The Haas And The Cambridge Double Star Catalogues

[cloudsweeper]

A catalogue is essential for the serious double star enthusiast.  Here I offer a brief comparison between the Sissy Haas (SH) Double Stars For Small Telescopes, and the Cambridge Double Star Atlas (CDSA).

They both have good intros - CDSA perhaps more technical; SH very approachable and clear.

CDSA has excellent charts, but if you have another atlas, that will suffice (albeit with less emphasis on doubles of course).  SH has no charts.

CDSA lists about 2500 multiple systems; SH, 2100.

Both give RA/Dec coordinates, but CDSA also gives SAO numbers.  The coordinates can of course be entered into a GoTo 'scope, but I personally find it easier to use the SAO option on the handset, so CDSA wins there for me.

CDSA gives more details about the components in each multiple system, but SH gives comments for every multiple, including typical apertures and magnifications.

If I was asked which I would recommend to someone who only wanted to buy one, I would say SH, for clarity and accessibility, but it's a close thing.  For me, they complement one another, so I am pleased to own both!

The first two images are CDSA; the second two, SH.

Doug.

[Knighty2112]

Nice write up Doug. I have both too, and even though SH doesn’t have the charts I would still recommend it as long as you have another star chart to use along with. Of course the CDSA compliments it very well. I did find one double in SH labellled incorrectly in its listing which caused a little confusion at first, but other than that it is an excellent resource. 

[domstar]

Thanks. Any experience of using them without goto? I run screaming from RA/Dec numbers. I think an atlas like this should be my next step but it'll take a bit of work to change from my current practice of trying to remember stellarium.

[cloudsweeper]

1 hour ago, domstar said:

Thanks. Any experience of using them without goto? I run screaming from RA/Dec numbers. I think an atlas like this should be my next step but it'll take a bit of work to change from my current practice of trying to remember stellarium.

Well, Dom, I have Stellarium out there with me - night mode, plus red acetate sheet over the screen.  So I get the target in the EP, then generally make sure by comparison with Stellarium.  Having the SAO number is very useful for locating targets in Stellarium as well as entering them in the GoTo.

But you could of course use the CDSA charts as your guide, and hunt round with a wide FOV.  (With a Newt, turn the chart upside down; with a frac or cat, imagine the chart being reversed side-to-side.  With Stellarium, this lateral inversion is easy - just use CTRL ^ H.)

Doug.

[chiltonstar]

I use both,  without goto. SH is for small scopes of course, and CDSA doesn't list optical doubles, although it charts them. So, it's not one or the other, it's both really IMHO as they are complementary.

I love the enthusiasm in the SH book, CDSA is a bit drier.

Chris

[cloudsweeper]

2 hours ago, Knighty2112 said:

Nice write up Doug. I have both too, and even though SH doesn’t have the charts I would still recommend it as long as you have another star chart to use along with. Of course the CDSA compliments it very well. I did find one double in SH labellled incorrectly in its listing which caused a little confusion at first, but other than that it is an excellent resource. 

Thanks Gus.  Now of course, you've got to tell me where that error is to spare me future confusion!

And for reference, my CDSA, on page 131, has 9 Lib as Zubeneschmali instead of Zubenelgenubi.

Doug.

[cloudsweeper]

27 minutes ago, chiltonstar said:

I use both,  without goto. SH is for small scopes of course, and CDSA doesn't list optical doubles, although it charts them. So, it's not one or the other, it's both really IMHO as they are complementary.

I love the enthusiasm in the SH book, CDSA is a bit drier.

Chris

Agreed on both counts, Chris!

Doug.

[Knighty2112]

37 minutes ago, cloudsweeper said:

Thanks Gus.  Now of course, you've got to tell me where that error is to spare me future confusion!

And for reference, my CDSA, on page 131, has 9 Lib as Zubeneschmali instead of Zubenelgenubi.

Doug.

Actually Doug, the error isn’t in HA as I’ve just checked. The problem was with Skysafari. The double in Cancer listed in HA as Sigma4 CNC, and also shown in the charts and lists in CDSA as Sigma4 too, is not listed In Skysafari as that, but only as 66 CNC, so that’s what’s caused my confusion when I was setting up an observing list in Skysafari. 

[Paz]

I use both atlases and that's a good summary. I don't use goto, I will either use a map having noted Ra/Dec or will use the SAO or HD reference to find it in sky safari.

Personally I'm only really drawn to looking at physical doubles as the idea of looking at a real star system is amazing, I never really go for optical doubles unless there's an interesting physical aspect such as colour contrast, so I use the Cambridge atlas a bit more.

[cloudsweeper]

7 minutes ago, Paz said:

I use both atlases and that's a good summary. I don't use goto, I will either use a map having noted Ra/Dec or will use the SAO or HD reference to find it in sky safari.

Personally I'm only really drawn to looking at physical doubles as the idea of looking at a real star system is amazing, I never really go for optical doubles unless there's an interesting physical aspect such as colour contrast, so I use the Cambridge atlas a bit more.

Thanks Paz.  Yes, gravitationally-bound systems do have the edge for appeal.  One interesting aspect is that the separations can change over just a few years, which is why different sources quote slightly different values.  (Very close systems change over days and move at high orbital velocities, but these of course cannot be observed visually.)

Fascinating stuff!

Doug.

[cotterless45]

Use both these , plus Sky Safari and Interstellarium. To avoid all this outdoors , I make a list of hopefully planning to see , or not. Sissy Haas is simply fascinating , with notations of historical and observational interest. It's quite challenging , with some entries getting " not seen ". I always double check some of the sub 2" separations as these change change pdq. There are also the big changes , such as Porrima.

With the amount of clear sky and targets to observe , I had to turn to goto. Be aware that only a large fraction of SAO numbers are in (Synscan) handset. Coordinates soon make sense as you tour  the sky.

What is amazing is that a large number of named stars are binaries, including 52 Cygnus. Add in details of their history , age and AU distances and you can have many hours of fascination. Or as they say at star parties " he's off on double stars, again !"

Certainly something we should encourage all observers , especially newbies and those living with light pollution to get into. The handiest web resource is what's left of Eagle Creek , see my signature.

In many books on observing , binaries get short shrift. It's great to have the resources at hand.  Under   

Clear skies ! Nick.

[cloudsweeper]

Thanks Nick (^) - Yes, I'm a convert to doubles, after initially thinking What's the big deal!?  I too have found that some SAO numbers do not appear in the Celestron handset.  Coordinates could be entered of course, but I usually just go for something else near the target and try to recognise it by comparison with Stellarium. 

Doug.

[glynnlondon]

I use both as well and wouldn't be without them. I use the cdsa outside (I have both copies but prefer the older one ) and then enjoy checking what I see against the Sissy Hass book.

Tonight for example I saw  E1695 in Urasa Major for the first time ( like a little globular planet with a small moon in the tal (( you gotta love fracs )) )

Reading the lovely description in the Hass book afterwards raised a smile.