Archives for April 2021

Telescope: ES Comet Hunter MN6 at f/4.8, Orion Atlas EQ-G

Camera: Baader modified Nikon 610

Filter: High Point 2” IR Blocking Filter

Guide scope: Williams Optics 50mm, ASI290MM mini, PHD

Exposure: 18x60sec, ISO 200, saved as RAW

Darks: Internal (Long Exposure Noise Reduction On)

Flats: 32×1/4sec, tee shirt flats taken at dusk

Average Light Pollution: Red zone, Bortle 8, poor transparency

Lensed Sky Quality Meter: 18.4 mag/arc-sec^2

Stacking: Mean with a 2-sigma clip.

White Balance: Nebulosity Automatic

Software: Backyard Nikon, Nebulosity, Deep Sky Stacker, Photoshop

M27, the Dumbbell nebula, is an expanding shell of gas that was ejected from a sun-like star as it exhausted its hydrogen fuel. Swollen into a red giant, the star shed its outer shell while its core collapsed into a white dwarf. Fierce UV radiation from the collapsed core sets the surrounds gas aglow with the blue/green light of doubly ionized oxygen. The diameter of the nebula is about 1 light-year with an estimated age of 9,800 years. Located between Sagitta and Cygnus, M27 is fairly easy to find with a small telescope. Visually, it shows two lobes connected by a neck of nebulosity, giving the nebula its characteristic dumbbell shape.

M27 is currently a morning object rising after midnight and is high in the east at dawn.

Telescope: ES Comet Hunter MN6 at f/4.8, Orion Atlas EQ-G

Camera: Baader modified Nikon 610

Filter: High Point 2” IR Blocking Filter

Guide scope: Williams Optics 50mm, ASI290MM mini, PHD

Exposure: 30x60sec, ISO 200, saved as RAW

Darks: Internal (Long Exposure Noise Reduction On)

Flats: 32×1/4sec, tee shirt flats taken at dusk

Average Light Pollution: Red zone, Bortle 8, poor transparency

Lensed Sky Quality Meter: 18.4 mag/arc-sec^2

Stacking: Mean with a 2-sigma clip.

White Balance: Nebulosity Automatic

Software: Backyard Nikon, Nebulosity, Deep Sky Stacker, Photoshop

M56 is a relatively small, dense globular cluster that tends to get a bit lost against the background Milky Way. I have always found this to be a somewhat challenging object visually (at least from my backyard) but it blossoms beautifully with a large telescope. This field also shows how well the Comet Hunter fills a full frame camera.

M56 currently rises in the northeast around midnight and is high in the east at dawn.

Telescope: Meade 12” LX850 ACF @ f/8, Orion Atlas EQ-G

Camera: Baader modified Nikon 610

Filter: High Point 2” IR Blocking Filter

Guide scope: Astro-Tech 60mm, ASI290MM Mini, PHD2

Exposure: 20x60sec, ISO 200, saved as FITS

Darks: 32x60s, saved as FITS

Flats: 32×1/2sec, Tee shirt flats taken at dusk

Average Light Pollution: Red zone, Bortle 8, poor transparency, haze

Lensed Sky Quality Meter: 17.8 mag/arc-sec^2

Stacking: Mean with a 2-sigma clip.

White Balance: Nebulosity Automatic

Software: Backyard Nikon, Deep Sky Stacker, Photoshop

This is M13, the Great Cluster in Hercules. M13 appears large in part because it is relatively close at a distance of about 25,000 light years. Also, it is in fact quite large with a diameter of 145 light years. Globular clusters like M13 are relics of the early universe and M13 is believed to be about 12 billion years old, about as old as the Milky Way. If you look carefully at M13 you can see a dust lane to the lower left of the cluster. This 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. I have tried several time to glimpse this feature visually, but so far it has evaded me. Something to keep working on!

M13 currently rises in the northeast late in the evening and is high overhead at dawn.