Last Friday was the final moonless night of the month, so I trekked out to Palomar Mountain to try out my new narrowband filter for a second time. I originally planned to photograph the Ghost Nebula, a smallish object with interesting colors. But at the last minute I discovered that narrowband filters don't work on reflection nebulas—that is, collections of dust and gas that are visible due to an external star reflecting light off them. The Ghost is a reflection nebula, so it was out.
With little time to choose a new target, I settled on the Heart Nebula, a well known object that's currently high in the sky. Unlike the Ghost it's an emission nebula—that is, a collection of dust and gas surrounding a star. It's visible thanks to starlight being emitted through it.
The picture turned out OK, but I made a fatal mistake: I didn't realize how big the Heart Nebula is. It turns out to be far too big for my 900 mm scope, which matters because it's supposed to look like a heart. But it doesn't if you cut off the top half. I was also a little disappointed that I got lots of reds but no blues.
Aside from that it's a fairly good image. It's a five-hour exposure (90 frames x 200 seconds each), and it looks sort of like a heart if you fill in the top half using your imagination.¹
¹Or a different picture that captures the whole thing.
Yes, I see the ventricles but the atria are missing
Looks a little like a broken heart.
(somebody had to say it.)
Great job Kevin. You put in a lot of time for this one.
Impressive.
great job ! looks fantastic!
You should invite readers to a astro photo shoot you do! I would fly down from Seattle and pitch in $100 any charity you want. Just an idea...
Your readers should buy you a nice camper van so you can comfortably snooze during these lonnnnggg astrophotog excursions. I’m in for $10.
So reflection nebula are scattered starlight. They only way that will be narrow band is if the star is narrow band and such a thing doesn't exist.
Second, narrow band is, well, narrow. If it passes both red and blue it is by definition not narrow band. If you want blue AND red, you'll need two narrow band filters to make two images and composite them.
You can buy dual band filters these days. That's what I have. It passes Ha and OIII and blocks everything else.
I love these. Thanks.