From: Milton Aupperle <milton@outcastsoft.com>
Date: November 8, 2010 1:59:11 PM MST
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Re: Partial Light Curve for pulsating variable star CY AQ
Dear Ron;
A movie contains all the frames and all the information on capture (Date, time in UTC for each frame captured) in it.
No stacking at all.
Al lI do in Astro IIDC 4.06 is:
0) Get Camera focussed on distance object before Flat frame (or if it was focussed last night, skip this step).
1) Create a Flat Frame of the clear blue sky as tiff file before sunset using "Grab Avg. Frame" and average 200 frames. I'm running at 7.5 fps 1384x1036 mono in 16 bit, so it takes a few seconds to do it.
2) Cool Camera to expected operating temp. Create a Dark Frame as tiff file using "Grab Avg. Frame" with anticipated exposure time and average 20 frames.
3) Record event as a movie (skipping all the target finding, focussing, find guide star in OAG, calibrate mount for guide star, play Halo Reach on XBox 360 while waiting etc.).
4) Use Astro IIDC to dark frame subtract the movie with my Dark frame.
5) Use Astro IIDC to flat frame correct the movie with my Flat frame.
6) Select "Measure Differential Photometrics..", pick my constant and variable stars and let it generate the text file reports.
7) Open Simple Report in AppleWorks, make a quick graph of my stars to see how bad the data is :)
8) Copy the JDN data column to first position and whatever stars I'm plotting curves of into another spreadsheet, then save it as text file
9) Import text file into "Plot" and have it generate the graph - and fiddle with the display[lay output until I'm, happy with it. You can read about "Plot" here:
http://plot.micw.eu/
I now use an existing copy of a "Plot" file I made, which means other than changing colors of data sets, the JDN labelling all comes out perfectly each time.
10) Copy the graph, paste it into "Goldberg", save as .png and upload the result.
That's all there is to it in this case. For objects with less of a range, like ExoPlanets or slow rotating asteroids , it can get more involved with extinction angles, B-V star color issues etc.
HTH..
Milton Aupperle
On 8-Nov-10, at 12:18 PM, cosmicrock2001 wrote:
Nice work, again! do you shoot a single frame time exposure every 25 seconds or a stream of video and then stack them? Ron
--- In Astro_IIDC@yahoogroups.com, "milton_aupperle" <milton@...> wrote:
Hi Folks;
I shot a partial light curve for pulsating variable star CY AQ tonight:
http://groups.yahoo.com/group/Astro_IIDC/files/Other/CY_AQR_PhotometryCurvePlot.png
That's the raw curve plot. Photometric measurements done with Astro IIDC (Measure Differential Photometrics..) and then the results plotted up in "Plot".
Unfortunately clouds moved in at the end (about 5 hours earlier than CSK predicted) so I could not complete the entire curve, just 58 minutes worth (total period is about 89 minutes). Each point in the curve is 25 seconds apart. You can see just how fast it brightens up at the end, which is 1.5 magnitudes (2.7 times) in just over 21 minutes. Imagine if the sun brightened up by 270% in 21 minutes...
Seeing was mediocre with stars jumping +/- 6 arc seconds, which is why we get saw tooth patterns. I was using the Luma filter on my C8, 1150 mm FL, Grasshopper Camera cooled to 0°C.
TTYL..
Milton Aupperle