Re: New member talk

Jim Varney (
Tue, 26 May 1998 22:31:33 -0700

On 26 May 98, Terry Pundiak wrote:

> Do you have any simple formulas for calculating sat's fractinal
> illuminations out there so I could use the values in Molczen's tle's?

Welcome to the list.

phase = 0.5(1 + cos(d))  where d = phase angle (sun-sat-observer angle)

and phase will range from 0 ("new") to 1 ("full").

> ... and maybe formulas for the tracking from original tle? ---  I don't
> mind trying to do this on a Mac just for the fun of it, but is is
> probably too large a project - anything to avoid the obvious (buy a pc).

has a NORAD document called "Spacetrack No. 3" that includes FORTRAN source 
code for several propagators.  You probably couldn't do it with Hypercard; 
you'll need a FORTRAN compiler or use another language and translate.

> I'd also like any recommendations observers have for binocs... now, I
> realize that the ones I have are poor... are 11 by 70 mm by Orion a good
> buy? (I don't want to spend more than they cost.) or any thing real good
> in the 7 by 50 format? 

You're in Pennsylvania!  Take advantage of an astronomy dealer in your 
state known for friendly service and low prices: Pocono Mountain Optics.

Generally the Orion line of optics has a mixed reputation so you'd better 
try them out first to see how you like them.  Fujinons are very good.

 -- Jim

Jim Varney
Member, Sacramento Valley Astronomical Society
Sacramento Iridiums