From: Mark Gaffney <markgaffney@me.com>
Date: June 5, 2010 3:05:37 PM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Plate solving
Milton,
The room I`m sitting in here is at present 15 degrees Centigrade at about 7.00 am in the morning.
It`s not a really cold night for here though. Surprisingly our lowest temperatures during Winter here match those for Sydney quite often, though the day time temperatures (if it`s sunny) can get up into the mid-late 20`s.
Not like your Summer extremes which appear to be at a low of 5 degrees..
I don`t know if the weather fluctuates in Alberta more up near the mountains..Here`s that picture of Brian Allan`s view of the horizon..
He`s managed this picture the other night of a comet;
I`ve been playing with that free plate solving app.
You can obtain an X & Y position in the image & Angles between selected stars in minutes for a basic FITS (it does do jpeg & BMP) image by doing a basic callibration from the FITS header.
To Analyse for re-centring you need to be connected to the telescope via ASCOM (or CDC is another option) & to take a reference image for re-centring you need your camera working.
The notes mention the common problem of putting an object inside the CCD frame. If you have an image of stars but can`t find the object you can re-centre quite accurately on the image centre (& object) & it`s co-ordinates by using this reference image method.
There`s a guy on the CAA group who does his alignments every night using the plate solving abilities of Maxim by taking a shot then re-centring according to it`s GSC data base then syncing his mount..
Maxim`s a rather expensive option (though it has many other aspects) & he uses it for guiding also, preferring it`s accuracy to PHD.
Elbrus will do this for free apparently on a PC or Mac emulator.
I realise you must have your own tried & true methods of doing this!
Mark.
On 06/06/2010, at 5:39 AM, Milton Aupperle wrote:
Mark;
On 5-Jun-10, at 12:40 AM, Mark Gaffney wrote:
> I had a reasonable PA done recently with All Star such that stars
> slewed to with the HC were just a little off centre in the DSLR`s
> FOV after hibernating the mount & waking it a couple of nights
> later. After a week of sleep however, the Tarantula nebula had
> migrated to the outside of the frame of the DSLR.
Then your not Polar Aligned if this is happening.
> I was intending to use the preserved alignment (which included a 3
> star done before the All star) & do the All Star again next time
> centring the star more precisely with the reticle of my illuminated
> reticle EP (I stretched the spring on it`s LED & it now will stay on
> permanently)
> Since then it`s rained heavily & consistently for several days & I
> brought the scope inside so have to begin again anyway..
> I have marks on my bricks at the base for the tripod legs but
> putting the OTA & weights back is always a little different to last
> time I`ve found...
I can guarantee that you will have to completely re-do the Polar
Alignment. As soon as you move the scope, it's back to square one.
This has been the worst May / June weather we've had for at least a
decade. We've had up to 18" snow, set 100+ new record low temperatures
for May / June across North America and right now it just started with
marble sized hail. The rest of the week :
http://www.weatheroffice.gc.ca/city/pages/ab-52_metric_e.html
is rain and below normal temperatures, so much for Global Warming
drying us out and cooking us. I have my scope double bagged with an
inner plastic bag liner and an outer heavy nylon shell (BBQ Cover)
which works great for keeping the sky dry.
TTYL..
Milton Aupperle