From: Milton Aupperle <milton@outcastsoft.com>
Date: December 10, 2009 11:25:07 AM MST
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Re: Occultation a bust for me [1 Attachment]
Hi Willie;
On 10-Dec-09, at 11:11 AM, Willie Strickland wrote:
<*>[Attachment(s) from Willie Strickland included below]
I am attaching a jpg of the 5 frames. Diotima is on the left and TYC 1252-803-1 is on the right. North is up and east is left. It was pretty cool to see Diotima converge on the star.
I needed 30 sec exposures and a clear filter using the main science camera (13 micron pixels, 512x512) to get these frames. Diotima was estimated at 11.9 mag & TYC 1252-803-1 is listed as 10.9 mag. The occultation was expected to last a maximum of 15.5 seconds and produce 1.4 mag drop in the star.
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.
I used Nebulosity to measure the distance. In the first frame I measured 110 pixels or 53.9 arcsecs. The last frame I measured 11 pixels or 5.4 arcsecs. That is 38.5 arcsecs in 1:12:10 which I calculate as .6736 arcsecs per minute. Someone else will have to figure out how fast Diotima was moving. :-)
They do move right along, see my Eros movie here, where every frame is 2 minute duration and each pixel is 1.26 arc seconds.
http://www.outcastsoft.com/AstroImages/Eros_20090919_MJA.mp4
Eros is moving about the same rate.
I also use "Plot" to re-plot the new light curve data again, so it's oriented in the normal Astronomy way (mag value decreasing as one move up from the base):
http://www.outcastsoft.com/AstroImages/Eros_V2_20090919_MJA.png
TTYL..
Milton J. Aupperle