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Telescope: Stock Unitron 155c 4” f/15 refractor

Camera: Canon EOS Ra full frame DSLR

Filter: 2” GSO IR Cut Filter

Guide scope: None

Exposure: 27 (of 32)x15sec, ISO 6400, saved as RAW

Darks: Internal (Long Exposure Noise Reduction)

Flats: 32×1/20s tee shirt flats taken at dusk

Average Light Pollution: Bortle 8, poor transparency, haze, low altitude

Lensed Sky Quality Meter: 18.3 mag/arc-sec^2

Stacking: Mean with a 1-sigma clip

White Balance: Nebulosity Automatic

Software: Backyard EOS, Deepsky Stacker, Nebulosity, Photoshop

M92 is the ‘other’ globular cluster in Hercules. M92 lies to the northeast of the popular M13 globular cluster in a relatively lonely patch of sky making it a bit harder to locate, but well worth the effort. Interestingly, M92 is listed as being fainter than M13 (Mv 6.4 for M92 vs. 5.8 for M13), but I find the core of M92 to be a tad brighter than M13. The larger apparent size of M13 likely contributes to its slightly higher total integrated brightness.

This is the 3^rd and last test image taken with my Unitron 155c in its stock configuration. Next up; moving the 155 over to my Atlas to see what it can do on a modern guided mount.

M91 currently rises in the northeast during the early evening.

Telescope: Stock Unitron 155c 4” f/15 refractor

Camera: Canon EOS Ra full frame DSLR

Filter: 2” GSO IR Cut Filter

Guide scope: None

Exposure: 28 (of 32)x15sec, ISO 6400, saved as RAW

Darks: Internal (Long Exposure Noise Reduction)

Flats: 32×1/20s tee shirt flats taken at dusk

Average Light Pollution: Bortle 8, poor transparency, haze, low altitude

Lensed Sky Quality Meter: 18.3 mag/arc-sec^2

Stacking: Mean with a 1-sigma clip

White Balance: Nebulosity Automatic

Software: Backyard EOS, Deepsky Stacker, Nebulosity, Photoshop

This is M13, the Great Cluster in Hercules. If you look carefully you can glimpse the tiny galaxy NGC 6207 (Mv 11.6) in the upper left corner as well as a dust lane to the lower left of the cluster. The dust lane is a very unusual feature for globular clusters and it is not clear if this is actually associated with M13 or simply lies in the line of sight with the cluster.

M13 currently rises in the northeast during the early evening.

Telescope: Unitron 155c 4” f/15

Camera: Canon EOS Ra full frame DSLR

Filter: 2” GSO IR Cut Filter

Guide scope: None

Exposure: 24 (of 32)x15sec, ISO 6400, saved as RAW

Darks: Internal (Long Exposure Noise Reduction)

Flats: 32×1/20s tee shirt flats taken at dusk

Average Light Pollution: Bortle 8, poor transparency, haze, low altitude

Lensed Sky Quality Meter: 18.2 mag/arc-sec^2

Stacking: Mean with a 1-sigma clip

White Balance: Nebulosity Automatic

Software: Backyard EOS, Deepsky Stacker, Nebulosity, Photoshop

This is the first test image taken with my Unitron 155c using it in it’s stock configuration with it’s original German equatorial mount ans synchronous clock drive. I was pleasantly surprised that the telescope was very easy to point using the setting circles and it was relatively easy to find and center the target. The tracking was very good and similar to modern unguided mounts. I found that I could get 70%-90% successful subs using 15 second exposures. Once the drive settled down 80-90% was more typical. Polar alignment using a QHY Polemaster was quick, easy, and accurate. This is a pre-1966 model which does not have a slow motion adjustment for the R.A. once the clock drive is installed, but I found that all I had to do was to point the telescope slightly east of the target and then turn the clock drive off, let it drift to the center of the field, and then turn the clock drive back on. The drive ran perfectly off of the 120VAC output from my lithium ion battery. The field of view of the EOS Ra was generous and the camera was sensitive enough to show the target on the screen in the live view frame and focus mode.

M3 is a beautiful example of a globular cluster in a relatively lonely stretch of sky. The cluster is a member of the galactic halo and spends much of its time orbiting well outside the plane of the galaxy. It is presently 33,000 light years away from us, 40,000 light years from the galactic core, and 33,000 light years ‘above’ the galactic plane. Home to about 500,000 stars, M3 is relatively young as globular clusters go with an estimated age of 8 billion years.

M3 is currently well placed rising in the northeast during the early evening.

Telescope: Unitron 155c 4” f/15

Camera: Canon EOS Ra, Interval Timer (no computer)

Filter: 2” GSO IR Cut Filter

Guide scope: None

Exposure: 32x1sec, ISO 800, saved as RAW

Darks: Internal (Long Exposure Noise Reduction)

Flats: None

Average Light Pollution: Bortle 8

Stacking: Mean with a 1-sigma clip.

White Balance: Nebulosity Automatic

Software: Backyard EOS, Deepsky Stacker, Nebulosity, Photoshop

Sigma Orionis is one of my favorite fields in the winter and spring sky. Sigma itself can be easily spotted with your unaided eye as a modest star just south of the easternmost star in Orion’s Belt; Alnitak. In a small telescope Sigma shows two nearby companions just off to the northeast as well as a wide pair off to the northwest (Struve 761). Close examination in a larger telescope shows a third companion to Sigma close by to the southwest, making Sigma a quadruple star system, and the southern star of the northwestern pair splits into a beautiful close pair of equal stars, making this a wonderful field of 7 closely arranged stars. (The brightest component of Sigma is actually a close binary system, making this a quintuple system!) During the winter months I always take a minute to stop by and to visit these old friends and I often use them to take a quick peek at the quality of the optics in a newly acquired telescope.

Sigma Orionis is currently well placed high in the southwest at dusk.