A night with Hercules

[Hughsie]

I hope people don’t mind but I wanted to share this article which I have written for my astronomy club newsletter. It follows on from the fantastic videos which SGL has hosted over recent weeks and the inspiration it has given me to do something different.

John

 

A night with Hercules

 

Lockdown has touched us all in different ways and we now find ourselves using new technologies for entertainment and socialising outside of the traditional TV, books and movies. Zoom, Skype and Teamster have now entered our vocabulary and have kept us in contact with family, friends and colleagues. YouTube has become another source of education and/or entertainment and in the world of Astronomy it allows us to keep in touch with missed BAA presentations and similar offerings from amateur and professional contributors. Who would have thought the day would come when part of your evening entertainment would be to catch up on a recording on music relating to astronomy “Herschel to Hawkwind”!

 

Recently I was inspired by such a Zoom presentation, not to take up the trumpet (though playing it under the stars at 2am to the annoyance of my neighbour and his bright security light did cross my mind) no, this was two excellent presentations by Ian and Mark @ Beaufort on splitting doubles and a guide to observing. On this occasion the host was The Stargazers Lounge, an astronomy forum which now produces weekly presentations on all manner of astronomy related subjects. For more information see https://stargazerslounge.com

 

The first presentation on doubles concentrated on five easy targets which anyone with a good pair of binoculars or a small scope would have no problem splitting. This was followed by a really interesting guide on observing in which the presenter walked through his approach to equipment, set up, target acquisition and the actual session itself. The video presented by Ian and Mark can be found here https://www.youtube.com/watch?v=qcHaTnrLaJw&t=0s

 

Astronomy can be as simple or as complicated as you want it to be and my garage is a testament to this with GOTO mounts, GPS, cables, cameras and the plethora of technology that never seems to end. Sometimes, the Mark I eyeball is good enough, though maybe on this occasion we will stretch to a small scope. 

 

Back to basics

 So, duly inspired to return to visual astronomy I broke out my Celestron Nexstar 6SE (F/L 1500mm) and SkyWatcher AZ5 mount. No GOTO, no electronics or gizmos unless you count my red dot finder. I also grabbed four eyepieces; 25mm, 15mm and 12mm BST StarGuiders with a 60 apparent field of view and a 40mm Vixen NPL with a 40° apparent field of view. Each offered 60x, 100x, 125x and 37.5x magnification respectively and fields of view ranging from 1° to 0.48°.

 

In addition, I dusted off my copy of the Illustrated Guide to Astronomical Wonders, Sky & Telescope’s Pocket Sky Atlas and Interstellarium Deep Sky Atlas. Tonight, planetarium software would be left on the shelf and play no part. 

 

Using the techniques described in the video I sat down yesterday evening with the Sky & Telescope Pocket Sky Atlas and determined that my target that night would be the constellation Hercules. Just after 11pm it would be visible high in the South where I would have a good clear view of it.

 

I then turned to the Illustrated Guide to Astronomical Wonders which provides details of targets to view in each constellation. Looking up Hercules I decided to keep the session light touch and just concentrate on five targets. On this occasion I chose;

 

• 64  (Rasalgethi)        -           an easy double.
• 65  (Sarin)                 -           another double just north of Rasalgethi.
• 75                              -           the last double on the list close to the upper left star making up the Hercules ‘keystone’ asterism.
• M13                             -           obviously! A beautiful globular cluster.
• M92                             -           another globular cluster but slightly harder to locate.

 

These targets were listed in my observing notes along with RA/Dec and the pages where they appear in the Pocket Sky Atlas and the more detailed Deep Sky Atlas. Both of these books would join me outside tonight.

 

Session

Observing commenced at 10pm BST and too early to observe my targets as the sky remained light. The Moon was visible in the West and I took the opportunity to check that my red dot finder was properly aligned to my telescope. Having established all was well with the finderscope I then took a look around the waxing crescent with my eyepieces. I must confess that I am ignorant of the Moon. As I spend most of my time imaging, I tend to either try and avoid it or shake my fist at it when gradients appear in my hard earned data. Tonight, I was in awe of it. Sadly, I couldn’t tell you the names of what I was looking at so maybe there is another project in the making.

 

By now Arcturus had revealed itself to me and I rotated the mount East and North to bring it into view. Lining up the red dot finder brought Arcturus into the centre of my 40mm eyepiece and I slowly worked through each, enjoying that soft red glow. The star was also shimmering due to the days heat rising from the ground and I thought that this would be a problem later but it proved not to be the case.

 

Having enjoyed Arcturus, I looked further East and could make out the triangle of Rasalhague and Kappa Ophiuchi with my first target, Rasalgethi, at the apex. Aligning my red dot finder, I was able to bring Rasalgethi into view. Both my 40m and 25mm eyepieces failed to separate the primary and secondary, however, switching to 100x magnification I did discern a small separation which was confirmed when I stepped up to 125x. I don’t’ know about you but I now see why observing doubles is so popular, watching that split ‘pop’ into view is so satisfying. Having seen that I could split two stars with a separation of 4.8”, I was confident about the rest of the night.

