Double the stars, double the fun – some nice multiple stars

[Dennis]

Hello,

The seeing was too poor on Monday night to obtain decent images of Jupiter, so I turned the Mewlon 180, TeleVue x2.5 Powermate and DBK21AF04.AS CCD camera to some double stars. The final results are stacks of between 30 and 180 frames from 1500 processed in Registax.

Final collage in Photoshop CS3.

Cheers

Dennis

[Dr Nick (Nick)]

Nice work!

[Ric]

Nice splits Dennis, that is something I haven't tried as yet.
What sort of exposure times do you use to split the close doubles?

Cheers

[Dennis]

Thanks guys – I enjoyed this multiple star foray. I tried for Antares and its companion at the zenith, but no go due to the jet stream/seeing.

I used the DBK21AF04.AS which is an industrial webcam. It has the same chip as the Philips ToUcam, but it appears to have better electronic circuitry as you can push the Gain right up, with minimal noise intrusion.

I think I was shooting at 15 frames per second, with an exposure of 1/15 sec and the Gain was between 850 and 950 (out of 1023) for the fainter doubles. I captured 1500 frames and punched them through Registax. Only between 30 and 180 frames were suitable for stacking from each run, as the bulk of frames were smeared and badly distorted due to the 3 or 4/10 seeing.

Cheers

Dennis

[ving (David)]

sweet!
great stuff dennis!

[Dennis]

Hi Ving

Thanks! I tracked these down via Hartung's “Astronomical Objects for Southern Telescopes” 2nd Edition - a beautiful publication.

I hope to make doubles more an integral part of my observing program, there is something quite bewitching about them. Just need to swot up on the various naming conventions and designations.

Cheers

Dennis

[matt]

Excellent work, Dennis. Very nicely captured and presented.

I thought you had the DMK...but I see it's a DBK.

Is there a major diff between the 2 other than it's a colour cam?

Did you give up on the idea of RGB imaging with a mono cam?

[Dennis]

Hi Matt

I was kinda wonderin’ who would be the first, eagle eyed observer to pick this up! Well done!

I received the DMK early January and ordered the DBK just over 1 week ago – it only took 4 days to arrive from The Imaging Source in Germany.

Reasoning:

• DMK is just superb for the Moon B&W.
• DMK is just superb for the Planets with the colour filter wheel.
• SBIG ST7E CCD camera plus colour filter wheel is great for DSO’s.

However, I was missing something in between, which didn’t require the more complex set up and processing of the ST7E, nor the resolution of the DMK + CFW, so I reckoned the DBK colour camera (without built in IR filter like the DFK) would fit the bill. It certainly easily outperforms the ToUcam 840K, but I suspect the 900 would be a closer comparison from what RobT reported previously.

I’ve only used it the once so far, and it was great on the doubles, although it struggled on around mag 7 or 8 stars whereas the ST7E would eat these, no problems. Early thoughts are that it is not as efficient as the DMK, that is, the images appear fainter which if correct, should be due to the fact that 4 pixels make up a 1R + 2G + 1B “colour” pixel.

Its early days yet, but I’d like to try the DBK on Jupiter along with the DMK + CFW too. Maybe I could ask Ian to bring his Mewlon 180 around again, mount them side by side and have a DMK vs. DBK shoot out!

Cheers

Dennis