LRGB image of M87, Virgo A

[timh]

I have wanted to get an image of the iconic M87 galaxy for some time but it is difficult to capture anything below 60 deg in the S and SW skies from home because of obstructions. Luckily I had the opportunity to try from another location and a couple of clear nights - which also provided an opportunity to try running everything remotely via Google desktop which generally worked well (although I did need to drive back from home once to de-snag a cable).

Equipment was a VX12 12 inch F4 Newtonian on an Ioptron CEM70 mount, with a Skywatcher aplanatic coma corrector, ZWO UV/IR filter and either an ASI294MM or ASI294MC camera. Guiding was via PHD2 and an F =-400mm *0 mm refractor and an AS 120MM camera.

The final image is from 30/04/25 -757x10s ASI 284MM 46Mb (luminance) frames (0.41 arcsec/ pixel) combined with 01/05 - 02/05 142 x 66s OSC ASI294MC 11Mb (0.81 arcsec/pixel) frames. For the lum frame capture there was minimal moonlight but the OSC frames were affected by a moon still setting in the NW. In neither case were the skies particularly steady -- the FWHM of the luminance image about 2.8 before sharpening.

Capture was in Sharpcap 4.1 and processing in Pixinsight 1.9. the 142 x66s RGB drizzle x2 CFA integration was registered to the 757x 10s luminance integration, background corrected and calibrated using Spectrophotometric colour calibration. The 757x10s luminance integration was gradient corrected and then corrected and sharpened using RC BlurExterminator. The stretch of the luminance and RGB integrations were matched using STF and applied using histogram stretch. Then the luminance was applied to the RGB integration using LRGB. In order to better bring out the jet the stretch at the galaxy centre was slightly reduced using a brightness range mask and HDMR multiscale processing. The image was adjusted using an arcsinh stretch and curves to adjust colour and stretch with brightness and contrast finally adjusted in Affinity photo.

M87 is of course a supergiant elliptical galaxy containing several trillion stars about 53 M ly away and the focal point of the Virgo galaxy cluster- famous for the giant - now imaged - active black hole near its centre. Aside from a jet of energetic plasma that originates at the core and extends out about 5000 light years whilst traveling at relativistic speed the galaxy exhibits no dust lanes and appears almost featureless aside from the 15,000 or so orbiting globular clusters. Lying at the center of M87 is a supermassive black hole, which has swallowed up a mass equivalent to 2 billion times the mass of our Sun. The plasma jet originates from the acretion disk of superheated gas swirling around the black hole and - comprising electrons, protons and other charged particles, is propelled to near light speed and concentrated by the intense, twisted magnetic fields trapped within it. The bluish light that we see (and the radio and the rest of the electromagnetic emission) is produced by electrons twisting along magnetic field lines in the jet, a process known as synchrotron radiation.

Summarising from Wikipedia -- which may or may not be accurate and up to date - At a diameter of ~ 130,000 light years M87 is one of the most massive galaxies in the local Universe, is spheroid in shape and about double the mass of the Milky Way galaxy. The luminosity ratio of 6.3 ± 0.8 implies that only about one part in six of the galaxy's total mass is in the form of stars that radiate energy. The total mass of M87 is estimated to be up to 200 times that of the Milky Way.

[Menno555]

Very cool and impressive Tim!
It's also on my todo list and now even more

Menno

[timh]

Ha. Yes I'm, sure you'll do better when you do finally nail this one Menno. The above image was effectively only a couple of hours exposure. The 757 x 10s is a mistype --should have read 357 - and only about half of the 146 x 66s exposures had reasonably good SNR. I was glad to have got it at all though and to at least be able to discern the jet and some of the globular clusters in the halo. I think that a better image would better show the extent of the halo. Tim