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[vsnet-campaign-be 128] Delta Scorpii
Delta Scorpii is very bright.
Yesterday I had the chance to observe it during several hours and I
estimated a 0.02 variation between 1.69 and 1.71.
I thought it was probably spurious but it turned out that when I search for
the period of the BCPE star lambda Scorpii I used for comparison, it was
incredible there:
The 1.69 took place when lambda is at its dimmest and the 1.71 when it is at
its brightest.
Since I used a mean value of 1.62 for lambda Scorpii, the actual value for
delta Scorpii is 1.70.
Lambda Sco's amplitude is variable, usually less than 0.05 magnitudes. Full
range is 1.59 - 1.65.
Ephemeris agreed with observations (JD 2452049.41 + 0.2136966 xE)
I was surprised by these results. But it only confirms that with a sequence
like this (0.1 or 0.2 mag. difference between comparisons; similar colors)
we can be very accurate.
Regarding the use of variable stars for comparisons: when the variations are
this small, visually there is no problem, since using any other star besides
lambda Scorpii would mean getting poor results, since essentially there is
no other bright star in the area.
About delta Scorpii: it is actually very bright. Standstills reported
recently may be due to lamda's activity so I have made corrections to my
recent observations.
This is the new table that shows exactly what nust be expected!!
JD / Past data / New data
2452028.781 / 1.77 / 1.77
2452034.678 / 1.76 / 1.76
2452039.639 / 1.76: / 1.76:
2452041.624 / 1.74 / 1.75
2452042.669 / 1.75 / 1.75
2452047.642 / 1.73: / 1.73:
2452048.581 / 1.73 / 1.72
2452049.679 1.70
Corrections will be sent to vsnet-obs.
Best regards,
Sebastian Otero
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