Tegmine, Castor and Meissa

[AlcorAlly]

Highlights from last night's doubles session under the glow of the full moon. All with 102mm f9 refractor and 4mm TV DeLite at 230x. 

Sketched at the eyepiece, there are probably some inaccuracies, constructive feedback is very welcome.

 

Edited March 25 by AlcorAlly

[mikeDnight]

Very nice sketches. Naming them if you know which doubles they are will make the sketches more valuable,  but the way you've captured the diffraction rings adds to their beauty. 

[SwiMatt]

Really like your sketches! Are you using paper with a lot of tooth? Is the medium pastel or pencils? I really like the soft glow that fills the eyepiece!

Any reason why you don't have any notes around the sketches? Things like instrumentation used, directions, etc. I find them useful to observe, and to add some "flavor" to the observation.

[AlcorAlly]

Thank you @mikeDnight @SwiMatt I do take notes, i just cropped them out in the image (they're not great), here's the full version. 

[AlcorAlly]

Right now I'm struggling with two things. 

1. Working out which way the view is oriented (NESW) when I keep rotating the diagonal. This maybe a very basic question, but how do you quickly determine which way is north when using an EQ mount and an diagonal at an unusual angle? 

2. Maintaining consistent and accurate proportions across my sketches - e.g. 1st magnitude star at 230x is 5mm on sketches, etc. For example, the Castor above seems a little too large now, in proportion with the other two. 

Any tips on the two challenges above would be very much appreciated. 

[AlcorAlly]

1 hour ago, SwiMatt said:

Are you using paper with a lot of tooth? Is the medium pastel or pencils?

This is pencil on paper, inverted in a mobile app, which a tiny dab of colour applied where needed.

[Franklin]

23 minutes ago, AlcorAlly said:

how do you quickly determine which way is north when using an EQ mount and an diagonal at an unusual angle? 

Find West by turning drive off, the other directions are relative to this depending on scope/diagonal configuration.

[SwiMatt]

21 minutes ago, AlcorAlly said:

Right now I'm struggling with two things. 

1. Working out which way the view is oriented (NESW) when I keep rotating the diagonal. This maybe a very basic question, but how do you quickly determine which way is north when using an EQ mount and an diagonal at an unusual angle? 

2. Maintaining consistent and accurate proportions across my sketches - e.g. 1st magnitude star at 230x is 5mm on sketches, etc. For example, the Castor above seems a little too large now, in proportion with the other two. 

Any tips on the two challenges above would be very much appreciated. 

I can mostly answer the 1st question. In the Northern hemisphere, West is the direction towards which stars are drifting (EQ or diagonal position should make no difference). If you place a star in the middle, the West direction is exactly where the star disappears from the eyepiece (with drive off, of course, as @Franklin says). Then, N is always 90 degrees from there, and whether it's clockwise or anticlockwise depends on your telescope and diagonal: a reflector with a star diagonal (i.e. image mirrored on the horizontal axis) will have N clockwise from W. Personally, instead of remembering clockwise and anticlockwise with respect to drift, I mark W, and then just think of where Polaris is in the sky, and that's North.

For question 2, I can say that we are sketching, not always representing reality. There is space for error and interpretation. But also, with time one gets better at proportions (true for sketching in general, not only astro)  

[AlcorAlly]

This is so helpful, thank you @SwiMatt @Franklin! I don't know why I didn't think of that, somehow I was completely stuck on trying to find north first, every time.

23 minutes ago, SwiMatt said:

There is space for error and interpretation.

True but I 'd like to have a system of some sort because I draw a lot of double stars and the sizes of airy disks and relative distances seem important when referencing past sketches.

[SwiMatt]

26 minutes ago, AlcorAlly said:

True but I 'd like to have a system of some sort because I draw a lot of double stars and the sizes of airy disks and relative distances seem important when referencing past sketches.

One way would be to carry some kind of "measurement" in your kit. E.g. a ruler with a table on paper attached on its back with a cheatsheet about your measurements?  

[AlcorAlly]

33 minutes ago, SwiMatt said:

ruler with a table on paper attached on its back with a cheatsheet about your measurements

great idea 

[JeremyS]

Splendid sketches. Really lifelike 👍🏻👍🏻👍🏻

[shinebug777]

castor looks super beautiful. great work!

[Franklin]

15 hours ago, AlcorAlly said:

True but I 'd like to have a system of some sort because I draw a lot of double stars and the sizes of airy disks and relative distances seem important when referencing past sketches.

If you make a note of the optics used for each sketch, then you should have a rough idea of the scale of each drawing. Knowing the True FOV that your eyepieces/scopes  produce is a useful thing.

[lunator]

Very nice sketches. 😁

As noted above find West first by watching the star drift. I like the idea of using "where Polaris is" as away to find North.

I usually just move the scope manually to confirm direction. 

Cheers

Ian