Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Sagitta : HJ 912, HJ 2941, BU 1484, GRV 320

  • Please log in to reply
1 reply to this topic

#1 The Ardent

The Ardent

    Aurora

  • *****
  • Moderators
  • topic starter
  • Posts: 4,679
  • Joined: 24 Oct 2008
  • Loc: Virginia

Posted 23 December 2019 - 10:16 PM

HJ 912 lovely optical double in Sagitta

 https://www.stelledo...?iddoppia=87632

 

HJ 2941 

"This double is physical" 

 https://www.stelledo...?iddoppia=86926

 

BU 1484

 https://www.stelledo...?iddoppia=86896

 

This is the last of the data from Nov 10, 2019. A somewhat cloudy night with a large waxing gibbous moon. A good night for imaging doubles in lieu of visual observing with my dob. The seeing and sky conditions weren't the best. 

 

Greaves 320 

"This double is physical" 

 https://www.stelledo...?iddoppia=86524

 

I had no knowledge of this system until harvesting the data from the pic. I thought that HD 351568 was a double, but not indicated as such anywhere. GRV 320 just looks like background stars! But there it was in SkySafari. Located just 21' from NGC 6886 at PA 311, or just 8' from Henize 1-5 at PA 215. I spent many nights locating and observing these two planetaries. He 1-5 is challenging, not only to locate in a crowded field, but simply to see. I had no idea about this double. A physical double hiding in plain sight. 

Attached Thumbnails

  • HJ 912.jpg
  • HJ 2941 BU 1484.jpg
  • IMG_1941 GRV 320 .jpg

  • lbim and flt158 like this

#2 fred1871

fred1871

    Surveyor 1

  • -----
  • Posts: 1,567
  • Joined: 22 Mar 2009
  • Loc: Australia

Posted 24 December 2019 - 05:43 AM

HJ 2941 - an interesting one, as the Proper Motion numbers in WDS are very different, see the Stelle doppie data, and the large differences suggest an optical pair. Hiowever, when I found the two stars in the Gaia DR2, there the PM numbers match closely, and the parallaxes are not very different. Indeed suggesting a physical pair.

 

The question is how the PM numbers got to be so different. What was the source for the WDS PM numbers for the secondary, in particular?  Unusual to find so large a change from WDS to Gaia DR2.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics