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Re Sirius
- VIZ SIRIUS:
THIS WAS A LIST I COMPILED WITH THE HELP OF STEVE (Tinderboxsky), Matt t,bombardon and some others.
1: SEEING - Must be excellent.
2: ALTITUDE - Well above the horizon in
most instances.
3: APERTURE - 100mm+, Cooled and well collimated, though probably no more than 12" due to the affects of seeing on large obstructed scopes; though it now appears certain, that even a 70mm achromatic refractor of long focal length can result in DETECTION!
4: POWER - The use of it is necessary - Helps darken sky background, and with limiting magnitude ; 200x + may be needed.
5: USE A MASK - Hex , may be necessary.
6: ORIENTATION - Is your diagonal/scope displaying an upright E/W view; If not adjust accordingly.
7: PRACTISE on Rigel say - Bright, with similar separation. Know what a separation of 10" will look like in your go - to EP - VIZ - Know your field.
8: DRIFTING - Let Sirius A drift past the field stop , and disappear, as B will surely follow.
9: WARM CLOTHING , and stool if necessary.
10: PATIENCE - and lots of it - It could take many attempts!
11: LESS GLASS - Use of EP with fewer elements 4/5 max to increase contrast and detection, may be of help.
12:AVERTED AND DIRECT VISION - Go back and forth between direct and averted vision, until the companion is held in direct view.
13: ZOOM EP - Use of a good marked zoom EP, to find the optimum power for the seeing and filters if necessary.
14:HIGHLY ACCURATE FOCUS - TOGETHER WITH A NICE FLAT FIELD, FREE OF CURVATURE - this is a must also , and you may have to re-focus often.
15:VERY STABLE MOUNT - Absolutely no wobbles!
16:VIEWING AT TWILIGHT - Can reduce the glare of Sirius A - and this goes for other bright primary doubles as well!
17: HOOD or COWL; this WILL help if streetlights or other bright light sources are a nuisance -- I rarely observe without one in any case.
Hope this helps.
Cheers bigjoe.
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