6 replies to this topic

[geminijk]

While observing NGC 2343 via EAA (C8f6.3 294mc 7x60s ) I noticed the presence of quite a few orange stars, but one in particular caught my eye as it was so reddish.

 

 

Digging into Stellarium didn't really help, but using SkyTools 3 I think i have identified the star as the suspected variable NSV 17351. However ST3 shows the variability as 2.6 to 3.8 and this star is well below that magnitude, and there lies the mystery. Now I'm not into variable stars or photometry (but would like to be) but doing a quick comparison to a field star TYC 05385-0309 1 which is 12.49mag, its darn close to that magnitude. 

 

So any additional information on this would be greatly appreciated. Perhaps the mag range in ST3 is just wrong, thus asking the experts here for any insight.

 

The screen grab below shows ST3 on the left with the star highlighted, and the one on the right is a zoomed in view from my EAA session and that star is the obvious red one.

 

 

 

[The Ardent]

Looking at your Skytools screenshot, it’s K mag (infrared) Visual may be 5-10 magnitudes fainter. 

[The Ardent]

15th mag visual

http://simbad.u-stra...=SIMBAD search 

[GaryShaw]

You can try magnitude comparisons and determinations visually through a scope but as soon as you put a camera in place of the eyepiece, you’ve entered a different world that requires all sorts of corrective gymnastics and other procedures in order to get at magnitude estimations.

 

If you are using a OSC camera there are a lot of things you have to do to even get close to determining a visual type magnitude. Then the procedure is quite different if you have a mono camera. 
 

Regarding identifying the star, did you upload the image to Astrometry.net? If it’s prominent enough in the FOV, they will likely identify it for you.

[MCinAZ]

  Comparing the representations in your screen shot, the bright object in the plot does not appear at the position of the red star in the image. The star is southeast (above and to the right) of the plotted object. The red star in your image is probably UCAC4 397-021165. There is a faint star (UCAC4 397-021158, mv 16.6) near but not coincident with the bright object in the plot. The field isn't all that far from the ecliptic -- is there any chance the bright object in your plot is an asteroid?

 

  Depending upon the catalog(s) used by planetarium programs, discrepancies between plots and reality aren't terribly uncommon, particularly beyond 10th or 11th magnitude. With more complete catalogs, it's become somewhat better in the past 15 years, though I expect mayhem if people start referencing GAIA data without recognizing the substantial difference between G, G_BP and G_RP passbands and how they relate to Johnson-Cousins V.

 

[NB: It's good practice to orient images north up/east left or add a marker indicating at least two orthogonal directions on the sky, preferably with field scale. I eventually determined that your images are rotated approximately 180 degrees from north up, but it took a while.]

[KMAO]

To Topic Starter
Your picture I perfectly oriented Southup Eastright.
Red object is indeed NSV 17351
but magnitudes given are in passband "K"
which is "near infrared".
My apology to all
who already said that...
best wishes
KMA

BTW
nice photos

[geminijk]

Thank you all for the additional information, and the clarification on K passband. Much appreciated.

 

John