Dave Smith

I use an Atik 460Ex with a photometric V filter. I am sure however many CCD cameras would be suitable. One consideration would be the field of view to ensure enough comparison stars are in view. My main interest was once imaging so I do have a filter wheel with sufficient places to take LRGB and Ha,O3,S2 as well as the V. You can screw a single filter onto the end of a CCD camera so a filter wheel is not essential. I used to use an Atik 314 Both Atiks are low noise and I find it only necessary to cool to -10 degC . The chip of the 460 is double the size of the 314. By the way it is no

Hi Steve It is better if the comparison stars are of similar magnitude to the target star if possible. I've just had a look at the aavso chart for S Cas and can see that it could be tricky. One of the brighter comparison stars have a few faint ones very close by. Dave

Hi Steve The purpose of defocusing is to help insure that the star image, and the comparison stars are not saturated. I don't go out of my way to defocus but don't worry too much about being in focus. It is important that you check that it is not too close to saturation. S Cas has a very long period, you may find it more interesting to try a star with a short period so that you can detect change. Ther are suggestions on the BAA VS web site. Dave

What mikeDnight has said is very relevant, You can alternatively study eclipsing binaries which have a regular periodic pattern so that you can get the full picture over a number of nights. I have mostly been looking at HADS stars that have a cycle of only a few hours and so it is possible to get one or more complete cycles in one session. See here for ideas https://docs.google.com/spreadsheets/d/1oGA2HaEHE8L6eX19ZoHqQQTu0LYV56HX3Srg7oCtOHo/edit?hl=en&hl=en#gid=883500896 Dave

I've never done that as the stars i have been looking at vary quite rapidly. I was advised that for longer period variations to just submit the individual readings. Dave

Hi Steve, I don't use that method at all. I get the comparison stars from aavso. If that doesn't work I get comparison stars from a star chart program "Guide" which has the UCAC3 star database. Usually the charts from aavso are sufficient. Personally I don't put the magnitudes in at the AstroImageJ stage but later when putting the data into the BAA spreadsheet Hope that helps. Dave

Hi Steve. With SGPro it slews to where it thinks it should but then takes an image, plate solves it and then makes a correction. It will do this until target is in the centre as accurately as you choose. Dave

I find that the plate solving facility in SGPro brilliant for getting the star right in the middle of the FOV. Dave

Each point comes from one image. No stacking involved. Each image has to have darks and flats applied before any analysis. This can also be done in AIJ. Hooe that helps. Dave

For a number of reasons I haven't been able to do any observing since the spring. Recently I did get out but unfortunately my scope would not go to the correct part of the sky. My target was just to the left of Mars but the scope kept on going to the right of Mars. It subsequently dawned on me what the problem was. My laptop had not done its usual automatic changing the clock to GMT. Once corrected all was fine. Since then I did have one evening where the results were rubbish and finally two successful nights. I had chosen stars in Cepheus to avoid interference from the Moon.

You don't have to but it makes the analysis run very smoothly. With my images there is a small drift and so I have to make a small correction about every half hour to an hour and unless it is done manually the program will lose the star. Dave

Thanks Steve. You could do that but it would be just as easy and more rewarding to choose a known variable and see some variation that you know should be there. What scope are you intending to use? Dave

An excellent find Michael. Adding them to the BAA database could be very valuable. Dave

Thank you all for your very nice comments. Roger has been my BAA mentor and I owe him many thanks for the guidance he has given me. Early on he introduced me to the HADS project run by Patrick Wils. I subsequently met Patrick at the AAVSO/BAA meeting in 2018 and have enjoyed participating ever since. Dave

I have no excuse as this isn't the first time! Dave

HADS star V417 Bootes. The large gap in readings was due to a technical error. i.e. I hadn't realised that the star was going to get so high in the sky and so the scope was gradually being covered by the dome roof. I interpreted the gradual fading of the stars as cloud but when I went out to shut down realised it was still perfectly clear. When I moved the dome back all was then fine so I started again - Duh !!! We live and learn. Dave

No record, just keeping myself occupied during this crisis. I cannot go out for anything else. If the sky is clear then why not?!! The lumps and bumps are due to to it being multi-periodic. If you add two (or more) regular curves of different frequencies together you can get shapes like this. By the way, did you attend the BAAVSS - AAVSO meeting in 2018 and sit in the middle of the second row in the group photo, then you are next to me with Jeremy on my other side? Dave

Another clear night and so another HADS star Dave

Two clear nights - two more HADS stars. Dave

Last night. 60 x 60s exposures. Dave

Very nice. Dave

Unfortunately not. Dave

It's worse than that really. Having opened the dome in the right direction, I control everything from indoors in the warm. While it is imaging I can be eating a meal, watching TV or having a whisky !! It can go wrong as it did last week, one of the two wasted nights, when I fell asleep for two hours to find that the scope must have hit the mount and had done its own meridian flip. I didn't realise it could do that!! Dave

This is one I like as it is quite close to Polaris and so I don't have to worry about moving the dome or to lift it on to the POD table. Dave

At last I have managed a long session on this star without any saturation. This one seems much more symmetrical than normal HADS stars (steep rise and slower decline) Dave