Messier 98 is an intermediate spiral galaxy about 44.4 million light years away. It is estimated to contain a trillion stars --dwarfing our own Milky Way. It is one the the most remote blueshifted galaxy, meaning it is approaching us rather quickly. The light from the nucleus is obscured by dust lanes.
The problem is .... full Moon. I decided to give it a try anyway hoping the Moon is far enough away.
On April 24th, I tried to image M98 with 11 inch SCT and ZWO ASI2600 OSC camera using 0.7 focal reducer and no filters. It was windy that night so many (most) of the subs had distorted images making then unusable. I used the same sequence last night and had much better results. I was able to capture 160 images (2 minutes, -10C, bin 1x1, gain 100), most of which were good.
I then used PixInsight to combined the 'good' images from both nights and ended up with 205 'good' images. The only process that I used on this image that is beyond my 'standard' processes is HDRMultiScaleTransform. This process is used to enhance the difference between the dust lanes and the remainder of the galaxy ... essentially adds contrast. I really wanted to make the dust lanes stand out.
For anyone interested in how PixInsight works.. the following are the steps I use:
Calibrate the flats
Integrate (stack) the flats into a master flat
Calibrate the lights using the flat master and dark master (from library)
Debayer the lights (required for one-shot color cameras)... this is what assigns each pixel a color
SubframeSelector ... this process (which many imagers do not use) provides statistics for each image such as S/N, FWHM, eccentricity, etc. I use this to grade each image and decide which ones to discard. I also use this to provide a 'weight' to each image which is used during stacking.
Blink... this is a standard tool that allows you to scan through each sub and decide which subs should be discarded. I do not worry about satellite trails since ImageIntegration takes care of that.
StarAlign ... aligns all images
ImageIntegration (stacks all images) to provide a single combined master.
DynamicBackGroundExtractor .... neutralizes background.
SpectroPhotometricColorCalibration ..calibrates the color
BlurXterminator .. this is an automatic deconvolution tool which cleans up the shape of the stars. While not a sharpening tool, it does act like one.
NoiseXterminator ... this is a 1 step noise reduction tool.
GeneralizedHyperbolicStretch ... very unique and powerful way to stretch the image.
MultiScaleLinearTransform...this tool can be used to either sharpen or smooth the image. In this case I used it to sharpen.
HDRMultiScaleTransform... this increase dynamic range .... used to bring out differences between dark and light areas.
CurvesTransformation ... standard curves tool.
Sounds like a lot of effort, but most of the tools are straight forward, especially when already configured for your equipment.
If anyone is interested in learning how to use PixInsight, I am willing to give a 'ZOOM' session. PixInsight can be intimidating but I have found ways to make the process painless.
Does anyone know why 'clicking' on the image no longer brings up a full size version ????
Roger
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