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.


Challenging quad in NGC281 BU1

  • Please log in to reply
4 replies to this topic

#1 Darren Drake

Darren Drake


  • *****
  • topic starter
  • Posts: 3,999
  • Joined: 09 Oct 2002
  • Loc: Chicagoland

Posted 09 October 2019 - 10:19 AM

The Burnam 1 quadruple star is a challenging 4 star system.  The first 3 are easy but the 4th can be very elusive.   How many here have seen that 4th star and what is the min aperture needed to see it?  I saw it coming in and out last night in my 18 but suspect an 8 can do it.  Thanks

Edited by Darren Drake, 09 October 2019 - 10:24 AM.

#2 dmdouglass


    Surveyor 1

  • *****
  • Posts: 1,901
  • Joined: 23 Dec 2007
  • Loc: Tempe, AZ

Posted 09 October 2019 - 12:14 PM



Interesting "Challenge" ... and of course, you are looking right into the middle of The PacMan Nebula.

My "observations" are all images... camera sees MUCH better than my old eyes.

I have an old image from 2013 that i looked up...


BU-1 Crop from 2013.jpg


Here is the Stelle Doppie information for this one.  

For "The fourth star" , my assumption is that your question is talking about the AD pair, with the "D" star at Mat 12.1.  




Will have to consider a "re-Image" and see what i can resolve...  (with, maybe, some better focus :) )

Edited by dmdouglass, 09 October 2019 - 12:16 PM.

#3 mccarthymark


    Vostok 1

  • *****
  • Posts: 171
  • Joined: 09 Jun 2014
  • Loc: SF Bay Area

Posted 09 October 2019 - 12:19 PM

I observed BU 1 AB (which is what I assume you mean) with a 12.5" in mediocre (5-6/10) seeing: 


BU 1: !! Right triangle of equal stars; the foot star has a very faint, 2-3 delta mag star very close ~1", faint split.  Some fainter stars wreathed about it. [AB seen, while AC, AD appear to be the other triangle stars.  17 visible stars in the system, which I suppose ought to be called a cluster.] -- Pac Man cluster
00H 52M 49.22S +56° 37' 39.5" P.A. 83 SEP 1.5 MAG 8.58,9.33 SP O6.5V DIST. 3030.3 PC (9884.84 L.Y.)


The B star appeared much fainter to me than the data, but I sometimes get these estimates a little off.


Interestingly Stelle Doppie says this is not physical

Edited by mccarthymark, 09 October 2019 - 12:20 PM.

#4 fred1871


    Surveyor 1

  • -----
  • Posts: 1,618
  • Joined: 22 Mar 2009
  • Loc: Australia

Posted 09 October 2019 - 08:45 PM

Darren, if by the 4th star you mean the tight AB pairing, mags 8.58 and 9.33 at 1.5", I recorded it as visible "a tiny point just separated from A" with a C8 at 200x back in the 1990s when I was observing from San Diego, Ca. So, yes, it's visible with an 8-inch. On a previous night of sub-standard seeing it didn't show (smudge seeing); with the steadier night when I saw it, I didn't think it difficult. I'd expect a good 6-inch refractor to show it.


The C8 also showed the dim wide-ish FG pair, mags 11.3 and 12.2, offset from the main group. Likewise the mag 12.1 E component, all at 135x.


I was surprised to discover that BU 1 is absent from the Cassiopeia listing in Sissy Haas's book Double Stars for Small Telescopes. Slightly too faint, perhaps? A pity, because on both nights I observed it I noted it as a fine object. Perhaps for a 4-inch it would be less effective due to the low magnitudes for that aperture.

#5 gfeulner


    Viking 1

  • *****
  • Posts: 933
  • Joined: 23 Nov 2007
  • Loc: Bergen county, New Jersey

Posted 09 October 2019 - 09:12 PM

I can routinely see ABC and D in my TEC 140 at around 250x if I'm at my dark observing site and if the seeing is steady. Any turbulence and the D star is very difficult or impossible to see. I'll have to look for the E star next chance I get.


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