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DSLR Documentation and Reduction
I've had an email exchange with Brian off the forum on this topic. I thought it might be of interest for others to see what I've been doing.
In the documentation on DSLR photometry, it is stated that the beginner reduction spreadsheet should be used only at relatively low air mass.
I've done some tests on a star field in Grus, with only slightly more than 1 degree separation between the comp, check and target stars (DSLR images taken through a 600mm focal length refractor).
The results suggest that the spreadsheet can be used at any air mass with no or minimum loss of precision. Remember, this spreadsheet does not specifically include calculations to correct for air mass.
I'd be curious to hear if anyone else has tried this. If you haven't, you might find it interesting to give it a go.
I finished the IRIS beginner tutorial, but my results seem to be off. I feel pretty confident about steps 1-5, but I may have made a mistake in step 6, photometry. In Step 6 a, the tutorial mentions configuring the magnitude constant, but I do not see where this is explained. As a result, I left the magnitude constant at 0.0. Maybe this is throwing off my results?
Here's what I got for Instrumental Magnitudes for the Comparison Stars:
Iam Aur -10.747
rho Aur -10.339
mu Aur -10.671
ome Aur -10.616
sig Aur -10.364
58 Per -11.190
I only took these values from one of the final separated green channel files. Is that right?
m = 0.111
Average Check V Mag = 4.743, which is more than +/-0.01 from the 4.705 V Cat
Finally, my average V Mag for the target star was 3.741Read more
Hi I have been experimenting with reducing scanned historic photographic plates lately, and I guess at some point I will want to report the reduced data to the AAVSO DB. But how should that be done? I think it would be more than wierd if my observer code would be next to a measurement that was done in (say) 1904.... Some credit must be given to the original observer, and the observatory and plate Id somehow should be encoded in the limited size of the comment field. But how exactly? Any suggestions? CS HB P.S.: I seem to have to limit the audience of this article to one of my groups In order to post it??? Is this a new website feature or a bug?? :-)
Embarrassing as it is, I am just now gearing up for some photometry. Has anyone determined the transforms on a Canon 5D Mark II? I am assuming it will be different than my 450D. I will be working with a Canon 100mm Macro and have a Kenko Sky Memo which allows tracking of 5 minutes without guiding. So--I am thinking I need to characterize this camera using Landolt fields. If skies during the Okie-Tex star party cooperate I should be able to get several nights worth of data. Any suggestions would be appreciated.
Earlier this month I took some wide field images of the area around Cassiopeia and Cepheus for photometry measurements. I was able to make a measurement of Delta Cep, however my measurement includes both components of Delta Cep, the variable plus it's fainter companion at magnitude 6.3. My question is, since I can't split the components of Delta Cep in a DSLR camera, should I submit the combined magnitude or should I calculate the magnitude of the variable primary by mathematically removing the fainter companion (a difference of 0.12)?