Hello Visual Observers,
David Gray asked if I would write a list of suggested stars for this time of year. I picked all of these because there is a bright star (or 2) on the chart to make them easy to find, for you star hoppers like me. Some will go dimmer than the range of your scope for part of their cycle, so if you do not see it, report it on WebObs as "dimmer than", by checking the box. Put the dimmest comp star you observe in the box for your estimate, them check "dimmer than".
Use the VSP chart plotter to make charts. My suggestions are for newtonian reflectors, so South is at top of chart, and East is at right. If you have a refractor with diagonal or a schmidt/cas, use Reversed charts. Just remember that the bright stars I make comments on will be at different positons, since on Reversed charts North is at top and East is to right.
When I say use both "b" and "d" charts, that means when the star is in its brighter range, say down to about 11.0 mag, use the "b", below 11.0 use the "d" chart. I like to set my own dimmest mag on VSP. Normally "b" will go to 11.0 comp stars. I set it to 11.5. The "d" will take you to the 14.0 to 14.5 range.
1. RV Her range 9.0-15.5 Eta Her is the bright star on the "b" chart. Use both "b" and "d" charts.
2. R Oph 7.0-13.8 Eta Oph is 2.4 mag star on the "b" chart. Use both "b" and "d" charts.
3. RS Her 7.0-13.0 #73 Her is the 5.7 star on the "b". Use both "b" and "d".
4. T Dra 7.2-13.5 Xi Dra is the 3.8 star on "b". Use"b" and "d". Be very careful, there is another variable almost touching T. Identify is carefully. In fact, when dim, I would even print off an "e" chart so you identify the correct variable.
5. T Her 6.8-13.7 5.0 to upper left is #99 Her, 5.0 to lower right is #104 Her on "b" chart. Use "b" and "d" charts. I love this star and the next, because they are actually on chart same chart, but the next, TV Her is not identified, so print off seperate charts for TV.
6. TV Her 6.8-13.7 The "b" chart has #104 Her left of center. Use both "b" and "d" charts.
7. W Lyr, also one of my favorites. 7.3-13.0 Kapa Lyr is bright star at right on the "b" chart. Use the "b" and "d".
8. RT Dra 9.6-13.8 Chi Dra is 3.6 star at center. RT is right next to it. Use "d" chart.
9. RV Lyr 9.0-15.6 Beta Lyr is in upper right of the "b" chart. Use both "b" and "d" charts.
10. U Dra 9.1-14.6 Delta Dra is the 3.1 star on the "d" chart. Use the "d" chart.
11. U Lyr 8.3-13.5 Theta Lyr is the upper 4.4 star on the "b" chart, Eta Lyr is lower 4th mag star. Use "b" and "d" charts.
12. R Cyg 6.1-14.4 Theta Cyg is at center of "b" chart. R is right next to Theta. Use "b" and "d" charts. You are now entering the Milky Way, so be careful with identification on "d" chart, the field will be loaded with stars.
13. RT Cyg 6.0-13.1 Theta Cyg at lower left of "b" chart. Use "b" and "d". Same comment about Milky Way. On the old charts before VSP, R and RT were on the same "b" charts.
Have fun with these 13 stars. Let me know how you do. A little later this summer I will give you some really nice stars.
Chris Stephan
Robert Clyde Observatory
Sebring, Florida USA
A follow up comment on T Draconis from the list above. Mike Simonson wrote a nice piece about this star on the Long Period Variable Stars (LPVS) Forum. Please check it out. It's entitled "My Favorite Double Star". He's actually refering to T Dra, has a finder chart, and talks about the variable right next to T Dra and can really fool people.
Chris Stephan
Robert Clyde Observatory
Sebring, Florida USA
Sebastian,
Could you possible make up a similar list like I did of some southern hemisphere variables for telescopes that are easy to locate. This list would be for the sky for the next few months. Thanks.
Chris Stephan
Hi Chris,
Thanks for the list. I intend to use this as my next step in my learning curve of observing variable stars. Hopefully the weather co-operates and I can get some observing sessions in very soon.
I looked at the clear sky clock yesterday and predictions said cloudy skies. Before I went to sleep last night I thought I pop outside. I was suprised to find that the sky was clear, using the Little Dipper I noticed that I could just see make out the less bright stars (normally I see the usual three - polaris and the two at the end of the bowl) using adverted vision. Lesson learned here is always be prepared for observing even if the weather predictions say otherwise!
Dave
I was inmediately going to complain about your Northern bias, Chris!! ;)
Anyway, you put me in a hard position because I am a bright star guy and you are mostly talking about faint stuff, or at least faint enough that you need a small telescope.
I'll include some interesting miras in my list, those that have underwent period changes and are in the South.
1) R Cen. This one usually goes from 6th to 9th mag. and has two maxima and minima per cycle. Its period shrinked from 550 to 495-500 d. over the last century. It's easy to locate near alpha and beta Cen. It is currently fading from maximum (a couple of nights ago I estimated it at V= 6.3)
2) BH Cru. The opposite case, a mira that increased its period from 420 d. at the time of discovery (1973) to 530 d. or so right now. It goes from 6.7 to 9.6 so it is very similar to R Cen but redder, since this is a SC-type star. With a B-V of 3-4 you have to face the problems we are discussing in the Carbon stars thread to estimate it. Now it is at minimum.
4) DY Cru. Just to continue with the carbon stars and to see the huge contrats between 1st mag. beta Cru and 9th mag. DY Cru, a deep reddish star with a B-V of 6. Very easy to find because it is in the same field of Mimosa but with small amplitude variability. Just to test your skills.
5) R Hya. Another bright mira that showed a period decline. In the 18th century its period was close to 500 d. Now it is 380 d. it may reach naked eye visibility at maximum (4th mag.) and drops to 9 at minimum. With its period being close to 1 year we have missed several maxima in recent years.
6) V PsA. This one is also in the same field of a bright star, 1st mag. Fomalhaut (Alp PsA). It is a semiregular variable with periods of 105 and 148 d. varying from 8.2 to 9.3.
7) Another bright mira is R Aql. This one had a period of 348 d. in the 19th century and now it varies between 6th and 11th mag. every 270 d.
8) R Nor. Another mira with a double maximum and a long period. This one varies between 7th and 12th mag. with a period of 496 d.
9) RS Sco is a popular 319-d. mira with a range 6.0 - 13.0.
10) RR Lib lies midway between beta Sco and theta Lib. It usually ranges from 8 to 14 every 279 d.
That's my Top 10 LPV stars. In the CS tutorial we include 11 stars for the Southern Hemisphere instead of the 10 in the Northern version so now we get even ;)
Cheers,
Sebastian