[AZ-Observing] Re: Delta Sco Fading

Thanks for your input Brian.

Yes! I noticed the JD comma instead of the decimal point after I sent 
it the message. Too late then. I was still a bit fuzzy from the 
night's observing.

Since I measure the UBV values I always state them. It's easy to do 
the math to get the color index. I was surprised at how bright it is 
in the U band. I plan to try again tonight (actually tomorrow 
morning). The stars are low to the south so not ideal for photometry, 
but at this latitude that' about as good as it gets for that system.

Check for Sebastian Otero's latest data at:

http://ar.geocities.com/varsao/delta_Sco.htm

On 1 April 2005 it was around V=2.1, but a few days ago (3 May 2005) 
it was V=2.05 and increasing in brightness so my observations may 
fall well within what might be expected. More observations will give 
more confidence. There may be a brightening trend right now at least 
that looks like a possibility from Sebastian's chart.

The B and thus (B-V) is interesting. The Yale Bright Star Catalog has 
(B-V)= -.012 and (U-B)= -0.91, so indeed a (B-V)= +0.12 is strange. I 
rechecked things and can find no error, but will check further. I 
used alpha Lib (B-V)= +0.11 where as the YBSC has it as +0.15 which 
makes things worse. The B readings were fairly consistent. Let's see 
what tonight brings. It would be nice if someone else was doing B and 
U band observations on it.

The system approaches the meridian around 00:30 (7:30 UT) which is an 
odd time, I must stay up late as getting some sleep and waking up is 
hard for me for a time like that. That means getting to bed around 2 
- 3 AM. I know, I'm just getting old.

Jeff

At 13:58 -0700 5/11/05, Brian Skiff wrote:
>>>   Delta Sco Results
>>>   JD 2,453,501,8201   2453501.8201, yes?
>>>   V= 2.028 SD= 0.006
>>>   B= 2.144 SD= 0.008
>>>   U= 1.262 SD= 0.018
>
>      Since I'm a photometrist, I tend to think in V mags and colors,
>rather than separate magnitudes, so:  B-V = +0.12 and U-B = -0.88.
>The usual colors of the star are B-V = -0.11 and U-B = -0.90, and
>V = 2.32.  So evidently the star is still brighter than normal,
>and the U-B color seems the same, but B-V is much redder.  Is that
>possible?
>
>\Brian

-- 
Jeff Hopkins
HPO SOFT
Hopkins Phoenix Observatory
http://www.hposoft.com/Astro/astro.html

*********************************************************
  Small minds speak about people * Average minds speak of events
************   Great minds speak of ideas!    ****************
*********************************************************
                     Hopkins Phoenix Observatory
                       7812 West Clayton Drive
                   Phoenix, Arizona 85033-2439 U.S.A.
                                www.hposoft.com
--
See message header for info on list archives or unsubscribing, and please 
send personal replies to the author, not the list.

Other related posts: