[Aavso-photometry] RE AN #348 Request to Observe HMXBs

[Michael Sallman]

Arne,

Thanks for the info. Out of curiousity, where/how was TASS off on the 
'd' comp? V, I or both?

Thanks again,
Mike SVI

arne wrote:
> Michael Sallman wrote:
> 
>>I notice that the comp star "d" for 1930+53 (AAVSO 1936+541) is much 
>>redder than the target star:
>>
>>	The Hipparcos and Tycho Catalogues (ESA 1997)
>>Star	RAJ2000		DEJ2000		Vmag	BTmag	VTmag	B-V
>>------	------------	------------	-----	------	------	------
>>Target	19 32 52.313	+53 52 45.40	10.60	10.375	10.568	-0.170
>>d	19 32 57.715	+53 53 38.57	10.24	11.987	10.398 	1.331
>>A	19 32 44.504	+53 49 39.42	9.68	9.707 	9.683 	0.019
>>
>>	TASS Mark IV Photometric Survey of Northern Sky (Droege+, 2006)
>>Star	RAJ2000		DEJ2000		TASS4ID	Vmag	Imag	V-I
>>______	___________	____________	_______	______	______	______
>>Target	19 32 52.34	+53 52 46.1 	2668236 10.440 	10.359	0.081
>>d	19 32 57.72	+53 53 39.0 	2668242 10.343 	9.032 	1.311
>>A	19 32 44.52	+53 49 39.4 	2668229 9.680 	9.608	0.072
>>
>>"A" is much closer in color to the target, though about a magnitude 
>>brighter.
>>Also the quoted magnitude for the target star (9.8) seems to be a little 
>>bright (unless it's a maximum, and not an average).
>>
> 
> All four fields *have* been observed at SRO, and BVRcIc photometry
> is available.  I expect Gordon and Richard to extract the magnitudes
> for their comp stars sometime soon.  I agree that "d" is too red
> for a good comparison star.
> 
> This will be a tough campaign, as there are 4 targets to follow
> (instead of just SS Cyg); the necessary precision will tax your
> ability to perform photometry (a good thing!); combining datasets
> that have not been transformed will require significant overlap;
> long time series will show trends due to extinction; etc.
> 
> The Sonoita data indicate DM+53_2262 is at V=10.4, similar to the
> magnitudes quoted above.  Note that, while TASS does a good job
> on comparison A, it misses the mark on comparison d.  Don't trust
> Tycho at these levels, and use TASS carefully.
> Arne
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