Davesellars

Session Date: 6th - 7th Feb, 2022 Incredibly, a new scope had arrived just that day and by 7pm it was perfectly clear sky. Obviously, they had forgotten to pack the clouds... I wasn't about to complain! I setup the 102ED on the EQ5 and it's as steady as a rock. The scope had about 20 minutes cool-down time while I was setting up and getting other things ready before the first observation. Session 1 Time: 8:30pm - 10:30pm Scope: 102mm ED refractor Transparency: Excellent Approx NELM: 5 So, for the 4" frac's first light I decided to do a whistle-stop tour of Messier objects. As I've seen these many times with my 120ST and 80ED I would be able to make a decent comparison at the end. Betelgeuse - I used this to align the 60mm finder and noticed perfect colour rendition of the red giant. No flare from brightness and a perfectly round pin-point of light once focused which was a breeze. M42 - the Great Nebula seemed like a good start to test its ability on the depth of nebulosity and the trapezium. With the 17.3mm Delos (41x) the nebulosity was truly extensive with the wings spanning a wide area. Going straight to the 5mm Pentax XW (142x) the depth of the nebulosity was stunning with great contrast with the dark areas within the nebula. The main 4 stars of the trapezium were pin-point still - the seeing seemed to be very good as well as the transparency being excellent. Not something I bother about at all - but I looked for the E & F stars of the trapezium and could easily make a very fine pin-prick of light in their positions. These were actually cleared with a 4mm eyepiece (178x). F was more difficult for some reason although the magnitude is approximately same - but, as I said before this is not something I've really bothered about before. Overall, the nebulosity seen was at the very least equal to the amount seen with my 120ST but with such a large objective is difficult to judge accurately. M78 + NGC2071 (reflection nebulae in Orion) - So, on to a different type of nebula - M78 itself was very bright with the 17.3mm Delos particularly around the 2 main stars but also extending outwards a reasonable distance. NGC2071 was lighter but quite a bit clearer than I have previously seen it with the 120ST on a night of good transparency. M31 / M32 - Not ideally positioned at the moment as getting quite low, however M31 really showed a really bright extensive core with the Delos 17.3mm. M32 surprised by its brightness in the same FOV. With the Delos 10mm the amount of dust was quite apparent. M45 - What a view! Just about able to fit in the entire cluster within the FOV of the Delos 17.3. The colour rendition and accuracy of the various stars and brightness is quite spectacular with this glass, like in my 80ED. Double Cluster - Again, just about managed to fit in both clusters in the same FOV with the Delos 17.3. One of my favourites to view but the 4" really does do it more justice than the 80ED. The whole view just lit up with pin points of light in various colours back-dropped by the nebulosity of the milky-way. At this point I was able to see that the stars were perfectly still in focus right to the edge and with zero (that I could make out) optical abberations. M37 / M38 / M36 (Open clusters in Auriga) - With the 10mm Delos, these cluster shows very nicely indeed, particularly M37 with its profound amount of fine stars and M36 showing its starfish shape well. I was perceiving at the moment that this was actually outperforming the 120ST with regard to the star magnitude it was getting to. I could easily follow the milky-way region which showed some structure while faint it was quite obvious with particularly around dark region inbeteen Cassiopeia and Perseus. I spent a nice bit of time just looking up and taking it in. M97 (Planetary nebula in Ursa Major) - No filter and no problem... I wasn't sure that 4" was going to show this nebula as it can be difficult even with my 120ST but it is dependant on the transparency and darkness. However, the nebula showed a decent size ball that appeared slightly inconsistent contrast in the centre. I didn't have my filters out with me but I went to the Pentax XW 7mm which affirmed an area in the centre as being slightly darker than the outer region but no further detail. M108 (Spiral galaxy in Ursa Major) - With the 14mm Delos this was clearly visibly direct vision but without any detail. With the 7mm Pentax XW, I could discern a very subtle change of brightness along the line of the galaxy. There has bee some clouds hovering around in the background menaning to spoil the party but they seemed for stay clear for the moment and let me get on with it... I was having a great time! Mizar (double star) - I'm not a double star observer as such so - but I think this is Mizar A and Mizar B - This was easily seperated with my Delos 14mm (51x) and Alcor also in the same FOV. M101 (Spiral galaxy in Ursa Major) - With the 14mm Delos this was direct vision visble as a mere ball of light of reasonable size. I spent some time varying eyepieces from 7mm to also 10mm. 14mm seemed to produce the best overall view in terms of contrast. With the 10 and 7mm, while larger some averted vision was required. M81 / M82 / NGC3077 (Spiral