Ngc3324 & NGC3372

bluescope · #1 17-03-2009, 05:27 PM

Hi all

After having finally done a solar true south alignment on my mount yesterday I was determined to get out in my obs last night before moonrise due around 11.13pm. So I waited for nightfall only to be confronted with strong winds from the NW. The wind finally abaited around 9.30pm and I grabbed my flt110 and headed out. This was also my first chance at reconnecting my setup to my old desktop which I had installed in the obs earlier in the week prior. By the time I had connected everything and re established the link between CCDOPS and the ST2000XCM and had done a 2 star alignment etc conditions had changed again and I found the moon already showing itself and also a cloud bank moving across the sky. Not to be detered I homed in on ngc3293 and it's close neighbour ngc3324 which was my chosen target for the night. Unfortunately due to the continuing build up of high and low cloud I was only able to shoot 5 exposures through the veil of high cloud.

I hope you like the result it's not what I wanted ... at least an hour would have been desireable on this object.
NGC3293 was also in the framing of this image but it detracted from the nebula so I have cropped the image to exclude it. I think the Gem Cluster is a target best displayed on it's own as well so I'll image it accordingly another night when there is no cloud.

I also attach a shot of NGC3372 from 4-03-09 that I hadn't processed to date ( 59 minutes total exposure )

NGC3324 details :
5x360 sec exposures
WO flt110 f7 apo triplet
st2000xcm @-11C self guided in CCDOPS
eq6 pro _ baader mpcc, uv/ir filters

bluescope · #2 17-03-2009, 06:37 PM

I just reposted the images because I edited NGC3324 slightly to lighten the nebula and for some reason NGC3372 has come up as the thumbnail for the thread ... don't ask me

multiweb (Marc) · #3 17-03-2009, 06:46 PM

Very nice details in both shots Steve. Yeah the wind can be a bloody nuisance at times.

bluescope · #4 17-03-2009, 06:47 PM

Quote:

Originally Posted by multiweb

Very nice details in both shots Steve. Yeah the wind can be a bloody nuisance at times.

Yeah it's windy here today and light showers ... thanks Marc !

gregbradley · #5 18-03-2009, 03:41 PM

A couple of nice shots there Steve.

360 seconds is kind of short for one shot colour though.

I talked with Alan Homes of SBIG one time as I had a one shot STL11.

His advice was to take the longest subexposure time you could like 20-30minutes to get the best results.

I think this is because the Bayer matrix causes the chip to lose a fair bit of QE (sensitivity) and also because it reduces the colour noise.

I think the best strategy is to max out the cooling - don't worry if its an odd number, use adaptive darks (in CCDstack you can select different ways of scaling your darks - I found it works really well). And to go for the longest subs you can with your tracking.

Greg.

bluescope · #6 18-03-2009, 03:55 PM

Quote:

Originally Posted by gregbradley

A couple of nice shots there Steve.

360 seconds is kind of short for one shot colour though.

I talked with Alan Homes of SBIG one time as I had a one shot STL11.

His advice was to take the longest subexposure time you could like 20-30minutes to get the best results.

I think this is because the Bayer matrix causes the chip to lose a fair bit of QE (sensitivity) and also because it reduces the colour noise.

I think the best strategy is to max out the cooling - don't worry if its an odd number, use adaptive darks (in CCDstack you can select different ways of scaling your darks - I found it works really well). And to go for the longest subs you can with your tracking.

Greg.

Thanks Greg ...........

I don't think my polar alignment would be accurate enough for 20-30 min subs and I haven't got to grips with drift aligning. I think I would get field rotation if I tried stretching it out that far. I remember doing a 20 minute sub once from here and it seemed ok actually but when I've tried longer subs since they don't work out well. When I get some clear nights and no wind I'll see how far I can go.

I use adaptive darks option in CCDOPS to compensate for any slight temp differences between exposures when I convert to fits files before stacking in DSS.

gregbradley · #7 18-03-2009, 08:56 PM

I don't think my polar alignment would be accurate enough for 20-30 min subs and I haven't got to grips with drift aligning. I think I would get field rotation if I tried stretching it out that far.

Hi Steve,

Have you tried doing polar alignment using your CCD camera?

I only just started doing that and boy what a difference! No more sitting at odd angles looking through the reticulated eyepiece!

You can start doing that at dusk as you only need to pick up a star so it doesn't have to be fully dark. You then would have it pretty perfect within 20 minutes or less of dark and ready to image.

I use Startarg from Andy's Shotglass astronomy to help. It has instructions in it to tell you what to do. Well worth it. Its an overlay on your screen and you then run CCDsoft as usual but follow the instructions to do your polar alignment. My tracking improved considerably once I did that.

Greg.

bluescope · #8 18-03-2009, 10:08 PM

Quote:

Originally Posted by gregbradley

I don't think my polar alignment would be accurate enough for 20-30 min subs and I haven't got to grips with drift aligning. I think I would get field rotation if I tried stretching it out that far.

Hi Steve,

Have you tried doing polar alignment using your CCD camera?

I only just started doing that and boy what a difference! No more sitting at odd angles looking through the reticulated eyepiece!

You can start doing that at dusk as you only need to pick up a star so it doesn't have to be fully dark. You then would have it pretty perfect within 20 minutes or less of dark and ready to image.

I use Startarg from Andy's Shotglass astronomy to help. It has instructions in it to tell you what to do. Well worth it. Its an overlay on your screen and you then run CCDsoft as usual but follow the instructions to do your polar alignment. My tracking improved considerably once I did that.

Greg.

That program looks very interesting and pretty cheap at only US$20 about AUD$30 by the time you convert and add fees etc. I will check it out some more Greg ... thanks mate !

RB (Andrew) · #9 19-03-2009, 01:15 AM

Nice detail in these images Steve.

I also have used Startarg and love it.
But you can also download a similar (free) application which Al Sheehan wrote.
It's in the files section called "AlsReticle.zip"

http://www.iceinspace.com.au/files.html

Give it a try.

madwayne (Wayne) · #10 19-03-2009, 07:43 AM

A couple of really nice images there Steve and thanks RB for the link to Al's reticle, looks very handy.

Wayne

bluescope · #11 19-03-2009, 01:41 PM

Quote:

Originally Posted by RB

Nice detail in these images Steve.

I also have used Startarg and love it.
But you can also download a similar (free) application which Al Sheehan wrote.
It's in the files section called "AlsReticle.zip"

http://www.iceinspace.com.au/files.html

Give it a try.

Thanks Andrew ... better to try a free one first and then see if it's worth buying another program that may be a bit better later. Glad you like the pics.

Quote:

Originally Posted by madwayne

A couple of really nice images there Steve and thanks RB for the link to Al's reticle, looks very handy.

Wayne

Thanks Wayne ... glad you like them.