Sunday, June 17, 2018

#143 - Friday, June 15, 2018 - I'll Take my Chances

I haven't been out in a while - we've had a lot of clouds, and even nights that had potential to be clear still had the threat of high-altitude clouds.  In order to keep up with my 50 nights/year average, I need to get in 8 more nights before July 15th!  The forecasts for last night were showing things like "mostly clear," although Clear Sky predicted no clouds and 4/5 transparency.  Usually for Clear Sky, poor transparency actually means high-altitude clouds, which the regular weather forecasts will show as "clear."  Despite the "mostly clear" forecasts from the regular weather forecasts, I decided to head out anyway - sometimes, the high clouds will clear out after sunset, especially if they're only spotty and not a blanket, which these were.

Before I went out to the observatory though, the club had a solar observing public outreach event.  I brought out my Oberwerk binoculars with my Seymour Solar filters, and we also had a Lunt solar scope owned by the club, another pair of binoculars with solar filters over them, and a narrow but long refractor with an image of the sun projected onto a white surface a few inches behind the eyepiece.  Unfortunately, the sun was pretty boring yesterday (as it's been for a while) - no sunspots.  There was a plage visible in the solar scope, which is a bright region that usually is paired with the formation of sunspots.

I got out to the observatory a little after sunset, chatted with another club member who came out as well to take their chances with the clouds, and got set up.  I had a hard time finding a target - most of the summertime nebulae I'm dying to image with my new camera are too low still in the first half of the evening, and the couple of larger galaxies are too high to be able to see through the slit of the dome without getting cut off by the top of the slit (M51 and M101, for example).  The Pelican Nebula was just high enough to maybe be mostly un-mushified by the atmosphere, so I decided to give that a shot.  I wasn't sure how much I'd be able to see of it, since it's large and diffuse and I'm fighting a lot of light pollution.  As it turned out, I wasn't really able to get it at all.
2-minute subframe on the Pelican's there, somewhere...

So I found a galaxy that wasn't going to be *too* small - M64, the Black Eye Galaxy.  I use SkySafari to judge how things might come out.  You can add telescopes, cameras, and eyepieces, and then choose a combo and it will display the field-of-view.

There were several little collections of clouds, and a few bands that moved through, but mostly the area I was imaging stayed clear.  It's a little harder to tell when I cloud moves through a FITS image, the file type I save out from my ZWO camera, since they're very 'raw' types of files.  But I'm getting better at it.

No clouds


And you can see a beautiful giant dust spot I need to go remove next time I'm out there.  

I took 60-second images because I think with the clouds there was a really thin haze that was scattering a lot of light from the surrounding towns, further increasing the effect of light pollution.  Also, I accidentally had the gain set to 300 instead of the unity setting of 139.  Of the 90 luminance frames I took, I was still able to keep 77 that at least looked like they didn't have clouds.  The final image came out a little noisy as a result of using synthetic flats, and it's just the luminance because that's all I had time to do last night, but on my next trip I'll get the red, green, and blue.

Date: 15 June 2018
Object: M64 Black Eye Galaxy
Camera: ZWO ASI1600MM Pro
Telescope: Vixen 140mm neo-achromat refractor
Accessories: Astronomik LRGB 1.25" Type 2c filters
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5
Subframes: L: 77x60s (1h17m)
Gain/ISO: 300
Stacking program: DeepSkyStacker 3.3.2
Stacking method (lights): Median kappa-sigma (2,5)
Darks: 20
Biases: 20
Flats: 0
Temperature: -15C (chip), 69F (ambient)

Once the luminance frames were done, it was 12:30, and there were still quite a few little clouds rolling through, and M64 was getting further and further to the west.  So I decided to call it a night.  But the luminance so far looks pretty decent!

M64 is an interesting galaxy.  It lies about 17 million lightyears behind the constellation Coma Berenices, home to a number of galaxies.  The "Black Eye" moniker comes from the fact that it has a very dark band of light-absorbing dust.  Probably the most interesting feature though is that this galaxy is made up to two counter-rotating disks, which is likely the result of a galaxy merger in the distant past.  

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