First Light: Coronado PST

[Woking]

I've not got round to doing a first light report before, so go easy on me;)

I recently acquired a second hand Coronado PST and after a few checks to make sure it was safe to use, decided to take the plunge with the lovely sunday afternoon we had today.

The PST is an old one and is showing the initial signs of the 'rusting', hence double checking no issues for safety or performance.

Further to a recommendation by a fellow SGLer, I've fitted the PST to my EQ3-2 using the Deluxe Vixen style dovetail supplied by Modern Astronomy. The 1/4 inch bolt fitted snugly, however typically I did not have the exact sized allen key from my collection of about a dozen! To ensure there'd be no play I also used the PST's bolt too, so it's snug and secure with 2 bolts connecting the PST base and dovetail.

Attaching to the eq3-2 I removed the 3.4kg counterweight which is usually on the mount and possibly did'nt even need the 1.8kg counterweight either but left it on anyway.

Alignment was fairly simple by a rough pointing of the PST at the sun and then with the axis clutches off aligning the sun's disc in the PST finder.

Job done, now to try with the EP. First EP was 18mm and decided to use a piece of card just in case. This process would have been quicker if I had remembered to take off the PST's front lens cover (won't be the first or last time!).

Projecting an image onto the card did'nt seem to work, so gave up and 'tested' with my non-observing preffered left eye. Was rewarded with a non focused red disc, now to play around with the focus and the etalon....

I was using a range of EPs and found each one required a focus tweak. The 18mm delivered the sweet spot for me but got some great detail in 24mm, 30mm and 6mm. Using the Nagler zoom, 6mm was about the highest mag, with 5mm and higher not producing sharp views.

The etalon was nice and smooth to use. Turning it towards the PST base brought out the sun's prominances and filaments, just wow! There was a nice big sharp sunspot about a third of the way down from the northern edge of the disc. Above this on the edge there was what appeared a hive of activity with flares heading straight up and some nice flares looping back down again. There was a whopping great big prominance. The detail was superb.

The surface was showing activity with at least 3 obvious filaments, one in the southwest of the disc looked like a massive long chasm in the sun. The detail was again sharp.

Adjusting the etalon away from the base towards the front lens just seemed to smooth the disc removing any activity just showing the sunspot. In fact the sweet spot for prominances and surface activity was just a fraction of a turn from the base end.

Am I missing something here?

All in all, a great few hours solar observing on a sunny sunday afternoon and importantly my eyes are still working!

Solar viewing is obviously pretty limited in terms of sight seeing but great for a occassional couple of hours outside enjoying a sunny day. Also I'll probably be now making the effort to set my alarm clock for Venus's transit in a few months time.

Couple of pics of the set-up taken using my naff Blackberry camera....

[twotter]

Great first light (that's a cracking pun for a PST ) and you've made me think I'd like to try one some day.

[twinhexydan]

The eyepiece is nearly as big as the ruddy tube, viewing through one sounds fantastic , I,ve made a baader film filter for my 12 inch dob but all is seen is sunspots nothing else, while wowed by seeing sunspots for first time I,m a bit disapointed with the restriction to just that.

would love to know what pst,s are made of.

dan

[Merlin66]

Woking,

Good first light! Glad you managed to pick up the level of detail you did, well done!

There are no ssafety issues with the PST - even with a "rusty" objective, they are still 100% safe to use.

The Ha tuning position by design is always close to the end of travel....it's normal.

Dan - not sure how to answer your question... if you mean what sort of filter do they use?

It's basically a three stage affair

The tunable etalon gives a series of images about 0.8A wide and every 10A across the whole spectrum, then the "mini-ERF" rejects 99% of the incoming energy and finally the blocking filter, at the eyepiece sorts out the various etalon images and only allows the one at Ha to get through...Majic!

[Woking]

Cheers Merlin, and you've provided more useful info than the actual PST instructional leaflet!

I'm really pleased with it and would recommend it to others, especially if you can pick up a good secondhand one for sale.

[JB80]

That's a nice report with lots of info, thanks for sharing.

I have always thought about putting it on the EQ3-2 but it's not an urgent issue yet.

Another good tip that may be of use and again it was suggested to me by Merlin is to use a vegemite lid to help with finer focusing, shown in the picture below. It can be a bit fiddly with the little knob.

The only thing is for it to work it must be a vegemite lid and you must have eaten the whole jar first.

I'm fairly certain you could use a similar lid though.

[Woking]

I like it Pibbles! Cheap or no cost mods are always the best.

The eq3-2 is the only tripod mount I've got and the PST was just fine on it. Nice only having to twiddle the one knob too.

[twinhexydan]

Hi merlin 66,

many thanks for your enlightening, will file that.

I love to make things myself as much as use them, I have a twelve inch reflector which I,ve made a baader filter for. but would love to know if making a system for a bigger scope than a coronado is possible in the diy range ??

the objective being to get more visual detail, or am I barking up the wrong tree here ?

I couldn,t help noticing your avatar pic of a merlin spitfire---being a aussie

lad , was wondering why the interest, as we dug one up last year on our farm.

I managed to get some damaged parts as souvenirs to keep, and one part (the prop connector) I have managed to include in my 630mm binoscope mount, in memory of the poor chap who manned the cockpit.

If you wish for an elaboration with some pics let me know.

the splined part was the only complete surviving piece of the whole plane.

regards Dan

[Merlin66]

I have a detailed write-up available on doing PST Mods ( to use a larger aperture scope)

PM me an email address for a copy.

In a previous life I designed highly detailed and accurate merlin engined Spitfire models for MS Flight Simulator - some 30 different types - over 30,000 downloads - just look for YAS Spitfires (Yet Another Spitfire)

My avatar - The merlin66 was the best merlin engine built by RR and powered the MkVIII in Australia.

[swamp thing]

Nice write up Darren. Not sure about that phone cam though.

With these lighter evenings it'll give you something to do whilst waiting for dark.

Regards Steve

[sungazer]

Hello Darren, A most interesting PST write up, i have used one for many years with great sucess, the only thing i would recomend is a light shield which makes it easier to use as this keeps stray light out of your eyes. BCF and Astro Equipment offer metal models, though home made ones are just as effective.All the best ,John.

[jam1e1]

Great write up didn't realise you acquired this too- now I'm jealous! May look at getting one in future, tho not for a while

[Woking]

We'll have to arrange a Surrey Observers solar viewing afternoon some day. The Venus transit is apparently at sunrise Wed 6th June, so if it's clear might be worth an all night session!

John, to be honest I did'nt find the glare from the sun that much of a problem. Possibly because the sun was'nt directly overhead or the angle of the EP was favourable? However some of the EPs which occassionally kidney bean on me seemed to be a bit worse, but no idea if related.

It's a great little daytime scope and LP is never a problem.

[Sam]

Great write up! I'm thinking about getting into solar astronomy so this post have provided some very useful information, thanks!