Just got a lovely view of Endymion right on the terminator with the rising Moon.



I used the 90mm Mak and a 19mm Panoptic (52.6x).



Images by CDC & VMA

 

The dead-center green-light is 532nm, last time I looked. However, that article on green-lasers Universe Today ran a bit ago has left me totally confused. They were advocating buying one with a minimum 50mW output! Last I looked, the lawful output is 5mW in the US, 3mW in the UK! I think that article should be retracted. A 50mW has a range of over 50 miles!

Good news on your wing, Ray. Sounds like you are justified to celebrate too much over the holidays! Do keep excercising? That's what helped be when I had a bayonette go through my left hand. It took a long time, but I got full range of usage in the bargain - except my left index-finger can't straighten out completely. That was caused by a Boston cop, who yanked my hand open after a physician had just sutured it back to normal, which pulled-out the sutures - while calling me a string of racist names. I was 13 at the time. I know how you have been, Ray. It's difficult to find the words to illuminate the many negative things this puts on through. Now that you have good news, you'll be feeling much better each day.

I have a GSO (not 'branded') 5X Apochromatic "Barlow." It works very well indeed. It has 3-lenses and is really more like a TeleVue® PowerMate than a classical Barlow. The TV's have 4-lenses. I'm planning to try a bit of Astro-Photography with it, with my beloved ST80! You're going to love the ST80 Ray. Come Springtime, I'm going to stay outside until the snow covers me up!

It's not even officially Winter until the 21st! This cold !%$##!!

On that note -

Dave

 

I really don't know about the short achromatic Barlow thing compensating CA on a short tube achro' like an ST80. I'm not saying it's bollocks, it's just a bit over my head.

According to the book Gerald North graduated in physics and astronomy, is a long term member of the British Astronomical Association and was a Guest Observer at the Royal Greenwich Observatory. So, it's not like he's Brian Cox then lol.

In most countries almost anyone can become an astronomer, but in the UK you usually have to be an ex pop star.



Scary isn't it? lol



It gets worse ...

Seriously though, it's kind of freaked me out a bit that an inexpensive short achromatic Barlow could possibly be more effective on a short tube achro' than an expensive apochromatic Barlow or amplifier.



Good job I didn't get rid of my cheap shorties then!

 

I'm not going to worry too much about the short Barlow issue but it's nice to know cheapo stuff still rocks lol. The ST80 sounds like a great present. I think Venus and Mars will be visible to you on Xmas Day just before and after the setting Sun. The phase on Venus is apparent even at low magnifications.


Venus and Mars are visible around 17:00 (GMT) here. Venus is very bright, Mars not so.



I've tried to predict the times for Long Island but I'm not sure if this Chrome dufus app has accounted for the time differential lol.



I went mad and ordered another book.

 

I've been doing more reading. I know the magnification changes with the distance and placement of the Barlow. I didn't often place a Barlow between the focuser and diagonal. The Skymax has a focal length of 1300mm and high magnifications are not a problem. It seems that if a 2x Barlow is placed between the eyepiece and diagonal it doubles the f/number.



So, a 2x Barlow placed between the diagonal and the focuser effectively triples the focal ratio. This would bring the ST80 to f/15. Essentially altering the focal length to 1200mm. This would certainly make high magnifications easier. I can see some advantages to this way rather than using a 3x Barlow more conventionally.

Predominantly less weight in the diagonal itself. For me though, it would need a substantial Barlow, and all of my expensive ones have compression rings. This rules out using my better quality diagonals which have tapered nosepieces. Of course, a 2.5x or 3x Barlow could be put between the diagonal and focuser. But then things could get crazy lol.

I've discovered that the 102mm Skymax has a 31mm obstruction. That's nearly a third! This technically only leaves a 71mm aperture. This makes the ST80 the bigger aperture in effect by 9mm.

 

Very intriguing experiment, Mak! I'll be reading what you find. Glad you're an excellent observer - I'm sure it will be very interesting indeed - whichever happens.

I just hope that no one uses this in buying a telescope based on a positive result. One should buy an ST80 for it's lower-powered, wide-field views these scopes truly excels in bringing. And I'm glad you understand that throwing more glass in the optical-pathway, does causes a bit of loss in the clarity and resolution. This would make a TeleVue® Barlow the best choice. But it should be checked out with many different Barlow's - now let's see... who has a whole army of Barlow lenses.....

I think I'll go play with my obsessive-compulsive disorder - er... I mean my filter-collection...

Dave

 

Yeah, I'm just thinking about stuff. Excessive focal lengthening would only be good for lunar/planetary anyway. I blame the weather. It's too pants to actually do any observing so I've only got my obsessive compulsive disorder to fall back on. lol

I was quite surprised about the 31mm obstruction in the 102mm Skymax though. The 90mm Skymax has a 29mm obstruction and the 127mm has a huge 39mm.

