Venus & Virgo (& Coma Berenices) - two nights running

[josefk]

After what seems like an age i was back out last night with clear skies in the forecast. Actually they were clearer than the forecast in NE Northamptonshire and very nice to the naked eye if not quite as nice through the scope.

I had two aims - 1) another daylight/early twilight Venus observation, 2) a wide field scan up Markarian's chain and galaxies in that general area.

It was lovely to see Venus in a blue sky again. I've posted a sketch over in the sketching forum - in short last night didn't deliver any darker cloud features or features encroaching from the terminator (that i could detect) but bright poles were clear (northern pole being larger) and were visible through several filters so i'm sure they were not an illusion. The phase at 58% was really picturesque. An #82A light blue filter was helpful to steady the otherwise slightly wobbly seeing. Seeing wasn't quite supporting the x200 magnification i was using but nether was this magnification over the top. I couldn't find Venus in the very pale blue sky till it was visible naked eye so i may have missed the best viewing earlier in the evening.

After waiting for it to go relatively dark (not true dark unfortunately) i turned to the second set of objectives. I had a spring galaxy target list in Virgo and Coma Berenices and i wanted to try and observe these at very low magnification (x32) and wide 2.4 degree FOV. i had a second "grand plan" to try and sketch several eyepieces worth of ground moving up the area step by step like a mosaic. It was quickly apparent this wasn't going to work - the sky was SQM 20.8 and the wide field eyepiece was giving me a 4mm exit pupil. I don't think the sky through the EP was even as dark as mid-grey. 

My next step down in EPs with this scope (the TOA) is x58, 1.2 degrees and 2.25 mm exit pupil. While still not really a dark or contrasted view it was better and this EP stayed in the diagonal the rest of the night as the best balance of exit pupil, contrast and FOV.

The observations in Virgo and Coma Berenices were the usual brighter spring suspects for many i suspect: NGC 4486 (M87 Virgo A), NGC 4478, NGC 4501 (M88), NGC 4552 (M89), NGC 4374 (M84 Markarian's Chain), NGC 4406 (M86 Markarian's Chain), NGC 4435 (The Eyes Galaxies with NGC 4438), NGC 4429, NGC 4254 (M99 Pinwheel Galaxy), NGC 4192 (M98), NGC 4631 (the Whale Galaxy), NGC 4490 (the Cocoon Galaxy), NGC 5457 (M101), and NGC 4382 (M85). There were five new for me Herschel 400 objects in that haul. 🙂 

The visual magnitudes for these galaxies ranged Mag-7.8 to Mag-11.3 (so in theory and in the main relatively bright).

Well if these really are at the easy end i need to move to a darker site or get a bigger scope (though I think it was quite a bit less transparent than a quick glance at the stars in the handle of UMi suggested) .

All except the Cocoon Galaxy and M85 (and less so the Whale Galaxy) had to be wrestled from the spring grey sky with prolonged study and careful field ID, though with a good wrestle and a bit of averted vision quite a few of the observed targets did then grow in stature and characteristics and i could detect elongation and correct orientation for most of the spiral galaxies for example. M101 was by no means pretty but i could see flocculence in the large faint patch. The Whale Galaxy was interesting though - i had a strange "flicker" in averted vision where it showed itself as relatively bright and quite striated in brightness variation along its long dimension. i could repeat the trick but never as strongly as the first time. 

By 2am every was running with water - goodness knows what the relative humidity was. wet i think is the technical description.

The forecast is good for a repeat run tonight and i have a few "did not find" on my list now from last night to try again with a slightly larger aperture. All the observations above are with a 5" refractor. Tonight i'll take a 7" Cassegrain for a bit more magnification at a useful exit pupil.

Clear skies all.

 

Edited May 21, 2023 by josefk

[Froeng]

Nice report! You are correct, the skies were not as transparent as they could have been due to the high humidity. Good luck for tonight!

[Stu]

Excellent report @josefk, I enjoyed reading that. Which TOA are you using?

