Basic Astronomy As Applied to PI

Mossyback

I've been running some tests on my equipment regarding tracking and comparing guiding vs no guiding. If I understand correctly that longer subs bring out more detail, I'd like to do this. Since, to this point, I haven't used guiding, I decided to experiment. Because of the bright moon, I chose the Heart nebula in the north. Running 10 minute subs guided and unguided, I can detect no difference in the results. (Paramount MYT).

My questions are:

1. Since I was photographing close to the celestial pole, does this account for the similar results? (smaller movement across the sky)

2. 50% of the subs had satellite tracks through them. Could this be because of the many satellites having geosynchronous orbits.

3. Do most astrophotographers guide?

I apologize if these questions are outside the PI discussions but without good data, my efforts in processing will go for naught.

Hank

BlockHead

Hank,

It depends on your platescale. Try ten minutes exposures at 0.33 arcseconds per pixel and you will not be happy with unguided results. You didn't say what  telescope you are using..but I am guessing your plate scale (probably with a short focal length system) is near or greater than 1" per pixel. This makes it easier to track. If your tracking errors are equal to or less than your pixel size unguided- you certainly do not need to guide. 

You can measure the resulting FWHM of the images with and without guiding- if there isn't a significant difference then you have your answer. I do not guide with the MYT Paramount I am using...but I am at 5" per pixel! (I take 10 minute exposures). 

The goodness of your polar alignment (in addition to mechanical things)  is usually the limiting factor.

1. No. Assuming some corrections occurred in Declination- this would be unaffected by the cosine(Dec) of RA.

2. Geosynchronous satellites lie along the celestial equator (roughly). So the satellite trails you are seeing are not Geos. The are lots and lots of satellites up there now everywhere in the sky.

3. Depends on the errors. All astrophotographers and professionals guide if the tracking errors are larger than the sampling size of the images. You didn't say...but I infer.

-the Blockhead