Re: splitting hairs in the backyard on a bonus night of poorseeing

Hi, Richard,

I always enjoy your narrow band images, and these turned out pretty good, it
seems. I also looked at the picture of your Stinger 450 Classical
Cassegrain, and noticed something in the slide area of the mounting. Between
the long aluminum slide and the square, steel-tube crossbars you have a long
device with a couple of holes visible in the end, suggesting to me a
ball-bearing slide or something similar. I would imagine it's there to
enable easy balancing of the declination load. Could you give details on how
that works?

Thanks,

Chuck

----- Original Message -----
From: "Richard Crisp" <rdcrisp@No-Spam>
To: "The Astronomy Connection" <sf-bay-tac@No-Spam>
Sent: Sunday, November 26, 2006 3:55 PM
Subject: [TAC] splitting hairs in the backyard on a bonus night of
poorseeing

Saturday night was forecast to be cloudy and it was at the outset.

Suddenly about 9pm the skies cleared but the seeing was poor. So I decided
to do some long delayed filter testing.

The Crab nebula is a great target for emission line filters because there
are so many different things in it. I needed to test my [NII] Halpha set,
having just purchased a new 3nm Halpha filter to go with my 3nm [NII]
filter.

The [NII] emission is actually a doublet with the typically stronger line at
658.3 nm and the other one at 654.8 nm. Halpha is at 656.3nm so at most
there is 2nm separating these two emission lines.

Those are the two that my filters are designed to separate and it was time
to put them to the test using the 18" f/12.6 classical cassegrain used with
a focal reducer to an effective ratio of f/7.1

When I last attempted to separate the lines I had a different Halpha filter
with this [NII] and was using a C14 at f/12.46 so things were a bit
different than in this case.

I took three x 20 minutes through each filter binned 2x2. The result is that
the lines did in fact separate.

http://www.narrowbandimaging.com/m1_mk1sn2_cm10_geg_cs_n2ha_2x2_page.htm

I started taking [OIII] but only got two frames down before clouds finally
shut me down for good. I went ahead and rolled up that data too, sort of as
a placeholder for things to come.

http://www.narrowbandimaging.com/m1_mk1sn2_cm10_geg_cs_n2hao3_2x2_page.htm

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