This double star presented an interesting color contrast compared to the actual spectra. The primary appeared pale yellow, with a fainter blue-gray companion. The primary is F6V, which is believable, but according to the 13th General Catalogue of MK Spectral Classification (Buscombe 1998), the secondary is a K0V star, which should appear yellow-orange if anything. Eric Graff noted White and Yellowish for the pair while using a 150 mm f/6 newtonian at 120X. Alain Gerard recorded pale yellow and yellow-orange. However, as with my observation, Jeff Burton noted pale yellow and blue while using a 203 mm SCT at 111X.
I estimated PA at 10 degrees and separation appeared to be 1/7 of the field of view, or about 100 arcseconds. The actual values are 4.1 degrees and 65.7 arcseconds.
|Subject||Tau1 Hydrae (HJ 1167)|
|Position (J2000)||Hydra [RA: 09:29:09 / Dec: -02:46:08]*|
|Position Angle*||4.1Â° (1991)|
|Magnitudes*||4.6 / 7.8|
|Spectral Types*||F6V / K0V|
|Date/Time||MAR 15, 2007 – 11:50 PM MST (MAR 16, 2007 – 06:50 UT)|
|Observing Loc.||Cinder Hills Overlook – Sunset Crater National Monument, AZ|
|Instrument||Orion SVP 6LT Reflector (150 mm dia./1200 mm F/L)|
|Eyepieces/Mag.||10 mm + 2X Barlow (240X)|
|Conditions||Mostly clear, calm|
|Transparency||NELM Mag ~6.0|
|References||The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996); Tycho Double Star Catalogue (TDSC) (Fabricius+ 2002); 13th General Catalogue of MK Spectral Classification (Buscombe 1998)|
*Based on published data.