Stephen Tonkin’s Binoc­u­lar Tour

A dou­ble dou­ble and a tricky trio of gal­ax­ies in Leo are among this month’s high­lights

Sky at Night Magazine - - CONTENTS -

Tick the box when you’ve seen each one


Let’s start our tour with one of the finest ce­les­tial sights for binoc­u­lars, Melotte 111. It ex­tends for nearly 6° and fills the view of small and medium binoc­u­lars. You can see it with your naked eye as a misty patch be­tween Cor Caroli (Al­pha (_) Canum Ve­nati­co­rum) and Denebola (Beta (`) Leo­nis). Gamma Co­mae Berenices is at the apex of an in­verted ‘V’ of the clus­ter’s brighter stars. Melotte 111 is un­usual in hav­ing no stars fainter than mag. +10.5. SEEN IT

2 28 & 29 CO­MAE AND STRUVE 1678

5° north­west of Vin­demi­a­trix (Ep­silon (¡) Vir­gi­nis) is a pair of white stars sep­a­rated by half a de­gree and ori­en­tated ap­prox­i­mately north-south. The fainter, southerly one is 28 Co­mae, the bright­est of a lit­tle par­al­lel­o­gram of stars. 29 is the bright­est of a triple star group. Its brighter (mag. +8.6) com­pan­ion is 5 ar­cmin­utes back to­wards 28 and the fainter (mag. +9.9) one is an ar­cminute closer, an easy split if your sky lets you see stars that faint. Also vis­i­ble, a de­gree to the west of 29, is Struve 1678, a slightly harder split at 38 arc­sec­onds. SEEN IT

3 M49

Our first galaxy is an el­lip­ti­cal ra­dio galaxy, M49. If you lo­cate Rho Vir­gi­nis (mag. +4.9) and place it on the north­east of your field of view, on the op­po­site side you should find a pair of 6th mag­ni­tude stars, just over a de­gree apart and ori­en­tated south­east­north­west. M49 is a small (9 x 7.5 ar­cmin­utes), slightly oval patch of light be­tween these two stars, very slightly nearer the more southerly one. Us­ing averted vi­sion, you can see lots of gal­ax­ies in this re­gion of sky, mostly in the direc­tion of Melotte 111. SEEN IT

4 7$8 $1' /(21,6

Did you know that Leo has ‘dou­ble dou­ble’? If you ex­tend a line from Za­nia

Vir­gi­nis) to Zav­i­jah (Beta (`) Vir­gi­nis) a fur­ther 6°, mag. + 4.9 Tau Leo­nis is the bright­est star in the field of view. A third of a de­gree north­west is its mag. +6.5 com­pan­ion, 83 Leo­nis. Look care­fully and you’ll see that each of these is a dou­ble star with a mag. +7.5 com­pan­ion. SEEN IT

5 /(2 75,3/(7

You may need to wait un­til Leo is high in the south­ern sky be­fore you can ob­serve our sec­ond ga­lac­tic tar­get, a trio of gal­ax­ies that is a chal­lenge in any­thing other than a dark, very trans­par­ent sky. If you put mag. +3.3 Chort (Theta

Leo­nis) just out­side the north­west of the field of view of 15 70 binoc­u­lars, the gal­ax­ies will be in the cen­tre. You may need averted vi­sion at first, but they soon be­come easier to see, al­though you will still need averted vi­sion to dis­cern the dif­fer­ent shape of NGC 3628. SEEN IT

6 /(2 5(*,21

Lo­cate the or­ange-yel­low mag. +5.6 86 Leo­nis be­tween Denebola (Beta (`) Leo­nis) and Zosma (Delta Leo­nis), and com­pare its colour to hot blue-white 90 Leo­nis 2° back to­wards Denebola. Re­turn your at­ten­tion to 86, and note the curved string of 7th and 8th mag­ni­tude stars ex­tend­ing 3° east­ward. The near­est one to 86 is FV Leo­nis, an or­ange, long-pe­riod vari­able star; the most dis­tant is blue-white FW Leo­nis, whose bright­ness vari­a­tion is too tiny to be vis­i­ble in binoc­u­lars. SEEN IT

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