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Help the SPA make a discovery?

david scanlan

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david scanlan

david scanlan

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Dear All,

Can you help the SPA Variable Star Section and possibly make a discovery?

On our current programme of variable stars are Delta Ursa Majoris and Beta Leonis, two suspected variables that were on the programme when the section was first formed but subsequently removed by a later director.

One of our main aims over the next coming years is to attempt to establish whether Delta Ursa Majoris and Beta Leonis are in fact variable stars and we need your help!

If you can spare 5 or 10 minutes out of your observing schedules to note the magnitudes of both these stars that would help us a great deal

One of the major rules is please only submit one observation of each star per month, too many observations of these by the same observer can invalidate results so please only one observation per star per month.

I would like to point out that no other major astronomical organisation currently observes these stars so here’s a real chance to make a discovery in the name of the Society for Popular Astronomy.

Please help us and send your observations to variablestar@popastro.com

Feel free to post any questions you may have

Regards

Dave

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david scanlan

david scanlan

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Thats fantastic news Steve :-)

Check out our webpage at http://www.popastro.com/sections/vs.htm

Its currently being majorly updated due to a change in director but all the nessecary information will be uploaded by hopefully by the middle of next week

If your looking for a great book on variables can I suggest Observing Variable Stars by Gerry A Good....awesome read and all you will ever need to know :-)

Dave

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david scanlan

david scanlan

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Oh my word yes absolutley :-)

Even one observation could provide us with vital information

Please can anyone who submits an observation email it to me at variablestar@popastro.com

in the following format

Your Name

Date

Time

Star being observed

Magnitude of variabe

Your more than welcome to also list what comparison stars you used to obtain your estimate

Thanks to all so far....response has been great :-)

Regards

Dave

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WebSentinel

WebSentinel

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If your looking for a great book on variables can I suggest Observing Variable Stars by Gerry A Good....awesome read and all you will ever need to know :-)

Thanks the book reference Dave,

I was thinking of buying Gerry Good's book anyway but it's always reassuring to get a good review by someone with a lot of knowledge on the subject, like yourself (it was also referenced a few times in Karen Hollands' paper on 'Why Observe variable stars?' from the institute of Astronomy, Cambridge. So, you're in good company).

I've also visited the SPA VSS website and printed off the SPA VSS program list. I'm just waiting on a dew shield and some decent weather.

Questions:

1. Any idea as to which stars in the program list would be better suited to a telescope like the C11? (it's got a large focal length, 2800mm, but a small FOV).

Note: Also, it takes a little while to get things set up so, I'm not likely to be observing frequently (not with the fickle weather we get!) therefore, longer period stars may be a wiser choice. What do you think?

2. Would it be possible for you to verify (or provide a method for me to verify) my results as I'm a complete novice at VS observing?

Thanks for any help you can provide on this fascinating subject.

Steve

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david scanlan

david scanlan

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Hi Steve,

Thanks for your interest

The programme you have probably downloaded maybe the older version, the new one will be up and running soon but if you pm or email variablestar@popastro.com your email address I will send over the new list straight away plus the associated charts :-)

With your scope, in addition to doing to naked eye variables Delta UMa and Beta Leonis, I would highly suggest S, T and Z Ursa Majoris, BU Tauri in M45 this can be seen with the naked eye but best views through a scope :-) and All the main trapezium stars in M45 as most of these are variable as well and we desperatly need data on them

Hope this helps

Dave

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winfij

winfij

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One of the major rules is please only submit one observation of each star per month, too many observations of these by the same observer can invalidate results so please only one observation per star per month.

Hi Dave,

Out of interest, why do you say that more than one observation per month per observer would invalidate the results?

I'd have thought that getting a number of observations from a given observer would allow you to validate the quality of those observations?

If the single observation is bad, it will throw the results out as well, won't it?

Are you expecting these to be very long period variables - have you ruled out a minimum period to date?

Cheers,

John

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david scanlan

david scanlan

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Hi

Thanks for your reply

One observation per month is asked for as as these are suspected variables then too many observations from the same person can end up being biased, it happend previously back in the 50's and 60's and invalidated all the results

They could be LPV's or anything to be honest.....my current theory is that they could be GCAS type variables but this is only a thought at this stage

Hope this helps

Dave

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WebSentinel

WebSentinel

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The programme you have probably downloaded maybe the older version, the new one will be up and running soon but if you pm or email variables@popastro.com your email address I will send over the new list straight away plus the associated charts :-)

Dave, I sent an email to the above email address requesting the new program and charts last week (1st Feb), thanks.

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Macavity

Macavity

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Tell me something Dave (or "et al.") I recall "Argelanders Step Method" has been used to estimate magnitude of variables. To me, really just a name, but is this something useful / contemporary? Looked like something that might be quite fun to limber up with generally - OR is it all "photometric", these days. :D

See: http://en.wikipedia.org/wiki/Friedrich_Wilhelm_Argelander

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david scanlan

david scanlan

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There is a lot of photometric being conducted these days but I am still an avid and purely visible observer :-)

The Step method is described below but for ease of use in projects like this I prefer non variable aquainted peeps to use the easy to follow 'two comparison stars' method....it tends to save a lot of of confusion as when people star seeing A(-1)V(B+2) etc etc it tends to send people running :-)

The Step Method: When an observer has gained a bit more experience, then it is recommended that the step method be employed in the making of estimates.

In the step method, you choose one or more comparison star that differ by no more than half (0.5) a magnitude from the variable. Steps of one tenth (0.1) of a magnitude are then used to make estimates of the variables brightness. For example if Delta Cephei is estimated to be 1 step fainter than comparison star D (Alpha Lac) and 2 steps brighter than star E (Epsilon Cep), then this would be recorded as D-1,E+2. The magnitude of the variable is then worked out from each of the step estimates. So Alpha Lac (mag.3.77) - 1 gives us a figure of 3.87 and Epsilon Cep (mag.4.19) +2 gives us 3.99, the average of the two gives us 3.93, this is rounded to the nearest tenth (0.1) of a magnitude, thus the brightness of Delta Cep would be 3.9.

You will see its basically the same but if people simply state they used comp stars that were 3.2 and 3.4 and the variable was between these at 3.3 then I am very happy with that and consider it to be a good estimate :-)

Hope this helps

Dave

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Sam

Sam

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This looks like something that I might give a go. How do you measure the magnitude? is it by direct comparison with a close by star (who's mag is known and fixed) - it just seems a bit subjective or does it work quite well?

would like to try it right now - but it's cloudy.

Sam

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david scanlan

david scanlan

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Thats great...the more the better :hello1:

Thats exactly what you do but estimate the variables mag against at least two comparison stars, one should be brighter and one should be fainter but hopefully all three will be within the same range so as to make the estimate as accurate at possible

Dave

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