Observations 16 July 2021

Evening All,

Last night several of us met at the Sugarloaf. It was a beautifully warm night. So much so that we observed in T-shirts (and some of us in shorts) for most of the night : )

I decided to bring two scopes with me last night: my f/8 150mm NF, and my f/5 250mm NF both scopes were mounted on a Dobsonian mount. I brought both scopes to compare the difference between how much of an object one can see with the extra 100mm of mirror. While there was no much difference when it came to the Moon every other object I observed showed way more detail in the 250mm. For example, star fields in Cygnus showed considerably more stars in the 250mm. Likewise, M13 dazzled in the 250mm. While the 150mm resolved many stars in 'Great Globular' cluster, those same stars were much brighter in 250mm. What's more, the arms of M13 were much easier to see too. There was also a considerable difference in pulling out detail on Saturn and Jupiter. This was most notable with the bands of Jupiter, and Saturn. For example, while I could see Jupiter's North Equatorial Belt (NEB) and South Equatorial Belt (SEB) in the 150mm, the 250mm revealed Jupiter's North Temperate Belt (NTB) and its South Temperate Belt (STB) easily. Furthermore, the contrast between the belts and zones was striking! 

Other objects I observed last night included:

- Venus
-  M51
-  M11 (Thanks Paul!)
-  M27 (Thanks Paul!)
-  Three ISS passes
- Lunar 'X'
- Lunar 'V', and
- The exceptional Lunar crater 'Albategnius'

On Lunar day 6.90 the Moon was 44.7% illuminated. Consequently, 'Albategnius' was very close to the terminator. To provide you with some of idea of what it looked like through my f/5 250mm NF, I've attached a sketch of it. The sketch was completed at the eyepiece at 278X. While it is far from perfect, I hope you like it.

Very many thanks for reading, and comments and feedback are always welcomed.

Darren.