galaxies in Ursa Major) - Both outstandingly bright with the 17.3 Delos however really showed their stuff with a 7mm Pentax with M82 showing its central bar (split) and M81 showing some extended dust surrounded the core region. Closeby NGC3077 showed as reasonably bright circular core surrounded with a touch of extension surrounding it. M65 / M66 (spiral galaxies in Leo) - Easily showed their bright cores only. Tried for the nearby NGC 3628 but something was up... Clouds had come in and covered most of sky. Although it looked perhaps temporary. It was 10:30pm and so I decided to pack away the scope, bring in the eyepieces etc and left the mount out for a possible session later on. after packing away the scope I noticed the clouds had indeed shifted off. I was hungry by this point anyway so had a good break until after 12:30 and looked outside again. It was stunningly dark and clear. All the stars just seemed to be a little bit brighter. All the neighbours had their lights off and all directions LP just seemed significantly less. I decided to pop the 120ST on the mount and get setup for the second session... Session 2 Time: 1am - 02:30am Scope: 120ST refractor Transparency: Excellent Approx NELM: 5.3 After spending 10 minutes just looking around and regaining dark adaption again I can could easily see M44 naked eye which appeared as a faint ball of dust against the darkness of the sky. M104 ("Sombrero" Spiral galaxy in Virgo) - It's been a long time since I've observed this and it was perfectly positioned. I spent a good amount of time with this at different magnifications down to using the 5mm Pentax (142x) which showed well the lighter dust from the galaxy. At the lower power, the contrast easily showed the darker region spitting the galaxy. M3 (Globular Cluster in Canes Venatici) - Some of the cluster resolved with the 5mm Pentax (142x). Very bright core. M64 ("Black Eye" Spiral galaxy in Coma Berenices) Very bright and with the 10mm Delos discerning a small dark area in the central region. M59 / M60 / M58 (spiral galaxies in Virgo) - It's been a long time since I last "delved" into the Virgo galaxy cluster... I shall be re-visiting soon enough with the 12" dob. These galaxies were nice and bright with the 14mm Delos but not showing any real detail. I could not discern the companion galaxy (NGC 4647) to M60. I have seen this before with an 8" SCT but this eluded me tonight. M89 and M90 were also obvious enough. M13 (Global cluster in Hercules). This was now sufficiently high enough to make a good observation. Indeed, with a bit of work and a touch of averted vision it was just about visible naked eye as a tiny ball of diffused light. M13 is spectacular - it's large and very bright and with high enough power (5mm Pentax) was able to start to resolve individual stars although not at the core. I have previously found that there is a massive difference to viewing this with good aperture (last time was with my 8" SCT) which easily resolves stars at the core. I'll be looking forward to seeing this again with the 12" dob. Nearby galaxy NGC6207 was directly visible but needing the 10mm Delos to bring it out properly as a faint small elongated smudge. M101 - This was now very high up and with the additional darkness was well worth re-visiting. It was now considerably bright with the 17.3 Delos very easy direct vision. Going to the 10mm Delos showed the disc of the galaxy. I stayed with it for quite some time and with averted vision helping to distinguish some areas of dark / light almost catching a swirl effect. M102 ("Spindle" Edge on spiral galaxy in Draco) - One of my favourites. Very bright core with a distinct dark lane running through it. I wasn't seeing the entire length but I'd imagine just a slight extension outside of the actual core. Impressive. NGC 5907 (Edge on spiral galaxy in Draco) - This one is considerably more difficult... It's very large and diffuse and no real bright core to speak of. Using the 10mm Delos and averted vision I was only able to see a very faint long area of brightening on the sky. I've seen this one considerably better with more aperture and it really needs much more light capture than 120mm. I was a little reluctant to pack up but I was tired and needed my energy for the following day so I called it a night at 2:30am and packed up. In all it was a really great session that food for the soul after February has been quite disastrous for observing (apart from a few shortish sessions observing the Moon). The 4" refractor really surprised me with its performance on DSOs - I would say that it pretty much matched the 120ST in what it was actually showing regarding nebulosity and picking out galaxies and detail. Obviously for star fields / clusters etc the 4" ED was by far the best and I certainly had a good feeling that the ED was actually going deeper than the 120ST regarding star magnitude. The performance of the 4" against the 80mm ED is a huge step imho comparing it with previous observations on DSOs with the 80mm ED. Can't wait to get in a session now observing the Moon with the new refractor (although would like a nice week of clear Moonless nights first to get the dob out for some good galaxy action around Virgo etc).

