Investigate using corrected NGC database

[mrosseel]

We are using the standard NGC database, whereas there are a few 'corrected' NGC databases going around.
It would be good to check these out and see if we can use them.

Steinicke (needs attribution):
http://www.klima-luft.de/steinicke/index_e.htm

More license friendly:
https://github.com/mattiaverga/OpenNGC/

[brickbots]

Sadly, the data quality on OpenNGC is not fantastic, so I think we should go with Steinicke. I'll reach out!