Arp 18

[wimvb]

Arp 18, or ngc 4088, is one member of a pair of galaxies. The other member is ngc 4085, here the smaller galaxy near the bottom. Ngc 4088 is situated in Ursa Major, at a distance of some 35 - 40 Mly. Other galaxies in this image are at distances ranging from 270 - 970 Mly.

Acquisition details:

• Telescope: SkyWatcher MN190 on a AZ-EQ6 mount
• Camera: ASI174MM-Cool with ZWO lrgb filters
• Exposures: L 106 x 2 min, RGB 50 x 4 min. Total integration time 13.5 hrs

Processed in PixInsight.

[tooth_dr]

These galaxies are amazing, by far the best time of the year if you can get a decent FL on them.

[wimvb]

39 minutes ago, tooth_dr said:

These galaxies are amazing, by far the best time of the year if you can get a decent FL on them.

1 m, but in combination with a small sensor.

[tooth_dr]

How are you guiding?  I've attached an OAG to my 1200mm FL scope, but am seeing a RMS of around 1.  With an finderscope guidescope I'm getting an RMS of 0.5-0.6 (on a shorter focal length but heavier scope).  Not sure what to do.

[wimvb]

I guide with an oag also. My rms values are atm also around or above 1", but that seems mainly due to issues with my mount, in particular stiction in dec. Last year I tested guiding with my st80, a finder guider, and oag, and I couldn't see much difference in the rms values I got. With the oag I can always find a star to guide on, but sometimes only at the edge, or only weak ones.

[tooth_dr]

1 hour ago, wimvb said:

I guide with an oag also. My rms values are atm also around or above 1", but that seems mainly due to issues with my mount, in particular stiction in dec. Last year I tested guiding with my st80, a finder guider, and oag, and I couldn't see much difference in the rms values I got. With the oag I can always find a star to guide on, but sometimes only at the edge, or only weak ones.

Thanks Wim. It’s a new Mesu so doubt there are any issues.  I’ll post another thread to see if I’m doing anything wrong!

[wimvb]

1 hour ago, tooth_dr said:

Thanks Wim. It’s a new Mesu so doubt there are any issues.  I’ll post another thread to see if I’m doing anything wrong!

Göran, @gorann, has a Mesu + oag, which works ok for him. His carries a dual rig Esprit 100 & Esprit 150. 

Edited March 23, 2020 by wimvb