 

It seems all Maksutov-Cassegrains have a large central obstruction. My 150mm has about 33%, or somewhere near there, obstruction. Though these critters aren't really made for their amazing light-gathering abilities, at close-up magnification of fine detail - they are amazing! Powerful little things. And a good slice less money for performance than a apochromatic-refractor.

I hope your OCD goes well. Your experiments sounds like great fun! But the recent nights - with -20°F temperatures - no way am I going to go out and bag the Moon with a Barlow - and catch pneumonia in the bargain!

Off to figure out a lesson-plan for a new person who is thinking of which telescope to buy.....

Have too much fun!

Dave

 

I could see Orion and the Moon for at least five minutes last night, before the freezing fog came lol. I know Mak's and SCT's have large obstructions but I often wonder how much they bite into the light gathering capability. I think the 102mm Skymax obstruction is 30.39%.

I was always a bit underwhelmed by Jupiter using the Skymax. Admittedly Jupiter's an odd target and hugely dependent on conditions, but I think aperture makes a real difference with it.

I can often get 250x on Jupiter with the Bazooka, often quite a while after opposition. I can see pretty good detail. The Skymax always seem to struggle with it. In fact, my ST80 did as well as the Skymax.

The Moon and Saturn look good with the Skymax though and I've had it to 260x, which is 19x above its resolution limit. It seems to be at its best at around 216x though.

 

Yeah, I'm not sure why the dufus Chrome app shows 21:30. My guess is that it is showing GMT and it hasn't taken into account the four to five hour differential. I know you have daylight saving time in NY as well. If you factor that in my screenshots are probably showing 17:30 Long Island local time.



You should see Venus at any time after 4:30 PM as a bright 'star' low in the south (weather permitting). If the weather seems decent you could set up in daylight if you feel up to it. Or try and view it through a south facing window. Mars will be higher in the sky and more difficult to see at first. At around 50x you should see the phase on both. A green filter can help mask the glare from Venus to see the phase more clearly.

 

DST is what we call 'Daylight Savings Time' over here - you're right, Mak. But it's ended this year. And our time-zone in Vermont & New York State is 5-hours behind the GMT. And there are 4 time-zones in the continental Untied Snakes. California, Oregon, and Washington State are 3 hours behind us civilized states.

Time-Zone class is over,

Dave

 

Yeah, I know time zones are a little more complicated Stateside. I had to get all learned up about it trying to figure out NASA events so I could watch stuff live on the Interweb without missing all the action. Texas is so big apparently it actually has two State time zones (Texas East and Texas West). No one here has any idea what daylight saving time is, even though we change from Greenwich Mean Time to British Summer Time and back, every year. We just say the clocks go forward or back.

They 'spring' forward in Spring and 'fall' back in Autumn. This expression would work much better if we still called Autumn the Fall lol. Autumn is from the Latin meaning really pants weather or something I think.

Still not sure why the dufus app showed NY as 21:30 though. You and Ray are both only about five hours behind me probably at a similar enough latitude to have similar skies. I've been thinking about this (bear in mind I've had brain damage lol) and you must have around the same amount of daylight I get. We're all in the northern hemisphere and it's winter for all three of us.



If the sky's clear I can often see a twilight Venus at around 16:15 GMT at the moment. The Sun's just disappeared below my horizon. This would be 11:15 (AM) for you and your sky should look something like this below:



Now, as the world's round apparently, and turning, you guys should get to roughly where I was watching a twilight Venus if you wait five hours. I think. lol

 

New York State is right across the lake from here. The time is exactly 5-hours behind you. No double-zones in NY. Unlike Texas. It stay the same until you hit Indiana. Last time I looked.

I, to have an app. or two that tells me it's 1/2 hour off. And, usually, these come with a check-box (somewhere - 'where' this is is the challenge!) that's already checked. "Why? Because they're STUPID!" ( From a great song/parody by the social-commenting group: The Capitol Steps.) You're situation is probably the same as mine, the bloody app. came pre-checked!

One good app. can throw the other charts, data, so forth - into chaos-theory. Exasperating. Until you figure it out and un-check the little box (from HELL! ).

"It's that 'special-time of the year!' I can't wait until that jolly, fat-man comes down my chimney, and going "Ho! Ho! Ho!" With his big bag of gifts for all! Then it's - BLAM! BLAM! BLAM! - Santa Stew!!"

'Ta,

Dave

 

Could explain it, I must have not checked or unchecked the chaos theory thing. It's just too Jurassic Park chaotic for me to figure out. According to Stellarium I may be able to see Venus at 16:00. Whether I've taken Daylight Chaos Time into consideration (or not) is a moot point.



Not to forget KStars ....

 

Yeah, dress rehearsals are almost as much fun! lol

 

Got to see Venus and Mars (90mm Mak). Venus is getting higher and brighter. 18:24:00 altitude, with Mars at 25:24:00.

 

Happy Solstice Everyone!



http://earthsky.org/earth/everything-you-need-to-know-december-solstice