3 clear nights, 3 scopes, 2 mounts, 2 diagonals...

[Captain Scarlet]

This last weekend was unprecedented: three clear(ish) night in a row, and the opportunity to use all three of them to play with my toys. I observed nothing particularly exotic, but there were some interesting moments nonetheless. On top of all 3 nights of the weekend, I got to use all 3 of my scopes, used both mounts, compared two premium 2” diagonals and learned how dramatically tube currents can utterly destroy one’s view (think hairdryer).

Friday.

As soon as I got home from work on Friday evening I took my Newt and Mak outside to cool. It was a crystal clear night, no cloud appeared at any point, and as the night went on my SQM-L reached 19.14, nearly as dark as I’ve recorded here (I have lots of data now) and significantly better than lightpollutionmap.info’s Atlas estimation of 19.05 for my location.

With my 8” Newt mounted on my EQM-35 pro, I spent quite some time staring at Sirius, trying to spot the Pup. I sort of imagined I saw something for a brief moment, but hand on heart I don’t think I did. Rigel and its companion were very easy by comparison and Castor was lovely. I spent similar time on M42 to try to spot the E star, again to no avail, but the nebulosity did show better and better contrast as the magnification got higher.

I had intended also to give my SW Mak 150 its First Light (!!!) after doing a straight swap with @FZ1 for my Mak 127 back in June. Unfortunately even as I lifted it I saw it was completely covered in dew! I abandoned that idea and continued with the Newt.

I vainly tried for my only deep-deep-sky object of the night, M81, but not a sausage. Although it looked clear enough for me to be able theoretically to see it, dew I think prevented it. M51 is out of the question at this time of year as my view East is blocked by my house, I only see anything above 50 degrees alt in that direction. Dew eventually did for me altogether and I turned in around 0200.

Saturday.

Saturday was forecast equally clear but in the event the whole evening was characterized by thin wispy cloud and occasional bands of thicker stuff. Not enough to send me back inside, but enough to not bother taking darkness measurements.

I decided to polar align and “star-align” as accurately as possible: I sometimes regard the handset’s “report” of how accurate, after the star-alignment, it reckons your polar alignment is, to be a form of competition. I polar-aligned with the mount fully loaded, for example, and used a high-quality cross-hair finder eyepiece to get my alignment stars exactly dead centre, neither of which I normally bother to do. As a result, my “report” was the best yet, both alt and az errors at less than 10 arc-minutes by the handset’s reckoning. The “goto” was also notably accurate for the whole night.

Using the EQ mount again, I started the evening off with the Newt and later swapped over to the Mak, having this time brought out a hairdryer, kept the Mak’s front cap on and brought out its wrap-around dewshield. I had a quick go at Sirius again, to no avail, also Rigel, Castor and Algieba, once Leo had pranced over the edge of the house. I had a quick glimpse of Uranus, a bluish disc but faint through the thin cloud so I didn’t spend much time on it.

The hairdryer did its stuff on eyepiece and secondary (for the newt) and kept dew off the Mak, but what was really interesting was the tube currents in the Newt immediately after using it! I was pointing at Castor, a lovely brilliant pair of highly distinct matched dots. I applied the hairdryer and immediately on re-viewing, the two dots had become one huge smeared fluid mobile splodge! Racking out the focus revealed violently-moving diffraction rings. After 10-20 seconds though, it settled down as the warm air got driven out and Castor reverted to its prior state. Fascinating.

What ended the evening was dew again, but differently. Dew had become ice, covering everything that I hadn’t hair-dried.

Sunday.

Two 2am nights on the trot normally precludes a third late night, especially if it's Sunday. But having gone outside to see if I could spot Venus through binoculars during the full daylight afternoon and succeeded, I thought why not, if only to see Venus through a telescope before it got too dark and the planet too bright.

This time I dragged out my SkyTee2 and put my 105 f/6.2 LZOS refractor on it. Using my bevel-box to fix the mount to around 24 degrees elevation, I scanned left and right with the 35mm Panoptic for a binoculars-like 18.6x until I found it, and climbed the magnification ladder. Most pleasing was 108x, but 186x was a bit too much: wobbly and too-visible diffraction artifacts. However Venus’ 77% phase was perfectly evident, the first time I’ve magnified it that much. My best ever view of Venus, though i don't have much experience with it.

What was especially interesting, though, was the difference between 2 diagonals I had with me. I started off with my Baader Zeiss BBHS 2” prism diagonal, very expensive, and at the higher magnifications there was obvious Chromatic Aberration on Venus. When I switched to my Revelation 99% dielectric mirror diagonal, there was none. So I guess f/6.2 is still too open a light cone for the prism to come into its own. The same test on my f/12 Mak 150 and f/10 Intes M603 will be interesting…

I finished off the night popping out from time to time as my chicken was roasting, by framing the Pleiades, Orion’s whole sword and Stu’s S at 18.6x with the Panoptic 35mm – lovely fields and trains of pinpoint stars. Except as I was looking at, I think, The Pleiades, bright dot after bright dot streaked through my view, exactly in line and one after the other. Courtesy of Mr Musk, I think.

Cheers, Magnus

[domstar]

Three days in a row. I can't remember the last time that happened to me. A very interesting read- thanks.

[wookie1965]

I've had no days in a row so Reading this made my day a bit jealous but glad that someone was out enjoying this frustrating hobby.

[Captain Scarlet]

20 hours ago, domstar said:

Three days in a row. I can't remember the last time that happened to me. A very interesting read- thanks.

If I'd had more fortitude it could've been 5 in a row, Monday and Tuesday were clear too! Last night I strolled outside with my 8x56 bins and got some consolation just before bed by quickly scooting through the Beehive, a failed attempt at M41 just 4 degrees S of Sirius, the Alpha Perseii Cluster, the small cluster around Meissa, the Pleiades, and Orion's belt-and-sword.

[Stu]

Good stuff Magnus. We've had a good run of clear nights just recently haven't we? I managed two nights, like you nothing exotic but still worthwhile.

[niallk]

Nice one Magnus!

I thought I was doing well getting out 2/3 clear nights

I got dewed out of it, but standing back at the end of tge night and using just the naked eye was still good for soul

[Barry-W-Fenner]

Looks like we have used up all our clear night allowance. I just looked outside hoping and preying for a clear night. Thick cloud again and real damp.  Not had a decent viewing session since last Sunday

 

Baz

[Marvin Jenkins]

I have to ask all of you this question in regard to how bad our weather is and if it is just a frustrated figment of our imagination?

Now I know the weather is rubbish for outrageous periods of time. But due to the fact that I only started Astronomy October 2018 I do not feel I can say for sure that things are worse now than say ten years ago.

I will say however, that astronomers of the past would identify an object, say asteroid or meteor and observe its path through the night sky and calculate it’s trajectory and finally it’s orbit.

To get me back to the heading of this thread, thank you Magnus, past astronomers would have needed many back to back clear nights to do this work. A back to back night, to just look at M31 and M42 has not happened for me for well over a year.

Astronomers back then must have had much longer clearer periods.

Marv