AAQ RESOLUTION SURVEY Observing Double Stars

July 2007 - Test Doubles in Circinus

HJ 4632 (RA. 13 59.0 Dec. -65 50) mags. 6.4 & 9.5, sep. 6.5”, pa. 14˚ (1991) The orange primary has a wide but faint companion. Should be OK for most scopes.

DON 680 (RA. 14 50.1 Dec. -67 06) mags. 7.5 & 9.8, sep. 1.5”, pa. 248˚ (1991) With a magnitude difference more than 2, and a close pair, this will be a challenge for smaller scopes.

WDS I 329 (RA. 15 14.0 Dec. -61 21) mags. 6.7 & 7.7, sep. 0.9”, pa. 339˚ (1991) The magnitudes are similar so this is a good test for the sub-arcsecond resolution capability of medium size scopes; persevere with this one. This double is located in a straight line with HDO 246 and WDS I 428 (see above) and they are all located just inside the same wide angle field of view.

B 1777 (RA. 15 16.6 Dec -60 54) mags 5.8 & 8.6, sep. 1.3”, pa 164˚ (1991). This is a tough one, and will probably need good seeing and at least a moderate size scope. Note that there are two similar magnitude stars in the same field. The one you want is the westerly of the two. It has a faint (mag 11.6) companion at 11” and 315˚ pa, but this is not the test ! It’s a much closer companion that we’re looking for.

CPO 16 (RA. 15 30.4 Dec. -58 22) mags. 7.0 & 8.0, sep. 2.4”, pa. 32˚ (1991) This should be accessible to most scopes in reasonable seeing.

Finder Chart for the Test Doubles in Circinus

Eyepiece Finder Charts for Circinus

Note: The left hand chart has a 5°(finder) field of view, with stars shown to approx. magnitude 7. The right hand chart has a 1° (eyepiece) field of view, with stars shown to approx. magnitude 10. The target star is on the cross hairs at the centre of the image. North is up and East to the left, to conform to the view through a finder, refractor or a simple Newtonian without a star diagonal; turn them to orient north and south to conform to your view through the finder or ‘scope. If you are using an SCT or finder with a star diagonal, the E-W directions will be reversed.

HJ 4632 (RA. 13 59.0 Dec. -65 50) mags. 6.4 & 9.5, sep. 6.5”, pa. 14˚ (1991).

DON 680 (RA. 14 50.1 Dec. -67 06) mags. 7.5 & 9.8, sep. 1.5”, pa. 248˚ (1991).

WDS I 329 (RA. 15 14.0 Dec. -61 21) mags. 6.7 & 7.7, sep. 0.9”, pa. 339˚ (1991).

B 1777 (RA. 15 16.6 Dec -60 54) mags 5.8 & 8.6, sep. 1.3”, pa 164˚ (1991).

CPO 16 (RA. 15 30.4 Dec. -58 22) mags. 7.0 & 8.0, sep. 2.4”, pa. 32˚ (1991).

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Astronomical Association of Queensland 2007 www.aaq.org.au