PinPoint / Astrometry.net now failing


#1

I’m rather a new person to SGP, but had very good luck with both of these plate solvers when using my SW100ED Pro (900mm), but I recently purchased an AT65EDQ (420mm) and tried it last night for the first time.

Sadly I couldn’t get any solving to work with either of these and the new scope. I created a new equipment profile with the telescope set at 420mm.

My exposure times where definitely long enough and very similar to the SW100ED and Canon T5i @ ISO6400 for 20 or even 30 seconds.

I was looking at NGC 7686 and even tried a simpler one (which solved with the SW100ED) M31.

Any idea what I may be doing wrong that would cause this smaller scope to be unable to solve? Did I forget a setting somewhere?


#2

Are you using the online or local version of astrometry.net? If you are
using the local version of astrometry (ansvr) make sure you have the
correct indices downloaded for your new scope.


#3

Assuming good data, the issue, 90% of the time is improper hint data.

Please see this post:


#4

Pixel scale perhaps? With the same camera, at 420mm vs 900mm focal length you’re looking at just over double the arcsec/pix. I know you said you changed the telescope settings but look at the hint data and make sure it looks about right. If your original setup was around for example 1.2"/px, this should be around 2.5"/px (roughly).


#5

I’m using the local one. I’ll have to check the indices I downloaded before, but I think I took most of the smaller FOV ones the first time around. Have to dig up the instructions on reviewing/adding new ones to refresh my memory.


#6

I’ll bet you that’s the issue. I remember using some FOV calculator, can’t recall which one, to figure out my 900mm with the Canon T5i. I simply copied the profile when I setup the AT65EDQ, so the values on the Camera tab are the same…with Scale: = 0.97.

That’s probably not going to work out well as exhibited by my experience last night.

Ah…now I remember! It was this one: http://www.skyatnightmagazine.com/field-view-calculator and your estimate is nearly right on. It appears that 2.3 should be the scale.

Sky’s won’t be great tonight, but good enough for a test to see if things improve.


#7

That did the trick! Took less than 10 seconds to solve M92 tonight. Thank you all very much for your suggestions I’m back up and running!


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