Daylight test

[ChrisM]

Sometimes people ask whether stars can be seen by day. With a clear blue sky today, I decided to find out.

Using the 8" SCT, I had to algin the telescope first so that meant finding Sirius and Canopus. They were both easily visible in the finder (8 x 50).

I then had a look for Orion and found all the main stars in that region (Rigel, Bellatrix, Betelgeuse, Alnitak, Alniham & Mintaka) relatively easily.

I then came back to Canis Major and searched for progressively dimmer stars until I exceeded magnitude 6 with 14 Puppis (SAO 153796) which is mag 6.13. This was seen 30 minutes prior to sunset. One surprise was a nice double in Puppis at magnitude 5.8

Up to magnitude 4, they were fairly easily to see in the FoV (x 77) but the mag 5 & 6 stars had to be searched for. I guess one issue here different to my usual night observing is that the eye has no focus reference until it actually sights the star.

What practical use is this? Well - I don't know, unless one wanted to get the alignment sorted well prior to a night observing session. In my case, it was probably just a bit of a once-off challenge.

I would be interested to hear if others have taken on a similar challenge.

Chris

[kinetic (Steve)]

Chris,
I used to show workmates Venus and Jupiter by day years ago.
At first they wouldn't believe me but when I lined them up on the
edge of a tree branch or building in the CBD, and their vision was
focused at infinity, most times they saw it.
The reaction was priceless and well worth the effort.

Nowadays it is much harder for me, mainly because of the over 40
eye deterioration. It is much harder, for me at least, to get my vision
to stay at infinity while relaxed.

Steve