Back to forums

Combining broadband data with dual narrow band.

Acquisition Deep Sky NGC3034 M82 Messier Objects
6 replies•180 views
Craig Dixon avatar
Craig Dixon avatar
My latest project is the Cigar Galaxy (M82), which is perfect for combining broadband data with some Ha data (A first for me).

Gear: Skywatcher 190MN (1000mm, f5.3) and ZWO ASI533MC Pro.

What ratio of time should i spend on each type of data?

I already have about 7 hours of data shot through the Optolong L-enhance filter. I was thinking of getting about an hours worth of 20 second subs through my Astronomik L3 filter for the stars. Then approx 14 hours of 5 min subs through the Astronomik L3 for the galaxy itself.

So:

7 hours @ 300 seconds - L-enhance
14 hours @ 300 seconds - Astronimik L3
1 hour @ 20 seconds - Astronimik L3 (for stars)

Or should I spend more time with the l-enhance?

my understanding is that I should stack two images separately and then combine after doing background extraction, NoiseX and BlurX.
andrea tasselli avatar
andrea tasselli avatar
I would invert L3 with Ha exposures and then some…
Craig Dixon avatar
Craig Dixon avatar
Interesting. So more l-enhance date than broadband. Is there much benefit to spending the time on the 300 second exposures through the L3?
andrea tasselli avatar
andrea tasselli avatar
Craig Dixon (craigdixon1986)Interesting. So more l-enhance date than broadband. Is there much benefit to spending the time on the 300 second exposures through the L3?

It depends on how much you want to tease out of the broad M82 fine structure but in general I'd say 7 hours are already plenty. L-enhance, I don't think 14 hours would do it justice.
Craig Dixon avatar
Craig Dixon avatar
Sorry, I’m confused. BY “I would invert L3 with Ha exposures and then some…” did you mean get more l-enhance data than L3? So Instead of 14 hours L3 and 7 hours l-enhance, aim for 14 hours l-enhance and 7 hours L3?
andrea tasselli avatar
andrea tasselli avatar
Craig Dixon:
Sorry, I’m confused. BY “I would invert L3 with Ha exposures and then some...” did you mean get more l-enhance data than L3? So Instead of 14 hours L3 and 7 hours l-enhance, aim for 14 hours l-enhance and 7 hours L3?

That's right.
Craig Dixon avatar
Craig Dixon avatar
Sorry just re-read your comment. I misunderstood. I’ll aim for 7-8 hours of luminance (L3) and then get as much l-enhance data as the weather will allow.