[vsnet-newvar 1647] Re: [AAVSO-DIS] Re: V 4742 Sgr

[DWest61506@aol.com]

Stan, Brian:
I added another observation and summarized the observations to date.  Any guesses on the type of variable star?  Maybe a Mira or SRB??  I am assuming our differences in V magnitudes are due to different comparison stars and their assigned magnitudes.

Regards,
Doug West
http://hometown.aol.com/dwest61506/index.html



GSC 6846:6 = IRC -30347 = IRAS 18001-2514
Measured position (D. West): RA 18 03 14.47 DEC -25 14 22.1  J2000, 15 GSC 1.1 stars

UT DATE  TIME  Photometry           Observer 
2002 Sep 18  01:55  11.49            West
2002 Sep 23 08:00 11.807V  9.659Rc   Stan
2002 Sep 30 01:33 11.29V       West
2002 Oct 10 08:00 11.384V 9.340Rc    Stan
2002 Oct 14 08:00 11.377V 9.300Rc    Stan
2002 Oct 17 08:00 11.328V 9.287Rc    Stan
2002 Oct 17 01:15 9.21Rc             West
2002 Oct 17 01:15 2.01 H alpha West
2002 Oct 18 01:23    11.03V                   West
2002 Oct 19 08:00 11.349V 9.296Rc    Stan

Notes:
1. Tycho 2 B-V = 1.5 per Brian
2. Spectral class: M6 per Brian
3. West comparison stars: SAO 186183 and GSC 6846:1080. Observations have not been corrected for color differences.
4. Finder chart: http://hometown.aol.com/dwest61506/page25.html


In a message dated 10/20/2002 3:15:47 AM Central Standard Time, astroman@xtra.co.nz writes:

Hi All,

I've now sorted out some colour corrections for my system. So I can now offer some more reliable measures of V4742 Sgr and the red star in the same field.

Date                    V 4742 Sgr                        6846 6                       Star to East

2002 Sep 23       10.110    1.381                11.807    2.148            10.703    0.722
2002 Oct 10        11.184    1.435                11.384    2.044            10.729    0.747
2002 Oct 14        11.531    1.548                11.377    2.077            10.765    0.765
2002 Oct 17        11.580    1.457                11.328    2.041            10.723    0.740
2002 Oct 19        11.611    1.438                11.349    2.053            10.732    0.745

These are V and V-R. The star to the east is about 10-20" away and is the one mentioned by Brian Skiff. I would not rely too much on the colours as the extrapolation is large. This also affects the derived magnitudes in V. But there seems to be definite variabity in 6846 6 and the nova shows some interesting colour changes. All measures are based on at least three images and as many as six in V and R filters. All UT's are ~0800.

Regards,
Stan

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