Horsehead Comparisons

[Littleguy80]

After Sunday night's dark site trip was cut short by fog, I was keen to return again last night. Some work issues threatened to end those hopes but by 9pm I was onsite at the Norwich Astronomical Society's dark site at Seething. There was one other member observing when I arrived. She was the proud of owner of a custom made F3.5 20" dob. It was a very impressive looking scope. This was my first time observing with this member but I knew she had a reputation as been an excellent observer. It took a few minutes to align finders, collimate and get the dew heaters set up. I started out with Comet Iwamoto, The improvement in the sky from Sunday night was immediately obvious with the view of the comet showing good contrast. I went up to 133x magnification and felt like I could have pushed it further. The core was bright with the rest of the comet quite diffuse and not showing a tail.

I haven't spent much time observing Leo this winter so I decided to put that right. I started with the Leo triplet. The two Messier galaxies were very bright compared to the side on galaxy NGC 3628. I used the Lunt 9mm XWA to get 133x magnification. All three members of triplet responded well to this. Tracking up, I was able to pick up the fainter NGC 3596 which was tougher spot with the bright star Chertan in the FOV. Moving into the tail of Leo and starting from 81 Leo, I nudged down until I found the faint galaxy NGC 3681. The 9mm eyepiece returned to the focuser.  With a small movement along I was able to see NGC3684. Another small shift and I got NGC3686. I then went back to the APM HDC 20mm and enjoyed all three in a line in the same FOV. A really nice little group of galaxies.

My fellow observer had already observed the Horsehead in her 20" dob earlier in the evening so I announced my intention to try for it with my 10" dob. Using the already proven combination of my ES82 30mm and Astronomik H-Beta, I centered on Alnitak. The Flame nebula could be seen though it was quite dim. Moving away from Alnitak, I followed the line of IC 434. On the third pass, with Alnitak outside the FOV, I caught a dark notch in the nebula. I found I had to look quite a way past where the Horsehead was for averted vision to pick it up. My observing partner, now asked me to describe what I was seeing and asked follow up questions. It really helped me focus on what was in the eyepiece as I tried to relate the position of IC434 and the Horsehead in relation to the stars that I could see, I tried to observe using the APM HDC 20mm but IC434 was much fainter at the higher mag/smaller exit pupil. The 20" dob was now targetting the Horsehead so it was time to swap scopes. . My heart was in my mouth awaiting her verdict. Was I really seeing the Horsehead in my dob? The initial response was "Your FOV is too big" and then a few seconds late "No, I see it. I had to get Alnitak out of the FOV". Looking through the 24mm Panoptic in the 20", I struggled to get my bearings with the increased image scale. A quick nudge and I tried again. It took about two seconds and then it clicked. Much bigger than in my scope, I picked out the reference stars I'd used in my dob as confirmation of the observation. I was struck by IC434 still being quite faint even in the huge 20" scope. I think we both thoroughly enjoyed seeing the famous target in each other's scopes. For me, it was great to have my observation validated by a seasoned observer.

With the H-Beta filter still attached, I headed over to the California nebula. Thick nebulosity flowed  across the eyepiece. The difference good transparency and dark adaption makes to these objects is stunning. I switched to the UHC filter and observed the open cluster NGC 1893 and it's associated nebula. I'm surprised this target doesn't get more attention. I moved across to and tried for the Flaming Star nebula, IC405 which was a struggle on this occasion and I left it not feeling like I'd seen much, if anything, of it.

Time was running out so I decided to finish with some galaxies. The first was the bright NGC2903 in Leo. It was bright enough to take higher magnifications and show some structure. It was totally eclipsed by M51 though. At 90x in the 13mm APM HDC is was absolutely stunning. Really clear spiral arms could be seen. It was beyond the grey fuzzy stage and was clearly the famous pair of galaxies. I wrapped up the session with M101 which wasn't as impressive as M51 but was also showing some spiral structure. Most of the views had over the session were shared which really added to the fun of it all. Comparing views of the Horsehead in my 10" dob with a 20" dob is something that will stay with me for a very long time to come.

