Sunday, December 04, 2005

Paul Couteau's Double Star List

Stars Processed Total Time % Cleansed
315 of 744 1d 05h 00m 42.3%

I'm currently updating Paul Couteau's double star list from his 1978 book ‘Observing Double Stars‘ in order to create a catalog of doubles for use with planetarium programs. The first catalog is going to be for ‘Planetarium for the Palm’ (PftP).

Couteau's catalog contains 744 doubles in order of right ascension. Updating the list involves updating his entries with current information from the Washington Double Star Catalog (WDS).

The process involves confirming the data on Couteau's list and linking this data to an Excel version of the WDS. I make use of SIMBAD and various desktop planetaria (Cartes du Ciel & SkyMap Pro) to help with the confirmation process.

After analyzing 130 stars I've found 5 stars needing an ‘update’ to Couteau's designation. Each star takes approximately 5 minutes to update. Total time for updating the list will take at least 70 hours.

To Couteau's original I will be adding the Aitken Double Star (ADS) number, coordinates for epoch 2000.0 with the addition of a difficulty index for star separations between 1 and 10 arc seconds derived from pLadic for the Palm. The magnitudes, position angles and separations will also be updated.

I'm looking for a way to group the doubles into subsets i.e. by separation or by difficulty index in order to keep the lists short. Some subsets I'm thinking of are:

• doubles visible in a 3" refractor
• doubles visible with mounted binoculars
• doubles visible with a 10" reflector

Viewing a sample of these stars with various optics will help clarify which stars belong with which lists.

Here are some screen shots for PftP with data pulled from the updated Couteau Double Star list. The star shown is 59 Andromedae — separation 16.5" / mag. 6.1 & 6.7. This double should be viewable with at least 10x binoculars.

The 1st screen shot shows the ‘Object Information‘ for 59 And. The 2nd screen shot displays a wide-field star chart highlighting the target star.

Screen Shots from Planetarium for the Palm

From ‘Observing Double Stars’ by P. Couteau:

Retain for updated database.
Verify with Washington Double Star (WDS) Catalog.
Override with WDS details.
Additions to Couteau's list.

• Running numbers from 1 to 744
• Name of double star pair
• Bayer / Flamsteed name
• Coordinates for equinox 1950
• Visual magnitudes of the components
• Position angles to the nearest degree
• Separations
• The corresponding year
• Difficulty Index
• Aitken Double Star (ADS) number
• Constellation
• Distance in light years


Tag said...

That'll be a nice addition to the other catalog you created and shared for the PftP. Hopefully, when you're completed, we'll be able to ride your coattails with a copy :^D.

The additional information will be helpful to determine where and how hard. How are you basing the "Difficulty Index"?

Thanks, peter

Ben C. said...


A copy of the catalog will be made available to all! Probably through the blog.

I'm looking for a way to best split up the list of 744 stars.

Take a look at the screen shots again when you get a chance. I just updated (before you posted the comment) the post with a sample of a 'wide' double with a separation of 16.5 arc seconds including what the display looks like for the object details and the star display.

The DI is from pLadic. Take a look at the link for pLadic in the post. The link talks about the theory along with a copy of the software for the Palm.


Tag said...

Hi Ben,

I overlooked the reference to pLadic. It would be a nice feature to see the separation information in addition to the component magnitudes displayed on the first line. Real estate is at premium to display that info?

Look forward to seeing your efforts realized.


Ben C. said...


Good points on the real estate for the 1st line when looking at the star 'charts'. It is limited. I've asked Andreas to collapse the details that appear on the right hand side of the screen i.e. RA and Dec onto one line. I might remind him about this. It would give us more space for the 1st line description.

Funny, I was just sitting down to redesign the layout. I'm eliminating the reference to Couteau's running numbers i.e. 1 to 744. Not necessary. Will also move the separation *before* the magnitudes since that is more important. All the doubles on Couteau's list are 'bright'.

Thanks for the feedback. Look for a revision message at the top of this post when I'm done.


Anonymous said...

Excellent compilation. How long have you been nova hunting??