ASTRO: Cass A at 17 hours (and still accumulating exposure time)

I now have 7.5 hours of Halpha, 7 hours of [OIII] and 2.5 hours of [SII]. If
conditions permit, I will shoot more [SII] tonight.

Once I get to 7-8 hours of [SII] I will switch to Helium II

If I am still not getting the interesting detail that Rick got, I may try
some RGB: we are headed toward new moon so that's a good time to do
broadband exposures. maybe it makes sense to shoot some unfiltered lum
during the new moon? that is always a nice way to bring out stars and
perhaps background galaxies if there are any in the FOV

Current stats:

F= 3366mm, using 18" f/12.6 classical cass focal reduced to f/7.2, image
scale: 0.42 arc-sec/pixel; FLI cm10 camera (kaf3200me sensor)

Cust Sci 4.5nm [SII], Ha and [OIII] filters

Sub exposures all 30 minutes

15 x 30 minutes of Ha

14 x 3 minutes of [OIII]

5 x 30 minutes of [SII]

Richard Crisp wrote:
I now have 7.5 hours of Halpha, 7 hours of [OIII] and 2.5 hours of [SII]. If
conditions permit, I will shoot more [SII] tonight.

Once I get to 7-8 hours of [SII] I will switch to Helium II

If I am still not getting the interesting detail that Rick got, I may try
some RGB: we are headed toward new moon so that's a good time to do
broadband exposures. maybe it makes sense to shoot some unfiltered lum
during the new moon? that is always a nice way to bring out stars and
perhaps background galaxies if there are any in the FOV

Current stats:

F= 3366mm, using 18" f/12.6 classical cass focal reduced to f/7.2, image
scale: 0.42 arc-sec/pixel; FLI cm10 camera (kaf3200me sensor)

Cust Sci 4.5nm [SII], Ha and [OIII] filters

Sub exposures all 30 minutes

15 x 30 minutes of Ha

14 x 3 minutes of [OIII]

5 x 30 minutes of [SII]

You are starting to pick up most of the pieces now. So what color do
you assign Helium II?

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

"Rick Johnson" wrote in message
...


Richard Crisp wrote:
I now have 7.5 hours of Halpha, 7 hours of [OIII] and 2.5 hours of [SII].
If conditions permit, I will shoot more [SII] tonight.

Once I get to 7-8 hours of [SII] I will switch to Helium II

If I am still not getting the interesting detail that Rick got, I may try
some RGB: we are headed toward new moon so that's a good time to do
broadband exposures. maybe it makes sense to shoot some unfiltered lum
during the new moon? that is always a nice way to bring out stars and
perhaps background galaxies if there are any in the FOV

Current stats:

F= 3366mm, using 18" f/12.6 classical cass focal reduced to f/7.2, image
scale: 0.42 arc-sec/pixel; FLI cm10 camera (kaf3200me sensor)

Cust Sci 4.5nm [SII], Ha and [OIII] filters

Sub exposures all 30 minutes

15 x 30 minutes of Ha

14 x 3 minutes of [OIII]

5 x 30 minutes of [SII]

You are starting to pick up most of the pieces now. So what color do you
assign Helium II?

that's a good question Rick

depending on how much signal is in the Helium II, I might blend it with
another emission line after stretching each to reasonable shaped histograms

that's what I would do with RGB data if I were to take that

I would take the red and blend with sulfur for example.

I might blend the halpha into the red too and then attempt to make a pseudo
true-color image

maybe the prescription for RGB blended in would be to mix the eline data
into the same color range of the vis spectrum and then do the scaled halpha
approximates hbeta trick

so that would be:

Red channel = red + halpha + sulfur

Green channel = green + [OIII]

Blue channel = blue + [OIII] + 0.3* Halpha + Helium II

That may be the best plan of action. Not sure just yet.

Richard,
as usual your images are getting better and better over time. You have the
patience not to stop before the image is "done".

Stefan

"Richard Crisp" schrieb im Newsbeitrag
t...
I now have 7.5 hours of Halpha, 7 hours of [OIII] and 2.5 hours of [SII].
If conditions permit, I will shoot more [SII] tonight.

Once I get to 7-8 hours of [SII] I will switch to Helium II

If I am still not getting the interesting detail that Rick got, I may try
some RGB: we are headed toward new moon so that's a good time to do
broadband exposures. maybe it makes sense to shoot some unfiltered lum
during the new moon? that is always a nice way to bring out stars and
perhaps background galaxies if there are any in the FOV

Current stats:

F= 3366mm, using 18" f/12.6 classical cass focal reduced to f/7.2, image
scale: 0.42 arc-sec/pixel; FLI cm10 camera (kaf3200me sensor)

Cust Sci 4.5nm [SII], Ha and [OIII] filters

Sub exposures all 30 minutes

15 x 30 minutes of Ha

14 x 3 minutes of [OIII]

5 x 30 minutes of [SII]

Richard Crisp wrote:

"Rick Johnson" wrote in message
...


Richard Crisp wrote:
I now have 7.5 hours of Halpha, 7 hours of [OIII] and 2.5 hours of [SII].
If conditions permit, I will shoot more [SII] tonight.

Once I get to 7-8 hours of [SII] I will switch to Helium II

If I am still not getting the interesting detail that Rick got, I may try
some RGB: we are headed toward new moon so that's a good time to do
broadband exposures. maybe it makes sense to shoot some unfiltered lum
during the new moon? that is always a nice way to bring out stars and
perhaps background galaxies if there are any in the FOV

Current stats:

F= 3366mm, using 18" f/12.6 classical cass focal reduced to f/7.2, image
scale: 0.42 arc-sec/pixel; FLI cm10 camera (kaf3200me sensor)

Cust Sci 4.5nm [SII], Ha and [OIII] filters

Sub exposures all 30 minutes

15 x 30 minutes of Ha

14 x 3 minutes of [OIII]

5 x 30 minutes of [SII]

You are starting to pick up most of the pieces now. So what color do you
assign Helium II?

that's a good question Rick

depending on how much signal is in the Helium II, I might blend it with
another emission line after stretching each to reasonable shaped histograms

that's what I would do with RGB data if I were to take that

I would take the red and blend with sulfur for example.

I might blend the halpha into the red too and then attempt to make a pseudo
true-color image

maybe the prescription for RGB blended in would be to mix the eline data
into the same color range of the vis spectrum and then do the scaled halpha
approximates hbeta trick

so that would be:

Red channel = red + halpha + sulfur

Green channel = green + [OIII]

Blue channel = blue + [OIII] + 0.3* Halpha + Helium II


strong HeII at 3038, 4690, 4866
strong HeI at 4471, 5875, 7065
But I suspect their contribution would be weak except in specific
cases - thats just a guess.
jerry


That may be the best plan of action. Not sure just yet.