KZ Hya / GW UMa - High-amplitude short-duration variables

Gents ... and J65,

Things are moving very slowly this time of the year as usual and due to the weather. On the odd night where the skies are clear, the seeing is horrific and which leaves one's hands tied.

The only means for me to be somewhat productive is to pursue some photometry and where I used the opportunity to go after a couple of well-known high-amplitude short-duration variables, namely KZ Hya and GW UMa. The former was particularly rewarding since Hyadra is very low along the sky for my location and the photometry was started with KZ Hya probably no more than six to seven degrees above the horizon.

(1) www.perseus.gr/Astro-Photometry-Hya-KZ-20110208.htm ... with a period of 85.70 minutes, one of the shortest duration variable stars

(2) www.perseus.gr/Astro-Photometry-UMa-GW-20110211.htm ... originally a Hipparcos satellite discovery

Anthony.

Anthony they are two really nice lightcurves. Paticularly the second given the low altitude - rule of thumb is not to go below 30 degrees due to atmospheric effects. Clearly, it can be successfully done - at least wih bright obects with reasonably large amplitudes. But even saying that, the dta is *still* very smooth.

As regards the first object - I'm interested in your com-check data. Were either of them variable in themselves? I see a small variation at the end of the data run there that might suggest either the comp or the check was variable. Easy enough to check - just plot both against a third (common) comp star.

Excellent work though and as you say, there is still lots to do even if the sky is clear but the seeing is awful.

Thanks for sharing.

Cheers
Dave - who has an observatory code

Hi Dave,

NO question that atmospheric extinction is a factor and which we all must be aware of. One means to mitigate it when it has the potential to be a (significant) factor is to match the magnitude and spectral type of the comparison and check stars to the variable so that the impact will be uniform.

With respect to the fluctuation you mention in relation to the comparison-check stars, this was strictly due to dew on the lens near the end of my session and which effectively increased my computed standard errors but had no visual impact on the light curve.

Anyway, it is really unfortunate that the skies are constantly cloudy with no hope of being productive.

Anthony.
(The one without an observatory code :blush: )

That's interesting about the dew.

And yes - we are the same here. Cloudy and I'm itching to get some MP curves finished off. And the MP's are fading fast Very frustrating.

I think I have had only four clear nights for work this year so far and which is MOST frustrating. To add insult to injury, the sky is richest right now and the nights are at their greatest length.

Let's beat up on Seanie to ease off some steam!

Anthony.

Hi Anthony,

Nice light curves. Did you submit your data to a variable star organisation (like AAVSO).

I was wondering if you used a filter,

John