm thinking that the Rigel will add less weight while still hopefully doing a decent job.

Thanks for the link - interesting to see the up to date reports. Yes I did use their leaflet to find sites but showing just 'Brendon Two Gates' on the cross moorland road did strike me as missing the opportunity of showing the other parking areas slightly further North on the same road - these are more open and in most cases allow you to get further away from the road than the site indicated on the map. The Goat Hill Bridge site is not shown in the tourist board leaflet - this one came from the 'Go Stargazing' web site.

Just found this thread - couldn't agree more. The Vixen is great. Mine was bought on a Saturday afternoon outing to Telescope House around 1988. I chose a refractor because although my preference is for looking at galaxies and nebulae I knew that I would be an 'off and on' astronomer... and so it has proved but the Vixen can be relied on to lie dormant in its box for ages on end and still perform when I want to drag it out and try to remember how to work it. It's also a suitable size for packing into the car to escape my local light pollution. I never had the Vixen eyepieces - BC&F traded these up to two Meade Super Plossls (6mm and 24mm) and swapped the eyepiece fitting when I bought it. It does have the original Vixen RA motor drive which still does its job. At the time I thought 'I can always buy the decl motor later'... wrong! The pic below is a bit rubbish (didn't even have the dew tube on) but the 2016 transit of Mercury was one of the few occasions when the scope has been out in the daytime. My initial good intentions about photography never materialised during film days but a Canon DSLR now allows me to attempt to muddle my way through some AP. Since the pic I've added an ADM dovetail on top to piggyback a cheapy Skywatcher ST80. A couple of weeks ago I finally got around to adapting a couple of 1.25kg weight training weights to balance the extra weight ahead of my trip to Exmoor. The scope and its little friend did their job well on the trip - a shame the operator was quite so out of practice! In terms of future plans... 1. I'm wondering if there is any way to update the polar alignment scope in the mount (or maybe just the diagram from the manual) - the indicated Polaris positions ran out circa 20 years ago... plus I still don't understand how to set the polar alignment scope dials. 2. Two eyepieces seems too few but I'm undecided about what would be a worthwhile addition. 3. Maybe some filters - currently I only have a sodium light pollution one which now seems like yesterday's news. 4. Getting the thing pointed in the right direction can be a faff so maybe a Rigel finder? I'm against sticky pads though so will need to find a better way to attach it.

Alas I'm now back to my familiar Midlands sky glow and the telescope is tucked up in its box. Not sure on the etiquette of cross posting/linking on here. Views from locals would be very welcome, as would views from visitors like myself.

Just back from a week on Exmoor... planned for the waning/new moon and with the telescope along for the ride. I had a few clear nights and needed to figure out where to set up. Doing a search online turns up pages and pages of recommendations but most seem to be either direct from the tourist board or various newspapers and travel sites basically rehashing the same info. Finding recommendations from people who had actually used a telescope on Exmoor proved more tricky and some postings on here were about the best I found so thanks to the folks who posted here. If anyone knows of any other good info (i.e. based on experience) then I'd be interested to know. Do other folks really spend their nights set up in rural car parks with occasional passing traffic? I didn't see anyone else doing astronomy, in spite of the moon phase and proximity to the Dark Skies Festival. A few experiences of my own, staying (this time) near Combe Martin at the West end of the moor... The tourist info centre has a leaflet with a map of the darkest areas and recommended locations for observing. I was puzzled by a 'minor road' shown running through the dark area which as far as I can gether is not a road at all but a boundary line. One cloudy night was forecast to clear later (it didn't). While waiting I checked out a few of the recommended sites... 'Brendon Two Gates'. A cattle grid on the B3223 road across the moor. Two big laybys to the south (enclosed) side. Continuing North is more fruitful - the road is then unfenced and there are several car parks with clear views to the West. A couple of these were my chosen observing locations. They can be pretty exposed in windy conditions. There were two distant pools of sky glow to the West, presumably from Barnstaple and Ilfracombe. The road was quiet at night with no more than 5 cars passing during the 2-2.5 hours I was there each night. Several car parks were occupied by camper vans parked up for the night. Watch out for sheep bedding down on the road too. 'Goat Hill Bridge'. Two laybys alongside the B3358 road. In a river valley with high ground to either side. I didn't stick around, feeling that there would be more passing traffic on this road. On one night I passed this location the fog was so thick you could cut it with a knife... fortunately the higher B3223 car parks were crystal clear. 'Valley of Rocks'. I was only here during daytime. Two off road car parks. A deep valley so forget anything near the horizon but if you want star trails with spectacular rock formations in the foreground then this is the place. The 'through' road goes across a private estate and I imagine that passing traffic will be minimal. 'Holdstone Down'. A proper off road car park on high ground overlooking the Bristol Channel with views across to South Wales and attendant lights. Higher ground to the South and West so objects near the horizon would be hidden. Ithe road here is very minor so I would expect minimal passing traffic. 'West Anstey Common'. Not one from this trip but I spent a few hours there on a previous trip when staying near Dulverton. Not in the darkest part of the park, having open views over the hinterland between Exmoor and Dartmoor. Parking near one of the boundaries it was possible to get a fair way off the road and the boundary shielded me from any approaching headlights from that direction. Passing traffic was infrequent. Anyone got anything to add about these or other sites?