A Globular, a Star Cluster and Three Galaxies

The new mount is performing admirably. Still a few items to take care of and calibrate, but the full functionality is working just fine.

First up is M68. Messier 68 is a globular cluster in the equatorial constellation Hydra. It was discovered by Charles Messier in 1780. William Herschel described it as "a beautiful cluster of stars, extremely rich, and so compressed that most of the stars are blended together". His son John noted that it was "all clearly resolved into stars of 12th magnitude, very loose and ragged at the borders". (Wikipedia)

M68 Globular Cluster in Hydra
EdgeHD-11 / ASI1600mm camera
40x10sec Lum

This monochrome image was taken on May 31, 2020, with my EdgeHD-11 and ASI1600mm camera. A combination of 40 luminance subs using very short exposures (10 sec).

Next is M88, a spiral galaxy in the constellation Coma Berenices. Recent analysis puts it at about 61.94 million light-years distant. It was discovered by Charles Messier in 1781. M88 lies in the thick of what is called the "Realm of Galaxies", and is among the brightest of the spiral galaxies in the Virgo cluster. The full extent of the disk, about 125,000 light-years across is dominated by dust all the way to the core of the galaxy.

M88 Spiral Galaxy
EdgeHD-11 / ASI1600mm camera
100x60sec Lum; 50x60sec RGB

This photo of M88 was imaged between June 8 and June 10, 2020. At 2.5 hours total integration time, it is composed of 100x60sec L subs and 50 each of 60sec RGB subs.

Next up are two elliptical galaxies, M49 and M89. Elliptical galaxies are a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the three main classes of galaxy described by Edwin Hubble in his Hubble sequence and 1936 work The Realm of the Nebulae, along with spiral and lenticular galaxies. (Wikipedia)

M49  is located about 56 million light-years away in the equatorial constellation of Virgo. This galaxy was discovered by French astronomer Charles Messier on February 16, 1777 and was the first member of the Virgo Cluster of galaxies to be discovered.

M49 Elliptical Galaxy
EdgeHD-11 / ASI1600mm camera
100x10sec Lum

M89 is another elliptical galaxy discovered by Charles Messier on March 18, 1781. It is also located in the constellation of Virgo, about 50 MLY from earth. It is nearly perfectly spherical.

M89 Elliptical Galaxy
EdgeHD-11 / ASI1600mm camera
100x10sec Lum

Finally, an open star cluster, M18. This cluster of stars, in the constellation Sagittarius, was discovered by Charles Messier in 1764. It is relatively close lying at about 423,000 light-years distant. It is a sparse cluster about 26 light-years across. This image was taken on June 13, 2020.

M18 Open Star Cluster
EdgeHD-11 / ASI1600mm camera
20x10sec RGB

Busy "Day" with the EdgeHD

Yes, the emphasis is on the word 'day'.

One of the unique capabilities of the Astro-Physics mount is that it can allow you to start your imaging session in the east with the counterweights UP.  Now that probably doesn't mean a whole lot to those of you who are not astro-nuts like me (and there are others of course who do get it). But one of the scary times of a long evening's imaging session is when the scope passes the meridian.

The meridian is an imaginary line that extends across the sky from due south to due north. It is the point where a German equatorial mount has to stop tracking, flip completely around to the other side of the pier, re-acquire the object it was tracking and then continue. Now I have had a relatively good success with my meridian flips. But even when they work you lose some precious imaging time while the scope re-acquires the object, and because the camera is now also flipped the post-processing gets a little trickier. When they don't work, the telescope stops tracking and you are done for the evening (if you are in bed).

But the Astro-Physics mounts allow you to start in the east with counterweights up, thus not requiring any flip. But there is a problem with this scenario - with the telescope essentially upside down the camera can find itself dangerously close to hitting the pier (or equipment that might be mounted on the pier). It has the issue when you are trying to image at high declination values (for you non-astro-nuts), that means directly overhead or to the north. So, we need to make sure that doesn't happen.

Astro-Physics APCC Users Guide

And that is what I did today. During the cool of the evening, while it was still light outside, I mapped out the whole allowable movement space of the mount for each declination 5 degrees at a time. With that data the mount has a mapping of the sky where the telescope is free to move without fear of striking the pier. A safe-zone so to speak. Took a bit of time, but well worth the effort.

Now, if only the skies would clear so I can try out this new capability.