HD 145913

[Michael Koppelman <lolife@bitstream.net>]

OK, I looked at HD 145913 last night. Check out my data here:

http://www.lolife.com/astronomy/hd145913/

I have some multicolor data, too. What I did was do BVRI for an hour 
then high time resolution in R for an hour, and then another hour in 
BVRI. My S/N was very high. For the program star it was (according to 
Mira) 800 or so. It was not saturated. The integrations in Rc was 30 
seconds. The standard deviation in the comp stars was 0.005. The 
standard deviation of the program star was 0.008.

There is a slight period to this flicker (13 minutes and 4.5 minutes), 
but it could just be noise. I would for sure call it noise except that, 
according to Mira, the errors are very low. The standard deviation in 
the comp stars is 0.005. The amplitude of the program star is 0.04, 
which is damn small but still 8 times the 1-sigma error and almost 3 
times the 3-sigma error. So maybe it is flickering. I had an exchange 
with Joe Patterson of the CBA (on another matter) and he had stated 
"Virtually all CVs flicker erratically on timescales of 1-3 minutes, so 
if your time resolution is much worse than ~40 s, you become blind to 
this and it appears merely as unwanted noise (which can be quite large, 
even ~0.2 mag)." This is what caused me to look at such short periods. 
This star is A5, so it's not red. I'm not claiming it's a CV and it's 
probably just noise and can be crossed off the list for a short period 
0.2 mag eclipser that John thought it might be (see below). I don't 
know.

Cheers,
Michael Koppelman



> Info from Aladin:
> ICRS 2000.0 coordinates      16 13 18.7377 +06 02 15.537
> B magn, V magn               7.97, 7.76
> Spectral type                A5
>
>
>
>
>
> John Greaves, 2002 July 12
>
>
> Okay, if somebody like Michael K. fancies a change from EW stars, this
> one has a possibility of being a delta Scutid.
>
> HD 145913 is spectrum A5, mag around V 7.8.  Welch-Stetson Index is 18.
> Amplitude appears quite low, maybe 0.2 V at very most.
>
> Not much on lightcurve structure on a per night basis from Tom's data,
> but the one good night looks interesting, though of short duration, and
> structured enough to look like a true lightcurve shape rather than an
> artefact.  Period may be very short if pulsator, around 0.2 or so days.
>
> Hipparcos (HIP 79493) noted a small 0.05 Hp mag range (5th and 95th
> percentile), but it's in neither the NSVs or GCVS or a New Tycho
> Variable for that matter.


Begin forwarded message:

> From: Patrick Wils <patrickwils@yahoo.com>
> Date: Sat May 3, 2003  6:10:01 PM US/Central
> To: Michael Koppelman <lolife@bitstream.net>
> Subject: Re: new stars and such
>
> Hi Michael,
>
> --- Michael Koppelman <lolife@bitstream.net> wrote:
>> OK, data divers, I need a new star. Hopefully something where 14h <
>> RA > < 18h or so.
>
> HD 145913 (from the July data set, I think) might be a possibility as
> well, RA near 16h, see
> http://www.tass-survey.org/tass/data/july_2002/hd145913.html
>
> Patrick
>
>
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