The eclipse predicted for the triple system b Per (HD 26961) is underway, about a week late. Photometry is urgently needed to follow the rest of the eclipse, which may last up to four days. Please see AAVSO Special Notice #333 for details.
Thank you and good observing - Elizabeth Waagen, AAVSO HQ
Took over 1000 images in B and V last night. Every 10 seconds or so. Based on the first half of the B data, I get over .05 mags of fading. Looks like the eclipse is still happening. Will reduce all data this morn.
Keep observing this campaign. Its just started.
I am doing photometry of b Per in all DSLR bands (TR,TG,TB). This is my first differential photometry (I hope I didn't make a serious mistake). So far I made photometry using Cannon 400D+lens 85mm/200mm/300mm in way described on Citizen Sky website. I was using intermediate-level reduction spreadsheet.
I've attached here my reduction spreadsheet for b Per differential photometry. The spreadsheet contains results of my observation from last night. Between clouds (winter weather this year is not for astronomical observations in central Europe) I took 50images of b Per with lens 85mm, F2,8, 6sec exposure and 200ISO. I reduced pictures using CS method. In Iris I got instrumental magnitudes of b Per, check star and comparison star from one stack for each colour TR, TG, TB (see point 3a of the spresdsheet) or from 5 stacks - each made of 10 pictures for TR, TG, TB colours (see point 3b of the spreadsheet). The results of the photometry using method 3a) and 3b) are nearly identical, but method 3b) is better because it gives the error of brightness determination.
The results of the photometry can be found in cells E21 ... F23, H21 ... H23.
The attached spreadsheet is a raw version. I was very determined (only 1 observation of b Per during eclipse in AAVSO db.). I decided to observe between clouds. Probably therefore measurements from the 2-nd stack (pictures number 11-20) are very different from the other. I enter results into AAVSO database from this spreasheet after deleting the row number 29.
Under normal circumstances (good weather!) I receive errors order of 0,01 - 0,02 magnitudo (see row 34 of the spreadsheet --> standard dev.).