[josefk]

Thanks @Stu - i'm about 5 months the proud owner of a TOA-130. Its sort of your fault because last year you counselled i needed a bigger exit pupil to benefit from using a UHC filter on the North America Nebula! Only joking i was already deep into simmering the idea by then. 🙂

[josefk]

What a treat - two nights running and with no moon!

I took the 186mm f13 Cassegrain out last night to go over much the same ground i'd been in with the 130mm f7.7 Refractor the night before.

There should be about 0.7 of a Magnitude difference in reach between these two scopes all things considered though i've never scientifically checked that calculation using them side by side in the field. No two nights are the same and on this second night humidity was much lower and the sky commensurately clearer than experienced in the report above so i'm still not any nearer making a solid comparison between the two except on planetary objects were there really is no contest. I can tell already the refractor is by no means embarrassed by the larger aperture Cassegrain even on DSO.

My observations last night (after a couple of warm up (actually waiting for it to get darker) doubles in Lyra and Draco) were galaxies with a visual magnitude between 7.8 and 10.3 (so at the brighter end of things really): NGC 4631 (the Whale Galaxy), NGC 4565 (the Needle Galaxy), NGC 4559, NGC 4459, & NGC 4552 (M89).

The Whale Galaxy was a repeat observation of the night before but this time at x102 (exit pupil 1.8mm) and x141 (exit pupil 1.3mm). It was an interesting comparison to the much lower x58 magnification of yesterday. At the larger scale the galaxy really was large and lumpy in outline - more or less half the width of my ~30' Delos 17.3mm eyepiece - but still quite faint and "flat" in grayscale (i.e no core or even brightness variation that i could see). I couldn't detect the nearby NGC 4627 but i also wouldn't have described the sky in that area as an even flat black so maybe my was detecting something there.

I drew the Needle Galaxy (NGC 4565) and i'm glad i did because while i couldn't see any structure when i look at online images today i can see which parts of it i was really seeing (i saw it flat and elongated but not as elongated as it really is) so i was seeing the bulging core and shoulders with elongation longer in one direction than the other.

the next two - NGC 4559 and 4459 are new Herschel 400 targets for me (yay!).

My observing note for NGC 4552 (M89) is a one word "dim". The Cassegrain didn't bring me a real gain over the night before; the note for the night before said "Hazy smudge. No shape". It's really a pity this area of the sky is where it is in this season and damn the cloud earlier this spring when these constellations were at least a little higher!

One thing i need to brush up on is my route finding in this region - i get totally lost in this area when it comes to that final definitive ID - i can see little smudges or ghosts here or there when using the slo-mo to move from one target to the next but a dearth of field stars means i have really struggled to be precisely sure of which faint smudge i've just flown over... This goes especially for the Markerian's Chain set - i know i'm not seeing some of these but because i don't see them i've lost my "audit trail" between one secure ID and another if that makes sense...

Here's hoping we've turned a bit of a corner on the spring cloud and we all get further attempts at them.

Cheers

 

[Stu]

3 hours ago, josefk said:

Thanks @Stu - i'm about 5 months the proud owner of a TOA-130. Its sort of your fault because last year you counselled i needed a bigger exit pupil to benefit from using a UHC filter on the North America Nebula! Only joking i was already deep into simmering the idea by then. 🙂

Ooh, that’s the first time I’ve been listed as a reason for buying a TOA130, I must be getting better 🤣🤣

Wonderful scope, and one that was on my wish list. I’ve just picked up the 128 so will give that another go on ‘The chain’ if I get some decent skies before the Moon gets too bright. Transparency hasn’t been brilliant here lately though.

[josefk]

@Stu transparency hasn’t matched the darkness here either I’m afraid. I’ve started on M13 both nights just easing in as it were and it’s been pretty enough but no glitter or sparkle. 
 

the TOA is exactly what I hoped and expected it would be - It has been unreal so far on Jupiter before it was gone, Mars briefly and now Venus. I compared the cassegrain on Venus these past two nights and there is no comparison (though tbh for my tastes in view it was never going to be a fair fight). 
 

good luck for clear skies with the FS-128