[vsnet 845] Comparison sequence for W Lacertae

[bas@lowell.edu (Brian Skiff)]

     The W Lacertae field is another one that Charles Scovil asked me to
observe about four years ago, but which I haven't got around to until now.
I worked from an (e)-scale chart (10"/mm) he supplied that was last revised in
April 1978 and whose sequence is based largely on visual estimates.
     I observed the six selected stars below on 13 and 16 October 1996 UT
using the Lowell 53cm photometric telescope with a 19-arcsec diaphragm and 
Stromgren b and y filters.  About a dozen standards were observed on each night
whose rms residuals were between 0.004 and 0.007 mag. in V and b-y.
     The AAVSO preliminary magnitudes have a consistent and significant
zero-point error, amounting to 0.3-0.5 mag. (AAVSO too bright).  The sequence
is unfortunately rather widely spaced in brightness because several of the
comp stars marked on the chart are pairs, and there were no suitable
replacements.  The stars "91" (BD+36 4767), "108" (GSC 3198-1622), and "106"
(GSC 3198-1470, actually V=11.1) are all readily visible double stars.  Using
the 19-arcsec aperture, I was able to measure the last star without
interference from the faint companion.  There is also the wide pair Ali 696,
indicated on the chart near the variable itself.  The few remaining single
stars will be entirely adequate for CCD use, but visual observers will find it
inconvenient.  (sorry guys!)
     In regard to W Lac itself, it is identifiable as IRAS 22053+3729 and also
GSC 3198-1060 at:  22 07 29.9  +37 44 07 (2000).  Keenan et al. (1975 ApJ
Suppl. 28,271) give a spectral type of M8-e, obtained on 12 July 1968,
apparently near maximum light.


Photometry of stars in the field of W Lacertae

Name               RA  (2000)  Dec        V     b-y   n  spec
BD+36 4769      22 08 53.3  +37 39 34   9.296  0.653  2   K2
                                         .000   .011
GSC 2732-0698   22 07 38.7  +37 29 38  10.199  0.383  2
                                         .013   .007
GSC 3198-1470   22 07 39.9  +37 54 55  11.126  0.540  2
                                         .004   .001
AG+37 2188      22 07 19.5  +37 43 25  12.327  0.341  2
                                         .021   .008
GSC 3198-1366   22 07 12.1  +37 42 39  13.00   0.46   1
                                         .03    .04
GSC 3198-1646   22 07 12.8  +37 43 41  13.79   0.75   2
                                         .07    .07



\Brian Skiff  (bas@lowell.edu)

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