Experimenting with a trunk mosaic

[Dave Smith]

Last night was the first clear night in ages and of course it was also a full Moon
I thought I would be brave (i.e. foolish) and try a 2 x 3 mosaic of IC1396 the whole of the elephant's trunk nebula. I have done it previously with a 200mm lens with one frame.

Last night I managed 16 x 600s for two panels, 5 x 600s for another and just 1 each of the other three. It is "interesting" to see how the Moon progressively ruined the subs as the evening/night proceeded. The last four frames were a complete waste of time with virtually no contrast. This was even with a 3nm Ha filter. I have previously succeeded in getting a reasonable Ha image with a near full Moon nearby (the flaming star nebula I think).

Here is a mosaic of the first two frames. The actual trunk was done first and then the one below. The dark sky is ruined by the Moonlight although the trunk detail seems quite reasonable. This, incidentally, was the first time I have used my new SharpSky Pro auto focuser and I am delighted with the way it performed.
This was also the first time I have tried a mosaic with SGPro and I thought the 10% default overlap looked rather small and intend to use 20% next time.


The posted image is 50% full size.

Although I haven't achieved a good image I have learned a few lessons, but above all it was fun to be using my kit again.

Dave

[Ruud]

Good image, Dave! Thanks for sharing.

[MarsG76]

Nice Image.

I'm actually glad that you had the moon light bleeding through your halpha filter. I had the same problem... Currently I'm imaging the horsehead nebula and I also was losing contrast by the moonlight coming through the filter and that is at ISO400 in 600s.  When I was imaging M16 through the same filter during he full moon I was imaging subs for 1800s also at ISO400, the contrast was fine. 

I'm thinking that he reason might be due to M16 imaged at F10 on a 8" scope and the horsehead is imaged on a 80mm frac at f6.25, so the slower optics on the SCT are not as susceptible to the moon light bleeding through the filter.... OR I cleaned my Halpha filter too hard... :-/

[Dave Smith]

Thank you both for your comments.

Dave