The Horse Head Nebula (first light with CCD camera)

[Carole]

My first effort with a CCD camera

SW ED80, Atik 314L+ and H alpha filter
600 x 9 (cooled to -12.8 I seem to recall)
Processed in DSS and CS3
No darks no bias (bias gave streaks accross the image)

Got the orientation round the wrong way, but for a first light I am quite pleased with this. 
Needs more time but HH sank too low.
Did not realise how tricky it would be to align and focus with an Ha filter on.  (Don't have a working filter wheel yet).

[Ivor]

Nice first light, it looks like we are going to be a parallel learning path with these new mono camera.

What capture software did you use (APT)?

For my DSLR work I was using Nebulosity but it doesn't support a filter wheel or temperature control so I've been using CCDSoft which came with my camera. It's OK but I don't like the focusing tool and way it saves the subs.

[Carole]

Hi Ivor,

I used artemis which came with the camera.  Also trying to learn Maxim, but I think that will be some way off before I can use that.
Apparently APT is introducing CCD support from April as well.

I think I need to tweak the processing on the above but had a very difficult day today with family problems so not had much time.

Carole

[JohnP]

Nice first light Carole - you must be pleased with that. What I often do when focussing through Ha is go to a bright star near by the image I want to take focus on that & then slew back.  John

[Carole]

Thanks John, yes I tried to focus and align the night before but it was really difficult and then the skies hazed up, so I guess the haze was partly responsible, then on the night I did the HH I focussed on Sirius and it was a bit easier, though obviously not as easy as without the filter.   

you must be pleased with that

I was hoping for less noise John on the reports on this camera and because of them I didn't take darks, however with set point cooling I can go back and do them afterwards when I get time.
Was pleased to have got it all working and to get a reasonable image. 

Onwards and upwards hopefully.

Carole

[RobertM]

Thats a good start Carole.  I would just do bias and maybe flats too (may not be necessary with the ED80) but I'd never bothered with darks with my H9.  You will need to use bias frames if you want to use flats so you'd better get those streaks sorted out.  Dithering will also reduce noise and remove hot pixels so I'd also recommended that.

The image does seem a little noisy to me for 90 mins of exposure time but it might be a combination of the haze and filter bandpass.  Did you buy a 'generic' filter ?  You would certainly get those sort of results with a wider passband filter and where you are probably also with a 7nm.

I concur with John on the focusing.

Robert

[Carole]

Hi Robert,

The filter is a Baader 7nm Ha filter which I bought from Bern.

Not sure what to do about the Bias streaks as I did stack them at first but the images looked awful, then tried without the bias and the streaks disappeared.  Spoke to some-one at SGL star party who said it was a problem with DSS and that I needed to use the Bias like dark flats to make it work, not sure if this makes sense to any-one and I have yet to try this.  I will try to give that a "go" this evening.

Would love to do dithering but Artemis does not support this.  Maxim is far too complex for me at the moment, though I am learning it VERY slowly.  I gather APT is going to support this camera from April, so hopefully will be able to dither with that.

Watch this space.

Carole

[MarkS]

Carole,

Was this image taken at home or at SGL7?  Same question for the Rosette.  I was assuming they were taken at SGL7.

If it was taken at home then the noise levels are pretty much as expected.  In fact they look subjectively very similar to John's HH taken with an Atik:
http://forum.orpington-astronomy.org.uk/index.php?topic=8126.0

Mark

[Carole]

Was this image taken at home or at SGL7?

Sorry, did I not say, they were taken at SGL7, but the skies were not brilliant, DSLR subs taken there without a CLS filter were very orange, no milky way could be seen and it was hazy some nights with some LP from Hereford, but it when wasn't hazy it was definitely an improvement on Bromley. 

Unfortunately it was a bit hazy the night these images were taken.

I look forward to trying the camera out at Kelling next month. 

Carole

[MarkS]

Hi Carole,

Hazy conditions would definitely explain the noise - it's pretty low in the sky right now.

It's a fine image for your first light.  It's just a shame it's the wrong time of year for continuing to catch nebulae

Mark

[Carole]

Thanks Mark, that has put my mind at rest.

Could some-one explain about set point cooling, as I thought I would experiment today and do some darks, but I have had the set point at -17 and it has only cooled to -7.8.

Is the set point the degrees below ambient, or the temperature I want it to be?
I was thinking the former, but it's behaviour is telling me otherwise.  

Thanks

Carole

[Ivor]

The set point is the temperature you want the camera to stay at however that isn't necessarily possible as the camera can only achieve a delta from the current ambient temperture. In the case of my camera that is 35C below ambient, however you don't want the camera working at 100% hence at the moment I'm taking subs at -20C and the camera is working at 60%.

As the temperature in your house today will be about 20C the best you could hope for is -10C which is inline with what you are seeing.

[Jim]

Hi Carole, get the same with my QSI. With a single stage TEC 20-30 deg below amb is about it. What I have resorted to doing is surrounding the camera with cool blocks from the freezer; seems to do the trick.

[Carole]

Thanks guys, that does seem to make a nonsense of being able to choose what temperature you want then, people have been telling me I can do my darks as any time with set point cooling, obviously that's not the case.  I even lowered the set point but it still didn't go down any further. 

Carole

[MarkS]

Be very careful when comparing the cooling capacities of different cameras.

The Atik 314 uses a Sony chip with very low dark current.  It therefore needs minimal cooling to provide a very clean image.

On the other hand the Kodak KAF 8300 chip has a relatively high dark current.  That's why cameras based on this chip generally need quite extreme levels of cooling.