1 Mar - Big Dob searches for Hicksons in a moon affected sky (Night Vision)

[alanjgreen]

Date: Sunday 1^st March 2020. (2240-0220am)

Scope: 20” f3.6 Lukehurst Dob with Paracorr (fl = 2089mm & f4.1).

Night Vision: PVS-14 with Photonis 4g INTENS.

Eyepieces: Plossl 55mm (f2 x38), Panoptic 35mm (f3 x60), Panoptic 27mm (f4 x77), DeLite 18.2mm (f5.8 x115).

Filters: Baader 610nm Red Filter

Moon: 39%

 

Introduction.

Wow, it’s already March and I’ve just completed my first real session of any note in 2020! The weather in the UK has been pants since Christmas. I have managed a couple of two hour dashes between the clouds but that is not enough time to really get into a session and do any real observing on any more than a few objects so I have mainly been observing the more famous and brightest night sky objects.

 

Galaxy season is here!

Yay, my favourite observing season is here. With all this down time, I at least had an observing plan to follow when the opportunity finally came. I had created observing lists in Sky Safari of the Hickson and ARP catalogs.

 

Making a start on the Hickson catalog with Night Vision.

There was a 39% moon in the West so I had to deploy a Baader 610nm Red filter to the front of my Paracorr2 to remove the unwanted moonlight from my view.

On the first object, I tested out all the eyepieces listed above to see which produced the “best” view. There is a trade-off with night vision devices of image brightness and image magnification and I wanted to identify the best eyepiece option up-front as I intended to attach my eyepiece heater tape and then stick with the one eyepiece for the session.

I settled on the Panoptic 35mm as my chosen eyepiece as it was giving decent image brightness resulting in more galaxy halo and the magnification (x60) was enough to provide something to see from these tiny objects.

 

Hickson 37 – I could see three galaxies in a row close to two field stars. One galaxy was a longer edge-on and one had a bright core with faint halo. I found the fourth group member nearby just the other side of a field star although this one was a challenge to hold in vision for long. The final galaxy was glimpses occasionally with a real effort and concentration needed.

Hickson 44 – Two small bright galaxies were immediately obvious, I soon located a third slightly separated galaxy of mid-brightness out in front. The final galaxy was the faintest of the four and was sited at 90 degrees to the side. All four galaxies were easily seen in direct vision.

Hickson 46 – This group was hard to locate initially then I spotted two cores appearing close together in the field of view. After letting my eye settle in the other two galaxies appeared one on either side of the first two.

Hickson 47 – Two cores were immediately obvious in the fov then one more emerged lower (near a field star). I did get glimpses of the fourth member which was in close to the third galaxy staggered to one side.

Hickson 38 – Another group that was tough to find. Found just above left of two bright stars. Time reveals three galaxies in a triangle formation. The lower galaxy was the easiest with a nice halo. The upper two were smaller and fainter.

Hickson 36 – The toughest so far! I found a possible very faint patch just below 6 stars. It looked like two groups of three galaxies but looking at images this morning then this looks incorrect so this goes down as a fail.

Hickson 35 – Found inside a triangle of field stars. Three galaxies easily seen in a flat triangle formation. There was a possible fourth galaxy glimpsed to the left which was fainter.

Hickson 41 – Two galaxies easily seen (one has a core and halo). The third was tough and appeared just under the fainter of the first two. No sign of the fourth member.

Hickson 60 – A small patch is easily seen in the fov. One core dot is seen within the patch off–centre.

Hickson 56 – This tiny group is located next to two much larger and brighter galaxies (NGC 3718, 3729) that overpower your vision as you reach the eyepiece. Once I was settled on my actual target then I saw two tiny bright galaxies first. Then the third was seen slightly separated to the RHS. Then one appeared LHS fainter giving a 3+1 appearance to the group.

Hickson 55 – The small patch was quickly located in the fov. I could see two dot cores appearing on and off within the patch but not much more.

Hickson 49 – not found.

Hickson 61 (Box Galaxies) – A nice sight. Three bright galaxies make up three corners of the “box”. A fainter larger galaxy sits at the other corner. The two brightest galaxies were at the top side. The bright lower galaxy has a halo.

Hickson 51 – Five galaxies are easily seen in the fov, appearing as 3+2. The galaxies appeared well spaced but were small.

Hickson 57 (Copeland Septet) – A very nice galaxy group! I could see 7 galaxies appearing as 3+3+1 formation. All easily seen.

Hickson 53 – I saw three galaxies in the fov in a 1+2 formation. The fourth member (off to the right) was not seen.

Hickson 52 – Two galaxies were easily seen. Another galaxy is glimpsed intermittently near to the second galaxy with time at the eyepiece.

Hickson 59 – 3 of 5 galaxies seen. Two are bright and easily seen. The third appeared at a right angle to the first two with the gain turned up.

Hickson 58 – Four galaxies are easily seen in a 2+2 formation. The fifth needed further exploration but clouds starting passing and my session was cut off in its prime!

 

Epilogue

I make that 18 Hicksons attempted last night which seems like a good start and I am pleased with that.

Most of the observations were taken with the Moon up so it will be interesting to try them again on a new moon to see if more can be seen…

It was great to be back outside after nearly two months of slim pickings!

 

Clear Skies,

Alan

 

 

Some Technical Background (Voluntary reading!).

This section is added for anyone wondering why I was only using x60 magnification with my setup and maybe “more would be seen with greater magnification?”.

While that would be true with traditional observing, night vision is best used with eyepieces with large exit pupils as the more light you get into the device then the more light it has to work with. Longer focal length eyepieces (greater than 27mm) also have a side-effect of increasing the effective focal ratio of your telescope system (as far as the attached night vision device is concerned) and as the NVD works at f1.2 then the closer we can get to that speed the better the results will be.

So the facts are that the 55mm Plossl with always show the brightest view possible with the most galaxy details possible seen within that view.

But when tiny objects are tightly packed then you may need more magnification to separate them (this is usually true for supernovae hunting for example).

But as you increase magnification and decrease the exit pupil/effective focal ratio of the system then galaxy detail will be lost from the view. I only ever view galaxies where I hope to see the spiral arms with the 55mm Plossl as I want maximum brightness and fastest effective focal ratio.

Edited March 19, 2020 by alanjgreen

[Martin Meredith]

Great report! Sound like a powerful observational machine to go after the Hicksons with. I'm impressed you could pick off 18 in a session.

Martin

[Bill S]

An amazingly productive session. With the slim pickings you mention, it's great to have a technique to make the most of rare opportunities. Excellent that you have developed a method that works with such a bright moon.

Bill

[Mike JW]

Impressed as always. Also very useful to post the extra detail for anyone wishing to pursue NV. Mike