Eagle eyed!

Last night was a calm, moonless night in Dublin with mostly clear skies. I used the 102SLT (a 102mm "short tube" refractor) for a relatively short observing session. Notes on the better objects that were observed are listed below. Most of the targets were relatively easy double stars in Aquila. I finished up in Andromeda with the magnificent Almach, one of the most beautiful doubles in the sky and notable for the apparent greenish colour of the secondary. Though stars cannot actually be green, the colour contrast make this one appear to have a green tint, and the effect is lovely.

Thanks for reading,
Mike


ID: WDS19153+1505
Type: Dbl; RA Dec: 191520+1505; Constellation: Aql
Name: STTA178 AB; Mag1: 5.7; Mag2: 7.6; Sep: 89.1"
Eyepiece: 40mm Plossl; Magnification: 16x; Rating 3/5.
Observations: Unequal, yellow bluish double, super wide at 16x, in a rich and colourful field.

ID: WDS19546-0814
Type: Dbl; RA Dec: 195438-0813; Constellation: Aql
Name: 57 Aql AB; Mag1: 5.7; Mag2: 6.3; Sep: 35.6"
Eyepiece: 40mm Plossl; Magnification: 16x; Rating 4/5.
Observations: Pair of bright, white stars, mildly unequal and attractively close at 16x. There is an equally bright deep orange star nearby in an otherwise rather sparse field. HDO155 is in the same field and there is a faint pair in between.

ID: WDS20066+0735
Type: Dbl; RA Dec: 200639+0734; Constellation: Aql
Name: STTA198 AB; Mag1: 7.1; Mag2: 7.6; Sep: 64.3"
Eyepiece: 40mm Plossl; Magnification: 16x; Rating 3/5.
Observations: White stars, with a modest difference in brightness, quite wide at 16x. A very bright orange star, γ Aql, dominates the field. The view is uncannily like an enlarged version of 57 Aql.

ID: WDS20113-0008
Type: Dbl; RA Dec: 201119-0007; Constellation: Aql
Name: S735 AB; Mag1: 7.2; Mag2: 8; Sep: 55.3"
Eyepiece: 40mm Plossl; Magnification: 16x; Rating 3/5.
Observations: Well split at 16x, this is a mildly unequal pair of golden stars. The rich field includes prominent yellow and orange stars and the brilliant, white θ Aql.

ID: WDS20152-0330
Type: Dbl; RA Dec: 201511-0330; Constellation: Aql
Name: STF2654 AB; Mag1: 7; Mag2: 8.1; Sep: 14.5"
Eyepiece: 20mm Plossl; Magnification: 33x; Rating 3/5.
Observations: This mildly unequal pair of pale yellow stars is attractively close at 33x, in a nice field.

ID: WDS20142+0635
Type: Dbl; RA Dec: 201410+0635; Constellation: Aql
Name: S740 AB; Mag1: 7.8; Mag2: 8.1; Sep: 43.6"
Eyepiece: 40mm Plossl; Magnification: 16x; Rating 3/5.
Observations: Yellow stars, of similar brightness, nice and close at 16x. The field is sprinkled with relatively faint stars.

ID: WDS20275-0206
Type: Dbl; RA Dec: 202728-0206; Constellation: Aql
Name: S749 AB; Mag1: 6.8; Mag2: 7.5; Sep: 59.7"
Eyepiece: 40mm Plossl; Magnification: 16x; Rating 3/5.
Observations: Golden stars, of similar brightness, nicely split at 16x, and forming a sharp arrowhead with a nearby orange star of matching brightness.

ID: WDS02039+4220
Type: Dbl; RA Dec: 020354+4219; Constellation: And
Name: Almaak A,BC; Mag1: 2.3; Mag2: 5; Sep: 9.4"
Eyepiece: 10mm Plossl; Magnification: 66x; Rating 5/5.
Observations: Brilliant golden primary with a much fainter secondary that appears to have a greenish tint. A magnification of 66x was required to pick out the secondary cleanly from the glare of the primary. This beautiful colour-contrast double is one of my favourites.

That is a lovely list of doubles in Aquila, Mike. I have been so lazy in recent times with observing. I have not had the apo out since 29th July -seems an age ago now.
But I am ready and keen to do some visual astronomy on Monday night. I wonder will the skies be clear?

However, having studied you great list, Mick, I have enjoyed 57 Aquilae in the distant past.

About Almach in Andromeda, I did study it earlier this year on 12th and 31st January. You say you see A as gold and B as green. Mmmmm...
On both of those dates I considered A as orange or gold -I agree with you. However on both evenings, I was content that B was blue.
Maybe your SCT makes B look green. My 158mm apo loves to kill false colours. I am happy that you do see it as green -I have no real problems with that. At the time I was observing it, I was paying more attention to Comet Lovejoy. It was, after all, my first comet for 8 years! It was only 5 degrees from Almach on the 31st January.

Clear skies to you, Mike.

Aubrey.

Cheers Aubrey. The greenish tint that I see is not real of course, just some sort of colour contrast effect. No doubt different observers will see it differently Moreover, I did not study the secondary very intently to try to discern its "true" colour, I was content to enjoy my first impression of the delicate colours of this pair. I remember you had a thread some time ago about greenish stars - I must revisit that.

Mike

Good man, Mike.

It was in 2014 when I thought for about 10 seconds that Zubeneschamali (Beta Librae) appeared green. But as I concentrated on it rather intensely for 2 nights, I judged it to be blue along with a few other Irish observers.

Izar (Epsilon Bootis): I have always seen its components as orange and blue.

Rasalgethi: Red and blue. However, I feel I should revisit this wonderful double star.

Clear skies,

Aubrey.