How do I do a plate solve and can my Tak mount do it?

[Paul Haese]

Hi all,

I am just trying to get my head around this. To explain: I bought a QSI a couple of weeks ago. Now I understand that I will most likely need to image a target over more than one night to get great results or should I say really great results. So from what I have read so far I need to do a plate solve to get the camera back into the same position each night. How do I go about doing that and given that the Tak EM400 does not seem to have a home position, how do I ensure that the mount is in the same position each night when I start? What do other guys do? I am using the sky 6 as my goto system.

This is not terribly urgent but I want to get my head around this before the QSI arrives.

[Dennis]

Hi Paul

What I have done in the past using CCDSoft and The Sky 6 Pro, is:

• Capture ccd images with CCDSoft whilst my EM200 is under the control of The Sky on the same computer.
• This automatically records the RA and DEC coordinates of the centre of the ccd frame in the FITS header.
• The next night I slewed to these coordinates and compared the (new) ccd FOV with the previously saved image and then nudged the mount using the manual movement buttons.
• By not removing the ccd camera (SBIG ST7) from the OTA I was able to realign quite easily.

This was with a mount that I set up and tear down each night and it was acceptable for my purposes in chasing the movement of asteroids over a couple of evenings.

With your QHY, it should be possible to establish the centre of the field using The Sky and then for the next evening (session) you could manually GoTo those coordinates and take a test exposure to compare it to the previously captured image.

I have noted that the resolution of the Temma telescope position indicator is less than that of The Sky, so the Temma bull’s eye often appears slightly off the target when zoomed in to small fields. This is a limitation of the Temma protocol from what I have read.

Cheers

Dennis

[gbeal]

Paul,
my knowledge on this is somewhat limited, and I tapped Jase for a bit of help ages ago, which worked at the time.
As I understand it "Plate Solve" is predominantly done by the programs you are using. In my case it is TheSky, and Maxim (although I have all but thrown my toys out of the pram with maxim).
For Maxim and TheSky to work you need either the databases or IIRC "Pinpoint". Maxim comes with Pinpoint LE I think. In my case I had to load on extra star databases.
So it depends on what software you are using, what do you capture with, and what planetarium software do you use if any?
Jase will know or others will be of more help no doubt. I am sure your mount will not be the weak link.
Gary

[wysiwyg (Mark)]

Paul,

With the mount not having a home position it certainly makes this challenging and time consuming but not impossible.
I know that using CCDsoft and The Sky 6 you can achieve a plate solve, CCD Autopilot uses this as one of its methods. Certainly Tpoint and Pinpoint will do this also.
Not sure if the QSI is compatible with CCDSoft though?

Mark

[Paul Haese]

Thanks guys.

Dennis, that sounds logical. BTW I am getting a QSI, not a QHY. Most likely is going to be the way I go about things for a while.

Gary, I will chase up Jase and see if he can help. Also waiting on Mike Sidonio to chime in. He has a Tak mount and has done this before from what I have heard. In any case I should be using Tpoint, but will need to get this online as the version of sky6 does not contain it. It can be plugged in from what I have read in the past.

Mark, CCDsoft is compatible with the QSI. It has a plug in that installs into CCDsoft. So I could use that instead of maxim.

Anyone know of a tutorial on how this is all done? This seems like a bit of mind field but I am sure someone has a tutorial. That way I can practice before I get the camera and at least be aware of the issues before it arrives.

Thanks so much for your help so far.

[Dennis]

Paul

I think that I read somewhere that you can “bypass” The Sky 6’s native telescope driver and use ASCOM?

If that is the case, then have a look at Chuck Faranda’s Temma driver for ASCOM. I believe that Chuck’s Temma driver does have a the “PARK” position functionality and if that is the case, you would then have to connect to The Sky using the ASCOM interface rather than The Sky 6’ native interface?

Cheers

Dennis

[Bassnut (Fred)]

Paul

Plate solving is a grief-ridden complicated path IMO, unless you want to go full automation, and your gear is very stable and repeatable. I bet the gurus here will bury you with info on how to do it (If they even bother with it at all), but its unessecary.

I always image over several nights on an object, and just eyeball composition with a sub from the previous night with a short Lum exposure, and jog untill they look roughly the same. You can get very good at how much to jog after a few projects. Alignment then sorts out the difference in processing, and perhaps some croping to rid the gaps at the edges.

[Paul Haese]

Thanks Dennis, that sounds great.

