ngc 6992

[alacant]

Hi everyone

A positive from Ritchie's 3 hour plate using the 23-1/2" f4 at Yerkes in 1901 alongside our  -far less of an achievement- 3 hour 2023 attempt with a 6" f5.

Love the twentieth century stars, sadly lacking in our effort.

 

 

 

Edited July 31, 2023 by alacant

[AstroMuni]

1 hour ago, alacant said:

Love the twentieth century stars, sadly lacking in our effort.

Nice one.

We just need to reduce our stars less using software 😉 and possibly not use the narrowband filters...Otherwise you would get something similar to Yerkes is my guess.

 

[alacant]

On 31/07/2023 at 15:15, AstroMuni said:

filters

Hi

Yes, exactly that. Our cheepo UHC destroys the stars; colour, brightness... everything.
I think the only way for a realistic star field would be to take unfiltered frames.

Cheers.

Edited August 1, 2023 by alacant

[GTom]

You need those early 1900's skies and L-frames.

[tomato]

Great images both. I’m assuming the Yerkes photo was guided in 1901, who stood there for 3 hours?

[alacant]

On 09/08/2023 at 09:40, tomato said:

who stood there

Dunno. Here's George Ritchie -the guy responsible for the 1901 plate- looking into a large telescope. There's also a guide telescope pictured.

I'm by no means certain, but I believe they had quite good tracking and guided by observing a star via a second telescope then using mechanical connections to the mount, the aim being to keep the cross hairs over that same star for as long an exposure as you needed. or I suppose until your patience ran out. I see you can still purchase cross hair eyepieces these days. I wonder if anyone here has tried guiding like that? Presumably back then, one got only one go at getting it right.

Cheers

 

[tomato]

Thanks for the info. I have manually guided many times back in the day with a reticle eyepiece and a hand controller, I used to manage 15 min exposures on emulsion film but when it was -5 deg C that was quite enough.

[alacant]

43 minutes ago, tomato said:

reticle eyepiece

Is it a case watching a star for the duration? Presumably you'd issue NSEW via the handbox if the star moves away from the cross hairs.