Here too, looking amazingly clear here with a deep blue sky should be fantastic transparency. I've been out all day but will try to get a good rest and hopefully it will be still like this around 10ish to get the dob out.

After a decent break had another couple of hours out from after midnight. After an abysmal February due to bad weather tonight has almost made up for it...

You're definitely good to go! I did all the Messier 110 list with a combination of my (then) Celestron C8 and 80ED refractor. The filters definitely help in some cases but I can't think of any Messier objects that I had to use them on in order to actually see the object.

Bit windy... but clear and the transparency was really quite good! Got in a 2 hour session (first light) with my Starfield 102 ED f/7 which arrived today! Did a whistle-stop tour of Messiers - report to come!

Yes, the 100mm f/9 Skywatcher is the same amount which would for me be really bad value for money now compared to this. Having said that The SW 80ED was definitely great value many years ago - I'm glad I bought it when I did and would not sell it although it could use an upgrade to the focuser I've serviced it so it's pretty strong now. I agree with the twist-lock fitting having played with it and also the fact that the force to do that rotates the focuser unless you have it really tight or grab on the focuser at the same time.

... and the new scope has landed! Absolutely love the focuser... it puts the one on the 80ED to shame.

Low clouds aren't so much of a problem if they are intermittent.. I would in this case just get out my refractor on the alt/az mount for easy moving from one location in the sky to another. High clouds are a bane as they are normally covering most of the sky and in this case transparency will normally be awful anyway for deep sky objects. I've become much more interested in observing the Moon lately so have been able to take advantage of a few nights when it's been quite cloudy to still view in the "windows" of opportunity.

The sky has been terrible all this month. All the "clear" nights have been low or very low transparency here - absolutely nothing like wonderous sky we were getting in January. Ensure that you wait for Ursa Major to be high enough before attempting M97 (later on in the night works much better at the moment) otherwise you'll be hitting much more LP which will easily wash out the nebula. M97 is one of those nebulaes though that reacts very well to use of an OIII filter - it can actually make it visible when it's not without the filter.

Yes, M7 will be nigh on impossible from up here. I managed it in Oxford after over years waiting for the perfect moment. and that's a couple of degrees difference. Still, some of the really low Messiers are at least bright enough to get a with small aperture if you vacation somewhere further down south at any time! Your 6" newt will be more that enough though to bag the rest that are far enough up though (the majority!) Like as has been mentioned it will depend completely on the darkness of your observing site and sky (where are you in Derbyshire?) as well as the transparency of the air on the night... M108 is quite easily drowned out by bad transparency and light pollution. Can you see M97 (Owl nebula) without a filter? If so, then M108 should also be visible.

Just bought the Starfield 102 ED f/7 from FLO for less than the Altair f11 I was looking at originally - I couldn't say no to that offer! Thanks FLO!

Thanks John for your invaluable input!!!

Urrgh... another frustrating one. It looked really promising at 7.30 ish with transparency looking OK - I could just about make out M31 naked eye. By the time I managed to get out at 9 after the kids were in bed it had got significantly worse and the sky seemed milky and bright. With the cold wind I decided against getting a scope out. Went out a few times until 1am and it had only got even worse....

Thanks @johninderby . I've also started considering the Bresser Messier MC-127 mak which seems a good price at around £360 - I noticed from some searching that you had this scope as well as the 6" CC - and have sold them both? Why did you sell them? and thinking back would you still recommend the 6" CC over the mak? The mak I think is quite a bit lighter although that's not too much of an issue if the CC really outperforms the mak on contrast and resolution and taking it higher magnification particularly for lunar observation.

Yep, just clouded here as well... so packed up. 🥴 At least, as mentioned there are a few promising looking nights this week.

It cleared quite well so had an hour with the 120ST until 9:30 but frustrating as hell with neighbours' lights on in various directions which is why I do most of my DSO observing after 10 or 11... Well venture out again in bit.

Glad to see it's a bit better elsewhere.. It's clear here but terrible transparency so will wait a while to get a scope out.. Hopefully it will improve!!!

If i'm going to get the 12" dob out then for me I need reasonably good indication of transparency for observing DSOs. You can normally get a feel for this in the afternoon while the sun is going down and if the sky looks a nice deep clear blue instead of whitish haze then I'll get the dob out early. Later on if it's cleared and I can see down to mag 5 stars clearly then it's going to be OK. Anything other than that i'll probably stick with a shorter session with the refractor. BTW, there are many NGC objects that are way brighter than those in the Messier list. I wouldn't see it another level of difficulty...

Just received the 21st Century Atlas of the Moon (Charles Wood). It's exactly what I was looking for and a nice compliment to Rukls' illustrations that are in the Collins Night Sky book. Also, with it being ringbound I can easily take a photocopy of a page or two of interest to use at the scope / notes.

Incoming storm!!! I remember when my 12" dob arrived we had to worst storm for quite some time that night while I set it up... Good luck with the secondary... at least it's not your first dob for setting it up! I bought the Moonlite focuser to replace the stock one directly (first newt as well) and foolishly replaced it before checking the original was collimated even.. Spent the next few days getting the collimation of the secondary dead on...

So the CC would be sharper than the Mak? I suppose this is because of the need for the glass corrector... ?

I hadn't thought about that. A fine helical focuser at the diagonal could alleviate the issue... What advantage does the 6" mak have over the 6" CC (with them both being f/12) ?

I've not tried a Mak however I really didn't like the mirror shift in my 8" SCT when I had it which i believe is also present in Maks as well.

Wait.. what??? the focuser is not straight?

Thanks Ricochet. Yes it's exit pupil is the issue as I start to get some floaters with my 80ED and the 4mm. which gives an exit pupil of 0.53. While it's not overly bad. I certainly wouldn't want to go any lower and find using the 5mm Pentax much more comfortable for prolonged periods (exit pupil 0.67). John: after some research I'm sure you're right that this calculation for loss of contrast (not talking about loss of resolution) is overstated and to me would seem an over-simplification anyway not taking other factors into account.