Double Trouble

[Richard N]

Last night I was looking for STF1695 in UMa. The Cambridge Double Star Atlas lists the binary as mag 6.0/7.8 sep 3.8".  Sky Safari Plus lists them as 5.8/7.75 3.9" but when I zoom in, no double is visible on my phone. Steallarium Plus (iPhone) lists it as HIP 112486A but says it's a spectroscopic binary and shows no double at the expected split. Stellarium (desktop) shows the double as per the CDSA. My eyepiece view did not reveal a close companion to the target (but that may well have been down to me). I'm confused. This chain of events has happened with several doubles that I have tried to observe.  Any ideas as to the descrepancies?

Edited September 16, 2021 by Richard N
Update

[grjsk]

Sky Safari/Stellarium does have quite a few holes in their star database. I have purchased the GAIA Extension Database to Sky Safari that add an additional 90 million stars, but I still encounter stars that arent shown. I only see 1 star when I look up STF1695, just like you. 

[Richard N]

1 hour ago, grjsk said:

Sky Safari/Stellarium does have quite a few holes in their star database. I have purchased the GAIA Extension Database to Sky Safari that add an additional 90 million stars, but I still encounter stars that arent shown. I only see 1 star when I look up STF1695, just like you. 

Thanks. I had hoped that the amazing omission of Mizar B in SkySafari was a one-off but clearly there are other omissions in the phone versions of SS and even Stellarium. I will now know not to be surprised even if I’m a bit disappointed. 

[John]

The Stelledoppie database has an entry for it:

https://www.stelledoppie.it/index2.php?iddoppia=55381

[grjsk]

41 minutes ago, Richard N said:

Thanks. I had hoped that the amazing omission of Mizar B in SkySafari was a one-off but clearly there are other omissions in the phone versions of SS and even Stellarium. I will now know not to be surprised even if I’m a bit disappointed. 

I can see Mizar B in SkySafari Pro on mobile, so I guess the In-App purchase atleast has some value.

Edited September 16, 2021 by grjsk

[Stu]

Yes, there are some surprising omissions in SkySafari in terms of doubles. I do now have Mizar but probably as an in app purchase.

[lunator]

STF1695 is listed in sky safari plus (Andriod) the double isn't shown in the map.

I checked my observation of this pair.

"A tightish uneven pair requiring a moderate magnification to split. A clean split was achieved with the 6mm (x100). The primary ia white and the secondary is yellow/orange"

The scope I used was am ST120.

Cheers

Ian

[wookie1965]

As Lunator has said Struve 1695 is doable "Hass" says mags 6.0` and 7.8` with a separation of 3.8°  I have split this in my 4" Hass says Sun yellow and pure Violet whereas Webb says White and Ash. I noted White with the companion having a yellow tinge..

Paul 

[lunator]

8 hours ago, wookie1965 said:

As Lunator has said Struve 1695 is doable "Hass" says mags 6.0` and 7.8` with a separation of 3.8°  I have split this in my 4" Hass says Sun yellow and pure Violet whereas Webb says White and Ash. I noted White with the companion having a yellow tinge..

Paul 

Hi Paul, 

I'm  glad we agree on the colours 😃

Cheers

Ian

[F15Rules]

22 hours ago, lunator said:

Hi Paul, 

I'm  glad we agree on the colours 😃

Cheers

Ian

I'm always amazed at the different colours ("hues" is probably a better word, as the differences are often extremely subtle) that people perceive when observing doubles.

I've noticed that as I get older, my colour sensitivity is less good than it used to be..I guess this is an inevitable side effect of the ageing process.

In truth, though, I have never been able to perceive many of the hues described by other observers, especially 19th century ones, and I do wonder if many of the "exotic" hues described by Victorian users of 3-4" achromatic refractors had as much to do with atmospheric conditions and the limitations of their optics, as it did with their having exceptional vision?🤔

Dave

Edited October 24, 2021 by F15Rules

[lunator]

Hi Dave,

I have always felt the 'colours/hues' are definitely affected by type of telescope.  The most vivid colours were in my ST120.

The most 'natural' colours were in my 200mm F6 newt. I most definitely peferred the view i the latter

Cheers

Ian

[F15Rules]

7 minutes ago, lunator said:

Hi Dave,

I have always felt the 'colours/hues' are definitely affected by type of telescope.  The most vivid colours were in my ST120.

The most 'natural' colours were in my 200mm F6 newt. I most definitely peferred the view i the latter

Cheers

Ian

Hi Ian, 

I think that makes total sense, as the ST120, nice views though it can deliver, has significant chromatic aberration, whereas your Newt is effectively apochromatic.

The same goes for my fluorite Tak FS128..visually apochromatic, whereas my F10 Vixen SP102m achromat, although quite well corrected, clearly shows some CA, especially on brighter objects.

Back in the 1970s, Vega was often described as a "bluish white" star...and so it looked in my F15 60mm achromat. Even the late great Sir Patrick Moore so described Vega in his Observers Book of Astronomy!😂

In my FS128 it is clearly pure white.

Dave

[Saganite]

1 hour ago, lunator said:

Hi Dave,

I have always felt the 'colours/hues' are definitely affected by type of telescope.  The most vivid colours were in my ST120.

Cheers

Ian

Yes, I was convinced Jupiter was purple until I got shot of mine....

Edited October 24, 2021 by Saganite

[Saganite]

1 hour ago, lunator said:

Hi Dave,

I have always felt the 'colours/hues' are definitely affected by type of telescope.  The most vivid colours were in my ST1

Cheers

Ian

This was the reason I gave up on mine and sold it asap, after viewing Jupiter.  It seemed like a purple blob.

[F15Rules]

Just now, Saganite said:

This was the reason I gave up on mine and sold it asap, after viewing Jupiter.  It seemed like a purple blob.

So you were "having a purple patch" in your planetary observing at that time, Steve??🤦‍♂️😂

[Highburymark]

I upgraded SkySafari for this reason - still come across the odd inaccuracy. Have noticed recently there were a couple of triple systems only showing as doubles