[John]

Great report Neil

It's a funny old target, the Horsehead nebula. It's very enticing as a visual astronomer even though we know that what we will eventually see will be far from spectacular even with 20 inches of aperture. Unless one uses NV of course, when it seems to become a routine thing to see.

It's difficult to explain the fascination of observing, or almost sensing, something that is right on the edge of being there and being invisible, but it is quite addictive

[scarp15]

Fabulous report Neil and good companionship with the person using a 20" dob, yes I think that she used to report on here. Very interesting comparison, in relating the impression and image scale of the HH and credit again for accomplishing this in your capable 10" dob. Good reminder as with some other reports concerning the galaxies emerging. NGC 1893 and IC 410 The Tadpole nebula is an interesting visual combination. Again valid comment to highlight the difference that good transparency and dark adaptation makes.  

[Littleguy80]

2 minutes ago, John said:

Great report Neil

It's a funny old target, the Horsehead nebula. It's very enticing as a visual astronomer even though we know that what we will eventually see will be far from spectacular even with 20 inches of aperture. Unless one uses NV of course, when it seems to become a routine thing to see.

It's difficult to explain the fascination of observing, or almost sensing, something that is right on the edge of being there and being invisible, but it is quite addictive

Thanks John. I found myself thinking about that whilst trying to split some double stars last week. I think it’s the mental discipline required that really hooks you in. I'm concentrating so hard that I lose all track of time. It’s such a great feeling when the concentration is rewarded with a view of something that not many people get to see  

[GavStar]

Great report Neil. I love to hear about horsehead observing. I’m hoping to try an experiment with it tomorrow...

Did you see the dark lane through the middle of ngc 3628? Previously I’ve found  this galaxy quite dim but I had a lovely session earlier this year at some dark skies where the lane was very clear. However I was using NV (which generally doesn’t improve galaxies that much, but did seem to that night).

[Littleguy80]

16 minutes ago, scarp15 said:

Fabulous report Neil and good companionship with the person using a 20" dob, yes I think that she used to report on here. Very interesting comparison, in relating the impression and image scale of the HH and credit again for accomplishing this in your capable 10" dob. Good reminder as with some other reports concerning the galaxies emerging. NGC 1893 and IC 410 The Tadpole nebula is an interesting visual combination. Again valid comment to highlight the difference that good transparency and dark adaptation makes.  

Thanks Iain. That’s interesting, I’ll have to see if I can find any of her reports. She was working through some faint planetary nebula last night which she was kind enough to show me too. 

[jetstream]

Great report Neil and your comments highlight the fact that contrast is fixed between the sky "darkness" and the objects luminosity. Making some objects bigger makes them easier to see, such as the HH notch itself. In fact I look for different things in different size scopes when obs the HH- in the 10" and smaller scopes I focus on seeing IC434 more and find the absence of it the HH notch. In the 15" I concentrate on the notch itself which is easy to see, with and without filters.

I prefer large AFOV eyepieces in the larger scopes and will use a 25mm plossl in the 10" , 32mm plossl/42mm LVW in the fracs and the fact that you find the 30mm ES 82 "brighter" is a good sign, you can use larger exit pupils effectively. The fracs need a tiny FOV but up around 40mm fl, kind of hard to find.

Just for reference IC434 is visible with no filter in scopes ranging from 90mm and up from my experience but the HH itself is extremely hard (for me) in the small scopes.

What SQM was the site? Btw, you obs partner has very good eyes....

[Littleguy80]

11 minutes ago, GavStar said:

Great report Neil. I love to hear about horsehead observing. I’m hoping to try an experiment with it tomorrow...

Did you see the dark lane through the middle of ngc 3628? Previously I’ve found  this galaxy quite dim but I had a lovely session earlier this year at some dark skies where the lane was very clear. However I was using NV (which generally doesn’t improve galaxies that much, but did seem to that night).

