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[vsnet-campaign 1363] Re: HD 23873

Sebastian wrote:
<
>>>Apparently HD 23873 has faded by ~0.16 magnitude.  SIMBAD lists HD 23873
  at V=6.606 with spectral class B9.5V.  The UBV catalog shows a range of 6.57
  to 6.62 for this star.  More observations will be required to confirm the
  fading of HD 23873.


  Dear Doug and colleagues,

  Last night I observed HD 23873 and it doesn't seem to be fainter....
  My visual observation is:

  HD023873     20030105.029     66      OSE

  The raw result was 6.63. There are good comparison stars. See my chart at:
  http://ar.geocities.com/varsao/Carta_BU_Tau.htm

  Maybe the proximity of  HD 23872 (V= 7.5) has its influence in some of the
  results??

  On the other hand, from GCPD and Hipparcos photometry, the magnitude of 18
  Tau (the "new"
  comparison star) is V= 5.66.

  Regards,
  Sebastian.>

To try to determine if HD 23873 has faded in brightness, I performed photoelectric photometry last night (01/13/2003 02:00 UT) using my SSP-3 photometer and a V filter.  The comparison stars used were SAO 76137 (18 Tau = HD 23324), V=5.651, B-V = -0.066 and SAO 76228 (HD 23850) V= 3.62, B-V = -.08.

Star         Measured V      SIMBAD V
BU Tau       5.02 +/- 0.02   5.048
HD 23873     6.62 +/- 0.02   6.606
HD 23872     7.52 +/- 0.02   7.54

The error of 0.02 takes into account signal-to-noise, comparison star magnitude errors, and the lack of color correction.  Color correction was not required due to the similarity in colors of the stars.

These observations indicate that HD 23873 is within two standard deviations of the catalog value.  Therefore, at least on 01/13/2003, it had not faded noticeably.  This doesn't resolve the question of the seemingly discrepant CCDV observations reported earlier.  I am going to go back and revisit these observations to determine if there is an instrumental effect causing an error or if the observations are valid.  I'll follow up to the list once this question is answered.

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

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