Target data entry resolution and accuracy


#1

I am entering my target data into SGP from Stellarium, using this format (e.g. for M97):

RA: 11:15:43.42 (Stellarium said 11h15m43.42s)
Dec: 5455’44.2" ( is the pre-existing degree symbol in the SGP target dialog)

Is that the proper/correct way?

I ask because SGP truncates or rounds off the data such that is is a one or two arcseconds off. I also notice that centering the target (with local Astrometrey ansrv) puts the center of my fov a few arcseconds away from the target (as shown in Stellarium) AND that moving the scope in stellarium back to the displayed target puts me actually on the target when I take images with SGP.

Everything is using J2000 (Stellarium, Stellarium Scope, EQMOD, ansrv. SGP) and my clock is sync’s to microsoft’s time server.

I don’t have this problem using Stellarium, Stellarium Scope, EQMOD, and astrotortilla. Astrotortilla puts me dead on the target and Stellarium shows that as well.

What am I doing wrong?


#2

Not sure if that will work or where the asterisk came from. In general, we have made location input easy by understand a whole bunch of formats… the easiest of which is a “space” or “:” separator. RA is always expressed in hours.

That’s certainly not desired behavior… can you provide an example of when and where this is happening so we can take a look?


#3

OK I think we chalk this one up (partially anyway) to me not understanding that a reference image set’s (or resets) the target location.

I thought that “reference image” was just to sync the mount, so I was solve and syncing after an initial goto for the target, and that ended up changing the the target location to the slightly inaccurate initial goto location.

Again, confusion over the difference in workflow between using planetarium software with Astrotortilla to get on target, vs. SGP.

However, a minor nit, SGP does turncate/round the decimal part of arcseconds (at least for display purposes).


#4

The truncation/rounding of RA seconds is more of an issue for me than the Dec arc-seconds truncation/rounding. Since SGP truncates or rounds the display, we currently have the declination display accurate to within 1 arc-second, but the RA display is only accurate to within 1 second = 15 arc-seconds.

It would be great if SGP could display 2 decimal places for RA seconds, for example 14:15:38.41, and at least one decimal place for Dec, for example +19°10'24.0". That would allow the target settings dialog display to reflect the actual pointing accuracy of the target centering routine, and also make it possible to copy/paste target coordinates from SGP into another app like a planetarium program.

Andy


#5

Also an easy fix. SGPro maintains the most precise RA and Dec it has been exposed to so increasing the accuracy of the display is an easy thing. This change will be available in 2.5.1.11.


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