Thanks Gavin. I’m becoming a firm believer that that the transparency is the deciding factor in whether you see it or not, assuming you have a suitable set up of course. I’ve tried for it on very dark sky trip this winter and have only seen it twice. On both occasions there was very little moisture in the air. 

I didn’t see the dark lane in NGC3628 but have to admit I was more taken with the bright Messiers. I’ll definitely look for it next time out. 

[Mark at Beaufort]

Neil a very enjoyable read and a great report. It must have been great to compare the two scopes side by side.

[Littleguy80]

6 minutes ago, jetstream said:

Great report Neil and your comments highlight the fact that contrast is fixed between the sky "darkness" and the objects luminosity. Making some objects bigger makes them easier to see, such as the HH notch itself. In fact I look for different things in different size scopes when obs the HH- in the 10" and smaller scopes I focus on seeing IC434 more and find the absence of it the HH notch. In the 15" I concentrate on the notch itself which is easy to see, with and without filters.

I prefer large AFOV eyepieces in the larger scopes and will use a 25mm plossl in the 10" , 32mm plossl/42mm LVW in the fracs and the fact that you find the 30mm ES 82 "brighter" is a good sign, you can use larger exit pupils effectively. The fracs need a tiny FOV but up around 40mm fl, kind of hard to find.

Just for reference IC434 is visible with no filter in scopes ranging from 90mm and up from my experience but the HH itself is extremely hard (for me) in the small scopes.

What SQM was the site? Btw, you obs partner has very good eyes....

Thank you, Gerry. I have an ES68 24mm at home which I didn’t have with me last night. It did occur to me that it may have been a good middle ground between the ES82 30mm and the APM 20mm. 

Looking for the abscence of IC434 in the 10” is a good description for finding it. Both times I’ve seen it by trying to follow the edge of IC434. 

We didn’t have an SQM meter last night so I don’t have a reading. There was a reading of 20.9 on Saturday night when there reports of heavy dew. I’m assuming with a dry night last night we were comfortable into the 21s

[GavStar]

30 minutes ago, Littleguy80 said:

Thanks Gavin. I’m becoming a firm believer that that the transparency is the deciding factor in whether you see it or not, assuming you have a suitable set up of course. I’ve tried for it on very dark sky trip this winter and have only seen it twice. On both occasions there was very little moisture in the air. 

I didn’t see the dark lane in NGC3628 but have to admit I was more taken with the bright Messiers. I’ll definitely look for it next time out. 

Yes agreed transparency is key and I can’t tell what it’s like until I look at faint objects.

I was out briefly last night NV observing Barnard’s loop and other nebula and have discovered that with two eyes I can pick up fainter objects much more obviously. Barnard’s was barely there with one monocular but with the binocular it suddenly showed full loop. I haven’t tried averted vision with two eyes - not sure i will find it possible... So I now see why some mad people have gone for massive reflector binocular setups!!

[Littleguy80]

3 minutes ago, GavStar said:

Yes agreed transparency is key and I can’t tell what it’s like until I look at faint objects.

I was out briefly last night NV observing Barnard’s loop and other nebula and have discovered that with two eyes I can pick up fainter objects much more obviously. Barnard’s was barely there with one monocular but with the binocular it suddenly showed full loop. I have tried averted vision with two eyes - not sure i will find it possible... So I now see why some mad people have gone for massive reflector binocular setups!!

Agreed. I’ve noticed a lot of the experienced deep sky observers have a few tester targets to see how the skies are looking. It seems to be the most reliable test of conditions. 

I’ve seen pictures of some crazy binoscope setups. Does make me wonder how tricky it is to keep them properly aligned so you don’t end up with ghosting. I’m not sure how tolerant our eyes/brains to merging images like that. 

[John]

37 minutes ago, Littleguy80 said:

...Looking for the abscence of IC434 in the 10” is a good description for finding it. Both times I’ve seen it by trying to follow the edge of IC434...

 

Thats just how I have seen Barnard 33, as a gap  or dark "bite" out of IC434.