Weird thing I've found in Sky6

[gurney]

Could someone have a look at this. It seems VERY odd to me!

I've been fiddling about in Sky6 and just stumbled across this weird collection of stars at the western corner of the constellation Crater. Surrounding the western most star (I'm guessing it's called Beta Crateris or something like that but Sky won't tell me!) are a multitude of magnitude 13, 14, and 15 stars in an almost perfect cross shape. It looks like an optical artefact but for the fact that SKy6 is cataloguing them all as individual stellar objects in their own right.

So this must have been seen and given a name. Can someone tell me what it is please?

Ta!!!

Here's a screenshot of it:

[gurney]

PS - why is there no dedicated forum on here for talking about software? ... Or is there and I haven't found it yet!

[gurney]

Here's the object info copied from Sky6 for the central star:

Object name: SAO 156661

Other ID: HIP 55705

Magnitude: 4.05

Equatorial: RA: 11h 25m 18.681s Dec: -17°43'59.311"(current)

Equatorial 2000: RA: 11h 24m 52.924s Dec: -17°41'02.435"

Horizon: Azim: 185°46'53.119" Alt: +32°19'13.538"

Alternate names: HIP 55705 GSC 6088:2155 PPM 224369

Visibility: Rise 13:15, Set 23:17

Transit time: 18:16

Flamsteed-Bayer: 15-Gamma Crateris

Name 6: HD 99211

Name 7: B-16 3244

Object type: Star

Spectral: A9V

Source catalog: Hipparcos Catalog

Sun distance (au): 5302446.49

Hour angle: 00h 20m 56.123s

Air mass: 1.87

Magnitude B: 4.33

Magnitude V: 4.10

Screen x,y: 625.00, 412.00

Parallax: 38.9000

Proper Motion: -97.01, 3.22

Position error: 0.6900, 0.4800

Sidereal time: 11:46

Click distance: 5.0000

Light years: 83.84

Parsecs: 25.7069

Catalog number: 156661

Julian date: 2454641.5270

Angular separation: 00°00'03.411"

[GazOC]

Starry Night shows nothing like that around Gamma Crateris.

[gurney]

Don't know if it is definitely gamma crateris at all - just a guess. Detailed info above. Would you mind checking please? I'm really curious now.

[GazOC]

The RA and dec you gave match Gamma.

[gurney]

What's your limiting magnitude on Starry night? these are all 13, 14, and 15 mag stars I think.

[beamish]

Could the s/w be imitating an image of it and a case of gravitational lensing ? Just an idea!

[GazOC]

I've had a quick look and it seems to be showing down to at least 14.5.

[Roy]

please ignore this, posted by mistake :oops:

[Paxo]

Looks like a software glitch in Sky6 to me. The info you provided does indicate tht it is Flamsteed-Bayer: 15-Gamma Crateris, I have Starry Night Pro which uses a mapped digitised sky survey and there is no similar astrism showing as you have indicated. It all does look a little too 'man made', probably minute errors in the mapping data?

Perhaps it could be known as the 'Gurney Patch' for future reference :laughing2:

A quick dabble on tinternt reveals nothing of interest to this conversation, a close double star, a type SRb semi-regular variable and Abt's star an 8.1 magnitude variable. Noticeable deep sky objects in the contellation NGC 3511, a spiral galaxy, NGC 3887, a barred spiral and NGC 3981 another spiral.

Steve

[Talitha]

Gurney, I've had the same thing happen a few times in Sky Tools with different stars. No idea what the glitch is, but it sure makes me stop and stare.

[gurney]

Perhaps it could be known as the 'Gurney Patch' for future reference :laughing2:

Oh yes - I like that!

I think you guys are right though - I think it's most likely an error. Very odd though init!

[Sam]

Perhaps it could be known as the 'Gurney Patch' for future reference :laughing2:

:laughing3: :laughing3: you own patch of the sky Gurney! even if it is virtual.

[gurney]

I know - it's a great day!

But back on planet earth, I've installed the software on my laptop and still have the same thing. So I've downloaded the latest update and, guess what.... IT'S STILL THERE!!!

So I've signed up on the software bisque forums and posted it on there. See what feedback I get.

[ringz]

This sort of thing happened when the sky hubble guide star catalogue photographic plates got automatically digitised. Very bright objects on the plates produced diffraction spikes and the software wasn't clever enough to know about diffraction spikes.

You can usually tell what is going on if, for example. you notice that the object gurney has highlighted has a cross of stars pointing to the central object, these are the digitised diffraction spikes.

Usually you can remove these artefacts because the converting program marks them as non stellar objects.

Here's a sky survey plate

(click to enlarge)

--

Martyn

[Talitha]

That makes a LOT of sense, Martyn!

[gurney]

Yes it does. Thanks Martyn.

But why on earth is it still in a well regarded piece of software, and why hasn't it been fixed yet? Very odd!!! Makes you sort of lose confidence a bit in the rest of the stars on there! Although thankfully this one did rather stand out!

The really peculiar thing though is that Sky6 gives me nice detailed information about each of the individual little 'stars' which form the diffraction pattern, each with their own unique catalogue number. Oh well. I guess Gurney's Patch will have to wait for another day.

[Paxo]

Good spot Martyn , mystery solved I think.

Steve..

[Kaptain Klevtsov]

Nothing in the digital sky survey image for that area though.

(click to enlarge)

Kaptain Klevtsov

[jcm]

And this is the guide 8 view of the area.

John

[gurney]

Just to draw a line under this. I've had some responses from Software Bisque about this issue. They say it is all done to the Guide Star Catalogue, which has a fair number of these errors within it.

The answer when using Sky6 is to turn off the GSC, and sure enough those annoying 'stars' have gone!

Software Bisque can't do anything about it because it's not directly their responsibilty to edit the GSC. Which I reckon is fair enough really.

Anyway - mystery solved!