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