Abstract

Using the UCAC4 astrometric catalog, a search for binaries not yet listed in the WDS was done. Seven of the unlisted binaries found were observed from the Little Tycho observatory and then manually checked using Aladin's DSS images.

A program was written to extract entries from the UCAC4 astrometric catalog ¹. The criteria for a star to be extracted were:

1. The star needed to be brighter than 13.0mv. This is the visual magnitude limit of my telescope.
2. The star needed to be fainter than 8.0mv. Anything brighter has probably already found its way into the WDS.
3. The star needed to have a proper motion greater than 2 mas/year. To be considered as a binary, a pair needs to show a good degree of common proper motion (CPM).
4. The star needed to be north of the celestial equator. The Little Tycho observatory has a poor southern horizon, further compounded by severe light pollution in the south. Northern declinations are preferred.

A list of possible pairs was generated. These pairs were then manually checked using the images from Aladin/DSS ² and proper motions from the UCAC4. Those pairs that had similar proper motions and were within 1.5mv of each other were then checked for prior WDS ³ membership. If they were absent from the WDS, they were chosen for observation.

The sky has been pretty well mined for CPM pairs, so those found are rather faint, in the 11 - 13 mv range.

In the images below, the UCAC4 data from the primary star are listed in the tables to the left of the image.

The images are from Aladin/DSS; all other data are from the UCAC4.

The magnitude sources are from APASS data or the UCAC4 fit model magnitude (F) data.

ρ refers to the separation of the pair in arc seconds.
θ refers to the position angle in degrees.
Both measures for each star were determined from the Aladin/DSS images using their "dist" tool.

"PM" refers to proper motion in milliarcseconds (mas) per year.

Primary RA, Dec: J2000 18:44:37.25 27:26:55.33 mv primary 11.7 APASS mv secondary 12.9 APASS ρ 10.7" θ 334° Primary PM in RA 1.4 Primary PM in Dec -12.2 Secondary PM in RA 2.8 Secondary PM in Dec -5.2 Primary UCAC4 Number 588-088331 Secondary UCAC4 Number 588-068327

Primary RA, Dec: J2000 19:41:48.67 18:29:50.03 mv primary 11.1 APASS mv secondary 11.7 F ρ 16.3" θ 55° Primary PM in RA 10.7 Primary PM in Dec -4.3 Secondary PM in RA 11.3 Secondary PM in Dec -5.2 Primary UCAC4 Number 543-103360 Secondary UCAC4 Number 543-103370

Primary RA, Dec: J2000 20:5:53.18 22:54:12.83 mv primary 11.9 APASS mv secondary 12.7 F ρ 21.1" θ 156° Primary PM in RA 3.6 Primary PM in Dec -11.9 Secondary PM in RA 7.4 Secondary PM in Dec -9.7 Primary UCAC4 Number 565-103726 Secondary UCAC4 Number 565-103733

Primary RA, Dec: J2000 20:26:24.22 25:37:23.81 mv primary 11.9 APASS mv secondary 12.5 F ρ 16.1" θ 357° Primary PM in RA 19.7 Primary PM in Dec 5.8 Secondary PM in RA 22.2 Secondary PM in Dec 3.2 Primary UCAC4 Number 579-100187 Secondary UCAC4 Number 579-100186

Primary RA, Dec: J2000 21:41:42.78 27:07:36.97 mv primary 11.1 APASS mv secondary 12.7 APASS ρ 21.6" θ 268° Primary PM in RA 15.1 Primary PM in Dec 8.0 Secondary PM in RA 16.1 Secondary PM in Dec 9.7 Primary UCAC4 Number 586-119848 Secondary UCAC4 Number 586-119837

Note: The 10.3mv (APASS) star at ρ = 17.5", θ = 135° from the primary is not a part of this system.

Primary RA, Dec: J2000 21:42:46.68 57:1:59.16 mv primary 11.4 APASS mv secondary 12.0 F ρ 11.8" θ 358° Primary PM in RA 8.3 Primary PM in Dec 4.2 Secondary PM in RA 5.2 Secondary PM in Dec 5.8 Primary UCAC4 Number 736-079756 Secondary UCAC4 Number 736-079755

Primary RA, Dec: J2000 21:56:24.1 48:28:44.31 mv primary 12.4 APASS mv secondary 12.8 F ρ 13.3" θ 128° Primary PM in RA 9.9 Primary PM in Dec -5.7 Secondary PM in RA 10.2 Secondary PM in Dec -3.4 Primary UCAC4 Number 693-105883 Secondary UCAC4 Number 693-105890

References

1) The Fourth US Naval Observatory CCD Astrographic Catalog (UCAC4). Zacharias, et al, 2012.

2) Aladin web site

3) The Washington Double Star Catalog Brian D. Mason, Gary L. Wycoff, William I. Hartkopf, Geoffrey G. Douglass, and Charles E. Worley, 2001.