Re: NROL-41 - search elements for actual launch time

rwier@concentric.net

----- Original Message ----- 
From: "Phil Karn" <karn@philkarn.net>
To: <seesat-l@satobs.org>
Sent: Tuesday, September 21, 2010 1:15 PM
Subject: Re: NROL-41 - search elements for actual launch time

> On 9/20/10 10:15 PM, Ted Molczan wrote:
>> Phil Karn wrote:
>>
>>> I was a little surprised by the 32-minute unplanned hold due to the
>>> vehicle near the launch sites. Don't polar launches usually have very
>>> narrow launch windows of no more than a few minutes?
>>>
>>> Does this suggest that the launch might have been into a lower
>>> inclination orbit, one with a wider launch window?
>>
>> The NOTAMs clearly indicate a 123 deg inclination - the retrograde 
>> version of the lower of the two
>> Lacrosse inclinations, i.e. 180 - 57 = 123 deg.
>
> Yet the launch visualization (the computer graphic shown after the live
> video has become uninteresting) seems to show the launcher flying south
> past the Channel Islands. By eye it seems to be flying just west of San
> Miguel Island, consistent with a classic sun-synch orbit.
>
> Unless, of course, the graphic was simply made up.
>
> Phil
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>
Hi Phil,

Just a lurker here who has watched many launches from my home in Phoenix, 
AZ. I travelled to Santa Maria to view this one. My recollection of the 
launch may give you additional info.

I, having no real knowledge, expected the launch trajectory to go in a 
slightly SE direction and therefore would have a decided "right to left" 
component from my viewpoint.

I was able to follow the launch with IS binos until 2nd stage cutoff (1st 
stage large orange-yellow, 2nd stage tiny blue/white).

I was quite startled to see NO right to left component to the arc. I watched 
for this factor very carefully and decided that the trajectory was ~30' 
(1/2°) West of a vertical plumb line through the launch site.

I don't  know what angle that is but someone could determine a fairly 
accurate launch azimuth by passing a great circle through my site (N = 
34.919103°, E = -120.435389°)  and the launch site, and add a 1/2° Westerly 
component to that result.

Just a wild guess looking at the maps of the area and not knowing what part 
of VAFB the launch went from, I would think that the launch AZ would be 
195° - 205°.

If the actual launch AZ is not in doubt, please ignore the above ramblings 
and I apologize.

Rob

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