Malpi12 Posted August 26, 2022 Share Posted August 26, 2022 (edited) I mentioned in @IB20 's Algol topic that U Sge looked like an interesting target with a sharp swift eclipse might fit into an evening/night viewing. I was mistaken ! :- With Stellarium helping and a few tripod shots with Canon 60D + 28 & 135 vintage lenses I found my target at about mag 6.5 a few nights ago. So far so good, then the task of extrapolating the one recent AAVSO obs on 29July. Using a period of about 3.38d x8 brought me to yesterday evening. Just as I had completed my back of envelope calculations 11pm, I found there was clear dark sky and Lo! a few more quick shots revealed it down at 7.5m already ! I followed until 3am (when it went out of view in trees) at about 8.5m ( EDIT actally on closer inspect about 9.09 ! see later post ) or thereabouts, I still have not processed all the images, Such a long duration minimum (on closer inspection zooming the avsso obs confirms it) surprised me and implies a much larger dark companion, in proportion, than in the case of sharp Algol. I am surprised that it has not got more obs on aavso given its prominent position in northern skies,what am I missing ? Nicely placed near M72 [ediit: M71 init doh!] and the The Coathanger, always nice to see. Edited September 12, 2022 by Malpi12 1 Link to comment Share on other sites More sharing options...
Malpi12 Posted August 29, 2022 Author Share Posted August 29, 2022 (edited) Deleted. Erroneous prediction ! Edited August 29, 2022 by Malpi12 Link to comment Share on other sites More sharing options...
Malpi12 Posted September 9, 2022 Author Share Posted September 9, 2022 (edited) my first go at an Eclipsing Binary, Data from night of25/26 Aug Using a DSLR camera (60d) with a 135mm lens on a fixed tripod. I didn't know what to expect so I collected bursts of 25 exposures ( each 2sec at f 2.8 iso800 ) at intervals from about 11pm through to about 3am when trees stoped play ! to speed processing time and for a first look, I choose samples of 5 subs at suitable intervals from the whole set. In Gimp I used the histogram-mean tool (with a rectangle selection of small size to just encompass the stars without too much background noise) to measure each star and plotted the results in Gnuplot. I was surprised at the sharpness of the entry into the long minimum phase of the eclipse. Gnuplot has a crafty tool to enable a 'best fit' of a polynomial function to a set of data. I have chosen a 2nd order quad g(x) for the fade and a constant f(x) to fit the min. data. EDIT : the x-axis is in decimal hours, local midnight bst is at '2' hours, the y-axis is in AAVSO style magnitude (m x 10 ) so eg. 80 is m8.0. Edited September 9, 2022 by Malpi12 1 Link to comment Share on other sites More sharing options...
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