 

Turning my attention North and a slightly easier separation of 11” between Sarin and its secondary, I could just make out a split between the two with my 40mm. My 25mm confirmed this as a clear double and Sarin’s white colour. The secondary was more difficult and neither my 15mm or 12mm eyepiece could confirm the colour either. It is listed as blue-white so I will have to take that as read or buy a larger aperture scope!

 

Moving on now to 75 Rho and the hardest double of the session with a separation of 4.0”. It was not only a hard because of the separation but also hard on my knees! “Oh, for a GOTO mount” I thought as I knelt on the patio looking up towards the Zenith through my finderscope wearing varifocal glasses and viewing through the wrong part of the lens. Not only was that a challenge but matters got worse when I discovered I couldn’t reach the slow-motion controls to move the scope. Oh, deep joy!

 

Still, I persevered and was rewarded when my target came into view. 40mm revealed no split but the 25mm suggested a split with averted vision. I decided to confirm if I was correct before increasing the magnification by checking the position angle, yep 321degrees, roughly where I thought I could see it. At 100x magnification I confirmed the split and colour of both stars as white. Maintaining a steady image was difficult due to the vibration of the scope as I adjusted focus and this got worse when I stepped up to 125x. Adjusting the azimuth to bring the double to the East side of the eyepiece I watched it settle and come into focus as it drifted across to the West, a lovely sight.

 

Next on the list was M13, the Great Hercules Cluster. By this stage I had decided not to observe M92. This was even further North than 75 Rho and I did not even want to imagine what position I would have to put myself in to locate it in the finderscope. Fittingly then I was saving the best view until last and it did not disappoint. Rather than contort my body to try and find M13, I took the chance that if I used my 40mm eyepiece with a 1degree field of view and rotated the scope towards the West I just might have M13 stumble into view…and it did.

 

What a sight. At 37.5x it was a bright smudge in the centre of the eyepiece and moving up to 60x I could discern the bright core separated from the halo of stars surrounding it. With averted vision I thought I could resolve brighter individual stars outside of the cluster. 100x showed some of the brighter stars around the periphery of the core but 125x looked slightly dimmer and did not offer any additional detail.

 

Conclusions

 The session ended at 23:54 BST and I could not have been happier with the outcome. I got to split some stars, view one of the best globular clusters in the Northern sky and stretch my back! 

 

Reflecting on last night, I now appreciate that viewing the night sky in this way is harder but it also gives you a sense of satisfaction. Being able to research your targets and plan a night’s observation is fulfilling and certainly gave me a better understanding of what I was looking at, how to use star charts and even where the cardinal points are in my eyepiece. I also think it helps your observing skills. Because I spent more time locating my targets, I felt compelled to spend more time with them and dare I say, observe rather than ‘see’. 

 

What would I do differently? I think it’s obvious don’t you…..I need to get better at star hopping for my back and knees sake!

 

Edited June 26, 2020 by Hughsie
Change in font colour

[RobertI]

Hi John,

I can't see any of your text - I think you might have used a white font or something (I am using the 'default' SGL theme)?

Rob

[Hughsie]

Does that help Rob?

Probably will be the best way to read it!

[RobertI]

19 minutes ago, Hughsie said:

Does that help Rob?

Probably will be the best way to read it!

Looks good, I can now read it! Thanks.

[RobertI]

Great report John, glad you enjoyed some 'eyeballing' and hope you do some more.

Like you, I don't know that much about the moon and have promised myself on several occasions to do more given how often it's there. If you've not come across it, the Lunar 100 is a good list for getting to know the moon, there are plenty of resources out there about it.

I'm glad you enjoyed the experience of doubles. I really love observing doubles, although not an expert, I am learning all the time, and it's something that can be done even when the moon's out. I bought the 150PL Newtonian specifically for doubles and it's working brilliantly. I tend to get bamboozled by colours with doubles. Often a brightly coloured primary can make the the secondary seem to have colour when it doesn't have any. I've never really managed to see the difference between white and blue stars, epsecially fainter stars. Shades of red are much easier to discern. Carbon stars are fun to find and observe.

I sympathise with your contortions, I remember cursing the last time I had my 100mm refractor out! I guess that's where a really tall tripod pays dividends. I must admit, I have found that my Newtonians are the most comfortable observing experiences, with the eyepiece always easy to access when standing, even when pointing near the zenith. And with slow motion extension cables hovering at waist height it's easy to control the mount. It's the best setup I have found to date.

I look forward to your next report!

Rob

 

[des anderson]

An enjoyable time had by you, and i can say an enjoyable time for me reading your report. Des

[wookie1965]

Great report enjoyed reading that I go for double stars and cluster's from home with my light pollution.

If you can get sissy Hass double stars for small telescopes cracking book for double and multiple stars.

Another good one is the Cambridge double star atlas.

 

Paul