Observatory Logo

From: TerryMoselaol.com
Date: Sat, 12 Jun 2004 19:20:37 EDT
Subject: Delta Scorpii Bright?

Hi all,

John McConnell reported last night that he thought Delta Scorpii was 
unusually bright. I quote:
   "Delta Scorpii tonight was estimated as not far off the brightness of 
Antares, unless it's my eyes playing tricks! According to Starry Night Pro 4.5, 
Delta is supposed to be mag 2.3 but it seems to be nearly equal brightness with 
Antares which is supposed to be mag 1.1 and that is still allowing for the 
difference in colour.
I know that Delta has been acting funny over the past couple of years, but 
this is the brightest I have seen it so far."

I had a look this evening, and it seems a bit brighter than usual (as it has 
been recently), but not comparable to Antares. I estimated at 22.50 UT this 
evening that Delta was about magnitude 1.8 to 2.0. I compared it with Spica, 
(mag 1), Antares (mag ~1: it's slightly variable, range 0.9 - 1.1), and Beta Sco 
(mag 2.6). It's very difficult for us to make reliable observations from our 
latitude, because of the effects of atmospheric extinction, which varies 
strongly with altitude.

Also allow for the difference in colour: Antares is reddish (spectrum = M1), 
while Delta is blue-white (spectrum = B0).

Observers in the far South of the Island have the best chance, as both Delta, 
and the comparison stars, are higher up. Other comparison stars are: Epsilon 
Sgr = 1m.8; Sigma Sgr = 2m.1 (both visible later in the night); Epsilon Sco = 
2m.3;  Eta Oph = 2m.5, Pi Sco = 2m.8.

What do you think?

Clear Skies,

Terry Moseley 

Last Revised: 2004 June 14th
WWW contact: webmaster@arm.ac.uk
Go to HOME Page Home Page