Which coordinate setting in Cartes du Ciel

[Uplooker]

Hi,

I would be very grateful if someone could inform me which coordinate settings I should be using in Cartes du Ciel. I am using it in conjunction with EQMod to control my NEQ6.

I seem to have gotten myself a bit confused after playing about with various settings. Have chosen  "Equatorial coordinates" for "Coordinate system" I then need to select "Type of coordinates"

Choices are:-

• Apparent true equator, …
• Mean of the date …
• Mean J2000 …
• Astrometric J2000 …

Please someone explain / put me out of misery.

Thanks in advance

[Uplooker]

Shameless bump. Feel free to reply, even if it is to tell me to stop being a "numpty" and to just select one at random [emoji16]

Sent from my Fone

[Bubbles82]

Is this in settings of CDC map or observatory data u mean

Sent from my iPhone using Tapatalk

[Bubbles82]

does this help

Sent from my iPhone using Tapatalk

[Uplooker]

Hi Bubbles,

Thanks for the reply. It's the setting under "Setup" -"Chart, coordinates"

Sent from my Fone

[Bubbles82]

My above pic is how mine is set up . I have never changed anything in this section of settings and I have had no problems using CDC. I'm not sure how much difference it makes to mount control as I use an neq6 too which is a eq mount as you know. I do however have the AZ option selected on the main sky screen in CDC on the left bar if you know where I mean just because I find it easier to scroll round the sky screen that way. I haven't tried it but I wonder if selecting AZ on sky map screen changes this in the coordinates settings in the background tab we are talking about [emoji41]

Sent from my iPhone using Tapatalk

[Merlin66]

Ian,

I'm pretty sure that Eqmod uses J2000 coordinates.

[chrisshillito]

it makes no difference to EQMOD which EPOCH you use - EQMOD will just move to the RA/DEC coords it is given.  Just pick an EPOCH and then make sure that all the apps that use EPOCHS are set to the same.

Chris.

[Uplooker]

Hi guys,

Thank you for the replies. My original question was not about the relationship / interaction between CdC and EQMOD. It was simply which coordinate setting to make within CdC. I am aware that we should J2000 EPOCH coordinates. I am just not sure whether I should then  choose Apparent true equator, Mean of the date, Mean J2000 or Astrometric J2000 and what the impact would be. If the answer is "It will have no impact" why is the choice available?

[chrisshillito]

OK  I won't mention EQMOD if that isn't relevant to your setup.

If you want to know the coordinates of objects as they are at present then you should use JNOW (mean of date). You get a choice because not all applications will precess their catalog positions to JNOW so if you are using more than one application its useful to be able to have them synchronised to the same EPOCH.

If you ever do want to have CDC command control your mount(s) then you'll need to make sure that its coordinate system is synchronised with whatever was used during the goto alignment process. The synscan handset uses a J2000 catalog for its objects but I don't know if it precesses this to JNOW when performing gotos.

Chris..

[Uplooker]

OK I won't mention EQMOD if that isn't relevant to your setup.

If you want to know the coordinates of objects as they are at present then you should use JNOW (mean of date). You get a choice because not all applications will precess their catalog positions to JNOW so if you are using more than one application its useful to be able to have them synchronised to the same EPOCH.

Chris..

Hi Chris, thank you. That is just the answer I was looking for. I do use EQMod with CdC to control my mount, but as I said previously, it was more which setting within CdC, as I did not know what impact one setting over another would have on accuracy of goto.

Thank you again and also to the others who responded [emoji3]

Sent from my Fone

[Singlin]

I also use Cart Du Ciel with my Mesu Mount.

The Sitech software which controls my mount uses J2000

Which of the bove should I set in Cart Du Ciel?