Binocular Session with Some Impromptu Darkness Tests - Monday 4th Oct 2021

[Captain Scarlet]

The past few days have seen some lovely clear nights, but this no-Moon season the prevailing weather has scuppered any chance of being able to set up any sort of scope. Said weather has comprised clear sky and sunshine (or stars), interspersed every hour or so with a sudden violent heavy rain-squall. And generally very windy.

Last night was better than most, but I had still not been allowed an opportunity during the evening to set anything up, and by the time it looked “set clear” it was too late and I was too tired for anything other than a binoculars session. But it turned out to be a nice one nonetheless, if short.

Aside from cruising the Milky Way from Cassiopeia to Cygnus, these are the moments I remember:

Nova Cas - I started by looking for the Nova in Cassiopeia, which for the first time in many views, I gave up trying after failing to find it. Mainly because my guiding-points, Shedar and Caph, were almost exactly at zenith, and following their line to M52 required me, literally, to bend over backwards. My binoculars of choice were Zeiss Conquest HD 15x56, i.e. quite big and heavy, and my patience and back wore out before I properly found my bearings. So I gave up on Nova Cas.

M31 - Once my eyes got adapted to the (21.57) darkness, I noted that M31 was easily direct-naked-eye. And through the bins a dust lane was evident, as were M110 and M32.

M33 - I moved down to M33, and couldn’t quite decide whether it was perhaps not just-about naked eye detectable. Through the binoculars, though, it was quite bright, with a hint of spirality.

Square of Pegasus - I was now facing, more or less, the Square of Pegasus, so I decided to try to count how many stars I could see naked eye. I eschewed the bins for this, as I didn’t want to prejudice my imagination. I counted 10 definites, and with averted vision there were coming-and-going hints of a handful more. Based on the definites, that puts NELM for my eyesight just over 6.0 taking account of atmospheric extinction.

MW's Shadow - I also remembered reading that in darkness such as this, the Milky Way ought to cast a shadow. So I put one hand above the other separated by perhaps 2-3 inches, and sure enough there was a shadow, and it moved when I moved my hand. Extraordinary! Testament not just to the lovely skies I’m lucky enough to have, but to the incredible range and sensitivity of our eyes!

M101 vs M33 - Turning around, and with M33 still in memory, I looked for M101. To begin with, I was looking in completely the wrong place, thinking it was 10-20 degrees North-ish of Mizar/Alcor. Obviously I couldn’t find it so I had to look it up. In fact, it’s much closer to Ursa Major’s saucepan-handle. It makes a more-or-less equilateral triangle with Mizar and Alkaid, only 5-6 degrees North-West of each and “halfway in between”. Once I knew where it was, I found M101 straight away, and I can report that it was MUCH dimmer than M33. Partly, that was down to atmospheric extinction, which by my formula would have reduced M101 by about 0.5 magnitudes more than M33’s extinction, on an already rather faint extended object. I also tried to find M51, but that was getting far too close to my Northern horizon and I couldn’t see it.

 

M13 & M57 - Finally I tried for M13, which is normally naked eye out here, but at only 20 degrees above my most light-polluted horizon last night I couldn’t see it without the bins. With the bins, of course, it was there. Finally-finally I tried for M57, the Ring Nebula, and although I definitely think I was seeing it, through the bins at only 15x times and hand-held (i.e. not perfectly steady platform), I couldn’t distinguish its “ring-ness” from that of neighbouring stars.

That was that, a short session but some things I hadn’t tried before and always a joy to stand under skies like this.

Cheers, Magnus

Edited October 5, 2021 by Captain Magenta