M87 is an elliptical galaxy in the Constellation of Virgo. It is about 53 million light years away. At first sight it seems a rather boring elliptical galaxy. As I am sure most of you know however, it is very interesting for a number of reasons. Firstly it is huge containing several trillion stars, compared to the Milky Way with 100-400 billion. It has a large population of Globular Clusters at about 15,000, compared to 150-200 orbiting our galaxy. Some of these are visible in the primary image, which is a close up of the galaxy to show the relativistic jet. However, if you zoom into the wider field image (Version B), which is the mouse over image, you can see a myriad of these. At least I presume what we are seeing are these globular clusters. In this wider FOV M87 can be seen in a rich field of galaxies, although the nearby ones are all elliptical in nature and thus relatively devoid of detail.
There is a super massive blackhole in the centre of the galaxy. This black hole is a behemoth with a mass of ~ 2.5 - 4 billion solar masses, compared to Sagittarius A* at the centre of the Milky Way which weighs in at 4 million solar masses. The latter was in the news this week having been imaged for the first time by the Event Horizon Telescope (EHT). However, the first black hole ever imaged by the same technology was that at the centre of M87, in April 2019. 
In the wider field image the relativistic jet can be seen as a bluish linear feature protruding from the core of the galaxy at about 8 o'clock. The jet is streaming out of one of the poles of the black hole. The black hole's huge mass and very strong magnetic fields, conspire to throw matter (protons, electrons & positrons) in a jet out of the pole at nearly the speed of light. You can read more detail of the complex mechanisms elsewhere, but I trust my simple description is adequate.  The term “relativistic” clearly relates to the speed of the ejection. This jet has such huge momentum that it streams away for over 5000 light years, before breaking up. Of course there is another jet facing the other way that we cannot see. The apparent length of the jet is about 22 arc secs to give you a perspective, so smaller than the apparent diameter of Jupiter.
For this image I captured quite a lot of Luminance data as I was looking for the best detail of the relativistic jet. However, I only captured sufficient RGB to give me the galaxy and jet colours. In fact I combined the RGB data with the Luminance data to create a Super Luminance, from which I produced the LRGB image. This shows the jet quite well, but I wanted to see if i could show it with more detail zooming right into M87's core. I had to work hard to get this detail. Although the wide field image (Version B) already contained the Luminance data, I felt I could do better, particularly to achieve a higher contrast to better show the jet. To achieve this I only partially stretched the Super Luminance image, before sharpening it. This avoided the brighter core area blowing out the jet. I then put this darker image into a layer in Photoshop above the main image, where I used it as a Luminosity layer. This had the effect of improving the sharpness and detail visible, but also dramatically improved the contrast, whilst still producing a colour image. This meant the whole length of the jet can be more readily seen, including the narrow beam coming out from the black hole and the wider knots further out as the jet breaks up.
Version C is a comparison with the Hubble (HST) image of the jet. Whilst there is always risk of showing the inadequacies of an amateur image against the superb resolution of the HST, I thought it worth the comparison. What is very pleasing is the correlation of the shape and structure of the jet in my image to that of the HST and therefore confirmation that the detail is real. Note I adjusted the orientation slightly to match the images up.