Fred, wow I thought I would be consigned to doing this weather I wanted to or not. It is great to know that this can be done the way you suggested. I was thinking of doing this but thought it was a bit amateurish (yeah I know) to go about things that way. Having perused your gallery though I can feel confident that if it is good enough for you then it will be good enough for me.

[gbeal]

Let me add to what Fred does, I do it too.
Usually shoot as much as I c an in the one sitting, but if over differing nights, just eyeball it using 4x4 binning, to align. Like Fred said the slight differences only mean a slight crop at the edges, if at all.

[Bassnut (Fred)]

hehe, NP Paul, theres less magic than you think in this game generally .

I have even removed the cam and reinstalled mid-project to a slightly different orientation and FL without trouble. Any decent stacking app does rotate and scale automatically during alignment (within reason, albiet with some enevitable croping).

[Dennis]

Hi Paul & other Tak Temma owners

I just had a look at my notebook computer where I have ASCOM 5 installed which I mainly use with Sky Tools Pro 3.

In the directory:
C:\Program Files\Common Files\ASCOM\Telescope\Planetarium Plug-Ins\TheSky
I found an “install.txt” document which when opened, has the following details:

"TheSky ASCOM Plugin
===================
This plugin allows Software Bisque's TheSky to communicate with ASCOM-compliant telescopes via TheSky's "TeleAPI" feature.

Installation
(1) Rename the file C:\Program Files\Common Files\System\TeleAPI.dll to TeleAPI-Original.dll
(2) Copy the ASCOM TeleAPI.dll to C:\Program Files\Common Files\System\TeleAPI.dll

One-time Telescope Setup
(1) In TheSky, Telescope menu, select Setup...
(2) In the Control System box, select "Telescope API"
(3) Click Settings... to open the ASCOM Telescope Chooser and select the ASCOM compliant telescope you wish to use.
(4) Now click Properties... in the Chooser, which will display the settings window for the telescope type you just chose. Make adjustments as your telescope needs.
(5) Close all windows including the TheSky Telescope Setup window by clicking OK or Close. Do not click any Cancel buttons:-)

Operation
(1) Make sure both your telescope and TheSky are set for the same geographic location and time.
(2) In TheSky, Telescope menu, select Link->Establish. You should see the cross-hairs indicating where the telescope is pointing".

So, it looks like you should be able to use Chuck’s Temma Driver which does appears to have a PARK command where you can either PARK at the current position, or slew to an Alt AZ coordinate position and PARK there.

I must give this a go myself now that I have more concrete knowledge!

Cheers

Dennis

[Terry B]

Paul
I plate solve all my images using Elbrus. It is free software from here
http://tech.groups.yahoo.com/group/S...rElbrus/files/
and the database files are here.
It has a routine for exactly what you want to do but you still have to slew the mount to match the old coordinates from your previous image.

[Paul Haese]

thanks guys, plenty to read up on now. Much appreciated.

[RB (Andrew)]

Ah thanks for the info Dennis, I'll have to try it and see how it goes.

Much appreciated Sir !

[jase (Jason)]

What's plate solving?

Yes, you can do it Paul. Depends on how hardcore you want to get i.e. your purpose for doing so. Plate solving has many advantages. I think a main one of yourself is planning an imaging session for guide star selection. As the focal length increases on-axis guide star selection can become a challenge. Using TheSky FOV indicators, you can determine the camera orientation to pick off a guide star. Then, when at the telescope, when you plate solve an image, you'll be able to match the camera rotation to nail the star you originally planned. This is simply one of the many wonders of using plate solving - there are far too many to conclusively list here. Comes down to what you want to achieve. I agree with Fred that is typically used for robotic/automated set ups to control actions such as pointing or focusing, but don't agree that its grief ridden. You do however need to be software savvy. I've contributed to a few threads in the past, heres one and helped others along to plate solving nirvana. Given you've already got TheSky, I'd simply use CCDSoft for data acquisition based its tight integration. The two will provide the plate solving service with a camera that writes out in FITS format. I would suggest you get all the key factors such a general telescope pointing, focusing etc under control before you embark on getting plate solving running. Sounds like you'll have a steep learning curve with the new camera to start with. You'll have a little fun determining the integrated guide port offsets to getting TheSky FOV indicator correct I suspect, though not as difficult as the Astrodon MOAGs. Anyway, yell out if you get stuck.

Cheers