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New star near Alf Cha... 2020/03/29

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ACN
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New star near Alf Cha... 2020/03/29

Friends,

I received 3 photos of a friend that show the same  star near Alf Cha... I estimate it as ~ 9.5

The AAVSO charts up to mag 12 do not  show this star. Can anyone examine  it?

See the attachment of the  photo ...number 3066.

Thanks,

Carlos (ACN)

 

VAastro
New star near Alf Cha... 2020/03/29

Carlos,

It looks like CD-76 361

See Aladin

http://cdsportal.u-strasbg.fr/?target=CD-76_361

File upload: 
ACN
ACN's picture
New star near Alf Cha... 2020/03/29

  The question mark was put wrong ..Indeed it  is for the faint star of the double!! . 

Sebastian Otero
Sebastian Otero's picture
Missing Tycho-2 star

Carlos,
as you found out yourself, there was nothing unusual with the brighter object of the pair, it is TYC 9394- 2945-1 a constant F0-type V= 9.7 mag. star:

ASAS-3 light curve.

which is in the AAVSO chart.
The missing one is the 10.3 mag. star PPM 784690 which is not in Tycho-2. That is the reason why it is not plotted. We use Tycho-2 and UCAC4 to plot stars of these magnitudes, but this object lies near the Tycho-2 limit that we use based on the assumption that all 10th mag. stars would be in Tycho-2.
At some point in the future we will probably adopt Gaia and avoid the use of multiple catalogues that may cause the absence of some objects.

The missing star is also constant (there is some contamination in ASAS-3 data):

ASAS-3 light curve.

A recommendation when you find something like this:
always check DSS images to see if a star is visible or not.

You have the "Would You Like to Display a DSS Chart?" option in VSP.

Also, you can search for all catalogue entries on the star using VizieR.

Cheers,
Sebastian

ACN
ACN's picture
Missing Tycho-2 star

Thanks,  Sebastian!

Next time I will see  also DSS images...

Cheers, Carlos

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