From: Mark Gaffney <markgaffney@me.com>

Date: March 24, 2010 10:28:00 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] New Images

Hi Milton, 

I`ve just been trying to verify what I did with this 2 weeks ago. Doing it again now, based on this SDSS source image..

 & using the i filter for luminance (there`s an  r, g , i, u & z filter fits image provided) & 60 seconds per light multiplied by 15 (for a 15 minute exposure) or 900 seconds altogether, this is the result given the Scorpion`s spectral details...

The simulation controls are there (inset) but perhaps not discernable...

I don`t know how many darks Astro IIDC removes but I have it set at 60, sky brightness is set at 17.0 V mag/sq" camera temperature is 0 degrees & there are 50 flat frames. I`ve left these settings pre much per rote only changing the seconds per light & number of light frames...

Mark. 

On 25/03/2010, at 2:15 PM, Milton Aupperle wrote:

Hi Mark;

It's around Mag 10. I shot luma but the turbulence was bad

http://en.wikipedia.org/wiki/Messier_61

I doubt if you'll pick up anything at 60 second exposures per frame.

With the Grasshopper (the CCD is about 4 times as sensitive as the the
one you have in the Scorpion), I need a 15 minute exposure with a C8
to get the central core area of M61 to be at 35% saturation (24,000
out of 65,535). If you binned it 4x4 and cranked the gain / brightness
to maximum, you might pick something up for 60 seconds, but it won't
be very pretty.

TTYL..

Milton Aupperle

On 24-Mar-10, at 8:49 PM, Mark Gaffney wrote:

> Hi Milton,
> I looked at M 61 too though I think it`s smaller & fainter than M
> 66 from memory...? Here`s a combined LRGB filter simulation
> (photomerged in Photoshop) I did, with the Scorpion 20SO`s spectral
> details entered, at about 60 x 60 seconds per filter... so 4 hours
> of imaging..
>
> Mark.