Another quick session - commando style.

[RobertI]

I keep my grab and go gear indoors for quick commando style observing sessions. Last night was wonderfully clear but with clouds approaching and a bed time not far away, I set up the Zenithstar 66 on the Giro-WR and Photo tripod. After leaving to cool I thought I'd have a go at Izar which I knew would be a challenge with this aperture - the companion is 2.9" away from its much brighter companion and I believe sits in the first diffraction ring in a 60mm scope. First attempt was not good, possibly bad seeing, so I tried some easier targets first.

• Rho Herculis - lovely close pair but easily split at 109x, with white primary and fainter secondary. Listed as mags 4.5 & 5.4, separation 4.1”.
• Alpha Herculis, aka Rasalgethi, is actually the fifth brightest star in Hercules, a beautiful double with orange primary and fainter white secondary. Listed as mags 3.4 & 5.4, separation 4.6”.
• Gamma Virginis was lovely, comprising similar magnitude white stars. Close but easily split. Listed as mags 3.5 & 3.5, separation 3.1”.

 

Back to Izar. The view was much steadier now, I think it might have been scope that was not completely cooled after being in the house.  There was still no split at 109x, but after peering closely for ten minutes I could see a persistent and clear brightening of the first diffraction ring to the N. This was consistent with the position angle of 345 degrees, so I think I can call that a 'probable' catch. I didn't have time to try the maximum mag I could achieve of 175x (would have meant a trip into the garage!) - but that's my job for the next clear night.  

Edited May 3, 2021 by RobertI

[Captain Scarlet]

Glad to be reminded of Izar, I’ll have a go too next clear night.

Have you tried for Polaris B with your Z61? I have a Leica 62mm spotting scope which I sometimes use as a “super finder” and have just about managed to detect Polaris B through it only once out of several tries. A couple of those times were with the scope side by side with my LZOS 105, through which Polaris B is always easy.

Cheers, Magnus

[RobertI]

9 minutes ago, Captain Magenta said:

Glad to be reminded of Izar, I’ll have a go too next clear night.

Have you tried for Polaris B with your Z61? I have a Leica 62mm spotting scope which I sometimes use as a “super finder” and have just about managed to detect Polaris B through it only once out of several tries. A couple of those times were with the scope side by side with my LZOS 105, through which Polaris B is always easy.

Cheers, Magnus

Hi Magnus, coincidentally I have just had another go at Izar with the Z66mm and posted a report. The quick summary is that I finally bagged Izar’s secondary by upping the mag to 175x - very pleased with that. Also coincidentally I did look at Polaris (at one point it was the only area of sky not covered by cloud!) - I found the secondary much harder than expected, with only fleeting glimpses, but the seeing was pretty poor in that area of the sky for some reason. Might have been easier at a lower magnification? 

Edited May 7, 2021 by RobertI

[Sunshine]

Nice commando session!  thanks for the Izar reminder, can't say I have given it a go before but it is on my list now.

[Captain Scarlet]

Oops sorry  I meant your Z66. Perhaps mag is something to do with it for me, my Leica zoom goes only to 48x. I might try simply hand-holding a higher-power eyepiece in the larger “hole” to see if that works…

Anyway, Izar beckons in a proper scope and thanks for the reminder

[Stu]

Great stuff @RobertI, some nice targets there. I don’t recall trying Alpha Hercules before and it sounds like a nice one.

I dug out this report from a while back about using my Telementor and TAL Alkor. It mentions that I got Izar at x94 in the Telementor but needed more (x133) with the TAL. I would expect your 66mm to be similarly capable to the Telementor, so do have another go on nights with better seeing perhaps. Familiarity always helps with these targets, and now you know what it looks like it will be much easier.

I had a similar experience with Zeta Herculis. This was my nemesis for years, I just couldn’t see it. Then I finally managed to spot it using my Mewlon 210 on a night of very good seeing which showed it beautifully, then with my 8” f8. As I got more familiar with it, I found I could then see it in my 4” apos (Tak and Vixen Fluorite), and finally I also managed it in the Heritage 150p.

In the thread I linked to, Chris has posted a simulation of Izar using Abberator to show how it looks with different apertures. This gives a good general indication of what is seen, and the location of the secondary relative to the first diffraction ring. I’ve found that in reality, the stars are significantly tighter than this in the smaller fracs, so that there is clear separation even in the 63mm.

Interestingly, Zeta Herc in the 4” scopes appears similar to Izar in the small scopes, ie a brightening on the first diffraction ring, whereas in the 150mm and 200mm scopes it resolves more clearly into two unequal airy disks (when conditions are good)

[wookie1965]

1 hour ago, Stu said:

Great stuff @RobertI, some nice targets there. I don’t recall trying Alpha Hercules before and it sounds like a nice one.

I dug out this report from a while back about using my Telementor and TAL Alkor. It mentions that I got Izar at x94 in the Telementor but needed more (x133) with the TAL. I would expect your 66mm to be similarly capable to the Telementor, so do have another go on nights with better seeing perhaps. Familiarity always helps with these targets, and now you know what it looks like it will be much easier.

I had a similar experience with Zeta Herculis. This was my nemesis for years, I just couldn’t see it. Then I finally managed to spot it using my Mewlon 210 on a night of very good seeing which showed it beautifully, then with my 8” f8. As I got more familiar with it, I found I could then see it in my 4” apos (Tak and Vixen Fluorite), and finally I also managed it in the Heritage 150p.

In the thread I linked to, Chris has posted a simulation of Izar using Abberator to show how it looks with different apertures. This gives a good general indication of what is seen, and the location of the secondary relative to the first diffraction ring. I’ve found that in reality, the stars are significantly tighter than this in the smaller fracs, so that there is clear separation even in the 63mm.

Interestingly, Zeta Herc in the 4” scopes appears similar to Izar in the small scopes, ie a brightening on the first diffraction ring, whereas in the 150mm and 200mm scopes it resolves more clearly into two unequal airy disks (when conditions are good)

Alpha Herculis also known as Rasalgethi  ( SAO 1026 81)  Orange/red with blue/turquoise companion  

[RobertI]

4 hours ago, Stu said:

Great stuff @RobertI, some nice targets there. I don’t recall trying Alpha Hercules before and it sounds like a nice one.

I dug out this report from a while back about using my Telementor and TAL Alkor. It mentions that I got Izar at x94 in the Telementor but needed more (x133) with the TAL. I would expect your 66mm to be similarly capable to the Telementor, so do have another go on nights with better seeing perhaps. Familiarity always helps with these targets, and now you know what it looks like it will be much easier.

I had a similar experience with Zeta Herculis. This was my nemesis for years, I just couldn’t see it. Then I finally managed to spot it using my Mewlon 210 on a night of very good seeing which showed it beautifully, then with my 8” f8. As I got more familiar with it, I found I could then see it in my 4” apos (Tak and Vixen Fluorite), and finally I also managed it in the Heritage 150p.

In the thread I linked to, Chris has posted a simulation of Izar using Abberator to show how it looks with different apertures. This gives a good general indication of what is seen, and the location of the secondary relative to the first diffraction ring. I’ve found that in reality, the stars are significantly tighter than this in the smaller fracs, so that there is clear separation even in the 63mm.

Interestingly, Zeta Herc in the 4” scopes appears similar to Izar in the small scopes, ie a brightening on the first diffraction ring, whereas in the 150mm and 200mm scopes it resolves more clearly into two unequal airy disks (when conditions are good)

Thanks Stu, I'll try Zeta Hercules with the 102ED and possibly the 150PL next time out. Interesting link btw. 👍