Return to the Cloudy Nights Telescope Reviews home page


Observing >> Double Star Observing

Pages: 1
Cotts
Just Wondering
*****

Reged: 10/10/05

Loc: Toronto, Ontario
Nice Double-Double near M81 new
      #6477902 - 04/20/14 07:32 PM

Observing with my TEC 140 on Saturday night, April 19th...

There is a very nice 'Double Double" about 10-11 arcmin SSW of the center of M81. They are in the WDS as STF 1387 and STF 1386.

The pair closer to the nucleus of M81 is STF 1387, mags 10.44 and 10.73, separation 8.9"

The more southerly pair (and thus further from M81), by about 130" is STF 1386, mags 8.73, 9.34, separation 2.0".

I had a very nice view and split of both with my new TEC 140 and a 5mm Nagler (196 power). The close pair is difficult with this aperture due to the combination of its closeness and faintness. It is possible to get the galaxy and both pairs in one field of view.....

Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
WRAK
Pooh-Bah


Reged: 02/18/12

Loc: Vienna, Austria, Europe
Re: Nice Double-Double near M81 new [Re: Cotts]
      #6478455 - 04/21/14 04:34 AM

Nice to read here after some time again a post about an interesting observation. Had these doubles already in my raw listing of interesting targets in UMa but was not aware that this is a double-double. WDS even lists an STF1386 AB,CD object with CD for STF1387 - although proper motion does not suggest this might be a physical double-double.

UMa is for spring and early summer an especially interesting field of view to keep in mind for clear nights with a bright moon - much better to have the headlights from behind making thus despite the bright sky a decent double star session possible.
Wilfried


Post Extras: Print Post   Remind Me!   Notify Moderator  
desertstars

*****

Reged: 11/05/03

Loc: Tucson, AZ
Re: Nice Double-Double near M81 new [Re: WRAK]
      #6479819 - 04/21/14 07:43 PM

I've added these to my checklist for the next night out.

Post Extras: Print Post   Remind Me!   Notify Moderator  
fred1871
scholastic sledgehammer


Reged: 03/22/09

Loc: Australia
Re: Nice Double-Double near M81 new [Re: desertstars]
      #6480353 - 04/22/14 12:42 AM

They're quite a neat combination, especially with a bit more aperture. Back when I was north of the equator I came across this double pairing, nicely offset beside M81. Viewed with a C8 at 80x the dimmer wider pair was obvious, and the close pair barely separated; 135x gave a neat view of both with the closer pair a good split at that power. I think the extra light of 200mm vs 140mm helped.

Cotts, interesting that your quoted magnitudes don't match the WDS listing. Are these Sky Safari numbers?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cotts
Just Wondering
*****

Reged: 10/10/05

Loc: Toronto, Ontario
Re: Nice Double-Double near M81 new [Re: fred1871]
      #6480657 - 04/22/14 07:21 AM

Quote:

They're quite a neat combination, especially with a bit more aperture. Back when I was north of the equator I came across this double pairing, nicely offset beside M81. Viewed with a C8 at 80x the dimmer wider pair was obvious, and the close pair barely separated; 135x gave a neat view of both with the closer pair a good split at that power. I think the extra light of 200mm vs 140mm helped.

Cotts, interesting that your quoted magnitudes don't match the WDS listing. Are these Sky Safari numbers?




Yes, Fred, they are from Sky Safari - I tried to get the WDS data but, apparently, the site is still down... (tried it just now - 404 not found...)

I think the mags from Sky Safari are too bright for the closer pair - they seemed to be fainter than the wide pair..... I guess we wait until WDS wakes up....

Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
fred1871
scholastic sledgehammer


Reged: 03/22/09

Loc: Australia
Re: Nice Double-Double near M81 new [Re: Cotts]
      #6480904 - 04/22/14 10:21 AM

Dave, yes, you're quite correct about STF 1386 being less bright than Sky Safari suggests - the WDS magnitudes for the closer pair are 9.30 and 9.34, which suggests that Sky Safari is listing the combined magnitude as the number for star A, and then giving the correct figure for star B. There's a similar pattern for STF 1387, but there the numbers don't add up, so it's some kind of muddle.

I download a copy of the current WDS from time to time, so I have a reference copy on my computer, and don't depend on the vagaries of the internet. The catalog doesn't change rapidly, given its size, so much of the data is the same for extended periods of time; that's especially true for photometry.


Post Extras: Print Post   Remind Me!   Notify Moderator  
WRAK
Pooh-Bah


Reged: 02/18/12

Loc: Vienna, Austria, Europe
Re: Nice Double-Double near M81 [Re: fred1871]
      #6481135 - 04/22/14 12:42 PM

Thought the SkySafari double star magnitude issue as solved with version 4 (including now the complete WDS catalog) - but is obviously not.
Wilfried


Post Extras: Print Post   Remind Me!   Notify Moderator  
ssmith
member


Reged: 06/28/12

Loc: Colorado
Re: Nice Double-Double near M81 new [Re: Cotts]
      #6482447 - 04/23/14 12:59 AM Attachment (27 downloads)

I went back and looked at the photos I took of the supernova in M82 back in January and saw that I had captured both doubles in the FOV but obviously did not split STF 1387 with my 80mm scope. Attached is a cropped view of M81 and the doubles.

Edited by ssmith (04/23/14 01:03 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
WRAK
Pooh-Bah


Reged: 02/18/12

Loc: Vienna, Austria, Europe
Re: Nice Double-Double near M81 new [Re: ssmith]
      #6482521 - 04/23/14 02:25 AM

Great picture. While STF1386 is not resolved it shows a hint of an horizontal elongation - corresponding rather well to the PA of 111.
Wilfried


Post Extras: Print Post   Remind Me!   Notify Moderator  
R Botero
Pooh-Bah


Reged: 01/02/09

Loc: Kent, England
Re: Nice Double-Double near M81 new [Re: ssmith]
      #6484976 - 04/24/14 06:25 AM

Great shot indeed!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1


Extra information
1 registered and 7 anonymous users are browsing this forum.

Moderator:  PJ Anway, Rich (RLTYS), rflinn68 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 645

Jump to

CN Forums Home




Cloudy Nights Sponsor: Astronomics