josefk

@JeremyS 

https://www.amazon.com/LOGOVISION-Apollo-Anniversary-Patch-Insulated/dp/B0CGXJPZMG/ref=sr_1_2?crid=K6H342N3IQ67&keywords=Apollo+11+lunch+box&qid=1701549128&sprefix=apollo+11+lunch+box%2Caps%2C212&sr=8-2 will need a scrap of foam to complete. 

@SwiMatt

I do have a sketch myself of the double cluster that will never see the light of day 🤣  yes I do believe globular clusters are a tad easier than open ones. 

Good stuff @SwiMatt. All three with the brushed pastel technique?

34 minutes ago, badhex said:

Now I've confirmed that I have astigmatism and know my prescription I was able to get help - @HollyHound to the rescue!

i find the one i use on my widest EP to feel like a super fine focus to use even after focussing. Its not 100% perfect (the prescription must not be an exact match to my own even though on paper it kind of should be) but its a huge 90% improvement over not having it. 

30 minutes ago, SwiMatt said:

Never! Snow is life 😛

i forget what my Finnish colleagues call snow - not the snow itself per se but something about its affect on bouncing light around once it arrives in the darkest winter months. Do you have a similar saying/concept in Sweden?

err.. my finder was icing up and slowing me down as i hopped in across a couple of other much smaller clusters [NGC 1647 and NGC 1662) coming from the Hyades and Aldebaran but as i got to M38 finally (from where i would have come down the classic Messier set here) - also my objective was beginning to get frosty so i beat a hasty retreat. i didn't have dew bands on. 🥶

Nice detail and thanks for posting because your top pic 100% validates my visual observation and sketches last night - i'm not imagining things - i'm chuffed to bits. 👍

You've got to move pretty fast @dweller25 in more ways than one. 😉 

10 minutes ago, woldsman said:

Great post. I also observed last night (my, it was cold!) & the GRS and apparent band break were very clear from the Cotswolds in an 80mm f11 refractor. Your fingers must be frost-proof!

Thanks and cheap sheepskin gloves! I find them better than even quite technical mountain gloves or mitts for the kind of on-off-on again routine with astro. highly recommended.

i am loving this scope not only for its big strength (flat and wide) but also for its ability to bring me a nice planetary view from a tiny package. Out last night observing the GRS transit on Jupiter at about minus three degrees...

Fabulous session last - a "best yet" Jupiter in the little GnG. Such a shame it was a school-night and i had had early evening plans because in my location it felt like it would have seriously rewarded a long session with bigger kit. Never-mind ~21:00 till 23:30 it was super enjoyable nonetheless both for the astro and for being out on such a lovely crips atmospheric evening.

I mainly watched the GRS transit the middle quarter/third over a period of about 90 mins. Great detail for a small scope, seeing felt very steady in deed for quite extended moments. Sketched over here: https://stargazerslounge.com/topic/416550-jupiter-grs-transit-in-the-frost-301123/#comment-4437018

What a fabulous night last night in the frost at minus something or other. Shame it was a "school night" because it felt like conditions were really superb.

I spent the best part of 90 minutes in a 2.5hr session observing only Jupiter and it was the best i've seen it in my 85mm scope. Really tantalising and interesting NEB/SEB "detail" while the GRS transited the middle quarter. Wonderful.

Here's a rough attempt at capturing the view - 3 sketches in the field and two tidied up this morning. For the starting sketch i made the mistake to try for too long to capture what i could see and so there is quite a bit of rotation error in it i think. I must remember to go much quicker (10-mins per thumbnail) in future.

Observation with an 85mm refractor and ortho' eyepieces 5mm, 4mm and 3.3mm. 5mm and 4mm  also with the Tak 1.5 extender for magnifications in the x135...169 range. 

Though NEB and SEB were showing lovely "roughness" or "ropelike" twisting the features were mainly large and darker-on-dark. i didn't see any small barge like features nor any light-on-dark pale ovals except, there was a medium small prominent dark area preceding the GRS seen straightaway and i had the feeling this was more visually prominent after the GRS transited the mid point.

Very nice @SwiMatt - i was working my way over to M36 last night but didn't quite make it - this is compensation enough 😉 

I would put a finer focuser on my fine focuser if i could (not joking). I may yet still add a bit of pipe lagging or similar to expand the circumference on my GnG set-up. When my hands get cold i think i pass quite a bit of tremble onto my lightly mounted GnG when trying to get that last bit of sharpness.

37 minutes ago, Mr Spock said:

...or to sell up and take up crocheting 

Long runs of cloudy sky make me crotchety. Does that count?

@Franklini can get it down to 21” per graduation with a x2 PM in a 2.4m focal length scope but this set-up isn’t preferred and I really would need x5 Barlow in other scopes.  Good fun though and educational already in its own way. 

10 minutes ago, Franklin said:

Here's another good explanation from a fellow SGL member.

That’s another great post to digest!

26 minutes ago, Franklin said:

The rate of sidereal drift is 15 arc seconds per second of time, so by timing the E-W drift of a star across a scaled line you can work out the size of the scale for a given magnification. Once you know the size of each mark on the scale, in arc seconds, you can use it to measure separations, just like using a ruler. The method is to set the scale in line with the E-W drift and with the star at one end, turn off the drive and time the drift of the star across the whole length of the scale. Do this many times and then take the average, then multiply this average by 15 to convert to arc seconds and then divide the result by the number of marks on the scale. If you change scopes or use a barlow then you must re-do the timings for the different optical configuration. There are also more accurate methods which take into account the cosine of the declination of the star but if you make your calibration timings with a star close to the celestial equator the simple method works fine.

