Dark Location Observing 13th September 2015

[MarsG76]

13th September 2015

Equipment: 80x500mm refractor

 

At home as the 8" scope was imaging M27, I took the Nexstar alt-az mount and the 80mm (500mmFL) refractor to closest dark site, roughly 30 minute drive.

 

There were more stars visible than at the home location, but not as many more as expected, it was not as dark and crisp as the last time I was up here. The Sydney glow was visible, it revealed that there must be some thin high altitude cloud.

 

Before observing I wanted to take some subs of the Milky Way with the Canon 7D, ISO6400 15 second subs, I took 30 since that was the only space that was left on the card. I didn't want to spend too much time on imaging the Milky Way since I wanted to do some observing.

 

First thing looked at was the Trifid Nebula, M20, through the 40mm eyepiece. There was nebulosity visible, but just, the UHC filter made it worse, this could be due to the thin layer of cloud or the size of the lens, most likely its the haze. The Celestron UHC/LPR filter improved the contrast and helped with the views slightly.

The lagoon nebula, M8, was visible as a patch of haze, but the split down the middle was very clearly visible, even the thin line running through it.

 

The tarantula nebula showed a fuzzy core and the outer whisps were also visible, especially made apparent with the UHC/LPR filter.

 

The sculptor galaxy showed the cigar shape, the central core mainly, but it only looked like a smudge, no detail was visible in it what so ever no matter what filter or eyepiece was used. 

Initially when I looked at NGC253 it wasn't even visible at the start of observing, but an hour later the seeing either improved or it moved high enough to be just visible.

 

M16 was also barely visible, but the glow of the nebula was visible.

 

Tonight's best views were of the open star clusters, M6 and M7 in Scorpius. They revealed quite a few stars, but as mentioned before, due to seeing they were not crisp points of light but slightly fuzzy.

 

To test the seeing, I moved the scope to Alpha Centauri. I remember what the double star looked like in my Tasco 60mm refractor, namely crisp points of light with slight diffraction rings around them. I figured that the optics in the 80mm Bosma would be higher quality and the lens is bigger, so at the very worst the view should be similar... But no, the stars were fuzzy, you could tell that it was a binary but nowhere what I was remembering.

 

Overall the seeing was quite bad, the views through the eyepiece had a blue hue to them and the sky was quite bright. In the past I have seen skies here that were much darker, crisper and overall had the wow factor. This is the location where I saw clear structure in M20 through the 8" scope using the f6.3FR and the 40mm eyepiece.  Of course the 8" would reveal more detail than the 80mm refractor but then sky glow and transparency was obviously much better. Back then I would have given seeing a 8/10 where tonight I would be a 4/10 at best.

 

Overall the location is great for observation since for example when trying to view the Eagle nebula, M16, from home during quite good seeing through the 8", on 14/15 May 2015, I didn't manage to spot anything more than perhaps a slight haze, where as the eagle was visible through the 80mm at maddens plains in very bad seeing conditions.

 

Another outing when the sky is clear is definitely a must, so the plan is to visit here again at October or November new moon period with the NS8 since the 80mm will be imaging some wide field shots.

 

Using the 11mm TV type 6 magnified the objects more, not dimming or taking any detail away, but in tonight's seeing condition didn't improve or reveal any more detail either.

 

Observing was carried out between 22:00 & midnight AEST, 12:00-14:00 13 Sep 2015 UT.

 

MG

[Mike22335]

Sounds like a disappointing night, hope you have better ones in the future.