RASC - St. John's Centre
Members Photos

I re-did "first light" images for a new ZWO Dual-band interference filter I received in early July, data which I took on the night of July 7. Messier 27/NGC 6853/PK 060 -03.1, the "Dumbbell Nebula", in Vulpecula. Total exposure is 30 times 2 min at -20C, for one hour; ZWO ASI294MC Pro camera on back of 12" Meade LX200 ACF (at f/6.7 ala focal reducer), autoguided by PHD2. A new manual filter holder was also in place, to contain the filter. The filter diameter is actually only 1-1/4", not 2", but happily calculations are confirmed by the lack of any vignetting. I shot calibrators two nights later, with precisely the same settings (also 30x120s for the darks). Registered and stacked in DSS 4.2 with kappa median rejection, curves in Gimp 2.10.

There's still a bit of a faint red gradient at the top (so the flat fielding is still not perfect), which I tried to diminish by blackening the background. It may be too black and "up too hard against" the nebula-proper, though you can still see the fainter outer lobes.

Click on image for full original photo.