My problem is I can’t get a magnification high enough to make the marks on the scale measure a meaningfully small number of arc seconds and I don’t fancy buying a x5 Barlow or similar especially to do it. 

I should say I use the Baader Polaris and it isn’t as finely graduated as the one you showed. 
 

11 hours ago, SwiMatt said:

Weirdly, I also believed that of myself until this summer... just sayin' 

i wouldn't repeat this out loud to anyone really artistic but i have a few (non-astro) "learn to sketch" type books and one of them opens by saying "sketching is a skill not a talent" meaning it can be practised and perfected by anyone 🙂. i live in hope even if so far i may be the exception that proves the rule 😂.

...meanwhile i bet you now you will recall the observations above far better in a few months time from having taken the time to sketch them and i would hazard a guess you probably saw them better at the time from setting out to sketch them and really looking (no offence to anyone not sketching).

Cheers

Hi @Sunshine - i found this to be a good read: https://www.handprint.com/ASTRO/bineye1.html#standard

Except the anomalous behaviour of the eye/scope combo at "diffraction magnification" (where the visual separation doesn't change even if you magnify it - something i understand in theory but don't know how to apply in practise) it's basically good sound advice to understand your EP FOV in arc minutes then go from there in estimating fractions.

With wide angle EPs i'm not too accurate visually dividing the FOV up to estimate a narrow separation but with narrower EPs (e.g.a FOV ~15') you can be surprisingly accurate estimating even at sub arc minute fractions and when i get my eye in even at +/- ~5" (e.g. <5", ~5", 5-10", 10-20", etc.) - especially when you are doing a few doubles in an evening. You sort of get calibrated as it were.

I tried an etched reticle (simpler than the one @Franklin shows) and it sharpened up my estimation for position angle (drifting stars from the centre of the EP out of the edge and using the guidelines on the reticle to do this precisely) but i can't get it magnified enough to usefully use the scale for "measuring" separation rather than just being a useful help to more accurate estimations.

Cheers

hi @badhex - the camping mat solution doesn't stop me also looking at proper dew shields with built in heaters because the camping mat is flimsy so is semi-consumable. But the big advantage of camping mat material is it is super light.

Here's a pic from the spring - this is at the end of an 8hr session. it wasn't super dewey but you can see from my car there was plenty of dew about by this time. 

I had run the dew heater for 8hrs on a 13,600mAh source and there was still some juice in it...the objective was clear all night though i also realise from this pic that i do extend my dew shield by quite a bit more than i thought with the camping mat (the end of my dew shield is just ahead of where that black elastic band is)...

I also don't have a load of experience with dew bands though i do use one on my bigger refractor.

I put mine just behind the dew shield (so probably around the lens cell more or less). So i can run it at the lowest power setting (and so leverage a small energy source for many hours) i put a short section of foil backed camping mat around both it and the dew shield extending the effective dew shield by a few cm by doing so. Seems to work so far. If i fear it is necessary to use it then i use it right from the off - i don't wait for dew to start to form.

I despise dew more than any other local impediment to observing. I like IP6x rated bird spotting optics!

How easy or not was Tethys at that proximity @badhex in the 100mm? I had similar proximity of the moons to Saturn one evening last week and could pick out Rhea (with 85mm) but not Tethys (and not Enceladus). There was some glare in the atmosphere but not loads.

15 hours ago, PeterC65 said:

Three EAA sessions in the last week which makes a nice change!

The first two (Monday and Tuesday) were with the 72mm Apo then last night I used the Explorer 150. The new Optolong L-eNhance filter was very impressive with both scopes, but it does benefit from longer exposures, 15s rather than the 4s that I normally use. The StellaMira field flattener has also improved the corner and edge stars with the refractor.

EAA sessions tend to go on for longer than visual sessions, last night I was observing for five hours, and so I'm experiencing dew problems with the refractor and the little Askar FMA135 that always rides piggyback on the main scope these days. I have the appropriate dew heaters on the way from FLO and plan to build a bespoke power wiring harness.

Since I've swapped to the L-eNhance, I've been concentrating on emission nebulae. M27 and NGC6888 looked particularly good last night, but I could also see form in the nebulosity of NGC1491, NGC1579, NGC7023 and NGC7129. These last two were better with filters other than the L-eNhance. NGC7023 needed the UV/IR cut filter as it is a broadband reflection nebula and NGC7129 turned out to emit in the IR band and looked best with the IR Pass filter. I mostly use the IR Pass filer for reducing atmospheric wobble when observing the Moon and Planets, so it was nice to find another use for it.

Here is M27 with the L-eNhance and 4s exposures ...

and NGC6888 also with the L-eNhance but with 15s exposures ...

Both images are snapshots of the live stacks from last night.

 

This looks fantastic. I've said it before - while i have a technical job and use screens all day at work i don't see myself getting into EAA (i need an analogue hobby as an antidote to work) but in the far future i can definitely see EAA (or more preferably NV if the prices come down) as an alternative to wrestling with a large or very large scope to achieve these views. Not instead of visual but a bit like you do as something to do "as well as". Super.

Uses your phone camera to do this: