From: Milton Aupperle <milton@outcastsoft.com>

Date: December 10, 2009 4:20:12 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: Occultation a bust for me

Hi Willie;

Unless the clouds were quite dense, you should have been able to image it at a much higher FPS than 1 frame every 30 seconds like the Astro camera was. A 24 inch aperture should have 9 times the light grasp than my C8 has and that Astro camera has huge pixels (2x the size of the TIS, so it can capture 4x the light) too.

If you were running the TIS in binned 4x4 mode and medium high gains with clear skies, you probably could have imaged  it at 10 to 15 fps. Your not so much concerned about image fidelity like one need for photometric observations with +/- 0.02 mag variations for asteroid photometric measurements,  your just looking for timing of when the event starts.

TTYL..

Milton Aupperle

On 10-Dec-09, at 4:00 PM, Willie Strickland wrote:

The scope is F9 and FL 5490.  I can use pretty close to the same exposure for the DMK that I use for the main science camera.  I had the DMK in the guide port centered on the star and the main camera centered on the star as well.

I can only image with one or the other in this setup, I just move the mirror slide into the light path to image through the guider port.  I was following on the main camera and ready to switch to video if conditions improved.

I just checked and IOTA needs 10 fps or greater, I thought it was 15fps.  I could tell conditions were not going to allow 15fps, so I figured I would just video the transit anyway if conditions improved enough.

Willie

On Dec 10, 2009, at 12:25 PM, Milton Aupperle wrote:

What aperture and focal length was the scope?

I was shooting Eros at Mag 10.5 to 11.5 using 2 minute exposures on the EXHad Grasshopper Camera. That was a bit much and I likely should have dropped to 1 minute for proper saturation.