Discovering gamma Arietis

Having packed away the three 70-mm entry-level refractors I was enjoying (last week), I returned to my Explore Scientific First Light 102-mm doublet refractor but now using the better oculars, 82-degree sealed from Meade (14mm; Series 5000) and Nagler (7mm; Type 1), and a Vixen 25-mm SLV Plössl for wider views. The mount was an Explore Twilight I gear-driven Altitude-Azimuth.

10 November 2200 hours. Nominally “clear” but with not much sky, still clearing from rain with high overcast. In Aries only alpha (Hamal) and beta (Sheratan) were easily visible. So, I swept the area. Below Sheratan was another faint star and I found the double gamma Arietis (Mesarthim). Both were about equally bright. The next day, I checked An Anthology of Visual Double Stars by Argyle, Swan, and James (Cambridge, 2019). 

Gamma Arietis was found by Hooke (1664) and verified by Herschel (1779) as being “almost equal” in magnitude. 

Land-based estimates of magnitude for them is Gamma-1 = 4.58 and Gamma-2 = 4.52 while more recent estimates from Hipparcos are 4.75 and 4.64 respectively. Combined they appear as 3.86 from the ground. Their common orbital period is about 5000 years.

 

Two thousand years ago, the vernal equinox was in Aries. (It is now in Pisces and moving to Aquarius, which brings in very many cultural references to new ages.) The coordinates for Mesarthim are given as 

Right Ascension 01 hours 53 minutes 31.76 seconds; 

Declination +19 degrees 17 minutes 37 seconds. 

 

PREVIOUSLY ON NECESSARY FACTS

Newton versus the Counterfeiter

A Successful Imitation of Alan Turing

Coins and Stamps

Burnham's Celestial Handbook