From: "doobisary" <tjp314@pacbell.net>

Date: November 8, 2011 5:45:41 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: Asteroid 2005 YU55 observations?

Okay, that's interesting.  I'd use my DSI Pro III (same exview HAD chip as the Grasshopper, I believe), but I can't get Nebulosity to link to it on the new Macbook Pro.

I might try a Mogg focal reducer with the Scorpion to get down to f/3, if it doesn't distort too badly.

-Tim.

--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@...> wrote:

Hi Tim;

It's moving about 7 arc second per second, or 7 arc minutes per  

minute , so it will probably be across your field of view in < 2  

minutes. On my AT8 RC Scope (1625 mm FL)  with the 1384x1036  

Grasshopper camera (6.25 micron pixels), it will take all of 3 minutes  

to cross the entire FOV.

For Asteroid "Euphrosyne" which is Mag 10.5,  I was using lowest gains  

(64) and 15 second exposures binned 1x1 with the EXHAD Grasshopper -  

LPR Filter and an IR Cut Filter too. With moderately high gains and  

4x4 binning, that would have been in the 133 ms exposure range.

So if you just want to capture it, use "Binned 4x4 Monochrome"  for  

"Camera Display Format", moderately high gains on the Scorpion and  

probably 266 to 1000 ms exposures with a 10" Aperture.  The scorpion  

has much smaller pixels and a HAD CCD so it's less sensitive on  

several fronts than the EXHAD CCD in the Grasshopper.

As to doing photometric your going to need a much shorter focal length  

to keep the Constant stars and Asteroid in the FOV to measure it's  

changes over time.

HTH..

Milton Aupperle

On 8-Nov-11, at 1:57 PM, doobisary wrote:

Hi all:

I wasn't sure we'd have clear skies tonight, since we had some  

really biblical thunderstorms As recently as Sunday night, but it  

looks like it will be clear.

Pegasus should be high enough to clear my house from the back yard  

by the time I get home and can get set up for imaging, so I plan to  

go out and do so.

Since the asteroid is fainter than 11th magnitude, I imagine setting  

the exposure time to a few seconds will be in order.  I'll use my  

Scorpion 1600x1200 mono camera for the video.  Probably without a  

filter, to pull in as many photons as possible.

I'll look over Milton's descriptions of how he did his light curve  

work on other asteroids, but I imagine my best strategy will be to  

simply start recording "video" and manually track the asteroid as it  

screams across the sky for as long as I can (or until I collapse or  

fill up my hard drive).

I'll use my 10" f/6 Newtonian on the Tak EM-500 mount for this.  I  

need to tweak the collimation on the primary, but the asteroid is  

going to be near Altair in the sky so I'll use it to collimate on.

If anyone has any suggestions as to my strategy that I haven't  

thought of, please let me know.

-Tim.