Eta Carinae in H-Alpha

[strongmanmike (Michael)]

Originally Posted by montewilson

Hi Mike - If you are thinking of killing me for my FSQ tell me first and I'll just give it to you ha ha.........

You've been a bit quiet on the forum lately. I guess it must be those fantastically dark New Castle suburban skies

I will post a bigger version of the shot soon. I loved the old 2415 days. There was something romantic about film that zeros and ones just don't have. I guess these days numbers like 2415 and Super HG400 are like special code for astro old timers that we can use to identify each other.

Will you be coming to the SPSP? If you do, set up at the house where will have our imaging area, generators, monitors et al are all OK there.

OK...I "will" kill you!...now, post 1 X FSQ106 to Acer Terrace Thornton NSW 2322

Yes quiet I know, only done one image in 4 months

Film huh? Lots of stories about using that stuff all soooo fond and romantic now (except for Joe)

I will most likely be at SPSP this year but as usual I will likely not bring my imaging gear. I like to treat SPSP as a bit of an astro holiday and get around and see and talk to lots of people and look through telescopes (and eat lots of donnuts) rather than get bogged down concentrating on imaging with my own gear and all the inevitable trials and tribulations operating a complex imaging setup tends to endure in unfamiliar surrounds. I did it one year and decided it just wasn't worth the trouble (although I scored my first SPSP astro imaging award that year with an image I took the morning of the competiton ). I will undoubtedly come over for a sticky at the house though and say high

Cheers

Mike

[robgreaves]

Hi Monte

Excellent shot

Regarding the noise, it's an interesting issue. Strictly speaking, with a dark frame removal, if done properly, it doesn't really matter what temperature you run at or how much noise there is in the raw .fits since a good master dark frame should (at least mathematically speaking) remove it. Even SBIG themselves recommend only a figure of 'x' degrees below ambient (not an actual specified set temperature), based on 75% or so cooler power/ efficiency figures. This, in reality, can translate to 'only' -7'C or -8'C on a balmy night. All this is in the CCDSoft manual somewhere.

However... running at a lower temperature again (assuming the cooler can handle the increased demand - it's not unknown for Peltier coolers to go pop!!) is very beneficial in that when you do your darks you are asking less of their performance and accuracy, if that makes sense, as you are having to remove less inherent thermal noise. OOI, to get to lower temperatures, I usually create a setpoint of say -15C, let it stabilise and let cooler power come down, then go to -20'C, stabilise, then -25'C where I then usually image. To go any lower I'd think about getting the 12V pump and a bucket of water out, especially in an Australian summer.

The key is getting a good master dark, from darks taken on the night on the same camera bootup sequence - not 2 weeks later..! 15 or more darks with a good median or Sigma reject combine usually work well. Also, if the sky looks good and you have time, darks in between light frames is good practice. If you end up with only a few dark rogue speckles in the final calibrated image from an 11MP sensor, you're definitely onto a winner and they're easily dealt with.

See you Wednesday.

Cheers - Rob