A few doubles near the Open Cluster IC 4665

[josefk]

As noted elsewhere i started my evenings observing on Saturday with Barnard's Star in Ophiucus. The rest of the evening was to be doubles and so i started near there with STF 2272 (70 Oph), STF 2287, STF 2288 and STF 2266, so far so good. Nothing difficult - all very enjoyable.

My next pair were STF 2212 and STF 2216 and with these pair and the one after (STF 2227) i realised were i was as a manner of speaking. Basically i had been working my way west towards the fabulous open cluster IC 4665 and it's this part of the evening i post here.

First Struve 2212 and Struve 2216. I observed these at x167 using my TOA and a 12mm EP in combo with a 2x powermate (incidentally proving to myself again i don't really need a real 6mm EP even though i  keep looking at them).

The qualities for separation and PA and magnitude on the card are from StellaDoppie. My field notes are:

STF 2212: An A B  split. Separation estimated at <4”, Position angle estimated at 130º [NB. A and B reversed!]. A fine split, pleasingly subtle but very clear. Even magnitude. No colour noted.

STF 2216: An A B  split. Separation estimated at 20”, Position angle estimated at 10º A considerably brighter than its companion. B very “fine”. No colour noted.

Next was very nearby Struve 2227:

Observing notes for STF 2227: An A B  split. Separation estimated at p8”, Position angle estimated at 300º [NB. A and B reversed again]. Even white pair. Sparkling field of view.

Though i didn't sketch it at the first attempt the notably "sparkling field of view" observable with STF 2227 alerted me finally to were i was 🤩

STF 2212/2216 are visually inside the boundaries of the open cluster IC 4665 and STF 2227 is right next to it. I don't know if any of them are actual cluster members (something to check). I had really enjoyed this open cluster a few weekends ago (stumbled over it then really).

Because i couldn't "see" the cluster at x167 (26'), instead of swapping out my EP i mounted up my FSQ side by side with the TOA (a first for me and i found out they were not quite orthogonal - maybe a degree or so out "north"/"south"). With an 8mm EP in the FSQ the cluster was revealed and the context made clear:

The EP 1.77-degrees EP view really was divided into a sparkling half and a "subtle" half - the sparkling half is the IC open cluster (not quite all of it in fact). In my field sketch at the lower magnification i could still see (and split) STF 2227 and i could also see a new Struve - STF 2223 (first seen as a pair in the EP then checked if it was a "target"). I didn't clock it at the time but STF 2212 and STF 2216 are still here (i should have been more careful to see if i could really see the companions at this lower magnification and sketched them - i didn't so their companion stars are missing below)):

Finally if this weren't visually pleasing enough - the less sparkling half of this FOV put me in mind of a "mini Orion" (very mini hah.)

 

So a fun little corner of the sky and highly recommended. I have quite a few double star thumbnails in this area now so i may be motivated to use a big bit of card for a multi-EP composite. On this evening IC 4665 was bright and sparkling but a few weekends ago, possibly in better transparency or just using in a different kit combo, the stars of this cluster were really striking steely blue stars so it would reward the effort of a "big sketch".

Cheers

Joe

 

Edited June 24 by josefk

[lunator]

Very nice report and sketches Josef. 😀

Cheers

Ian