Jump to content

Narrowband

Bad weather, column defects and Melotte 15


Hughsie

Recommended Posts

As well has having my own imaging equipment at home, I also subscribe to iTelescope. This gives an outlet to scratch that imaging itch when the weather in the UK is poor, access to equipment I can only dream about as well as deep sky objects I will never capture with my own gear.

Whilst the Heart Nebula is visible from my location in North Essex, I was more interested in the heart of the Heart and Melotte 15. iTelescope have in Nerpio, Spain a 12” Planewave CDK Astrograph and so I attempted to give this a go to capture Ha, O3 and S2. I started at the beginning of October but like here in Essex, Nerpio was also suffering with poor weather but eventually I prevailed after rebooking my image runs several times, naturally to coincide with a near full Moon. Ah well.

So here is 6 hours in total (2 hours of each channel) of Mel 15.

Mel_15_final.png.adcf8e12e04d526f867fdaf1f5332387.png

 

iTelescope provide the sub-frames already calibrated with darks, flats and bias frames, however, this data needed a lot of help as the camera sensor had significant column defects which the calibration did not remove. The image below is 24 stacked Ha subs using the ImageIntegration process in PixInsight. The image looks blurry as the subs have not been star aligned. This is deliberate as the intention is to reveal the problems more clearly by stacking the defects (they already exist on the sensor in the same place in each sub) whereas if we ran the StarAlignment process first before ImageIntegration each defect would be in a slightly different position.

HaStackedWithColoumnDefects.png.9ff34e133187f8b3c7361827222f312e.png

 

Fortunately, PixInsight has two great scripts for identifying and locating (LinearDefectDetection) as well as removing' (LinearPatternSubtraction) these defects and a bit of CloneStamp finished the job.

 

 

 

Edited by Hughsie
I proof read three times, submitted then realised I can’t spell
  • Like 4
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.