Newly collimated 8 inch dob - evening mostly ruined by cloud

[Yellow dwarf]

This was quite a disappointing evening, not much to see because of the clouds. Clear Outside said that the night would be completely clear, so I set up my 8 inch dob and waited for it to cool down. Unfortunately, the clouds started to come in, and within ten minutes, almost all the sky was covered in a layer of thick cloud. When there was finally a small break in the clouds, almost 20 minutes later, I did a star test with my dobsonian on Vega, and it was perfectly collimated thankfully. The clouds then rolled in again, and I had to wait another half an hour for them to clear. After they did, Hercules was well placed high to the south, and I decided to look at M13. Even though the atmosphere was quite unstable, the view was impressive at 75x magnification(using a 32mm plossl with a 2x barlow), with individual stars moving in and out of resolution because of the turbulence. However, 15 minutes later, clouds rolled in again, and blanked out everything for another 20 minutes. After they cleared, I found M57 in Lyra. I’ll be honest, the sight blew me away. A perfect ring, basically looking like a black and white version of the pictures. I gazed in awe at it at 160x magnification, using my 7.5mm plossl, until the clouds rolled in again. I waited 15 more minutes, but then packed up my telescope and went to bed because it was getting late and the clouds weren’t budging.

 

All in all, this was a fairly disappointing evening, although the 2 DSOs I did see were very impressive. This is the first time Clear Outside has really been this wrong before, so it was a suprise that it was this cloudy. Although it was frustrating, it was also an encouraging evening, as this was the first time I have used my 8 inch dob properly collimated, and the views were fabulous.

 

Just need to ask this question: Can anyone recommend a filter for viewing DSOs with an 8 inch telescope, as the Veil Nebula should be well placed over the summer and I would love to see it.(The fact it is a supernova remnant is so awesome to me for some reason)

 

[John]

The best filter for the Veil Nebula is the O-III filter. Brands such as Lumicon, Astronomik or Tele Vue Bandmate II are very good ones. A UHC filter will show it but an O-III filter really shows this object at it's best.

The O-III type filter also enhances contrast in planetary nebulae as well.

 

[Yellow dwarf]

9 minutes ago, John said:

The best filter for the Veil Nebula is the O-III filter. Brands such as Lumicon, Astronomik or Tele Vue Bandmate II are very good ones. A UHC filter will show it but an O-III filter really shows this object at it's best.

The O-III type filter also enhances contrast in planetary nebulae as well.

 

Thank you John, I should get the O-III filter then. Is the UHC better for reflection/emission nebulae then? 

[Stu]

11 minutes ago, Yellow dwarf said:

Thank you John, I should get the O-III filter then. Is the UHC better for reflection/emission nebulae then? 

These filters only work for emission nebulae which emit light at specific frequencies so the unwanted light can be filtered out. Reflection nebulae are broadband in nature so generally don’t benefit from filtering, only a dark sky really works for these.

The difference between OIII and UHC filters is just the frequencies of light which are passed through. An OIII only passes the two OIII frequencies, whereas UHC filters tend to add Hb and sometimes others ie they are slightly broader in their bandpass.

The Veil responds very well to OIII filters as John says, much better contrast.

These graphs show the differences for Lumicon for instance.

http://www.astrosurf.com/buil/filters/curves.htm#Lumicon UHC

[Yellow dwarf]

Thanks for all the information, it’s really helpful for someone new to this 😀

[Kon]

Very nice report and despite your frustration with the clouds you managed a couple of nice targets. I got the Televue Type 2 OIII filter (https://www.firstlightoptics.com/televue-filters/tele-vue-bandmate-oiii-filter.html) after recommendations from SGL members here and it was worth the £100! I have seen the Veil and North America several times now and it does not stop amaze me. I saw the Rosette, the Eagle, Swan and many more diffuse ones with this filter and it is well worth it. Be aware that many of these nebulas are rather diffuse, not much surface brightness,  and you will need rather dark skies (I am bortle 4 edging to 3) with good seeing to see them even with the filter. 

[Yellow dwarf]

Thanks very much Kon, I’ll probably buy the OIII filter in the future then. I live in a bortle 5 zone so it probably would be a challenge to see those nebula, but it’s one I’m up for. Hopefully the skies will clear soon.

[Stu]

41 minutes ago, Yellow dwarf said:

Thanks very much Kon, I’ll probably buy the OIII filter in the future then. I live in a bortle 5 zone so it probably would be a challenge to see those nebula, but it’s one I’m up for. Hopefully the skies will clear soon.

I can just about see the Eastern Veil from Bortle 7 skies with a good OIII but dark skies definitely help. A good Bortle 5 (eg more like mag 20 or more SQM) should show it clearly with good dark adaptation but the darker the better.

[Yellow dwarf]

49 minutes ago, Stu said:

I can just about see the Eastern Veil from Bortle 7 skies with a good OIII but dark skies definitely help. A good Bortle 5 (eg more like mag 20 or more SQM) should show it clearly with good dark adaptation but the darker the better.

That’s good then, seems like a good target to try for with the right filter.